INSY 3021 Final Exam
Role of Engineers:
1. Define the problem and goals of the project 2.Observe and understand the process 3.Gather and analyze data 4.Provide recommendations 5.Monitor and report results
If more than ___ of the components in a product are fasteners, the assembly logic should be questioned
1/3
Standard Performance is rated as
100
Idle%
100 - E
Total Allowance is usually around
14-18% DONT COUNT LUNCH
Therbligs
18 kinds of elemental motions used in the study of motion economy in the work place. Effective: Reach, Move, Grasp, Release Load, Use, Assemble, Disassemble, Pre-Position Ineffective: Hold, Rest, Position, Search, Select, Plan, Unavoidable Delay, Avoidable Delay, Inspect
1 step = _______ feet
2.5
The time to attach often consumes _______ of assembly time
20-50%
If the time study is less than ___ minutes, you can give one rating for the entire sequece
30
Grip span should be restricted to around ________ cm for maximum strength
5-8
Manual Assembly Line
A production line consisting of a sequence of workstations where assembly tasks are performed by human workers as the product moves along the line.
Workstation Design Criteria
In ergonomics, the variation within the target population is commonly accounted for by using the 5th and/or 95th percentiles of important design characteristics with the intention of accommodating at least 90% of the target population
Machine Element
An element performed automatically by any process and once started cannot be influenced by a worker except to terminate it prematurely
Occasional Element
An element which does not occur in every work cycle of an operation but which may occur at regular or irregular intervals
Repetitive Element
An element which occurs in every work cycle of an operation
Constant Element
An element whose cycle time remains approximately the same, cycle after cycle
Variable Element
An element whose time varies within a specified range of work. - Human Cycle Times - Drilling (different thickness of plates)
What do healthcare systems engineers do?
Analyze processes and find ways to make the process better: - Streamline processes - Improve efficiency - Remove NVA activities - Decrease waiting times for patients and staff - Improve patient safety We utilize a variety of frameworks: PDSA, DMAIC, Lean methodologies, etc.
Quantitative
Information that can be measured and written down with numbers
Standard Deviation
It is a common method for comparing variability between data sets. A SD close to 0 indicates that the data points tend to be very close to the mean
Pareto Chart
Items of interest are identified and measured on a common scale - Graphed on a bar chart in a descending order as a cumulative distribution
Turning
Machine process in which a single-point tool removes material from the surface of a rotating workpiece T = L/F(m) where T = cutting time (min), L = total length of cut, F(m) = feed (in/min) F(m) = (3.82*f*S(f))/d where f = feed (in/r) S(f) = speed (surface ft/min) d = diameter of work (in) (Examples in Lecture #12)
Rough Assembly (heavy parts) Work Surface Height
Lower the work surface up to 8 in to take advantage of the stronger trunk muscles
Machine Work Allocation
Machines Excel In: - Performing routine, repetitive, or very precise operations - Doing many things at one time - Ability to repeat operations very rapidly, continuously, and precisely the same way over a long period of time
Effective Utilization
Maintenance of a standard pace while performing essential elements of the job during all portions of the day except that which is required for reasonable rest and personal needs
Produce Value
Manufacture a product, service a customer
Avoidable Delays
Social visits, day dreaming, idleness, long breaks and early quits, unnecessary work interruptions. Not accounted for determining standard time
Standard Time
The amount of work that can be produced by a qualified employee when working at a normal pace and effectively utilizing their time where work is not restricted by process limitations
Standard Time
The amount of work that can be produced by a qualified employee when working at a normal pace and effectively utilizing their time where work is not restricted by process limitations.
Cycle Time
The average time between the start of production of one unit and the start of production of the next unit. Cycle time for a process is the time it takes for that process step to be completed.
Statistics
The body of methods for collection and analyzing data
Poka Yoke philosophy
The cause of defects lie in worker errors. It follows that mistakes will not turn into defects if worker errors are discovered and eliminated beforehand - Humans make mistakes - Equipment must be designed to prevent the errors operators may make - Mistakes must be caught where they are made (Gemba) - "obvious at a glance"
Normal (Standard) Pace
The effective rate of performance of a conscientious, self-paced, qualified employee when working neither fast nor slow and giving due consideration to the physical, mental, or visual requirements of the specific job.
Definition of Industrial Engineering
The engineering discipline concerned with integrating people, materials, information, and equipment into an efficient system
Controlled Move: M6 Examples
Two Stages > 12 in: - Open and subsequently close a cabinet door. - Shift a lever back and forth more than 12 in. in each direction. - Raise and lower the cover of a copying machine. 1-2 steps: - Push a heavy box across a long table 5 feet.
_______________ (TPS) included a strong focus on eliminating the seven types of muda (waste)
Toyota Production System
__________ is designed to increase the rate at which employees learn and build skills
Training
Physical Training
Training involving physical models, simulators or real equipment is best for complex tasks
____________ is also known as stenosing tenosynovitis
Trigger Finger
T or F: DFA/DFM is recognized as one of the most common and effective methodologies for reducing product cost
True
T or F: For DFA, we want to minimize tangling and meshing
True
T or F: ON/OFF control of tools should involve more than one finger
True
T or F: Once the performance rating has been recorded, it should not be changed
True
T or F: Standard time data for assembly of a 1/4" nut with a bolt, Loctite, a lock washer, and cleanup takes 50 seconds
True
T or F: The measurement of variability is at least as important as measurement of centrality
True
Approach for Handling Human Error
Try to change situations, not people
How many work days in a year?
Typically 250 to 242
Workstation
Work area that is set up to perform a processing step in the manufacturing process
Shigeo Shingo
a Japanese industrial engineer who helped establish the Toyota Production System
Jig
a device which holds and locates a workpiece and guides and controls one or more cutting tools - Reduces inspection needs
Fixture
a device which holds and locates a workpiece during an inspection or manufacturing operation - The fixture does not guide the tool
Assembly Line
a manufacturing process (often called a progressive assembly) in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in sequence until the final assembly is produced
Non-Value Added
a processing step that does not enhance the product. Transport, Movement, Inventory, WIP, Inspection, Rework
Poka Yoke
a quality management concept developed to prevent human errors from occurring in the production line
Population
a set or collection of all possible objects or individuals of interest
A proper workstation pivots motion about the _________
elbows
Micro-motion Studies
film an activity, replay and study it in slow motion to analyze the movements
Micro-motion studies
film an activity, replay and study it in slow motion to analyze the movements
Theory with fewest __________ is best
assumptions
Cyclegraphic Studies
attach a light to a certain body part and photograph it as the individual performs a task, which produced a "trail" that marks how the body part moved during the task
Methods Engineering
attempts to design optimal processes to produce value, with processes involving humans and machines
Poka Yoke translates to....
avoiding inadvertent errors
MOST calculations are _______ times faster than MTM-1 with ________ loss in accuracy
five; little
Gemba
"Go to the spot; Know the actual situation"
Design for Assembly
(DFA) involves making directions and methods for attaching and joining the parts of a product simpler
Overtime pay
For covered, nonexempt employees, the Fair Labor Standards Act requires overtime pay to be at least one and one-half times an employees regular rate of pay after 40 hours of work in a workweek
Rules for Flow Charts
- Always format your flow from left to right or top to bottom - Maintain consistent spacing between symbols - Use the correct symbol for each step (diamond shapes are for decisions, rectangles are used for processes, start/end shapes should be the same)
High Volume Production
- Assembly Line or Machine Work - Typically short cycle time - Bound geographically
Body Motion
- B - Vertical - B0: No body Motion - B3: Sit or stand no adjust (bench), bend and rise 50% (hands don't reach below the knees) - B6: Bend and Arise: any type of vertical motion that allows the hands to reach below the knees (hands don't have to actually reach below the knees) - B10: Sit or Stand with adjustments (chair) - B16: See table; through door includes all types of doors including 3-4 steps to move through the doorway
Four variants of MOST
- BasicMost: used in operations ranging from less than a minute to about ten minutes - MiniMOST: is commonly used for short (less than about a minute) processes - MaxiMOST: for longer (more than several minutes), non-repetitive operations - AdminMOST: for administrative or clerical tasks
Types of Maintenance Work
- Break Down - Planned Work - Preventive/Predictive
How to minimize part count
- Build in fasteners - Design parts with self-locating features - Design parts with self-fastening features
Where do you get standard data?
