Aiming for zero defects

Birmingham (GB) based Barkley Plastics produce 6.5 million injection moulded parts each month, every month, making quality control an essential part of the business process.  With many end user customers now demanding “zero parts per million defects”, just a few out of spec parts in a delivery can incur significant costs.  This is a major problem, especially for export orders, when the parts are needed to keep a production line running.  The only solution is for the end user to manually sort the consignment and bill the cost, which can be more than the value of the order, to the supplier.  Like many injection moulders, Barkley have been using cavity pressure monitoring for several years to try to identify out of spec parts before they get into the delivery system.

For the past 10 years, Barkley had been using a simple 2-channel peak cavity pressure monitoring system that was difficult to set-up and had become problematic.  To protect its reputation and bottom line, two of the old systems have now been replaced with the latest 4-channel CoMo Injection systems from Kistler Instruments.  Interestingly, this new, state-of-the-art system cost about the same as the old system did 10 years ago making the much more sophisticated CoMo Injection system very good value for money.

According to Barkley’s Business Development Manager, Matthew Powell, by monitoring all aspects of the cavity pressure curve during the moulding process, the CoMo system ensures that all out of spec parts are rejected quickly and reliably.  “Because the CoMo system automatically provides perfect rejection of faulty parts,” he says, “it is possible to run the moulding machines in the dark with little or no supervision.” 

In addition to monitoring the process, the CoMo system can be used to balance the hot runners, which Matthew Powell describes as a “massive bonus” that is essential to maintaining consistently high quality parts.  This feature alone makes life much easier for setters and technicians, a benefit that is not always obvious.  The availability of accurate data about the performance of the moulding machines allows communication between departments to be based on hard facts, rather than experience and intuition.  Typically, mould design is part science and part knowledge and the precise data supplied by the CoMo system compliments the high quality tooling manufactured by Barkley Plastics in its in house toolroom and design facility.

Matthew Powell again, “Although the new system is much more sophisticated than our old system, it is actually easier to use.  However, to get the best results in the shortest time demands expert training, which is what Kistler supplied.  We have already minimised the number of rejects and can see the potential to eliminate rejects totally as we become more familiar with the CoMo Injection system”.

The injection moulding industry is very competitive with quality and zero defects often being more important than price, especially when the economy is far from buoyant.  A reputation for delivering a first class product will win new and retain existing customers more effectively than a low price.  With production running at around 80 million parts per annum, minimising rejects can make a major contribution to Barkley Plastics’ reputation and profits, which is why the company is now planning to install more CoMo Injection systems from Kistler.