Chapter 37: Automation of Manufacturing Processes
Powerhead production units consists of:
- a frame - electric driving motors - gearboxes - tool spindles
List three types of coding systems:
- bar coding - magnetic strips - radio frequency tags
List the four types of industrial robot wrists:
- cartesian (rectilinear) - cylindrical - spherical (polar) - articulated (revolute, jointed, or anthropomorphic)
List and describe the four functional elements in NC:
- data input: numerical information is read and stored in the tape reader or in computer memory - data processing: programs are read into the machine control unit (MCU) for processing - data output: information is translated into commands to the servomotor (servomotor moves the table by means of linear or rotary movements - position control on a NC machine
A point-to-point system is used mainly in (3):
- drilling - punching - straight milling
Applications for robots are described by the three D's and three H's, which are:
- dull, dirty, and dangerous - hot, heavy, and hazardous
List the two types of robots:
- fixed-sequence - variable-sequence
Describe the nine advantages of numerical control:
- greater flexibility of operation - ability to produce complex shapes with good dimensional accuracy and repeatability - high production rates, productivity, and product quality - lower scrap loss - machine adjustments are easy to make - less lead time required for setup and machining - program can be recalled at anytime - fast prototype production is possible - required operator skill is less than that for qualified machinist
Conventional end effectors are equipped with:
- grippers, hooks, scoops, electromagnets for material handling - spray gun for painting - attachments for spot and arc welding and arc cutting - power tools - measuring instruments
Describe the three major limitations of numerical-control:
- high initial cost of the equipment - the need and cost for programming - special maintenance
Describe the three basic functions of an adaptive control system:
- identify unknown parameters or measure performance - decide on a control strategy - modify the process parameters through input to the controller
Implementation of automation has resulted in (4):
- improved product quality by the use of repeatable processes - improved productivity by reducing manufacturing costs through better control of production - reduced human involvement, boredom, and possibilities of human errors - economized floor space in the manufacturing plant by arranging machines, material movement, and related equipment more efficiently
Name the two methods of position measurement in NC machines:
- indirect methods - direct methods
A contouring system is used in (4):
- lathes - milling machines - grinders - machining centers
Factors that influence robot selection (9):
- load-carrying capacity - work envelope - speed of movement - reliability - repeatability - arm configuration - degree of freedom - control system - program memory
List the four robot components:
- manipulator - end effector - control system (controller) - power supply
Applications of robots are (6):
- material handling, loading, unloading, and transferring workpieces - spot welding - machining operations - applying adhesives and sealants - spraying painting and cleaning operations - automation assembly, inspection, and gaging
Sensors that are of greatest interest in manufacturing operations are generally classified as (6):
- mechanical - electrical - magnetic - thermal - others
Two loop systems for NC machine are:
- open-loop - closed-loop
Describe the applications of smart sensors (3):
- perform logic functions - communicate two-way - make decisions and take appropriate actions
Name the two types of control systems:
- point-to-point - contouring
Control types of numerically-controlled robots are (2):
- point-to-point - continuous path
Two major components of transfer machines are:
- power head production units - transfer mechnisms
A sensor is a device that (2):
- produces a signal in response to its detecting or measuring a property - measures a physical quantity and converts it into a signal which can be read by an instrument
Adaptive control in manufacturing optimizes (2):
- production rate - product quality
Describe the five things that one needs to consider in material-handling methods:
- shape, weight, and characteristics of parts - type of movements and distances involved, position and orientation of parts - transportation path - operator skill required - economic considerations
Two types of transfer mechanisms are:
- straight rails - circular or rotary patterns
Automation:
- the process of following a predetermined sequence of operation with little or no human labor - using specialized equipment/devices that perform and control manufacturing operations
Numerical-control is concerned with these four aspects of machining operations:
- tool locations - speeds - feeds - cutting fluids
In deciding to automate, one needs to consider (6):
- type of product manufactured - quantity and rate of production required - particular phase of manufacturing operation to be automated - level of skill in the available workplace - reliability and maintenance problems associated with automated systems - economics
