Equipment Efficiency: Availability, Quality and SMED

1
Equipment EfficiencyAvailability, Qualityand
SMED

• Operations Analysis and Improvement
• 2009 Spring
• Dr. Tai-Yue Wang
• Industrial and Information Management Department
• National Cheng Kung University

2
Presentation

• It has become increasingly important to
  economically manufacture products in smaller
  product batches.
• Product lead times must be kept as small as
  possible.
• Product customization continues to increase.
• Number of parts produced on manufacturing systems
  continues to increase
• Batch sizes have been reduced.

3
Presentation

• Companies should be as agile and flexible as
  possible.
• Reduce machine set-up time times to minutes
  instead of days or hours.
• The Single-Minute Exchange of Dies (SMED) is a
  clear easy-to-apply methodology.
• Good results in many cases very quickly.
• It was developed by Shigeo Shingo in Japan from
  1950-80s.
• Achieve good results without costly investments.

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Introduction

• Set-up process.
• Time required to go from the end of the last good
  part from one batch to when the first good part
  of the following batch is produced.
• The trials needed to obtain the first good
  product are considered part of the set-up process.

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Introduction

• SMED -gt Single-Minute Exchange of Die.
• Designed so that the set-up process should be
  made in less than 10 minutes.
• During the 1960s the set-up time for a large
  stamping press could take more than a full day.
• It is possible to achieve reductions around 60
  of the original set-up time.
• In reductions of about 90 the project costs
  become significant.
• It is not always necessary to reduce the machine
  set-up process.
• Tires on your personal vehicle vs. car racing.

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Introduction

• SMED is contemplated in the Just-in-time and
  in the 20 keys methodologies (key number 5).
• SMED improves the availability rate as well as
  the quality rate.
• This set-up time includes the trial phase.
• Startup losses included in the quality rate are
  produced in this trial phase

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Basic steps in a set-up process

• Four typical classes of set-up operations
  regardless the type of the machine or equipment.
• Prepare, adjust and check (new materials and
  tools).
• Remove old tooling and install new tooling on the
  machine.
• Measure, set and calibrate (fixtures, tools and
  tooling).
• Produce initial parts (production trials) and
  adjust the machine..

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Basic steps in a set-up process

• Prepare, adjust and check operations focus on
  making sure that the tools and materials that
  will be used for set-up are available when the
  set-up is scheduled.
• Produce initial parts and adjust depends on the
  set-up specialists know-how.

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Traditional strategies

• For high volume manufacturing applications, the
  set-up process duration was not particularly
  important.
• Manufactures could afford to have customers
  waiting.
• Production was scheduled based on manufacturing
  needs.
• These set-ups hardly affected the products
  price.
• Shutdown production facility to for two weeks
  while machines and tools were set-up for new
  model year production.
• Today, manufacturing lot sizes have decreased.
• Manufacturing flexibility needs to increase.
• Same quantity -gt increased part variety and with
  smaller delivery quantities.

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Traditional strategies

• The possible production of defective parts at
  set-up coupled with the increased frequency of
  set-up has forced manufacturers to make more
  products than required.
• In order to reduce set-up process affects,
  companies usually use two different strategies.
• Try to make the set-up as fast as possible.
• Increase the production lot size.

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Skilled based strategies

• Many companies have used set-up specialists to
  reduce changeover and set-up times.
• Skilled in the operation of specific machines.
• Familiar with the needed tools and methods to
  carry out the exchange.

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Skilled based strategies

• Dependence on these specialists can be strong.
• Skill that a set-up specialist needs.
• Set-up process complexity.
• Not all the tasks that set-up specialists carry
  out are critical.
• The specialist can get help from the machine
  operator.

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Large batches based strategies

• The larger the batch size is, the smaller the
  impact of the set-up time will be on the
  production cost of each part.
• Cost per part is based on the company cost
  system.
• The system shares all company costs to each
  product.
• There is a section that depends on the time to
  manufacture and also on its respective set-up
  time.
• If the lot size is large, the set-up time effect
  is spread out more than if the lot size is small.

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Large batches based strategies

• The higher the set-up time, the bigger the profit
  will be.
• This reasoning supports the lot size increasing.
• Some companies only accept orders that exceed
  certain lot sizes.