- Build it yourself (Historical, calculate) - Buy a database - Books, Handbooks, etc. (Table/Charts/Nomograms)
Value Stream Mapping Symbols
- C/T = cycle time - C/O = change over - S/T = set up time - D/T = down time - Yellow Triangle = WIP/Raw material and finished goods inventory
Gain Control
G0: - no gain control; holding G1: - light object - if its not G3 its G1 - if there is control to be gained, it is at least a G1 - object may be jumbled with other objects (obtain a washer from a bin full of washers) - object may be lying close against a flat surface (obtain a sheet of paper from a desk) - Can use two hands for one object Examples: - pick up a hammer from a work bench - obtain one washer from a parts bin full of washers - using both hands, pick up a book lying by itself - obtain one sheet of paper from the top of a desk - pick up pencils grouped together in a holder - grasp a lever, crank, knob, toggle switch, pushbutton, or foot pedal G1 Simo: - Each hand is picking up a light object at the same time G3: - look at chart - if you have any of the factors given (such as disengage), it is justification for going to G3
Typical Rates of Learning
- Large or fine assembly work: 70-80% - Welding: 80-90% - Machining: 90-95% - Typical rate of learning: 70% - No learning: 100% (fully automated processes)
Learning Curve v. Time
- Learning is time-dependent! - The time required to perform a task decreases as a worker gains experience. - As the total quantity of units doubles, the time per unit declines at some constant percentage. - 80% rate of learning: As production doubles, average time per unit declines by 20%.
Locate all Tools and Materials Within Reach
- Locate all tools and materials within normal working areas - Fix locations for all tools and materials to permit the best sequence - Arrange tools, controls and other components optimally to minimize motions
Maynard Operation Sequence Technique
- MOST - Developed in 1980 by Zjell Zandin - Establishing the standard is at least 5 times faster than MTM-1 with little sacrifice in accuracy (95%) - MOST is a work measurement technique that concentrates on the movement of objects - It is used to analyze work and to determine the normal time that it would take to perform a particular process/operation - Measurements are in TMU
Methods-Time Measurement
- MTM - Developed in 1946 - by H.B. Maynard, JL Schwab, and GJ Stegemerten - Westinghouse Brake and Signal Corporation - Basic motions were reach, grasp, move, position, release, etc. - Filmed Workers: frame-by-frame and analyzed movement and duration
Manufacturing Sequence and Tools
- Make or Buy? - Rearrange or combine operations - Manufacture near the net shape (minimize material removal) (casting/injection molding)
Three types of assembly lines
- Manual - Automated - Hybrid
Controlled Move: I (Align)
- Manual Actions following the Move Controlled or at the end of process time to achieve alignment of objects. - I1: Align a mark on a plank to a table saw blade. - I3: (2 points, <=4"): Align a straightedge to two marks located 3 in. apart. - I6: (2 points, > 4"): Align a straightedge to two marks located 8 in. apart. - I16: Precision: Align a drawing template with several points.
Ten Rules of DFA
- Minimize Part Count - Build in Fasteners - Use COTS (commercial off the shelf) parts - Use the same parts throughout the design - Use Modular Design - Make connections unique - give parts clear orientation - Make parts easy to manipulate - Avoid delicate parts and no-touch areas - Design for real-world tolerances
Most Important Rules of DFA
- Minimize part count - Build in fasteners - Use modular design - Give parts clear orientation - Design for Real-World Tolerances
DFA Guidelines
- Minimize part count by incorporating multiple functions into single parts - Modularize multiple parts into single subassemblies - Assemble in open space, not in confined spaces. Never bury important components - Make parts to identify how to orient them for insertion - Standardize to reduce part variety
How to make parts easy to manipulate
- Minimize the use of flexible components - parts made of rubber - gaskets - cables - Should be limited as handling and assembly is generally difficult - Modular Assembly (Wiring Harness)
Why DFAM?
- Most cost saving opportunities happen at the design stage - 70% of manufacturing costs of a product (cost of materials, processing, and assembly) are determined by design decisions
Application of MTM-1
- Motion >> Time - Alpha Rating (modifier) - Complicated - Specialized Training is essential to the practical application of these techniques - Times are at 100% which eliminates performance rating - Measurements in Time Measurement Units (TMU) - 1 TMU = 0.00001 hour - 1 sec = 27.8 TMU
Strength of MOST
- No Subjective "Performance Rating" - Quick Analysis - No process required (Good for new model)
Critical Path
- the minimum time needed to complete the project - The shortest time is the longest path - critical path is often hard to see on a Gantt Chart
Capacity
- the upper limit for throughput in a production process - In most cases, releasing work into the system at or above capacity causes the system to become very unstable
Snapback Time Studies
- watch is snapped back or reset to zero after each recording - Benefit: each element is measured independently and directly (OT) - Short elements can be difficult to time - Fractions of time are lost in each cycle during the time it takes to reset the watch
Problem 1: Give the time in TMU below, calculate the time in seconds (1 decimal place) for each of these MOST sequences: 1. A1B0G1 A3B0P3 A3 2. A6B0G3 (A2B0P1) A6 (4)
1. 1+0+1+3+0+3+3 = 11 * 10= 110 TMU >>> 0.036sec/TMU so 4.0 sec normal time 2. 6+0+3+4(2+0+1) +6= 27 x 10 = 270 TMU >>> 0.036sec/TMU so 9.7 sec normal time
Problem 2: Assuming your company uses an allowance of 18%, what would be the standard time (in seconds) for the process described below: 1. A1B3G3 A1B0P6 C10 A1B0P1 A0 2. A1B0G1 (M10X24I3) A3 (2)
1. 26*10= 260 TMU >>> so 9.36 sec normal time >>> 9.36 sec*(1+0.18)= 11.0 sec standard time 2. 79*10= 790 TMU >>> so 28.44 sec normal time >>> 28.44 sec*(1+0.18)= 33.6 sec standard time
Strength of Time & Motion Study
Gemba: "Go to the Spot"
Who developed the DFA concept?
Geoff Boothroyd, at the University of Massachusetts Amherst, 1977
What is the "old school" way of getting standard data?
Handbooks and Sliders: - Expensive - Information may be available on "pay" web-site Nomograms: - Also called a nomograph, alignment chart or abaque, is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a mathematical function
General: Gain Control: G3
Heavy or Bulky: - High Muscle Force - Hesitation or pause required for muscles to tense
Human Work Allocation
Humans Excel In: - Perceiving patterns and making generalizations about them - Ability to exercise judgement where events cannot be completely defined - Ability to profit from experience and alter course of action - Ability to perform fine manipulations, especially where misalignment appears unexpected
3D rule for deciding whether a robot should perform the process
If it is: - DULL: repetitive tasks - DIRTY: Jobs the average person does not want - DANGEROUS: Jobs which put humans in harmful or unsafe conditions
Minimum time to complete the entire project is the ______ path from the initial node to the final node
longest
Optimal
lowest cost, highest quality, most reliable
Process Layout
machines grouped by the type: e.g. all lathes together, all drill presses together - Advantage: area expert >> job shop
Product Layout
machines placed in the order used in the manufacturing process: - Advantages: reduce travel time >> few products
Value Added
processing step that enhances a product or service before offering the product to customers Value Added = value after step - value before step
Design for Manufacturing (DFM) and Design for Assembly (DFA) are the integration of _____________ and _______________ into one common activity
product design; process planning
What would happen if a company did not have skilled workers?
production rates would be slower, product quality would be poorer and overall productivity would be lower
Working Sampling is used to determine...
production standards, machine and personnel utilization, and job allowances
No correlation
r is between -0.5 and 0.5
Positive correlation
r is close to +1
Negative correlation
r is close to -1
What time should you choose for Work sampling?
random times
The IQR gives the....
range of the middle 50% of the observed values
In regards to action distance, an object is within reach if....
the operator's feet don't move
Manufacturing
the transformation of materials into items of greater value by means of one or more processing and/or assembly operations, . . . The key point is that manufacturing adds value to the material by changing its shape or properties, or by combining it with other materials that have been similarly altered.