Small-batch production produces a quantity ranging from:
10 to 100
Batch production produces lot sizes between:
100 and 5000
Mass production is defined by quantities of:
100,000 and over
Adaptive control is:
a dynamic-feedback system
The tool path controlled is that of the:
center of the tool
The development and implementation of ACO is:
complex
In adaptive-control constraint (ACC), the system places a:
constraint on a process variable
DAC are used for:
control
In ACO, mathematical models are needed to:
describe the manufacturing process
Production quantity is crucial in:
determining the type of machinery and equipment and the level of automation to produce parts economically
In Direct Numerical Control (DNC), several machines are:
directly controlled step by step by a central main frame computer
In a point-to-point system, each axis of the machine is:
driven separately
In soft automation, the machine can be:
easily and readily reprogrammed to produce a part that has a different shape or dimensions than the one just produced
Point-to-point robots are:
easy to program and have a higher load-carrying capacity and larger work envelope
The end of the robot wrist is equipped with an:
end-effector
AS/RS is a combination of:
equipment and controls which handles, stores, and retrieves materials with precision, accuracy and speed under a defined degree of automation
Hard automation is also called:
fixed-position automation
Soft automation is also called:
flexible, or programmable automation
Machine vision is particularly suitable for parts with:
inaccessible features, in hostile manufacturing environments, measuring a large number of small features, and in situations where physical contact with the part may cause damage to the part
In numerical-control, the system automatically:
interprets these input data and converts it to output signals
In a playback robot a operator:
leads the playback robot and its end effector through the desired path, teaching the robot by showing it what to do
Coding systems are used to:
locate and identify parts in progress throughout the manufacturing system
Automation can be applied to:
manufacturing all types of goods, from raw materials to finished products, and in all types of production from job shops to large manufacturing facilities
Inerpolation is:
movement of tool along a certain path
Response time in ACO:
must be short in order for AC to be affective
Digital sensors produce a:
numeric or digital output that can be directly transferred to digital computers
Greater flexibility in soft automation is achieved through:
numerical control (NC) of the machine and its various functions
Tombstone fixtures are also referred to as:
pedestal-type fixtures
A fixed sequence robot is a:
pick-and-place robot, programmed for a specific sequence of operations point-to-point movements, simple and inexpensive
A point-to-point system is also called the:
positioning system
In visual sensing, cameras:
scan an image, and the software processes the data
Transfer of parts from station to station is usually controlled by:
sensors
Clamps are:
simple multifunctional devices
Job shops produce:
small quantities per year
Resolution, also called sensitivity, is the:
smallest increment of motion of the machine components
The knowledge required to make a decision can be built into a:
smart sensor
In hard automation, machines are:
specialized and lack flexibility (cannot be modified to accommodate products with different shapes and dimensions)
Data concerning all aspects of the machining operations are:
stored on hard disks
In a closed-loop system there is feedback control which:
terminates table movements when proper coordinates are reached
The machines in hard automation are usually built on:
the building-block, or modular principle
Repeat accuracy is defined as:
the closeness of the agreement of the repeated position movements under the same operating conditions of the machine
Tactile sensing is:
the continuous sensing of variable contact forces, commonly done by an array of sensors
Material handling:
the functions and systems associated with transportation, storage, and control of materials and parts in total manufacturing cyle of a product
Sensor fusion involves:
the integration of multiple sensors in a manner in which the individual data from each of the sensors are combined to provide a higher level of information
Sensors may be referred to as:
transducers
Tombstone fixtures have between:
two and six vertical faces
Output signals in numerical-control control:
various machine components
Jigs are:
various reference surfaces and points for accurate alignment
A closed-loop system is equipped with:
various transducers, sensors, and counters that measure the position of the table
Automated Storage/Retrieval Systems (AS/RS) utilizes:
warehouse spaces efficiently
Flexible fixtures are:
workholding devices
Automation has been implemented in these areas (5):
- manufacturing processes - material handling and movement - inspection - assembly - packaging