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Large batches based strategies

• If set-up time and production time were about the
  same magnitude
• it would not make sense to search for large
  lots size.

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Economic Lot Size strategy

• Large set-up times -gt large batch size.
• Increase in inventory cost and potential loss for
  products becoming obsolete.
• The economic lot size is a direct relationship
  between the inventory cost and the set-up cost.
• The effect of the set-up cost decreases
  exponentially according to the increase of the
  batch size.
• This hypothesis is based on a constant set-up
  time.

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Economic Lot Size strategy

• As set-up cost decreases, the economic lot size
  would also decrease until reaching the unit
  product lot size.
• It would be profitable to only accept orders made
  up of one article a batch size of one!

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SMED methodology

• 1950 in Toyo Kogyo factory.
• Shingo discovered that the exchange of an 800 ton
  press was delayed because of a missing screw.
• Two types of operations in the process of change.
• Those that should be carried out with the machine
  running producing parts from the previous lot.
• Shingo called these activities External set-up.
• Those that required the machine and for it to be
  idle while they were performed.
• Shingo denoted as Internal set-up.

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SMED methodology

• In 1957 Shingo improved the SMED methodology.
• Placing an extra table in a Mitsubishi Company
  machine.
• Convert some of the internal set-up tasks to
  external set-up operations.
• Shingo reduced the set-up time for a screw
  machine manufacturer from 8 hours to 58 seconds.
• At the Mitsubishi Company from 24 hours to 2
  minutes and 40 seconds.

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SMED. 4 conceptual stages
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Preliminary stage

• Studying the current set-up process because
  simply put what is unknown cannot be improved.
• Know the process, the variability and the
  cause(s) that produce this variability.
• Collect values for the set-up times.
• set-ups can be frequent or sporadic.
• By means of the time study process.

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Preliminary stage

• the SMEDs goal is not to eliminate specialists
  job.
• set-up specialist opposition can lead to project
  failure.

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Separating internal and external set-up

• Classify set-up operations according to the given
  definition of external and internal set-up.
• It takes into account the same operations and
  duration included in the current method.
• Without improving any particular operation.

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Separating internal and external set-up

• Assure that the operations defined as external
  set-up can all be carried out with the machine
  running.
• Time to get the necessary tools and materials is
  not allocated to the operators.
• It is possible to reduce the exchange time by as
  much as 60 without any capital investments.

25
Converting internal set-up to external set-up

• The set-up process time reduction from the first
  stage can be very significant but is not where
  SMED ends.

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Converting internal set-up to external set-up

• This stage examines two important aspects.
• Re-evaluate the internal set-up.
• Check or see if some of them were considered
  erroneously as internal.
• Look for alternatives that allow internal set-up
  to be carried out in whole or in part as external
  operations.
• For example, is it possible to screw a die to a
  press before placing it inside the press chamber?

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Converting internal set-up to external set-up

• This stage will require an economic investment.
• Carry out a cost justification.
• Sometimes the investment will be necessary in
  spite of the economics.

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Converting internal set-up to external set-up

• Other important aspect to consider.
• New process or system reliability.
• The possible appearance of new operations.
• The benefits and possible risks of the new
  process.
• It is possible to achieve set-up process time
  nearing ingle minutes (lt 10 minutes)

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Streamlining all aspects of the set-up process

• This stage tries to improve all the set-up
  operations.
• Both internal and external.
• Trying to eliminate some operations.
• SMED methodology recommends that one follows
  systematically these four stages.
• Common sense -gt not be invested in operations
  that previously have not been optimized.

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Streamlining all aspects of the set-up process

• stage 3.
• Improvement of the external set-up operations.
• Revisit of the internal activities that have not
  been possible to convert into external.

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First stage tools

• Numerous time wastes take place in many set-up
  processes.
• Materials are moved to the warehouse with the
  machine stopped.
• Tools and dies are supplied late, or incorrectly.
• Tools and dies that are not needed, are taken
  back to the supply room before starting the
  machine.

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First stage tools

• Some required screws and tools were not collected
  during the set-up process.
• Some nuts are just too tight when trying to
  remove them.
• It is necessary to eliminate all these wastes.

