Mastering product versatility with Engel injection moulding machines

Heavy-duty connectors for commercial and industrial use are the mainstay of a German family business, Bals Elektrotechnik, whose head offices are located in Kirchhundem-Albaum in Germany’s Sauerland. A broad range of models, safety and flexibility are best practices that Bals lives up to every day. This is clearly evidenced by a tour of the production facility in Freiwalde, Brandenburg where some 4000 different plastic components for almost 3000 different types of connectors are manufactured using 500 injection moulds.

After successfully completing a restructuring process, a new and highly-flexible approach to injection moulding production, which was designed and implemented in cooperation with Engel, ensures improved competitiveness. The central aspect of the production design is that of restricting machine deployment to just two sizes, global use high speed mounting systems and standardization of machine/mould interfaces. Electrical connectors are very common standard parts! If this is your opinion before you visit one of the manufacturers of these industrial products, reality will soon teach you a different lesson. The real situation is completely different, as there is no such thing as a universally valid standard. This is caused by the need to observe national legislation and situations on the one hand, and the requirements of specific applications on the other. The consequence is a huge number of configurations and just as many connector types. No matter whether you need a connector for use in a dusty environment, in case of strong vibrations, in a moist environment, or in contact with chemicals – special configurations are needed for every single application.

- We manufacture up to 3000 connector variants, from simple 16 A wall sockets and matching plugs, through to heavy-duty 125 A connectors. Our range covers everything from industrial configurations to military specifications. Our mission, of serving the market as a full-range manufacturer, demands this kind of product diversity - says Dr. Gerald Sondermann, Director of Production, describing the situation, and adding the following while walking through the injection moulding production department: - As more or less 100 percent of our connectors and sockets are made of plastic, we have 500 ‘active’ injection moulds, and we manufacture 5 to 10 different plastic components with each one.

But this does not do justice to the company's product diversity. On top of different configurations, colour variants are required for standards compliance. In our assembly shop, we combine them with contact inserts and add-ons – which depend on the country and customers specifications – to finish the final connector variant.

In this environment, flexibility is the key to success – flexibility in both production and logistics. Optimisation, that is minimisation of the quantities of semifinished products kept in stock – is a major success factor. The consequence for parts production is a plant concept that guarantees a minimal response time to a product order. The search for this optimum concept was part of a major
restructuring process. Head of production, Sondermann: - We discussed the task with several injection moulding machine manufacturers, however, Engel gave us the most convincing answers, not least because they went far beyond the norm and showed us a fundamental change in our approach to production.

Comprehensive analysis of the existing range of moulds was the first step in the restructuring project. Part sizes, shot volumes, mould sizes and opening strokes all had to be recorded and categorised. The aim was to identify a standard, universally deployable machine type and introduce sufficient numbers of the right machine. The machine pool would allow the manufacturer to achieve maximum product flexibility without needing to worry about specific machine/mould combinations. After evaluating all the technical data for the moulds, a compromise in the shape of just two machine types, with clamping forces of 900 and 1200 kN, was found.

Production capacity was distributed to support two machine pools, comprising 11 machines from the Engel victory series with tie bar-less, type 500/90 clamping units, and 3 Type 500/120 machines; thanks to their identical technical resources, the two pools supported flexible production assignments. But this
was not sufficient in itself. To be able to leverage free capacities without technical barriers in each machine class, it was necessary to standardise machine/mould interfaces throughout. The basis of this standardisation was to equip all the machines with Engel’s proprietary high speed mounting system.

For the injection moulds, standardisation meant retrofitting adapter platens and matching tensioning bolts. With respect to media connections, Bals also opted for standardisation, but not for fully-automated coupling. The aim was to give the machine operator maximum support.

Central media terminals and labelling of all media lines help to avoid errors and reduce the installation time. On top of this, conventional sprue cones and runners still exist, and need to be removed by sprue pickers – all machines are fitted with “Speed Pickers” manufactured by Engel. As sprue is separated from the moulded parts, free-fall demoulding is possible. - Six to ten mould changes in an 8 hour shift are business as usual for us. Short-term production orders no longer seriously faze us, compared to previously because our fast and trouble-free retooling processes bind far less human resources - says the production manager looking back. The ‘flexible’ department manufactures
most of the connector components.

This department is supplemented by a custom production shop which manufactures the 2-component moulded parts for patented cable pull relief products. It goes without saying that a full range of sizes is served here, too.

Specialties and enormous variety, and thus genuine customer and task-orientation characterise Bals's production. - Our cooperation with Engel has already borne fruit. Thanks to rationalization effects we have been able to increase our production capacity and turn the Freiwalde Plant into a competence centre for high-voltage connectors inside our company. This has helped us create further jobs and further improve our competitiveness. All told, we can look back on a successful project - says Product Manager Sondermann summing up.