“There is no future in seaside buckets and spades”, said Commercial Manager Richard Kempa four years ago when discussing the reasons why Waldon Ltd. had installed Kistler Instruments’ Como Injection cavity pressure monitoring system in 2009.
The aim was to reduce the 5% internal reject rate to increase productivity and eliminate the risk of rejects reaching the end customer. Within 12 months a second system had been installed on an eight cavity mould and the internal reject rate was down to less than 1%. Richard Kempa again, “Good quality processing is essential to good product quality and the Kistler Como Injection system provided us with a window into the cavity. As a result, within 12 months Waldon had become best in group for product quality and virtually zero reject production.”
The company’s Commercial Manager, Richard Kempa is an engineer, not a “bean counter”, and is well aware that success in the injection moulding market depends on quality, precision and dependability. After all, customers expect to get the mouldings needed to keep their own production running at top efficiency; missing delivery dates or delivering out of specification products is the quickest way to lose business and reputation. According to Richard Kempa, just one customer complaint can easily cost the company £10,000 to rectify, not to mention the damage to customer relations.
This high cost of customer complaints made it a “no brainer” to take full advantage of the Como Injection system by installing upgrades as they became available. In 2012, the success of the systems over the previous three years gave Waldon’s parent company the confidence to approve a £1M investment, including installing ComoNeo, the latest, and more comprehensive process monitoring system. The new system expands the use of cavity pressure-based analysis to provide automatic optimization, monitoring and documentation of the whole injection moulding process.
Although the new ComoNeo system is more sophisticated than the system it replaces, it is considerably more user-friendly whilst providing far more detailed information on the production process. In particular, ComoNeo identifies rejects precisely, including notification of which cavity produced the reject, and delivers them automatically to a robotic handling system for recycling. The high level of process control and monitoring provided by the new system allows Waldon to run its injection moulding machines “lights out” for 24-hours a day, six days a week with rare problems being advised to the duty maintenance engineer by an automated SMS message. But perhaps the major benefit brought by ComoNeo is the dramatic reduction of rejects which is now less than 3ppm and is forecast to be zero shortly.
“Let’s be honest” says Richard Kempa, “the injection moulding industry has been talking about achieving zero rejects for many years but it is only recently that we have actually achieved genuine zero rejects consistently throughout production. At Waldon that has been made possible by the Kistler ComoNeo system where the only scrap we produce is at machine start up. What more could we want?”
Well, it turns out that there is something more and that’s the latest development to the ComoNeo system; something called MultiFlow, the next link in the automatic control of the whole moulding process; fully automatic hot runner balancing.
Adding MultiFlow to the ComoNeo capability monitors the pressure profile of each cavity of a hot-runner mould from injection, through compression and holding, to the cooling phase. During the injection and holding pressure phases, the MultiFlow software analyses the pressure curves in all cavities. The synchronous rise in pressure in all cavities is achieved by the system automatically calculating the optimal setpoint temperature for each hot runner tip, which is then transferred via an interface to the hot runner controller.
The mould is automatically balanced during process start-up, and continuous optimisation keeps it stable throughout the production run. The balanced mould always exhibits congruent cavity pressure curves during the injection and holding pressure phases. At the same time, ComoNeo continuously monitors the quality of all of the parts produced and signals any need for automatic separation of rejects.
Hot-runner balancing with MultiFlow completely eliminates the need for time-consuming manual optimisation and adjustment of the hot-runner temperatures during set-up and production. The system compensates in real time for variations in the operating environment, such as temperature fluctuations caused by external doors being opened or changes in the external air temperature and humidity, which can increase reject rate, especially at the tight tolerances adopted by Waldon. The precise control over the entire injection phase consistently delivers a process capability (CPK), of much better than 1.33.
Kistler ComoNeo with MultiFlow hot runner balancing is highly sophisticated but is exceptionally easy to set-up and to operate. This has been demonstrated at Waldon Ltd by Miguel Nogeuroles, a Spanish graduate trainee from the Polytechnic University of Valencia, who taught himself to set-up and use the system in two days, with only the operation manual and two telephone discussions with Duncan Webster, Kistler’s ComoNeo specialist.
The operational benefits of achieving “genuine zero rejects” are considerable. From a business point of view, foremost is the ability to accurately quote for new business by eliminating the need to include a contingency allowance to cover the cost of rejects. This delivers a confidence that the costing is both accurate and achievable resulting in highly competitive pricing for even the most complex mouldings. Add to this a return on investment of around six months it’s no surprise that Waldon is now equipping all new moulds to take advantage of the ComoNeo automatic control of the moulding process.
As an engineer, Richard Kempa is not given to hyperbole but he confidently declares that “ComoNeo with MultiFlow is just wonderful”.
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