Line Efficiency
How do you calculate theoretical time?
# of shifts * 60 minutes
For a line running a product valued at $2/unit and a line speed of 120 cmp, what is the cost of downtime
$240/min, or >$14,000/hr
What drives manufacturer's nuts in trying to plan their operations?
* Competition - both foreign and domestic, is pushing manufacturers to reduce costs and improve productivity * Customers - they are demanding more variety
Quality is a fraction that is __ ___ the waste
1 minus
What are two methods to select the appropriate machine capacity?
1. Increase capacity of each machine in the downstream direction - jams stop the entire line - line empties out after the jam is corrected 2. Key Machine approach to line planning - Capacity of key machine is equal to or greater than the planned line capacity - Higher capacity machines upstream and downstream - Should also look for the limiting piece of equipment
What are 4 things machine efficiency depends on?
1. Operator decisions (based on skill and knowledge) 2. Machine maintenance (clean, in good repair) 3. Container characteristics (round, PE consistency) 4. Environmental issues like weather (temp., humidity, etc.)
What are two ways to minimize changeover time
1. SMILE 2. Schedule and plan changeovers - have personnel ready, have required parts ready, keep record of machine settings, use machine automatic changeover (Note that changeover times can vary widely)
What are the dimensions and capacity for a "large size" accumulator
10' x 14' ~2800+ aluminum cans
Example of throughput
240 pkg/minute (expected) * 97% efficiency = 230 pkgs/min (actual)
If a machine/system runs 50% effective with 1 operator and becomes 65% effective with 2 operators, the effectiveness goes up ___%, and the efficiency is dropped to ___% based on labor
30%, 50%
What are the dimensions and capacity for a "small size" accumulator
4' x 4' ~ 290 aluminum cans
A perfect bottle could have 100% quality, but if half have to be thrown away because of defects, the quality yield is only ___%
50% (AKA you are 100% effective, but only 50% efficient)
What is the Industry Productivity Index?
72.3%
What is the equation for Quality
Actual Good Product / Product Output
What is the equation for performance?
Actual speed dr / Normal Speed
What is the equation for OEE?
Availability x Performance x Quality Or B/A x D/C x F/E
What is the best location for an accumulator?
Before or after key machines or both - you really never know until trial and error Depends on floor space, reliability, capabilities If you have 1 min of line time, that gives 1 min of line time to repair any breakage
What are the three main causes of downtime?
Changeover, maintenance, and stoppages
What are causes of downtime?
Changeovers, supply interruptions, packaging components, product interruptions or changes, maintenance, cleaning, stoppages and line jams, power failures, operator absences
What is the only workable approach?
Computer modeling and simulation
Effectiveness is the relation between what ____________ at the end of a process and what _________ at the end of a process
Effectiveness is the relation between what THEORETICALLY COULD BE PRODUCED at the end of a process and what ACTUALLY CAME OUT/WAS PRODUCED at the end of a process
How can you keep manufacturing costs to a minimum?
Extend production runs to minimize the cost per unit
T/F: During downtime, there is little production
False, NO production
How can you minimize stoppage time?
Have a plan in place (Plan for Failure) to fix jams, breakages, machine failures Who - is doing the work What - work needs to be done When - will it be done Where - it will be done
What are two things high OEE numbers are indicative of?
High schedule fulfillment Optimized labor
Example of effectiveness
If you machine or system is capable of making 100 quality products an hour, and it only makes 70, then it is 70% effective (but we don't know how efficient b/c we don't know what we had to put in)
What is the Key Machine approach
Increased the probability of adequate supply to the key machine Decreases the probability of blockage of output from the key machine
What are three costs of downtime?
Inventory Lost production capacity Employee costs
OEE is the rate between what two things?
It's the rate between what a machine theoretically product and what it actually did
What is computer modeling and simulation?
Known or assumed probabilistic patterns of machine operation and failure Run a simulation many times Vary the size and locations of accumulators and other components
How can you reduce plant operation costs?
MAXIMIZE production runs (uptime) MINIMIZE changeover, maintenance, and stoppages
What are two "reality checks"
Machines may not preform at the predicted efficiency or capacity Machines of the desired capacity may not be available (purchase next larger or multiples of same)
Effectiveness is: Making ____ Making ____ Making ____
Making the right things - the right product or SKU at the right speed (PERFORMANCE) Making it the right way - no rework, no defects, no waste (QUALITY) Making it at the right time - producing as planned, minimizing time losses (AVAILABILITY)
What are six ways to maximize uptime?
Minimize production time used for maintenance - schedule it during off hours and regular inspections Monitor the ongoing production process - might use Statistical Process Control (SPC) to tell when parts are about to wear out or need replacing Minimize stoppage time (see how on next card) Use accumulators and conveyors Update the controls Consider if a new(er) machine is appropriate for this need
What is redundancy?
