Rugby Plastics, part of the Thomas Dudley family, has recently invested in smart manufacturing equipment and systems, including Wittmann 4.0 and Temi+ MES packages. BP&R sits down with Dr Stephen Pepper, Managing Director, to discuss how these benefit the business.
rugby plastics
Not so long ago, the term ‘black art’ applied to several plastics manufacturing processes. The injection moulding sector was one of the first to lose this label, led by experienced businesses who tackled complex moulds and produced parts in any material – a competence often referred to as ‘technical moulding’. Fast forward to today’s Industry 4.0-based factory, all the attributes of ‘technical moulding’ need to harness the successful use of data.
Back in the pre-connected world, setting and operational skills would have to regard the machine system as one of pressures and speeds, subject to basic programming from the control panel. Machine setters and operators – often via trial and error – would use handwritten notebooks to record the typical parameters for each different job. Ancillary equipment – materials handling, automation and granulation – would be mixed and matched piece meal as various jobs required.
For Stephen, this approach is history. “As suppliers of manufacturing services, we still never know what challenges will be presented in terms of new products from new and transferred tools, wider material ranges, improved sustainability demands and quality requirements, all while reducing operating costs.”
However, the key to successful injection moulding today is data management. As Stephen says, “The most important question to ask of any new production system is: what data can it supply us with?
He continues: “Today’s IMMs generate an enormous amount of process information. Real benefits arise from leveraging the accurate and real-time information from the whole system. The machine data can tell us exactly how to decrease cycle time, improve quality and ensure full traceability, transparency and repeatability while reducing energy cost and eliminating error. Data know-how enables us to make finer adjustments to the whole production system to deliver profit.”
Such useful IMM machine data can include:
- Process stability trends
- Critical-to-quality parameters
- Cycle variation
- Statistical capability indicators
- Deviation alarms and analysis
- Real-time monitoring
“Good decisions are made from useful data, not just more data,” Stephen claims. “As moulding moves further into Industry 4.0 thinking, processors increasingly need machines that don’t simply run parts but also provide insight into their own processes.”
Data management begins with the end in mind
Previously, the injection moulding cell was described in physical terms: sizes and kN forces. Today’s production cell has a complete virtual/informational counterpart, visible to the user through the ‘dashboard’ of a Manufacturing Execution System (MES). Stephen explains, “Such systems have been available for many years, and most can provide useful information on productivity and wastage. Many of the latest IMM’s also allow a direct real-time interactive communication interface to a MES via OPC type protocols. In an ideal world, your MES system should provide:
- Visual dashboard for all to see
- Efficient production planning
- Real-time production monitoring and alerts
- Real-time IMM process monitoring
- Key reports such as OEE, OTIF, Machine Downtime, Cycle time variance
In addition, it could also incorporate:
- Tool maintenance scheduling
- Machine preventative maintenance schedules
- Quality control measurement and reports
- Upload/download machine process cycles
- Ability to access all relevant documentation directly from the MES, such as drawings, quality standards, maintenance procedures and other process information
HMI: critical for operations
In the wrong hands, today’s smart machines and MES systems could generate much more ‘noise’ than ‘signal’. The successful IMM machine designer needs to create an extremely friendly human interface, where raw data becomes useable information and key aspects of production are easily communicated with clear iconography and text. “A user-friendly machine is essential for our moulding technicians,” says Stephen. “As the main user, a logical, fast HMI (human machine interface) ensures that process trials can be conducted quickly and that salient data is captured to generate comprehensive process cycles which can be saved and recalled at will.”
Rugby Plastics sources all Wittmann technology, including the B8 Control system. This offers a large display screen with easy-to-use tabs for each major setting function. The screen input flow is systematic and provides instant graphical information to aid the process of setting.
Overall machine cost – not the same as price
Ergonomics are one significant factor in improving operations. Another is the total lifetime cost. At one time, IMM selection simply involved issues of clamp force, shot weight, tie bar spacing and price. Stephen expands this further, “The purchase price of an injection moulding machine is only the beginning. The bigger question to ask – not necessarily an easy one – is: what will it cost me over the next 10–15 years?” When purchasing a machine, you should think beyond price and finance cost and consider:
• Energy use
• Maintenance requirements
• Downtime risks
• Spares availability
• Productivity gains
“As we all know, the rising cost of energy has become a major issue for a moulder – unlikely to diminish in the long-term”, he says. “Moulders owe it to themselves to conduct energy validation processes as part of their machine purchase process.” Rugby Plastics undertook a controlled comparison between a Wittmann SmartPower machine and an older machine, measuring energy consumption using both external monitoring equipment and the IMM’s built-in energy monitoring function. The results demonstrated an energy saving of 80.4 kWh/1,000 parts, equivalent to 82.3%. This clearly proves that the cheapest machine is not always the least expensive machine.
Make more of your space
Space is normally at a premium in most successful legacy moulders. Recent machine orders have been won or lost in the marketplace because of being oversized by just a few centimetres. The question of 3D machine footprint has risen in importance over the last ten years. Plus, a moulding machine never arrives alone, which suddenly makes the production cell footprint much larger than expected.
Stephen concludes, “The needs of a complete cell layout keep enabling us to source larger-capacity systems to be introduced without major increases in occupied floor space. Thinking in terms of complete production cells rather than individual machines can unlock capacity you didn’t realise you had.”