Managing Manufacturing Bottlenecks

A manufacturing bottleneck is a constraint or choke point that limits production output.  Many manufacturing operations suffer from bottlenecks caused by one or more machines and the bottleneck may change depending upon the actual product being manufactured. Identifying and managing manufacturing bottlenecks can have a major impact on output and profits.

A bottleneck restricts all production and time lost at the bottleneck can never be recovered. Attention and resources should therefore be focussed on bottleneck machines to ensure that they continue to run as long as possible.

A real time manufacturing information system like PlantRun can be invaluable due to the indepth analysis of historical data available and control parameters with alarms, maintenance efficiency.  Ways of effectively managing manufacturing bottlenecks include;

Optimise bottleneck machine speed

As the bottleneck machine restricts production it is commonly assumed that it should be run as fast as possible.  However this may not be true in all situations as faster running may increase downtime due breakdowns, maintenance and reduce yield due to poor quality product. 

By analysing the effects of different run rates using Plantrun it is possible to track whether faster running does adversely impact production and to achieve a proven optimum running speed.

Ensure the bottleneck machine is well maintained

Resources should be focussed on the bottleneck machine to ensure it can run effectively for as much time as possible.  PlantRun monitors machine cycles and can alert when maintenance is due on any machine based on usage ensuring maintenance is neither under or over performed.

Effective maintenance also improves yield by minimising scrap, rework or poor quality product being produced at the bottleneck. Errors produced by a bottleneck further reduce its output. You should also ensure that high quality product is received at the bottleneck as errors created upstream negatively impact output at the bottleneck.

Provide a constant buffer stock upstream of the bottleneck

Bottleneck machines should never be stopped because of a shortage of stock or materials.  This can be avoided by ensuring that there is a buffer stock in front, upstream of the bottleneck.  Putting a buffer stock in place does increase inventory (WIP) and associated waste and costs so it should be kept to a minimum.

To do this PlantRun monitors buffer stock and alerts staff when stock needs replenishing.  Plantrun can also go further by automating product flow through a bottleneck based on the drum buffer rope ‘pull’ scheduling of Lean Manufacturing.

Reduce time wasted in set ups and changeovers

To keep the bottleneck machine running longer, changeover times should be reduced. When you have a bottleneck there is little benefit reducing changeover and setup times on non bottleneck machines. You should focus on the constraint or chokepoint and techniques like SMED - Single Minute Exchange of Die can be used to reduce changeover time.

PlantRun can ‘count down’ to a changeover or set-up period and alert staff beforehand. This allows staff to prepare for the changeover while the machine is still working.  Careful analysis should be done to see if any work that is normally done during the changeover can be done before or after instead – minimising downtime.  PlantRun can be used to analyse changeovers on the bottleneck machine to identify ways to reduce downtime and track the effectiveness of initiatives taken.

Also by using the PlantRun Recipe facility unlimited settings can be stored electronically to automate changeovers and tool setups.

Train more operators for the bottleneck machine.

To ensure that bottleneck machines are not idle due to a lack of operators, staff should be cross trained to use them. The PlantRun On-line Maintenance facility aids operator training by storing training documents and videos centrally for easy and convenient access.

Run the bottleneck machine longer than other machines

Where possible it may be advantageous to add shifts, overtime or operators. This can allow the bottleneck to be run longer than the other machines.  Although this may seem an expensive option, the overall impact on production can be positive.

Continuous Bottleneck Management

As you manage, control or eliminate one bottleneck it may shift or another appear which in turn becomes the focus of attention.  The product mix, raw materials variation or other factors may alter the bottleneck from one day to the next.  Managing manufacturing bottlenecks therefore becomes a continuous process and a real time system like PlantRun is an invaluable tool for bottleneck management.

Depending upon the severity of the bottleneck it is often presumed that capital expenditure will be needed to replace or augment the assets that cause the bottleneck. However with effective management most bottlenecks can be controlled and improved without extra capital investment in new or replacement assets.

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