Adaptive control is used in (3):
- ship steering - chemical-reactor control -rolling mills
In an open-loop system (2):
- signals are sent to the servomotor by the controller - the movements and final destinations of the worktable are not checked for accuracy
CNC are widely used today because of the availability of (3):
- small computers with large memory - low-cost programmable controllers and microprocessors - program-editing capabilities
An industrial robot is:
a machine formed by a mechanism including several degrees of freedom, often having the appearance of one or several arms ending in a wrist capable of holding a tool, a workpiece, or an inspection device
Numerical-control is:
a method of controlling the movements of machine components by directly inserting coded instructions in the form of numerical data (numbers and letters) into the system
In direct methods for measuring position in NC machines:
a sensing device reads a graduated scale on the machine table or slide for linear movement
A program for numerical control consists of:
a sequence of directions that cause an NC machine to carry out a certain operation
Analog sensors produce:
a signal that is proportional to the measured quantity
Computer Numerical Control (CNC) is:
a system in which a control microprocessor is an integral part of a machine or equipment
Backlash in indirect methods can:
affect measurement accuracy
Analog-to-Digital Converters (ADC) interface:
analog sensors with difical computers
In distributed numerical control, a centeral computer serves:
as the control system over a number of individual CNC machines having onboard microcomputers
Tombstone fixtures are typically used in:
automated or robot-assisted manufacturing
In adaptive control, the operating parameters in a process:
automatically adapt themselves to conform to new circumstances such as changes in dynamics, or disturbances
An automated guided vehicle (AGV) is a:
battery-powered driverless vehicle
A variable-sequence robot can:
be reprogrammed to perform another sequence of operations
Automation gaging and inspection systems in transfer mechanisms may be used:
between operations
Positioning and cutting operations in a contouring system are:
both along a prescribed path but at different velocities
A contouring system is also called the:
continuous path system
A contouring system allows for accurate:
control and synchronization of velocities and movements
Circular interpolation is when:
coordinates on endpoints, center and radius are used
Adaptive control in manufacturing minimizes:
cost
Sensors are essential to:
data acquisition, monitoring, communication, and computer control of machines and systems
Fixtures are:
designed for special purposes
Production machines in hard automation are:
designed to produce a standardized product, such as engine blocks, valves, gears, and spindles
The machines used in hard automation are:
expensive, thus economic use requires mass production of parts in large quantities
G-Code generators produce numerical code from:
geometry data files
AGV are:
guided along defined pathways in the floor
Positioning accuracy in numerical-control machines is defined by:
how accurately the machine can be positioned with respect to a certain coordinate system
A crucial disadvantage of DNC is:
if the computer goes down, all the machines become inoperative
Plant layout is an:
important aspect of the flow of materials throughout the manufacturing cycle
Machine vision is capable of:
in-line identification and inspection of parts and of rejecting defective ones
In adaptive-control optimization (ACO), optimization may involve:
maximizing material removal rate (MRR) between tool changes or resharpening
In DNC, the status of all machines in manufacturing facility could be:
monitored and assessed from the central computer
ADC are used for:
monitoring
Transfer mechanisms are used to:
move the workpiece from one station to another to enable operations to be performed on the parts
A numerical-controlled robot is:
programmed and operated like a NC machine
Flexible fixturing is capable of:
quickly accommodating a range of part shapes and dimensions, without the necessity of changing or extensively adjusting the fixtures or requiring operator intervention
In an indirect method for measuring position in NC machines:
rotary encoders or resolves convert rotary movement to translation movement
In cloud computing, sufficient data (from incorporated sensors) is communicated from:
the machine tool to another computer that has more processing power and has the ability to solve complicated physics models, and then provide instructions to the machine in real time
In an adjustable-force clamping schematic, the strain gage mounted on the clamp senses:
the magnitude of the clamping force
A work envelope is:
the maximum extent or reach of the robot hand or working tool in all directions
Linear interpolation is when:
the tool moves in a straight line
Parabolic interpolation and cubic interpolation are when:
the tool path is approximated by curves based on higher order mathematical equations
Total production quantity is:
the total number of parts to be made