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First stage tools

• Try to answer certain questions before starting
  the set-up.
• What has to be done before starting the change?
• How many screws are necessary in order to fix the
  die? Of what type?
• What tools are necessary? Are they prepared for
  proper conditions?
• Where should the tools be placed after using them?

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First stage tools

• A group of visual controls have been developed.
• Checklist.
• Questionnaire that should be checked before each
  set-up process.
• Verify in advance that all elements that should
  be prepared are in fact ready and available.
• Can be universal for all products changeover or
  specific for each product.

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First stage tools

• Check panel placed next to the machine.
• Small number of tools or exclusive tools.
• The worker can visually check if all the
  necessary tools are located.
• In some check panels the tools are silhouetted.
• Another strategy is to code the tools with two
  stickers.
• A sticker is placed in the machine and another is
  placed on the tool.

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First stage tools

• Function checks.
• The checklist or the check panel do not show the
  die and tools status.
• Material inlays.
• Special devices for checking the molds before
  placing them in the machine.
• If the company does not own one -gtsecond stage.

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First stage tools

• Parts and tools transportation improvements.
• Transportation from the warehouse to the work
  area should be carried out before the exchange
  begins.
• traditional press exchange process
• Removes the used mold -gt loads it in a crane -gt
  takes it to the warehouse -gt loads the new mold
  -gt place it.
• new changeover process
• Load the new mold -gt leave it next to the
  machine -gt take out the mold -gt leave it next to
  the machine -gt loads up the new mold -gt set the
  machine into operation -gt carry the used mold to
  take it to the warehouse.

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First stage tools

• This new changeover looks like it takes longer
  than the traditional method.
• According to Shingos definition of set-up time,
  the time with the machine stopped is drastically
  reduced.

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Second stage tools

• The second stage usually runs parallel with the
  third stage.
• SMED methodology offers some recommendations that
  facilitate complex cases studies.
• Movements around the machine should not be
  questioned.
• Will be analyzed in the third stage.
• It is not that some operations will be
  eliminated.
• There are several methods broadly intended to
  enhance the set-up process.

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Endless material method

• When a reel is empty, it should be removed and
  replaced with a full one.
• Rolling mill or on packing machines.
• The changeover time of reels could potentially be
  eliminated if the end of a reel is welded or tied
  to the beginning of the following one.
• The product made with the welding seem would be
  scrape.

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Endless material method

• Temporary containers.
• If it is not possible to weld or tie the reels to
  carry out the changeover operation.
• Save set-up time considerably because they
  eliminate the movements to locate and bring in
  the new reel.
• If the reels allow it, it might be possible to
  tie the previous reel with the following reel and
  with a simple turn, carry out the exchange.

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Second stage tools

• Press die preheat.
• There are devices that heat the molds up before
  being placed in the machine.
• The main concern in this case is labor safety.
• Function standardization.
• Standardize some measures (height and depth).
• The set-up process should be as safe as before.
• The quality of the manufactured pieces should not
  be adversely affected.
• Add new functionalities or features to the mold.

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Second stage tools

• Tools duplication.
• Have two or more identical elements (cranes,
  tools, pallets,) to reduce the set-up time.
• A single six pack is as easy to handle as a
  single can of soda.
• With a double crane it is possible to prepare the
  next mold and to extract the previous one without
  the need of removing and placing the molds again.

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Third stage tools

• The improvement or elimination of an operation
  requires reengineering some aspect of the product
  or process.
• it is possible to make the operation in a
  different way?
• Is this operation necessary?
• Is this procedure the most appropriate?

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Third stage tools

• Up to this stage, external operations have not
  been analyzed.
• Will the set-up specialist have enough time?
• Schedule the changeovers so that the specialists
  are not needed at the same time in two machines.
• Internal operations can be improved.
• Analyze in detail the movements around the
  machine.
• Determine the optimal number of workers that
  should take part in the set-up process.

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Improving tool storage. Indicators strategy

• Begin with the 5Ss.
• Organize tool storage in an efficient way.
• Keeping high use items close for easy access.
• Organizing the tooling so that it is easily
  located and identified.
• The 5S methodology offers a common orientation
  when choosing the coding standards.