What is the goal of functional decomposition?
to transform a complex task into a sequence of smaller tasks that are easier to understand, and then easier to find practical ways of achieving
Line graphs
use a line to highlight a trend
Chronocyclegraphic studies
using flashing lights which allow the speed of the motion, not just its path, to be recorded
Manufacturing is a ______ addition system
value
Manual loading/unloading times _________
vary
How do we know its good data?
Data always shows some variability. Central Limit Theorem
Ratio Data
Ordered units with intermediate values; distance between units is the same
ST for whole system
The sum of normal times * (1 + allowances)
Design for Manufacturing
(DFM) design activity that is based on minimizing the cost of production and/or time to market for a product, while maintaining an appropriate level of quality - A primary strategy in DFM involves minimizing the number of parts in a product
Single-Minute Exchange of Dies
(SMED) is a collection of techniques for dramatically reducing the time it takes to complete a changeover
Lead Time
(Sojourn Time) is the time it takes for one unit to make its way through your operation. Sum of all Cycle Times.
Example: It took a Korean shipyard 125,000 labor-hours to produce the first of several tugboats that you expect to purchase for your shipping company, Great Lakes, Inc. Boats 2 and 3 have been produced by the Koreans with a learning factor of 75%. At $40 per hour, what should you, as purchasing agent, expect to pay for the fourth unit?
(Use Learning Curve coefficient table) 2nd boat build time: 125,000 * 0.75 = 93,750 hr 4th boat build time: 125,000 * 0.562 = 70,250 hr 70,250 hr * $40/hr = $2,810,000 All Boat Labor: 125,000 hr * 2.946 = 370,000 370,000 hr * $40/hr = $14,800,000
Work in Process
(WIP) is the product between the start and end points of a product routing. It does not include Raw Material Inventory (RMI) or Finished Goods Inventory (FGI)
TMU Conversions
- 1 TMU = 0.00001 hour - 1 TMU = 0.0006 min - 1 TMU = 0.036 sec - 1 hour = 100,000 TMU - 1 min = 1667 TMU - 1 sec = 27.8 TMU
Therbligs
- 18 kinds of elemental motions used in the study of motion economy in the workplace - The smallest unit of activity in a task
Methods Engineering
- A branch of industrial engineering specializing in the analysis of methods and the improvement and standardization of methods, equipment, and working conditions - A subspecialty of industrial engineering and manufacturing engineering concerned with human integration in industrial production processes
Assembly Workstation
- A designated location along the work flow path at which one or more work elements are performed by one or more workers - Products are assembled as they move along the line - At each station a portion of the total work content is performed on each unit
Check Sheet
- A form (document) used to collect data in real time at the location where the data is generated (1 of the 7 quality tools) - When the information is quantitative, the check sheet is sometimes called a tally sheet
Precedence Diagram
- A graphical (network) representation of the sequence of work elements as defined by the precedence constraints - Precedence Constraints are sequencing requirements, the order in which the work elements can be accomplished is limited
General Move Parameters
- ABG ABP A - Action Distance (A): horizontal distance - Body Motion (B): vertical distance - Gain Control (G) - Placement (P)
Controlled Move
- ABG MXI A - Get Move Return Parameters: - Action Distance (A) - horizontal distance - Body Motion (B) - vertical distance - Gain Control (G) - Move Controlled (M) - Process Time (X) - machine time - Alignment (I)
Frederick Taylor's Success
- Concluded that optimal shoveling weight was 21 pounds - 12.5 tons/day to 47 tons/day - $.072 cents/ton to $.033 cents/ton - Worker wages increased by 60%
Gloves
- Decrease grip strength around 15-20%, but in maximum pulling or torquing type exertions increases around 20-30% have been recorded - Reduces tactile sensing and dexterity - Safety PPE for hot, cold or chemical exposure
Manufacturing
- Derived from Latin, "manu factus" meaning made by hand Design Engineering >> Methods/Process Engineering >> Production/Line Engineering
Tolerances and Specfications
- Design Engineers are not manufacturing engineers - Designers tend to incorporate tolerances that are more rigid than necessary - Why? to be extra sure that product will function in all situations. Unaware/unconcerned with cost. It is perceived to reduce risk, but it can add unnecessary cost
What do methods tools allow us to do?
- Develop an understanding of how a process works - Document and communicate a process - Study and plan improvements on a process
Types of Labor
- Direct (touch) - Indirect - Expense
How to Calculate Allowances
- Direct Observation: requires observers to study two, or three operations over a long time. Observers record the duration of and reason for each idle interval - Work Sampling Study: Requires taking large number of random observations, thus requiring only part-time, intermittent services of the observer
How to distinguish similar parts
- Distinguish different parts that are shaped similarly, or hard to distinguish, by non-geometric means, such as color coding - Not red and green - About 4.5% of the population is color blind
Tool Rules
- Do not use the hand as a hammer (usually parts fit issue) - Avoid pressure spots and pinch points to the palm - Use grips with round edges and pad surfaces - Avoid tools that transmit vibration to the hand (Reynard's Syndrome aka White Finger) - Do not operate tools frequently and forcefully by hand; a machine is better suited for such activities
Disadvantages of Work Sampling
- Doesn't provide the detailed data that direct study does - Cost may be high if sampling rates are frequent - Subjects need to be located close together to eliminate travel - Theory of why it works is confusing for some people
General Rules of Using MOST
- Each activity sequence is fixed; no letter may be added or omitted - Index values are fixed; no interpolation; round up if necessary
Index Values
- Each parameter is assigned an index value based on the motion needed to perform the activity - Index values are then used to generate the total time required to perform a task
Standard Data
- Elemental times obtained from time studies that have been stored for later use - Frederick Taylor proposed this idea first - Allows development of a job (or parts of a job) without the use of a stopwatch or PDTS
How to improve efficiency with MOST
- Eliminate Steps - Eliminate body motion such as "Bend and Arise" (decrease 61 TMU) - Minimize or Eliminate "Get" Phase (Reach distance 5 TMU per category) - Avoid Repositioning and lifting heavy objects (about 1 TMU per 1 kg reduction)
Process Improvement Using Therbligs
- Eliminate ineffective therbligs (if possible) - Avoid holding objects with hand (use work holder) - Combine therbligs: perform right-hand and left-hand motions simultaneously - Simplify overall method - Reduce time for a motion (shorten distance)
Efficient Workstation Design
- Eliminate wasted motion - Minimize reaching - Eliminate twisting, turning, and walking to get parts - Eliminate Part and Tool Search - Allow two hand work - Fixturing
Types of Maintenance
- Equipment Service: Welder, Millwright, Electrician, Instrument/Controls Tech >>>>> Multi-craft - Tool/Setup - Die/Tooling/Machinist
Advantages of Therbligs
- Excellent way to describe motion details - Powerful tool for improving the skill of observation in most people (develops motion awareness) (helps identify wasted motion) - To predict standard times for new or modified jobs
What does a Gantt Chart show?
- Expected start and completion times - Duration of events - Sequence - Actual completion times are shown by shading the bars - Resources usage and conflict
Frederick Taylor
- Father of Scientific Management - In 1881, as chief engineer for Midvale Steel, studied how tasks were done (concerned about soldiering) - Shoveling Study - Time Study
The Gilbreths
- Founders of Modern Motion Study - Studied body's motions when performing tasks to eliminate wasteful motion and to determine the most efficient sequence - The Quest for the One Best Way
Harrington Emerson
- Friend of Fredrick Taylor - Twelve Principles of Efficiency - The first successful application of scientific management to a large railroad system.
