IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 1

Dr. Rupy Sawhney

Quality

People make fewer mistakes when they follow simpler procedures.

Mistakes made during setup have the potential to affect the entire batch.

With standardized setup procedures, trial and error adjustment can be eliminated.

Costs

When changeover times are small, smaller batches may be produced more frequently.

Reduction in WIP and finished goods investment

Reduction in required labor hours and skill level of employees

Reduction of scrap generated as a result of setup procedures

Flexibility

The ability to more readily meet customer demand is enhanced.

Worker Utilization

Simple setups do not require special skills and may be done by operators, thus

reducing their idle time.

Setup technicians may then be used to address higher level concerns, such as

technically difficult setups or continued

setup improvements.

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 2

Capacity and Lead Times

When current capacity is nearly filled, reduced setup time is a low cost alternative

to overtime or equipment acquisition.

Make to Order becomes possible in traditional Make to Stock businesses.

Lead Time is diminished due to decreased lot sizes and a reduction in time spent

waiting for setups.

Process Variability

Each setup is itself a process with several discreet steps.

Therefore, there is variability inherent in looking for tools, tearing down old fixtures, building up

new ones.

When these steps are ill-defined, the potential for variability is increased.

The ultimate setup reduction is the elimination of the setup entirelythis then eliminates the setups contribution to overall process variability.

Reduced setup times allow

More Setups per period

Smaller Batches

Increased Flexibility

Improved Response Time

Increased Time Available for Production

But with all these benefits,

why are setups neglected?

Setup reduction takes dedicated effort frompeople who know the equipment and operation

best: machine operators and setup people.

In many cases these individuals have never been asked to do analysis, contribute

suggestions, or take responsibility for anything

beyond their job descriptions.

There is often a preference towards the purchase of new equipment rather than

the improvement of existing equipment.

There may be reluctance to improve equipment that one would like to see

replaced at a future date.

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 3

People with technical backgrounds or who may have had exposure to automation

often come up with complicated or costly

solutions which are dismissed as

impractical.

(In fact, however, most improvements can be achieved through relatively simple means.)

Improvements to machines and tools often require the skills of machinists and tool

makers, who are usually busy fixing

broken machines.

Setup reduction requires these people be allocated time for setup projects.

Reducing setup on just a few machines or processes has little impact, so individual

setup projects are hard to justify

Setup reduction cannot be achieved on all fronts simultaneously, and it takes time

before benefits are felt globally.

Maximize the transfer of responsibility to the operators.

Minimize machine downtime due to setups.

Abolish setup.

NOT to abolish setup specialists. Their skills should be used in other activities such as Standardization of setup activities.

Modification of procedures, tools, and fixtures to improve setups.

Methodology

Single Minute Exchange of Dies

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 4

SMED methodologies were developed in Japan by a consultant to Toyota, Shigeo Shingo.

Though developed primarily for metal-working processes in the automotive industry, SMED is

now applied universally to any system

encompassing a processing station.

Type 1 Retrieving, preparing, and checking materials, tools,

etc. before the setup; cleaning the machine and workstation; checking and returning tools after the operation is completed

Type 2 Removing tools, parts, etc. after completion of the last

lot; mounting tools, parts, etc. prior to the next lot

Type 3 Measuring, setting, and calibration

Type 4 Producing and evaluating test product

Stage 1: Identify Internal and External Steps.

Internal: Must be performed while the machine is stopped. Equivalent to downtime.

External: May be performed while the operation is running.

Most Type 1 Setups are external.

Type 2,3, and 4 are generally internal.

The main focus of setup time reduction is on

internal setupsNOT on total setup time. While reducing total setup hours is desirable,

it is not of primary importance.

Stage 1, Step 1: Analyze the existing setup.

Detailed analysis of the procedure. May involve the use of stopwatches, video taping, interviewing setup personnel

Stage 1, Step 2: Classify the steps in the setup procedure.

Determine whether steps are internal or external. Determine whether steps might be eliminated.

Sample SMED Worksheet

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 5

1) Breaks setup down into discreet steps, or

elements.

2) Classifies whether the steps as they exist

are Internal or External.

3) Accounts for time.

4) Accounts for the individual performing

the setup.

Stage 2: Convert internal steps to external steps.

Readily converted steps include:

Heating dies or tooling

Locating tools or fixtures

Other preparatory steps

Referring again to the example, observe that all steps are done after the machine is stopped.

Steps 1 and 2 (Check in, die transfer) could be done while the machine is still running.

Step 4 (return old die to storage) could be done after the machine resumed production.

Stage 3: Improve all aspects of the setup operation.

