The risk of scratch formation was greatest during retooling as well as during the regular polishing required by the steel mould inserts (material: 1.2343 ESU). In the worst-case scenario, this meant: remove the tool, allow cooling, strip down, re-polish and then remount – a process which can take up to a week, for example, if the mould needs to be sent out for reconditioning. That is an unacceptable situation for the high-performance production facility in Bocholt, because speed is essential. “A good 90% of customer orders require delivery already within three days,” says Stefan Schlottbohm. Immaculate results and speed – in light of these challenges, the suggestion made by coating partner Oerlikon Balzers to treat certain tools with the innovative BALITHERM PRIMEFORM method was spot on.
The BALITHERM PRIMEFORM approach creates a wear and scratch resistant diffusion layer with high surface hardness in the base material using a plasma-assisted process. Because this is not a deposited coating, but rather a ‘depth treatment’ of the surface, the tool can subsequently be polished to high-gloss with no difficulty. This significantly reduces the maintenance effort required because the moulds no longer have to be sent out either for re-polishing or for stripping and re-coating.
The demouldability as well as the injection and flow behaviour of the plastic material, in this case ABS, are also improved. This facilitates the manufacture of products which have nearly invisible weld lines and thus solves a ubiquitous problem faced by high-end suppliers in the industry.
Cycle duration reduced by more than 10 %
A further perpetual challenge is the reduction of the production cycle duration. In an initial step, BALITHERM PRIMEFORM delivered a reduction of about 10% at the Gigaset facility in Bocholt. Further improvements over the total product cycle of around four years with a projected quantity of approximately 570’000 parts appear to be possible. Up to this point, the single-cavity mould for manufacturing the charging cradle of the ‘Sculpture’ telephone as well as the two-cavity moulds for the charging cradle cover and the upper shell of the handset have been treated – all three are high-gloss components. Previously, moulds for structured elements were protected by a TiN coating which required additional maintenance work if damaged. “With BALITHERM PRIMEFORM, this, too, is a thing of the past. And if all goes as planned, the way will be clear for further high-gloss products,” predicts Stefan Schlottbohm, taking a look at future developments.