Three Sequence Models of MOST
- General Move: moved freely through space; about 50% of manual work occurs as general moves - Controlled Move: movement restricted; attached or in contact; accounts for about 33% of manual work - Tool Use: using common hand tools (including your hands); about 17% of work
Key Performance Indicators for Maintenance
- Hands on Wrench Time - Reliability (%) - Planned Work vs. Unplanned Work - Equipment Mean Time Between Failures - PM Attainment - Main OT/Budget - WO Completed on time
How to Evaluate Tools
- How will they will be used? - Weight/Torque (Big tool? Automation) - Noise
Missed Breakpoints
- If you, the observer, miss a breakpoint (change from one element to the next), immediately place an "M" in the W column under the missed element - If the operator misses or skips an element in the sequence, a dash "--" through that element's W column
Typical Problems of Maintenance Work
- Inadequate communication - Unavailability of parts, tools, equipment - Interference of production employees - Overstaffing of the maintenance job - Rework - Improper Planning - Not unusual to find that the workforce is productive only 30-50% of the time
The increase in indirect and expense labor is due to...
- Increased mechanization/automation of industry - Increased paperwork brought on by government - Office and maintenance work has not been "methodized" or "standardized" like direct labor
Unavoidable Delays
- Interruptions from supervisor, dispatcher, machine/material faults - Interference from servicing: Quality checks, tool change, model change, cleaning/servicing - Material Handling: Parts in/out, boxes/pallets
Training Methods
- take effort - take time - best method depends on individual learning style (individual motivation)
Advantages of PDTS
- No stop watch on the floor - No timing is required so it eliminates inaccuracies associated with stop watch time study - Eliminates the need for performance rating - Procedure is useful in methods design and planning (before the process actually operates or exists) - Calculations are relatively accurate and consistent
Two conditions for a controlled move
- Object or device is restrained by its attachment to another object, such as a push button, lever, door, or crank (Actuate: usually involves M and X) - Object or device is controlled during the move by the contact it makes with the surface of another object, such as pushing a box across a table
Machine Cluster
- One-machine/one-worker station, the machine is manually operated or semi-automated - Operator Control - Partial Machine Control (manual load/unload) - Machine Cluster is a collection of two or more similar machines that are serviced by one worker
Controlled Move: X
- Only meant for short process times (7 seconds). - Extended Index Value table for Process time is available (MOST book goes up to Index 330=124 seconds). - Instead just add the time in seconds at the end. - If Process Time is long, look for something else for the operator to do during processing time. - X examples: After pushing the copy button, a process time of 6 seconds occurs wile the copy is made (X16). After hitting the palm buttons, a punch press cycles in 1.5 seconds (X3).
Rule of Thumb for Avoid/Minimize Fasteners
- Only use fasteners if the product must be disassembled by the customer - Ideally we want to use snap fits, then fasteners, then adhesives
How do we analyze data?
- Organize the Data: range, rank, order distribution, frequency distribution - Analyze: mean, median, mode, standard deviation - Plot Data: scatter plots, histograms, bar chart, normal distribution - Report: Draw Conclusions
Tracking
- PO/Day (Computer Tracking) - Backlog/ Plan vs. Actual Delivery - Cases/Day - Clicks/hr.
Picking Categories for Studies
- Pick an indivisible step - Pick elements that are as small as possible but not less than 0.05 minutes - Elements that end with a sound are best - Less than 0.5 min - Better to have too many than too few
Gantt Chart
- Planning and sequencing technique - First project planning and control technique - Developed by Henry Gantt in 1910 - to manage complex defense projects (WWI) and systems
Continuous Time Studies
- Preferred - Watch is allowed to run for the entire study without stopping - The running time on the watch is recorded at the break point of each element (W) - Calculate to determine the actual observed times for each element - CALCULATE FROM LEFT TO RIGHT - Element OT = Watch time when element ended - watch time when previous element ended
What ways can we apply IE techniques to indirect/expense labor
- Process Flow chart - Travel chart - Queuing Theory - Benchmarking (Ratios/KPI's) - Work Sampling (time study/MOST) - Electronic Monitoring (handle with care/morale issues)
Two types of layouts for plants
- Product layout - Process layout
Work Design: Chair
- Provide a comfortable chair for the seated operator - Lumbar Support - Provide adjustability in the seating - Seating posture reduces both the stress on the feet and the overall energy expenditure - Comfort is an individual response - Strict principles for good seating are difficult to define
Rating Training and Maintenance
- Provide initial, refresher, and continuing training to all assigned analysts - Record all ratings in analysts file - Refresher Training
Operation Purpose
- Questioning Attitude - Never be afraid to ask "Why are we doing this?" - The most efficient process is one we are not doing
Benefits of Methods Tools
- Rapid data collection (walk through the area and observe the workplace) - Identifies problems within a particular area, department, or worksite - Provides an overall perspective of the situation
Sequence of Controlled Move
- Reach with one or two hands a distance to the object, either directly or in conjunction with body motions - Gain manual control of the object - Move the object over a controlled path - Allow time for a process to occur - Align the object following the controlled move or at the conclusion of the process time - Return to workplace
Human Factor Perspective for "Mistakes obvious at a glance"
- Reduce the work load on Working Memory (Decrease the amount of information stored/retrieved) - Brings information into the real world
Learning Strengths of the Tactile-Kinesthetic Learner
- Remembers what they DO, what they experience with their hands or bodies (movement and touch). - Enjoys using tools or lessons which involve active/practical participation. - Can remember how to do things after they've done them once (motor memory).
Learning Strengths of the Auditory Learner
- Remembers what they hear and say. - Enjoys classroom and small-group discussion. - Can remember oral instructions well. - Understands information best when they HEAR it
Learning Strengths of the Visual Learner
- Remembers what they read and write. - Enjoys visual projects and presentations. - Can remember diagrams, charts, maps well. - Understands info best when they SEE it.
How to Build a Histogram
- Select Process Measure (n, 50 - 100 points) - Determine the range (R = max - min) - Determine the number of bins (k) - Compute the width of the Bins (H) - H = R/k - Compute the frequency in each bin & plot
Key Words for control move
- Slide/Drag - Push/Pull - Roll on a conveyor - Crank (but not a tool) - Button/Lever
Why are assembly lines so productive?
- Specialization of labor (minimized skill labor) - Interchangeable parts - Work flow principle - Line Pacing
Procedure for conducting Time Study
- Standardize the method or working to achieve performance standard accuracy - Select the operator for study ( average performer) - Record the details
How to take the observation
- Take the observation from the same physical place each time - Approach work area without being observed (come from different angles) - Try to record only the minimum data that you will need to successfully reconstruct the observation - Instantaneous classification of activity - Verify any discrepancy with the supervisor or foreman - Don't interact with operator until after observation is noted - Don't schedule tour during lunch
Elton Mayo
- The Hawthorne Effect - The Hawthorne Works had commissioned a study to see if their workers would become more productive in higher or lower levels of light. - The workers' productivity seemed to improve when changes were made, and slumped when the study ended. - Engineers confused, Elton Mayo industrial psychologist consulted - Interpreted by Elton Mayo and others to mean that paying attention to overall worker needs improved productivity. - "Employees are not merely motivated by financial gain, and productivity is not simply a byproduct of incentives and optimized working spaces."
