Hasco Low-stress standard components pose a minimised risk of warpage
Germany – Developing and producing high-performance moulds for plastic injection moulding is a complex process. Hasco, a leading standard mould component manufacturer, explains why reducing the inherent stress in the materials used for all plate products is key for producing high-quality moulds.
When steel is produced and processed, stresses are automatically introduced into the material. This cannot be completely avoided. If these stresses are not consistently reduced through various methods and measures, they can lead to warpage after machining. Stressed processed plates are then of no use to the mould builder, and costs and delays will be incurred. Hasco minimises this risk of warpage over the length of the entire value added process – from the production of the steel at the supplier's works to the processing of the plates at Hasco, then right through to the provision of support for its customers in achieving the optimum design of mould.
At the steelworks, the steel used by Hasco for manufacturing plates is first produced by uphill casting and then formed to the desired dimensions by open-die forging or rolling. Stresses develop in the steel as a result of the heating, cooling and processing. To achieve a clear reduction in these stresses, Hasco has an agreement with the steel producers and suppliers that they should incorporate an additional production stage, namely stress relief annealing. The material is slowly heated to 550 to 650°C in an annealing furnace and kept at this temperature for up to two hours according to its size, which considerably reduces the stresses that have developed. Following this, the steel is cooled down gradually in order to prevent the build-up of new stresses.
The steel produced in line with Hasco's requirements is delivered in big slabs to begin with. These have to be divided into smaller-sized plates for further processing. Hasco employs a high-performance, automated sawing technology for this. The gentle separation process with a precision circular saw minimises the amount of stress introduced into the material's edge structure through continuous cooling of the saw blade and the material, among other measures.