set-up time is an important indicator of lead time. The capability of any
organization is demonstrated by how flexible it is to change between products or
services to meet customer demand. When demand fluctuates more flexibility is
required to deliver the product or services on time, every time.
There is a
direct correlation between changeover and lead time:
I always find
it interesting to ask a simple question during a first visit to a company. "How long does it take to changeover this machine to run the next
One answer I
received was, "Well, it
takes about an hour." One would think that because machine downtime
(including changeovers) is an factor which influences lead time that all
companies would track it effectively. When the changeover was recorded using a
video camera it actually took 2 hours 35 minutes to produce a good part. It
demonstrated a lack of understand by the management team about how to define a changeover.
The definition of changeover
The time between the last good
part off the current run and the first good part off the next run.
Typical most companies will
only include the time taken to changeover the tooling in its set-up time. However this
does not allow for all the other activities which must be completed to produce a
good part. There are four specific processes required to complete the changeover. Each process takes
a specific amount of time, lets take a look at a typical breakdown of changeover
activities. The following diagram shows these four processes based on the
percentage of time taken to complete:
||Measurements, calibration and
||Trail runs and
The length of
set-up time for
any machine or process will determine if you can "manufacture to
demand" or have to use "batch manufacturing."
The ability to
"manufacture to demand" requires a
very short set-up time to achieve total flexibility throughout the manufacturing
process in order to supply customers on demand.
Batch manufacturing is usually
a result of long set-up times which increases the overall lead time required to
get a finished product into the hands of the external customer.
Lean manufacturing creates an
environment where you only make what is required to meet the demand of the
customer. Long machine set-up times will not allow you to do this, so as part of
the lean implementation you will need to reduce set-up time, preferably to 10
minutes or less.
It is not unusual to experience
reduction of set-up time from hours to minutes by following a simple process
called "SMED" which is short for "Single Minute Exchange of
Dies." This process was developed in Japan by Shigeo Shingo during the
It required an analysis of the
set-up procedure to determine which activities are internal and external.
elements of work can be completed while the machine is still running e.g. get the
next tool, get all your clamps, get lifting equipment in place, put
equipment away, etc.
elements of work can only be done while the machine is stopped e.g. change
the tool, adjust the machine depth, sharpen a tool (which requires the
machine to be stopped), etc..
As you can see from the diagram once you
can define an internal or external
element, you can separate them. This will allow you to complete all external
elements for the next set-up while the machine is still running the current
parts. When the current run is finished, everything required for changeover to the next part is available and ready.
Set-up Reduction Case Study
TEiM coached Roplast Industries
Inc. through their lean implementation. Part of this process was set-up
reduction in a conversion area of their facility. There are several machines
which took on average 120 minutes to changeover to get a good part and the
machine was ready for production. Because of these long set-up times Roplast
would run a product for a long as possible (typically 3-4 days). Roplast
management preferred to build up inventory rather than break the machine down
and set-up the next job.
Over a period of 12 months and
after a series of kaizen events which focused on set-up reduction, the
changeover times are now down to an average of 23 minutes. Roplast has set a
goal to get the average changeover time down to 15 minutes.
When we first approached the
operators during a set-up reduction training session and suggested that they
could reduce their set-up times by at least 50%, many of them thought we were
crazy. After the first kaizen the set-up times were reduced to 38 minutes,
that's a saving of 68%.
The people at Roplast went
through a major paradigm shift which allowed them to take a chance at the
possibilities. In doing this they have achieved great success.
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