Multiple machines instead of one high capacity machine Various management approaches Use simulation to better understand the situation
What are the bold headings in the reading - How to Calculate Overall Equipment Effectiveness: A Practical Guide
OEE Overview and Efficiency versus Effectiveness A simple example The A-P-Q's of OEE Availability Performance Quality Time Equals Money The Straightforward approach to OEE A practice definition of OEE Scope of Analysis OEE and the cost of quality The concept of Downtime as understood in availability A proven technique in manufacturing comes to packaging
Formal definition of OEE 2
OEE is defined as the product or cost function or interplay of all availability or uptime of the operative mode multiplied by the performance or actual resultant production speed (from actual dialled rate and ramping rates) divided by the normal or steady state speed and then multiplied by the quality or the output of quality product divided by the input of the critical component or aggregate of all the inputs (components consumed, lost, reworked, destroyed or unaccounted for during the production process).
Formal definition of OEE
OEE is the Overall Equipment Effectiveness of a defined production process during the defined operative period or mode in which all activities related to production, personnel and inputs are accounted for during all producing or dependent activities within a defined scheduled time or operative mode time.
How much production time is OEE typically calculated for?
One week's or one month's production of a given size and product (smaller slices might not give enough info) Looking at less than 10,080 minutes (one week) of operating time isn't significant
What does OEE stand for?
Operational Equipment Effectiveness
Why is there employee cost for downtime?
People get paid for standing/sitting around
What are the two parts downtime is broken into?
Planned downtime and unplanned downtime (changeover and maintenance are planned, stoppages are unplanned)
Yield is also known as what?
Quality (basically saleable product)
What is the efficiency ratio of a single machine?
Ratio: Actual time worked/theoretical time worked
What is the equation for availability?
Run time / Total operative mode time
What does SMILE stand for?
Setup Minimization to Improve Line Efficiency (it is like the "pit crew" of the packaging world)
What are the benefits of the key machine approach?
Smaller capacity machines Lower capital expense Less floor space required
What is the "Cost of Quality"?
The cost of not creating a quality product or service
What is production schedule time?
The time period in which allotted defined products are to be produced
What is the equation for throughput?
Theoretical Processing Speed (expected) x Efficiency of Machine Theoretical Processing Speed (expected) is NOT the speed the machine can run - the machines would wear
What are planned events defined as?
Those events which no output of saleable product results and which management has control over the timing and extent of the activity Ex. holidays
What can OEE do when broken into its three main components?
Track down where we lost bad product (If we run 50% OEE everyday, we can lose units in three different ways, and every loss has its own cost structure)
T/F: There is NO known way to determine the best size, or locations, analytically, for an accumulator
True
T/F: Two accumulators is always better than one
True
T/F: Adding another independent machine or multiple independent machines to an existing will ALWAYS lower the line efficiency
True (assumes that no machine runs at 100% efficiency)
T/F: Efficiency varies from day to day
True (most downtime on Mondays and Fridays)
What is more critical, uptime or downtime?
Uptime
Example of efficiency ratio
[(# of shifts x 60 minutes) - downtime] / (# of shifts x 60 minutes)
What is the ratio of Actual to Theoretical Production
[Actual output / (# of shifts x 6o minutes x rated capacity)] * 100
What is the ratio of Actual to Theoretical at a Particular Production Rate
[Actual output / (# of shifts x 6o minutes x set capacity)] * 100
What helps to run downstream machines?
accumulators and conveyors
What did the PMMI study look at?
average efficiencies for types of machines a specified set of (9) machines the calculated efficiency of the combination of machines
OEE has been around for ___
decades in it's elemental form
What is Packaging Line Efficiency?
efficiencies of single machines, system of machines, and issues that influence system efficiencies
Efficiency is typically ___ at lower speed setting
higher
What is predictive
likelihood that something will fail
Inventory reduction is the major benefit of ___ ___
minimal downtime
What are Secondary Machines (SM)?
minor unit ops that convey, manipulate, collate, inspect, code or mark the package such as conveyors, combiners, dividers (when separate from a primary unit op), coders (laser, inkjet, impression, etc.), checkweighers, X-ray, Gamma inspection, independent fill, cap or label detection, rejection units
The actual ___ ___ equals the theoretical speeds, and, as a result, the output is never as high as it is planned to be
never equaals
What is preventative maintenance
prevents something bad from happening, like oil spills, tighten screws
What is rework considered within?
quality
OEE is purely ___ based
time (time converted)
What are Primary Machines (PM)?
unit ops that are capital equipment that has a direct involvement in assembling the package such as unscramblers, rinsers, fillers, cappers, labelers, cartoners, case packers, palletizers, etc
What is Actual output?
what occurs with stoppages. i.e., 273 cpm due to production downtime
What is Theoretical output?
what you will set the line to run. i.e., 300 containers per minutes
If any asset is removed from the process in such a way as to make the process for a given product not viable then the expected OEE number is considered ____
zero (total recall also yields zero)