5.25 - Process Changeover Reduction

Key Factors

Quick changeovers are an integral part of the JIT philosophy. The benefits of quick changeovers can be realised by simply changing the way in which we go about changeovers. It is estimated that 80% of the possible reductions can be achieved by improving changeover methodology. It is not as simplistic as working faster. It means designing the whole system to be more effective with target changeover times at about a minute. The potential benefits to the business include the outputs on the input / output diagram below:-

Using small dedicated teams, creative thinking, sound engineering principles and an open mind it is possible to achieve big reductions in the time needed for changeovers. There are two main elements in achieving quick changeovers and four key steps are required improve things.

The two elements are:-

Internal - Operations can only be performed when the machine has stopped (e.g. tool change). Improvements may include:-

• Quick change tooling
• Better tooling design to eliminate a number of changes
  Standardised locating base plates
• Combined left and right hand tooling
  Stabilise process capability and tolerance limits
• Use of common datum
• Rationalised component design to minimise changeover times
• Parallel operations etc.

External - Such operations can be performed whilst the machine is still running and are management activities with reduced support elements. Improvements may include:-

• Pre-setting of tools
• Pre-kitting of gauges
• Used of prepared base plate assemblies incorporating fixtures
• Ensuring all equipment is ready
• Getting NC tapes or CNC programs ready
• Rehearsing the sequence using video and
• Training of operators and manufacturing craftsmen.

The four key steps can be summarised as follows:-

When steps 1 - 4 are complete then:-

• Define areas for continuous improvement and practice
• Set performance standards and targets
• Regular formal audits to evaluate rates of continuous improvement