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Parallel operations

• For large machines, it is necessary to carry out
  operations at the front of the machine as well as
  at the back of it.
• The worker can waste important set-up time when
  walking around the machine.
• The set-up time and complexity can be reduced
  with the help of a second worker.

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Parallel operations

• Utilize a task map to indicate what operations
  will be carried out by each worker
• Starting with the initial situation.

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Parallel operations

• Two workers executing the exchange in a parallel
  way.
• Table shows task sharing and those tasks that can
  be carried out simultaneously as well as the
  times where the workers should be waiting.

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Parallel operations

• Allows the Lean thinker to discover which are the
  most important tasks that should be improved.
• Labor safety, once again, is a priority in this
  type of synchronized work.
• Safety mats that stop the machine when they are
  activated.
• Confirmation buttons.

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Third stage tools

• One-Motion Method.
• Perform more than one task simultaneously.
• Electric and hydraulic connections.

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Third stage tools

• Functional clamps.
• Devices that are used to passively hold an object
  in a fixed position with the minimum effort.
• The SMED methodology seeks to eliminate the use
  of screws and nuts as fixing elements.
• Pear-shaped holes.
• U-shaped washers rings.

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Third stage tools

• Functional clamps.
• C-shaped washers.
• Guttered thread.
• Single-movement method.
• Reduce the tools variety.

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Eliminating trials and adjustments

• Can represent 50 of the total changeover time.
• They are not only decreased but eliminated.
• A set-point should be used instead of an
  adjustment.
• Without applying the trial and error method.
• The adjusting procedures must be written
• The machine parameters value should be specified.
• OTED (One Touch Exchange of Die).

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Process Automation

• The last resource after the successful
  implementation of the previous methods.
• Process automation supposes high investments
  costs.
• Regardless of its expensive implementation, in
  some cases it is the best alternative.

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Zero changeover

• When Shingo died in 1990, Sekine and Arai
  continued his work.
• They tried to achieve set-up times of less than a
  minute.
• They create a strategy called Zero changeover.

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Zero changeover

• The only way to achieve set-up times near to
  seconds was to automate the exchange process.
• Represents large investments.
• Many of the achieved improvements, came from
  ideas developed by Shingo.

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SMED effects and benefits

• Easier set-up process.
• New changeover procedures.
• Set-up process is simplified and easier to carry
  out.
• Many of the operations can be carried out by the
  majority of the employees.
• Increased safety also results from the improved
  changeover simplicity.
• Eliminate defective parts.

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SMED effects and benefits

• On-hand stock production.
• Manufacturing batch size can be decreased as
  well.
• Work-in-process will decrease.
• Mean time of material flow will decrease.
• Lead time will decrease too because it is
  directly related with the time of material flow.
• Workplace tasks simplification.
• Tool coding, a clean and upstanding machine
  environment.
• Easier to locate tools.

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SMED effects. Productivity and flexibility

• The main benefits.
• Productivity.
• Flexibility.
• Productivity.
• Decrease the machines load in order to increase
  the productive period.
• SMEDs principal benefit is to increase
  flexibility as it will be show next.

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SMED effects. Productivity and flexibility

• Productivity increase.
• SMED is an alternative among other methods
• Increase in flexibility.
• SMED is the only solution
• Buying a new machine does not provide an increase
  on the flexibility.

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SMED effects. Productivity and flexibility
63
Economic benefits

• Economic benefits depend on the machine situation
  in which the SMED is applied.
• Saturated machine.
• Liberate the machine from its load time to
  increase the machine availability
• The benefit takes place due to the economic
  margin in the sales increment.

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Economic benefits

• Not saturated machine.
• The necessary time to carry out a production
  order will decrease.
• Saved cost in the workforce.
• If the goal is to increase flexibility can be
  impossible.
• Qualitative benefits derived from SMED.

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Summary

• This chapter has presented a basic but helpful
  methodology to reduce the set-up time in a
  machine.
• SMEDs methodology proposes the arrangement of
  the needed tools used in the set-up process
  before the machine finishes the previous lot.

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Summary

• The main benefit of the set-up time reduction is
  the increase in the flexibility of the
  production.
• Nevertheless, the economic justification of a
  SMED project, focus on flexibility increment, is
  quite difficult.