Minimize Transport
- The best way to handle material is NOT to handle it - Transportation is not value added - Moving, storing, positioning, tracking - Insuring that materials get where they need to be when they are needed - Bar codes - Material Handling Institute surveys says 35% to 85% of the cost of getting a product to market is associated with material handling - Muther's Systematic Layout Planning (SLP)
Part Design
- The greatest driver of the cost of making a product is the design of that product - Design for Manufacture and Assembly (DFMA) - Before we develop a method, always ask, "Make or Buy?" - What is the best design so it is easy to make? - Design Engineers are not manufacturing engineers
Disadvantages of PDTS
- The need for trained personnel (training and certification) - Although PDTS eliminates the need for performance rating, judgement is still required for various stages - Can be some variability between practicioners
Learning Curves
- They are based on the premise that people and organizations become better at their tasks as they are repeated. - It was first applied to industry in a report by T.P. Wright of Curtis-Wright Corp. in 1936. - Wright described how direct labor costs of making a particular air plane decreased with learning - Learning curves have since been applied not only to labor but also to a wide variety of other costs, including material and purchased components
Why do we need to measure work?
- To discover and eliminate lost or ineffective time - To establish standard times for performance measurement - To measure performance against realistic expectations - To set operation goals and objectives
Why collect data?
- To identify and/or verify a problem - To analyze a problem - To understand, describe, or monitor a process - To find a relationship between inputs and outputs of a process - To test a hypothesis
Seven Types of Muda
- Transport - Inventory - Motion - Waiting - Overproduction - Over Processing - Defects
Service Industry, Job Shop, Craft Workers
- Typically longer cycle times - Tasks vary - Cycle Time varies with task - Not Rigidly Controlled - Not bound geographically
Process Flow Chart
- Understand the sequence of operations (Line Flow) - To study the process in a systematic way: - To identify ways to improve layout (eliminate, reduce, rearrange) - To identify ways to reduce delays - To identify ways to reduce material handling - To compare alternative layouts - Show the big picture
Parts Bins
- Use gravity feed bins to deliver small parts and fasteners - Materials and tools should be located to permit the best sequence of motions
How to pick fasteners
- Use the same fastener throughout the product - It is easy to confuse which screw should go where - Minimize purchasing issues - Whenever possible, a single tool should be used for the whole assembly
Flow Diagram
- Uses a drawing of the physical layout of the plant - Arrows are used to show the flow of materials, information, people, etc. - In analyzing operations, it is usually extremely helpful to document the current facility - Aim for harmonious flow of work
Flow Process Chart
- Uses same symbols as Operation Process Chart, plus 3 more symbols (Non-value added) - Contains greater detail than the operation process chart - More complex (larger) drawings - Consequently, it is not usually applied to entire assemblies but rather for subassemblies and component
Value Stream Mapping
- VSM - A flowchart method used to illustrate, analyze and improve the steps required to deliver a product or service - Shows flow of material and information - Shows cycle time, change over/setup time, WIP, total processing time, and sojourn time
Why do healthcare systems need engineers?
- Value-based purchasing - Rewarded based on quality of care, how well we perform, and how much we improve
Learning Styles
- Visual (spatial): prefer using pictures, images, and spatial understanding - Aural (auditory-musical): prefer using sound and music - Verbal (linguistic): prefer using words, both in speech and writing - Physical (kinesthetic): prefer using your body, hands and sense of touch - Logical (mathematical): prefer using logic, reasoning and systems - Social (interpersonal): prefer to learn in groups or with other people - Solitary (intrapersonal): prefer to work alone and use self-study
Block Flow / Process Flow Diagram
- Visual representation of process - High level representation - Not to scale / Not geographically correct - Flow/Sequence is correct
Speed Rating Benchmarks
- Walking @ 3 mph - Dealing 52 cards in 0.5 minutes - Assemble 32 pins in a pin board in 0.433 min
What to look for in an Admin Flow Chart
- Waste and inefficiency - Dead Ends - Approval Loops
Advantages of Work Sampling
- Well suited for high cycle time and low repetition rate jobs - Does not require the analyst to continually observe the job - Operator not subjected to long periods of observations - Single analyst can study a crew - Conducted over a long period of time - Study can be postponed if something more urgent arises
Material Handling Direct Measurement
- Work Sampling - Travel Chart/Layout - Pareto Chart
Direct Measurement/ Improvement
- Work Sampling - Travel Chart/Office Layout - Process Flow (approval flow/procedure flow)
Major Factors of Fatigue
- Working Conditions - The nature of the work - Monotony, Boredom - Mental Strain, Precision Work
Swimlane Diagram
- a flow chart that illustrates who does what in a process - Categorize steps into a lane for each person, group or department - Lanes can be vertical or horizontal - Identifies responsibilities, bottlenecks, waste and other inefficiencies
Heat Map
- a tool for visualizing warehouse activity - Improve Efficiency - Reduce Congestion - Path Planning
Gang Process Chart
- an adaptation of the worker and machine chart - a worker and machine process chart helps determine the most economical number of machines one worker can operate - It shows the exact relationship between idle and operating cycles of the machine and the idle and operating times per cycle of the workers who service that machine
The Pareto Principle
- developed by Italian economist Vilfredo Pareto (1906) - Who observed that about 20% of the pea pods in his garden contained 80% of the peas - Applied to real estate - AKA Pareto analysis / the 80-20 rule / The Vital Few
Methods Engineering
- includes designing, creating, and selecting the best methods, processes, tools, equipment, and skills to manufacture a product - a subspecialty of industrial engineering and manufacturing engineering concerned with human integration in industrial production processes
Worker and Machine Process Chart
- it is used to study, analyze and improve one workstation at a time - Shows the exact time relationship between the working cycle of the person and the operating cycle of the machine - Uses standard times, not times straight from a stopwatch - Reveals idle time for both machines and workers
Crashing
- reducing the project completion time - is done by reducing the time of activities on the critical path
Operation Process Chart
- shows the chronological sequence of all operations, inspections, time allowances, and materials used in a process - The chart demonstrates the entrance of all components and subassemblies to the main assembly - helps analysts visualize the process, so that a new and better process may be devised - Focus is on manufacturing steps/Inspection steps - Non-Value added steps include WIP/Inventory, Inspection time, Movement - Process on one page
Therbligs Classification
1. Motions required for performing an operation - Transport empty - Grasp - Transport loaded (carry) - Position - Use - Assemble - Disassemble - Release load - Inspect 2. Motions that tend to slow down type 1 motion: (minimize) - Search - Find - Select - Plan (person thinking) - Pre-position (Set up) 3. Motions that do not perform an operation: (eliminate) - Hold - Unavoidable delay - Avoidable delay (standby) - Rest
Nine Approaches to Operation Analysis
1. Operation Purpose 2. Part Design 3. Tolerances and Specifications 4. Material 5. Operation Sequence 6. Setup and Tools 7. Material Handling 8. Operation Layout 9. Work Design
Three types of Time Studies
1. Work Sampling - Better for macro studies 2. Stopwatch + Performance Rating - "Gold Standard" according to Dr. Davis 3. Predetermined Time Systems - MOST - "Platinum Standard" according to Dr. Carpenter
_____________ new robots will be installed in factories around the world by 2020 according to a forecast by the International Federation of Robotics
1.7 million
Measure time in
1/100 minute
Controlled Move: M1 Examples
<= 12 in: - Engage the feed on a cutting machine with a short hand lever - Press a light clutch pedal with the foot - Open a hinged lid on a small tool box - Push a box 10 inches across a workbench Button/Switch/Knob: - Press a telephone button - Flip a wall light switch - Turn a door knob
Outliers
> 1.5 * IQR
Controlled Move: M3 Examples
> 12 in: - Push a carton across conveyor rollers. - Close a cabinet door by pulling it shut. - Open a file drawer full length. Resistance, Seat/Unseat: - Engage the emergency brake on an automobile. - Twist on a radiator cap securely. - Push a heavy box across a table. High Control: - Turn the dial on a combination lock to a specific number. - Slide a wood block on a machine table to position a mark on the block to a bandsaw blade prior to cutting. - Slide a fragile item carefully across a workbench. Two Stages <= 12 in: - Engage and subsequently disengage the feed on a cutting machine with a short hand lever. - Shift from the first to the third gear with a manual gearshift.
