Monday, September 29, 2008

Elimination of Adjustment

Adjustment is a major source of downtime due to changeover. It is closely associated with conversion of internal to external – the adjustment is done externally. One of the basic ideas behind conversion from internal to external is elimination of assembly during downtime. By a simple exchange of preassembled components, setup is reduced.

To eliminate adjustment, the preassemble component is adjusted externally, or all assemblies are standardized, so that no adjustment is required. Examples of external adjustment are pre-heating of plastic injection molds, and shimming of dies in a trial press. Examples of standardization to eliminate adjustment is using a common die height for all tooling going into a specific stamping press or injection molding machine, and the use of keyways and locating pins to place tooling in a precise position without the need to measure off a datum point.

In most cases, it will require detailed study to determine the relationship between final settings and the conditions of the setup – what factors are influential, and how to measure and adjust for them prior to starting the setup. Keen observation, statistical analysis, and trial and error are all useful approaches. The key approach is to insist that it is possible to understand the relationship, and to make the necessary adjustments beforehand. Chemical processes can be particularly difficult to understand completely. In many cases, simple approaches, such as cleaning, and maintaining a constant environment, including temperature and humidity, will go a long way toward reducing and eliminating the amount of adjustment required as an internal activity.

Saturday, September 13, 2008

Separate internal from external - not as easy as it sounds

We have indicated that the simplest and most effective way to reduce setup is to separate internal from external. But we have also indicated that there are many reasons why this does not happen. Some of the key reasons are:

  1. The person responsible for the setup is also the operator/value creator. This means that there is no time to carry out the external tasks while the operations are in process, since the operator is engaged in value creation. Many organizations are not convinved that a separate setup function can be justified, especially if customer demands are being met. Some organizations designate setup an “indirect” function, and follow a management metric regarding the ratio of “direct” to “indirect” labor – the higher the ratio the better. Another reason given for operators to perform their own setup is that this places full responsibility for the setup on one person. When efficiency or performance to standard is used as a measure of performance, it is thought that setup personnel will rush to complete the setup, and may not pay sufficient attention to quality.
  2. The scheduling system has a “standard” for setup, and the standard is being met. Consequently, there is no perception that setup needs to be reduced, especially if large lots are not understood to be more costly that small lots. Furthermore, the perception is often that faster setups are synonomous with simply working harder, or rushing and cutting corners. If customer demands are being met, the standard is unlikely to be reviewed. The fact that the standard may have been set without significant study, or even arbitrarily, is usually quickly forgotten by those setting up the scheduling system, and completely unknown to those who come after. It is even the case that when the standard is not routinely met, the extra time taken to set up is allocated to some other aspect of the reporting system, usually breakdown.
  3. For various reasons, what to do next is not communicated to those responsible for the changeover. Often, expediting is the way the next job is selected. This can be a result of “first come, first served” – reasonably so in, for example, a restaurant. Or perhaps there are constant change to priorities – again, reasonably so in, for example, an emergency ward of a hospital. On the other hand, in some instances, each sales person or manager believes that his or her job is more important, and selection is a result of last minute negotiation. It may also be the case that jobs take an unknown amount of time to complete, perhaps because of material shortages, breakdowns, labor shortages, and so forth. In this instance, the perception is that scheduling is futile, and one might as well wait until the job is complete before deciding what to do next.

It may thus be the case that there is a lot of change required, before the simple rule of separation of internal from external can be applied, to reduce setup. A strong vision of how to get to the point where setup reduction can be applied to significantly improve customer satisfaction while improving profits is required. This vision is encompassed by the term “Lean” or “the Toyota Production System”. We thus refer to “lean healthcare” or “lean manufacturing”, and other lean business systems. The key element is “flow”, or lead time reduction.

Friday, September 12, 2008

Steps to shorter setups

We have seen that separating the internal and external elements of a setup, and carrying out the external elements while the value is still being created, is the first and usually largest part of reducing setup time.

The complete list of steps to minimizing setup time is:

  1. Separate internal from external, and carry out external operations while value is still being created.
  2. Carry out the internal operations as several simultaneous operations.
  3. Convert internal operations to external operations.
  4. Simplify and automate all remaining internal operations to speed them up.

Briefly, these steps are understood as follows.

Carry out internal operations as several simultaneous operations: This is often referred to as “parallel work”. The typical image is of the race car pit stop, where four tires are changed, fuel is topped up, the wing is adjusted, and so on, in just a few seconds. Anyone who has watched a car race will have seen how this is done – utilizing five, six, or more pit crew. By analyzing the tasks of the pit stop, and dividing the work into tasks that can be done simultaneously, the internal work is done in a fraction of the time it would take if only one task was done at a time.

