There are eight basic steps to reducing changeover using the SMED system which can be implemented as
Develop and complete the external set-up checklist.
Create a list of molds/dies, tools, fixtures, materials and gauges.
Develop and complete set-up reduction observation forms.
It includes the following steps
- Observe the whole process (videotape if necessary).
- Identify and list each step.
- Time each step (from last good part to first good part).
- Classify into P, R , L or A activity.
- Classify into internal or external activity.
The P, R, L and A activities are
P – Preparation activities – This is the preparation stage for changeover (or set-up).
- Actions performed to support the changeover process
- Ensures all parts, tools and dies are located in their proper locations before and after a changeover has occurred
- Includes both transportation and storage of these items
- The quality of the materials and tooling being utilized must be verified.
R – Replacement activities – It includes mounting, replacing, securing and removing of dies, tooling, blades, etc. after completion of the process. The attachment of parts and tools needed to perform the next job
L – Locating activities – It refers to the measurements, settings and calibrations that must be performed to successfully complete a process. It involves performing the various activities like centering, aligning, dimensioning and adjusting temperature and pressure which places items in their proper position:
A – Adjusting activities – They are actions repeated in order to attain the correct machine setting to produce an acceptable part. It is the most difficult aspect of the changeover process and its frequency depends on the pre-planning and accuracy of previous steps (P, R and L)
Convert internal to external set-up
The third step is the most important step. Here company involves subject matter experts and brainstorm on the following
- Re-examine operations to see if any steps were mistakenly assumed to be internal.
- Analyze ways to convert internal steps to external steps.
- Move required materials and tools to the workstation prior to the start of the changeover.
- Remove previous tools and materials after the changeover is completed, or, use separate material handlers for the task.
Standardize
In it, the size changeover tools are examined and replaced with standard sizes as with aging of machines, their maintenance deteriorates, as they are often fitted with non-standard parts (sometimes due to non-availability of the original parts). In this step, company remedies the situation by
- Standardizing sizes and dimensions of machine parts and tools.
- Standardizing functional elements of tooling, fixtures, molds/dies, etc.
Standardization requires uniformity necessary for set-up operations like
- Clamping
- Centering
- Dimensioning
- Grasping
- Removing (expelling)
Use clamps and “one-touch” fasteners
It involves
- Use one touch functional methods such as wedges, cams, clamps or springs.
- Use interlocking methods that simply fit and join parts together.
- Analyze the direction and magnitude of the force required in clamping methods.
Use intermediate jigs
As intermediate jigs reduce external and internal set-up time, they can be used on large machines with multiple dies/guides/molds to reduce clamping and positioning time
Adopt parallel operations
Company should clearly define each and every person’s role and responsibility during the changeover/set-up operation. It should be synchronized such that not even a second is wasted. This step benefits as
- Two people performing operations simultaneously reduce the muda of movement.
- Increases the operating rate of the machine
- Parallel operations can reduce set-up times
Eliminate adjustments
Company should clearly differentiate between settings and adjustments. Settings occur when the position of a limit switch is changed. Adjustment occurs when the limit switch is tested and repeatedly adjusted at a new position. Adjustments can be eliminated if a gauge is used to precisely determine the correct position of the limit switch.