Time Standards are based on the concept of __________
A Fair Day's Work
Statistic
A characteristic of a sample (an estimate for the population)
Parameter
A characteristic of population
Fixturing
A custom nest or support (usually including locks and clamps) designed to hold a part or multiple parts during an assembly or manufacturing process
Fixturing
A custom rest or support (usually including locks and clamps) designed to hold a part or multiple parts during an assembly or manufacturing process
Histogram
A frequency distribution of a set of continuous data
String Diagram
A geographic model of the process on which the path of workers, materials, or equipment during a sequence of operations is traced
Bottleneck
A point of congestion in a production system (an assembly line) that occurs when parts arrive faster than they can be processed. High WIP in front of bottleneck. Low WIP after bottleneck
Predetermined Time Study
A procedure that analyzes manual operations or methods into the basic motions needed to perform it, and assigns each a pre-determined time based on the motion and environmental conditions
Non-Value Added
A processing step that does not enhance the product - Transport, Movement, Inventory, WIP, Inspection, Rework
Value Added
A processing step which transforms raw materials or work in progress into a more valuable good and service to customers downstream
Qualified Employee
A representative average of those employees who are fully trained and able to satisfactorily perform any and all phases of the work involved in accordance with the requirements of the job under construction
Work Sampling
A statistical sampling technique that discovers the proportions of total time that various activities contribute to the job by taking a relatively large number of observations at random times
Butt Welding
A welding technique used to connect parts which are nearly parallel and don't overlap
Allowances
A worker cannot work all day continuously. He will need break time. So extra time is added to the normal time.
Example: Reach to a work table (within reach) and finger tighten a bolt 3 turns. Write the MOST Equation
A0B0G0 A1B0P1 F6 A0B0P0 A0
Problem 8: Write the MOST equation for the task: "An engineer takes a pencil from his shirt pocket, and then writes a six-digit part number on an inspection form on his desk. He then clips the pencil back into his pocket."
A1 B0 G1 A1 B0 P1 R10 A1 B0 P3 A0
Problem 6: Write the MOST equation for the task: "Following a sanding operation, an operator standing at his work bench picks up a brush (located within reach) and brushes the dust from his six square foot work table. He then lays the brush aside on the work table."
A1 B0 G1 A1 B0 P1 S42 A1 B0 P1 A0
Problem 5: Write the MOST equation for the task and calculate the Standard time for the process (in seconds). The allowance for the job is 15%: "Grasp an adjustable wrench (within reach at the work station) and fasten a bolt with 5 wrist strokes and set the wrench aside on the workstation"
A1 B0 G1 A1 B0 P6 F16 A1 B0 P1 A0 270 TMU >>> 9.72 sec normal time >>> 9.72 sec*(1+0.15)= 11.2 sec standard time
Problem 7: Write the MOST equation for the task: "A worker slides a ruler (within reach) and pushes it 20 feet and aligns it with two points that are 3 inches apart. After placing the ruler, the worker returns to her original position."
A1 B0 G1 M16 X0 I3 A16
Problem 3: Write the MOST equation for the task and calculate the Normal time for the process (in seconds): "An operator reaches down to grasp a heavy box located on the floor. She walks eight steps and stoops to position the box on an elevated pallet (36 inches from the floor) and returns to her initial location."
A1 B6 G3 A16 B3 P6 A16 1+6+3+16+3+6+16= 51* 10= 510 TMU >>> 0.036 sec/TMU so 18.3 sec normal time
Example: Before marking off a measurement on a 2ft by 2ft sheet of metal for a cutoff operation, an operator takes a rag from his back pocket and wipes and oily film from the surface. Write the MOST equation
A1B0G1 A1B0P1 S32 A1B0P3 A0
Example: Grasp wrench and fasten bolt with 3 wrist strokes and aside the tool. Write the MOST Equation
A1B0G1 A1B0P3 F10 A1B0P1 A0
Example: An operator fastens a bolt with 3 wrist strokes using a wrench from a worktable at which she is standing. She then lays aside the wrench. The allowance for the process is 20%. Calculate standard time.
A1B0G1 A1B0P3 F10 A1B0P1 A0 180 TMU * 0.036 = 6.48 sec 6.48(1 + 0.2) = 7.8 sec
Example: A worker picks ups a micrometer located on a table and then walks two steps and checks the diameter of a shaft on a lathe using a 4" micrometer. After the check she returns the micrometer to the table. Write the MOST Equation
A1B0G1 A3B0P1 M42 A3B0P1 A0
Example: A worker picks ups a micrometer located on a table and then walks two steps and checks the diameter of a shaft on a lathe using a 4" micrometer. After the check she returns the micrometer to the table. Write the MOST Equation.
A1B0G1 A3B0P1 M42 A3B0P1 A0
Example: A worker slides a ruler within reach and pushes it 6 inches (15 cm) to measure two points that are 8 inches apart. Write MOST Equation
A1B0G1 M1X0I6 A0
Example: Reach to a bin full of washers, collect a handful, place 6 washers, loose fit, return excess washers to bin. Write the MOST Equation
A1B0G3 (A1B0P1) A1 (6)
Example: Grasp heavy box located within reach, walk eight steps, position on a table, and return to initial location. Find Normal Time in seconds
A1B0G3 A16B0P6 A16 420 TMU * 0.036sec/TMU = 15.1 sec
Example: Grasp heavy part located within reach, walk 22 ft, position the part on pallet (at knee height) and return to initial location. Find Normal Time in seconds
A1B0G3 A16B3P6 A16 450 TMU * 0.036sec/TMU = 16.187 seconds
Example: A worker seated at sewing machine, uses a foot pedal located under the machine to start the process. The operator holds the pedal 3.5 seconds. He releases the pedal & returns to his original position. Write the MOST Equation
A1B0G3 M3X10I0 A1
Problem 4: Write the MOST equation for the task and calculate the Normal time for the process (in seconds): "A worker walks five feet and collects three washers out of a box located on a waist high table and then return to the original location."
A3 B0 G3 A0 B0 P0 A3 3+0+3+0+0+0+3= 9* 10= 90 TMU >>> 0.036 sec/TMU so 3.2 sec normal time
Example: Grasp marker located three steps away on the floor, move three steps to table, and put in holder. Write the MOST Equation
A6B6G1 A6B0P1 A0
Carpal Tunnel Syndrome
AKA median nerve compression, is a condition that causes numbness, tingling, or weakness in your hand. It happens because of pressure on your median nerve, which runs the length of your arm, goes through a passage in your wrist called the carpal tunnel, and ends in your hand
Advantages and Disadvantages of Standard Data
Advantages: - Cost & Time - Consistency - Available ahead of production Disadvantages: - Availability - Applicability - Database Cost
Secondary Data
Already available for engineers to use
Constant Element
An element for which the basic time remains constant whenever it is performed
Variable Element
An element for which the basic time varies in relation to some characteristics of the product, equipment, or process
Foreign Element
An element observed which does not form a part of the operation being studied
Governing Element
An element occupying a longer time within a work cycle than that of any other element which is being performed
Speed Rating
Based on the speed or tempo of the output of the operator compared to that of qualified worker
Processing
Being worked by a resource
Processing
Being worked by a resource. - Value Added
How does work tracking effect morale?
Big brother is watching you
Humans and machines
By selecting the sequences, tools, equipment, systems, facilities
Humans and Machines
By selecting the sequences, tools, equipment, systems, facilities...
Ordinal Data
Categorical variable. The difference between the two is that there is a clear ordering of the variables (qualitative)
Independent Variables
Caused or determined by a dependent variable response
Samples of Convenience
Characterized by the selection of easy to obtain members from the population. May or may not be random.
Primary Data
Collected first hand by the engineer
Descriptive Statistics
Consist of methods for organizing and summarizing information (Average, Frequency)
We are Engineers, so our data must be...