Convert internal operations to external operations: Many internal tasks consist of replacing and assembling several parts of a machine, a file of information, a kit of some kind, and any other setup that has several components. Take the above example of the pit stop – a tire change consists of replacing a tire mounted on a rim. By mounting the tire on a rim prior to the pit stop, what would otherwise be an internal activity (putting the tire on the existing rim) has been converted to an external activity, at the expense of having an extra rim. Another example is the use of a kit of materials, tools, parts, etc., that eliminate searching and selecting. A large part of internal operations that is usually considered separately is measuring and adjustments, to assure that the value creating operation produces an output that meets specification. By standardization, these operations can be eliminated.

Simplify and automate all remaining internal operations to speed them up: Further setup reduction allows value creation to more closely match demand economically, but safety, repeatability, and ergonomics must not be sacrificed. This calls for simplification and automation of tasks such as fastening, moving, data entry, and communication. Special tools and programs, codes and signs, design for changeover, and other similar approaches are utilized to gain speed.

It is, of course, also necessary to apply some of these techniques and technologies to the external setup. With shorter setups, and shorter periods of value creation between setups, external operations must be carried out in less time. This means better organization, simplification, mistake proofing, and automation.

Saturday, September 6, 2008

Shingo's insight: separate internal end external to reduce setup by half

Let’s look at what Shingo discovered about setting up stamping presses. He spent time observing the setup process, and had the great insight that there were two kinds of activities taking place: Those that required the press to be stopped in order to be carried out, and those that didn’t. Both were done while the was press stopped.

Typical activities that require the press to be stopped: unbolting the die, pulling it out of the press, bolting the die in place.

Typical activities that can be done while the press is running: finding the next die, and moving it next to the press, finding wrenches, and other tools, placing the new material next to the die.

Shingo called the first kind of activity “internal”, the second kind, “external”.

He found that typically, half the activites done while the press was stopped were external. As an industrial engineer, he realized that a bit of planning would yield a significant reduction in setup time. If the tasks that did not require the press to be stopped were done while the press was running, then the changeover would take half the time.

There are lots of reasons why internal and external elements are mixed – only one person is doing the setup, and there is no time to prepare, the next job isn’t chosen until the current run is finished, running the press and setting it up are separate jobs, and the setters wait until the run is finished, there is no pressure to set up quickly, the amount of time for setup is part of the schedule, so there is no need to rush, no one believes that setup can be reduced, everyone involved in the setup appear to be working as hard as they can, everyone hates setup, and want to stretch the run until the end of their shift.

The question that remains, once Shingo’s insight is understood, is how to put in place countermeasures to these reasons for long setups.

Friday, September 5, 2008

Setup - the great barrier to delivering more value

CUSTOMERS want different things, in different quantities, at different intervals – what we call VALUE. All value creators, be they manufacturing companies, service providers, such as healthcare, accounting, taxi drivers, or retail stores, community groups, government, and any other means of value creation, have customers. How they deliver value to customers has a significant bearing on the opinion the customer has of the value creator. There is no right or wrong in this opinion – it is just what the customer wants. When the customer has a choice of value creators, they mostly choose the one that delivers value as nearly as the customer wants it delivered.

As choice broadens, customers act more and more on their wants. But no two customers are alike – each one has different needs and desires. The value creator who wants to be the provider of choice to the largest number of customers, must be able to meet the broadest range of needs and desires. To do so economically is the challenge that has always faced value ceators – how to set up the value creating process to meet a multitude of different customer requirements.

Despite an increase in knowledge, about machinery, chemistry, information processing, ergonomics, consumer behavior, and all other aspects of the creation and consumption of value, it is still a challenge for most value creators to provide the low volume, high mix, offerings required to meet customer needs, in an economical and timely manner. The great barrier is setup – believing that it can be reduced, determining how to do it at relatively low cost, embracing it as a strategic business tool, simplifying it to sustain it, and constantly challeging the current method to do better in the future.

Success in setting up quickly and correctly is referred to as SMED or Quick Changeover. SMED stands for “single minute exchange of die”, and refers to the challenge of setting up a metal stamping press in under 10 minutes. Shigeo Shingo, who wrote “A Revolution in Manufacturing: The SMED System” developed many of his ideas about setup reduction from stamping press studies.

This blog is dedicated to exploring all aspects of setup reduction.