Converting internal steps to external steps reduces setup time considerably, although usually not enough to be in the single minute range (

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 6

The primary goals for stage 3 are:

Setups will now take less than ten minutes. ?

Setups involve no more than a single touch procedure.

OTED: One touch exchange of dies.

Implement checklists of standard setup procedures.

Equipment malfunctions that make themselves known only when they are about

to be used will increase internal time.

Therefore, regular equipment checks and

repairs must be performed.

Daily setup schedules ensure that tools and personnel are available when they are

needed.

Parallel Setup Tasks

Internal setups can sometimes be improved by having multiple workers doing

setup tasks simultaneously.

Ideal for large

machines

where setup entails a

good deal of walking.

A multiple person setup is a team effort, meaning individuals scattered throughout the plant must be assembled.

Workers functioning in parallel must coordinate actions.

Danger of one worker starting a step which may injure another.

Not a simple technique, and therefore only a good solution for short term.

Much internal setup time is spent securing fixtures and materials to machines

Bolts are the most common method of attachment, though very inefficient.

Attachment activities may be simplified by: Reducing the total number of fasteners used

Standardizing the size of fasteners so that only one tool is necessaryeliminate searching for the right tool!

The longer the bolt, the more turns necessary to tighten it.

However, in reality it is only

The LAST turn that tightens a bolt.

The FIRST turn that loosens a bolt.

Given this reality, setup time may be

reduced through the use of one-turn bolt

attachments.

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 7

U-Shaped Washers The washer has a hole bigger than

the bolt and is slipped underneath

prior to tightening.

Pear-shaped holes Fixture may slide into place and

then be fastened.

Split-Thread Bolts Drops easily into hole and may be

tightened with just 1/3 turn.

T or L-shaped Heads When high torque is not required,

this fastener type eliminates the

need for a tool

Parts and fixtures may also be held in place by standard sized holders and pins.

Simple clamping devices are particularly useful in turning machining setups into one-

movement procedures

Most setups include a period of adjustment, no matter how skilled the operator.

Adjustment generally incorporates a run-measure-adjust cycle that must be repeated many times.

Such trial and error procedures are often the most time consuming part of the internal setup procedure.

What if trial and error could be eliminated, replaced by a single motion?

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 8

There are 2 types of adjustment that must be approached in different ways.

Type 1 involves the setting of parts and fixtures to the correct position.

Type 2 involves the right combination of speed, pressure, feed rates, temperatures,

and other adjustable variables.

When dies and fixtures are of varying sizes, the use of shims and inserts will greatly reduce

spatial adjustments.

Shims and inserts may be fabricated and then stored with dies to be used as needed.

Cassette-type holders may also be employed to similar effect.

Here dies of varying heights are

accommodated by shims.

Cranks, handles, levers, switches, and other adjustable mechanisms are common to many machines.

Positioning of these mechanisms is often a source of delayparticularly in cases where the mechanism itself or the associated gauge may be dirty or broken.

Correct combinations of settings, when found, should be written down and stored.

All mechanisms should have calibrated scales.

Observe the mechanism below. With the configuration on the left, it would be very difficult to

find the precise setting without trial and error. With

scales such as those on the right, it becomes much

easier to set the mechanism to values specified in a

checklist.

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 9

Stage 4: Abolish setup.

The ULTIMATE setup improvement beyond OTED. But how are setups eliminated?

1) Reduce or eliminate differences between parts.

- Fewer or no differences means fewer changeovers.

- Design-based approach to setup reduction.

- Determine what parts can be standardized and used

on all or many products.

- Group technology.

2) Make multiple kinds of parts in one step.

- For example, form two kinds of parts from a single

stroke of a press rather than forming the two parts

sequentially with a setup in between.

3) Dedicate machines to making just one item.

- If only one item is ever made on a machine, then

obviously that machine never needs a changeover.

- This approach is clearly only practical when the cost of

acquiring new machines is relatively inexpensive when

compared to the cost of performing setups.

It should be noted that in order to abolish setups it is not necessary to have gone

through the first three stages.

The alternatives for abolishing setup may be doable in short order.

Storage Everything needed for setup should be as

close as possible to the setup site.

Items used frequently on a machine should be kept at that machine.

When the number of different setup items is large, space constraints may dictate that they be stored together. In such cases, color coding helps to facilitate quick removal.

Kitting

When all items needed for setup are available in one place at one time there is no time lost searching.

Kits may be stored on

carts and kept close

at hand

Carts should be

partitioned and visually

differentiable

Material Handling equipment should be right-sized for the job. Use of forklifts, which require time to arrive on

site, should be minimized if possible

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 10

IE 427- Lean Production Systems Spring 2014

Department of Industrial & Systems Engineering The University of Tennessee 11

QUESTIONS