Consistent, reproducible, and explainable
DFMA
Design for Manufacturing and Assembly refers to DFA and DFM
Work Measurement
Determination of the amount of time required to perform a unit of work. Used to uncover inefficiencies and non-value adding activities and waste that exist in a workplace
Measures of Centrality are important, but measures of __________ are equally important
Dispersion
How to figure out what classification the move is
Do you use a tool? If yes, its a tool use equation. If no, does it move freely? If yes, it is a general move equation. If no, it is a controlled move equation.
Line Efficiency
E = (sum(SM)/sum(AM)) * 100 E = efficiency SM = Standard minutes per operation (sum of cycle times) AM = allowed standard minutes per operation (slowest cycle time * number of stations)
What drives your job as a process engineer?
Economic: - New Products/New Models - Capacity Changes Efficiency Improvements: - "Debottlenecking" - Large amount of scrap or rework - Manpower Reductions - New processing technologies/Manufacturing Techniques Quality Control Problems: - Market Claims - Spec Conformity/Product performance problems - Process Improvements Safety: - Technology Upgrades - Human >> MSDs, high accident rates, excessive fatiguing, dust, etc
Determine work surface height by ________ height
Elbow; - Neutral Position
Basic Fatigue
Energy expended to carry out the work and to alleviate monotony (4% for normal conditions)
Safe Workstation Design
Ergonomic: - Ergonomics (from the Greek word "ergon" meaning work and "nomoi" meaning natural laws) - Ergonomics is the science that seeks to adapt work and/or working conditions to suit the worker - "Make the tool fit the worker"
The Westinghouse System
Evaluates performance with respect to: - Skill - Effort - Conditions - Consistency
Random Sample
Every member of the population is equally likely to be a member of the sample. The gold standard of sampling
T or F: Fatigue is homogenous
False
T or F: Methods tools tend to be exactly the same for each company
False, they tend to be slightly different (Style and Preference)
Frederick Taylor
Father of scientific Management. - He proposed that the work of each employee be planned out by management in advance - Replaced rule-of-thumb work methods with methods based on a scientific study of the tasks. - Established proper work methods and provided tools - Standard time determined for each job - Matching employees to right job - Providing the proper training - Establishing incentives for work - His theories were not widely accepted (conflict with management)
What do IE's do?
Figure out how to do things better. They engineer processes and systems that improve quality and productivity. They work to eliminate waste of time, money, materials, energy and other commodities
Neutral Posture of Elbow
L-shape
Tabular Data for Machining
Lathes, Drills, Milling Machines: - Chip producing equipment Critical Factors: - Material being cut (hardness) - Type of tool - Size of chip - Feed Rate
How does Production move?
Like a freaking river
Range
Max - Min
Hybrid Assembly Line
Mixture of manual vs automated assembly process. - 15-85% automation
Hybrid Assembly Line
Mixture of manual vs. automated assembly process
Qualitative
More detail on behavior, attitudes and feelings; Subjective
Toyota Production System included a strong focus on eliminating the seven types of ______
Muda (waste)
Scientific Management
Need to take into account the socio-psychological aspects of human behavior in organizations.
NT
Normal Time = OT * Rating
Active Elements for a Work Sampling study should be
Observable, Mutually Exclusive, Collectively Exhaustive, reasonable in Number (less than 100)
OT
Observed Time. How long it takes.
Expense Labor
Office clerical, accounting, sales, management, engineering
Random Servicing (Asynchronous)
Operation or downtime occurrences are unpredictable: e.g. machine breakages, field service calls, etc. - Complex worker and machine processes must often be computed through the development of a mathematical model.
Synchronous Servicing
Operations (usually done by machine) take a predictable amount of time, so the operator(s) "servicing" actions can be synchronized with the machines' cycle times. - Maybe possible to optimize machine and operator time
Remission
Operator forgets something learned when away from the job
Place
P0: - Hold, Toss P1: - Lay aside Examples: - lay a hand tool aside after using - place a pencil on a desk - lay a manual on a table - place a washer on a bolt - place a coat hanger on a rack P3: Examples: - place a key in a lock - place a bolt into a threaded nut - place a looped wire around a terminal - place a moist stamp on an envelope - press a thumb tack into a cork board - insert an electric plug into a socket P6: Examples: - Thread a needle - place a soldiering iron to a crowded circuit connection - place a book in a very tight slot on a bookshelf (Note, don't use weight of object to determine) - place a nut on a hidden bolt - place a chair in a neat row - Palletization
Tool Use
Parameters: - Fasten (F) - Loosen (L) - Cut (C) - Surface Treat (S) - Measure (M) - Record (R) - Think (T) ABG ABP * ABP A - ABG = Get Tool - ABP = Put Tool - * = Tool Action - ABP = Aside Tool - A = Return
_______________ is probably the most important step in the entire work measurement procedure. It is also the step most subject to criticism, as it is based entirely on the experience, training and judgement of the work measurement analyst
Performance Rating
Pictorial Instructions
Pictures or photographs used with written instructions have proven to be very effective in training operations
_______________ can result in major costs through increased travel time, increased material handling, etc.
Poor Layout
Scatter graphs
Present large amounts of data and show general trends. Show the relationship between two variables. They are often used as follow-ups to cause-and-effect analysis to determine whether a stated cause truly does impact the quality characteristic
Value Added
Processing step that enhances a product or service before offering the product to customers. - Value Added = Value after - Value before
How does Production flow?
Production flows like a river. Soichiro Honda said "Aim for a harmonious flow of work"
On-the-Job Learning
Putting the operator directly on a new job without any training is a sink-or-swim approach
Lower Fence
Q1 - 1.5*IQR
Upper Fence
Q3 + 1.5*IQR
IQR
Q3 - Q1
Fine Assembly Work Surface Height
Raise the work surface up to 8 in to bring the details closer to the optimal line of sight
Determining Standard Rating
Rating is the measure of efficiency of a worker. The operator's rating is found out by comparing their speed of work with standard performance. The rating of an operator is estimated by the work study engineer and the workers supervisor.
Automated Assembly Line
Robotic
Automated Assembly Line
Robotic spot welding lines in automotive final assembly - 100% difficult for now
Variance
SD^2
Two goals of Workstation Design
Safe and Efficient
Systematic Sampling
Sample is chosen on the basis of an ordered system. May or may not be random.
Normal Conditions
Seated, good working conditions, no special sensory or motor demands
Phases
Sequence models are structured into phases used to describe the action performed
Interval Data
Similar to ordinal data, except that the intervals between the values are equally spaced
Methods Tools
Simple tools that are visual or provide a "one page" representation of the "key" parts of the process
Written Instructions
Simple written descriptions of the correct method are an improvement over on-the-job learning, but only for relatively simple operations
Carriage Bolt
Square section part of the bolt is for gripping purposes, so it will not move or turn when you spin the nut
ST
Standard Time = NT*(1 + allowances)
Benchmark
Standard, or a set of standards, used as a point of reference for evaluating performance or level of quality
Anti-Fatigue Mats
Standing for long periods of time on hard floor surfaces is very physical fatiguing. Leg muscles become static and constricted as they work overtime to keep that person in an upright position. Blood flow is greatly reduced causing pain and discomfort.However, if a person is allowed to stand on an anti-fatigue mat, his muscles will subtly contract and expand as they adjust to the flexibility of the mat. This muscle movement increases blood-flow and increases the amount of oxygen reaching the heart.
The Gilbreths
Studied body's motions when performing tasks to eliminate wasteful motion & to determine the most efficient sequence: - The Quest for the One Best Way - Continuous Improvement - The traditional brick laying method, involved unnecessary stooping, walking and reaching . . . About 125 times per hour for brick and 125 times for mortar. - Application of the Gilbreth system of motion analysis reduced the motions per brick from 18 to 5 and increased the number of bricks laid per hour from 125 to 350.
Voluntary Response Sampling
Subjects from the population determine whether they will be members of the sample or not. Usually not random.
Normal distribution
Symmetric around the mean. 68% of the values lie within mean +- s. 95% of the values lie within mean +- 2s. 99.7% of values lie within mean +- 3s.
When balancing a line, we want to
Synchronize the rate of production with the rate of demand
Example: How long would it take to turn 18 in of a 1 in bar stock on a lathe running at 300ft/min and feeding at the rate of 0.005 in/r?
T = L/F = 18/5.73 = 3.1 min F = 3.82fS/d = 3.82(0.005)(300)/1 = 5.73 in/min
Median
The middle value or point that divides the distribution of values in half
Mean
The most commonly used measurement. Arithmetic average of data set.
Mode
The most frequent value in a distribution
Annual Capacity
The planned activity levels or output for a given year taking into account efficiency, scrap, and idle capacity. Annual Capacity = Nameplate Capacity * work days Ex: 1000 units/day * 300 days/year = 300,000 units/year
Fillet Welding
The process of joining two pieces of metal together whether they be perpendicular or at an angle. These welds are commonly referred to as Tee joints.
Functional Decomposition
The process of resolving a functional relationship into its constituent parts
Work in Process (WIP)
The product between the start and end points of a product routing. Does not include Raw Materials or Finished Goods
Takt Time
The rate at which a finished product needs to be completed in order to meet customer demand
Takt Time
The rate at which a finished product needs to be completed in order to meet customer demand. Takt Time = Available Time/Customer Demand
Inventory
The raw materials, work in process, products and finished goods
r
The sample correlation coefficient, a measure of the strength of the linear relation between the x and y variable
Motion & Time Study
The systematic observation, analysis, and measurement of the separate steps in the performance of a specific job for the purpose of establishing a standard time for each performance, improving procedures, and increasing productivity
Motion and Time Study
The systematic observation, analysis, and measurement of the separate steps in the performance of a specific job for the purpose of establishing a standard time for each performance, improving procedures, and increasing productivity
Capacity
The upper limit for throughput in a production process
Rating greater than 100 means
The worker's performance is greater than standard (110% = 10% faster)
Rating less than 100 means
The worker's performance is less than standard (90% = 10% slower)
Personal Needs
Those interruptions necessary to the general well-being of the employee (5%)
Where do time standards come from?
Time study is the gold standard for setting time standards. Pre-Determined Standards/Systems is the Platinum Standard for setting time standards
What is the goal of DFA and DFM?
To make a product easy to build and economical to manufacture
Finding Q1 and Q3
Use the median to divide the ordered data set into two halves. If there are an odd number of data points in the original data set, do not include the median in either half. If there are an even number of data points, split this data set exactly in half. The lower quartile is the median of the lower half of the data. The upper quartile value is the median of the upper half of the data.
Nominal Data
Values represent discrete units. Changing the order does not change their value (Qualitative)
Dependent Variable
Variable assumed to depend on or be caused by an influence
Flowchart
Visually displays the sequence of activities in a process and who is responsible for those activities
Stratified Sampling
When a population is split into non-overlapping sub-populations; Random samples are drawn from the sub-populations
Handling Foreign Elements
When they occur during an element, they are recorded in the Foreign Element List, given a label, and then noted in the NT block of the appropriate regular element
Rating should be recorded without the _____________ being known
actual time
Manual Element
an element performed by the worker
Training
an intentional effort to improve performance by helping employees acquire the skills and knowledge required for their work
What is a poka-yoke device?
any mechanism that either prevents a mistake from being made or makes the mistake obvious at a glance
Sample
any subset or sub-collection of a population
System Functional Decomposition
breaking down a system into its component parts: System >> Subsystem >> Assembly >> Subassembly >> Component >> Part
Correlation does not equal
causation
Inferential Statistics
consist of methods for drawing and measuring the reliability of conclusions about population (Confidence Interval, Hypothesis Testing)
Machine cycle times are usually _________
constant
Design for Manufacturing is concerned with reducing overall part production ____
cost
Throughout most of history, ____________ , a single worker, made products
craftsman
A company's ___________ is one of its main resources
labor force
MOST is a good method to ___________ movement to look for inefficiency
decompose
Real, actual data considers....
delays, environmental conditions, fatigue, correct methodology, work pace, and the elemental breakdown of the task
Most methods and standards work has been for ______ labor
direct
The factory system began to __________
divide the craftsmen's trades into specialized tasks
Since 1900, the percent of indirect and expense workers has more than __________ that of direct labor workers
doubled
Activities not on the critical path have ______
float or slack
What is Baka Yoke?
fool proofing or idiot proofing (rejected by Shigeo)
Muda
futility, uselessness, wastefulness
The higher the tolerance, the ________ the allowable variation from the desired measurement
greater
Proper workstation design allows for use of preferred _________
hand; - 90% right handed - 10% left handed
When giving parts clear orientation, do not....
hinder access
Improving tolerances and specifications can reduce cost due to....
inspections, scrap, and rework
Produce Value
manufacture a product or service a customer
Tolerances are generally inversely proportional to __________
manufacturing cost
Assembly Line
manufacturing process (often called a progressive assembly) in which parts (interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in sequence until the final assembly is produced
DFM and DFA seek to reduce...
material, overhead, and labor cost
Generally, tolerance is given in the form of....
measurement +- tolerance
The 5 number Summary
min, Q1, median, Q3, max
Videotapes and DVDs
movies can show the dynamics of the process
The number of machines an operator can be assigned (Walking) (Synchronous Servicing)
n <= (l + m)/(l + w) where: n = number of machines operator handles l = total operator loading and unloading time m = total machine running time w = worker time between machines ROUND DOWN!
How to calculate sample size for work sampling?
n = ((z^2)(p)(1 - p))/e^2 Z =z value (1.96 for 95% CI) p = percentage expressed as decimal e = Acceptable error percentage as a decimal (.04 = +- 4%)
The number of machines an operator can be assigned (No walking) (Synchronous Servicing)
n = (l + m)/l where: n = number of machines operator handles l = total operator loading and unloading time m = total machine running time ROUND DOWN!
Choose hand tools to keep the wrist _________
neutral (straight)
MOST is used to analyze work and determine the _________ time.
normal
Methods Engineering attempts to design _________ processes to produce ________, with processes involving ________ and machines.
optimal; value; humans
When giving parts clear orientation, we want to maximize ________
part symmetry; - the more complex the part the larger the time penalty for reorientation - the more precise the alignment the heavier the time penalty - symmetry eliminates reorientation - symmetry of a part makes assembly easier - minimize handling - self aligning parts
An assembly line process with zero idle time would be called a _____
perfectly balanced line
Each of the predefined sequence models has a different set of ______
phases; Ex: General Move >> Get, put, return
Use ______ grip for precision
pinch
Regarding workstation design, the designer should encourage _______ flexibility
postural
Use ________ grip to exert force
power
For the Service Industry, process flow charts are______
procedural steps
Indirect Labor
shipping and receiving, trucking, stores, inspection, material handling, tool-room, janitorial, maintenance
Use of modules in product design
simplifies manufacturing activities such as inspection, testing, assembly, purchasing, redesign, maintenance, service
Some engineers use ___________ for long cycle time and __________ for short cycle times
snap back; continuous
Methods engineers use a ______ procedure to make things more efficient
systematic
Adjust the work surface height based on the ___________ being performed
task;
Float
the amount of time that a noncritical activity can be lengthened w/o delaying the projects' completion date
Cycle Time
the average time between the start of production of one unit and the start of production of the next unit of production
Definition of Work
the displacement (movement) of a mass or object - Work = Force x Distance
MOST is a system to measure ______: therefore, MOST concentrates on the movement of ________
work; objects
Learning Curve Equation
y = kx^n y = cycle time x = number of cycles or of units produced n = exponent representing the slope k = value of first cycle time
Can we apply work standards to maintenance?
yes