A feasibility study of manufacturing methods for large size moulds

Abstract

Most very large moulds are manufactured in Europe, especially in Germany and Italy. The main reason being that South Africa does not have enough very large size CNC machines on which these could be machined. A large size mould half can be split into two or more smaller parts for machining purposes and then reassembled later. In this way many large size moulds, especially rotational moulds can be manufactured on medium size CNC machines. Since the large component has been split into small parts, these can be distributed to different subcontractors to machine simultaneously, and thereby reducing the total manufacturing lead-time. The project then uses three case studies to advance the proposed concept for mould manufacture. A small size rotational mould for a model drum is manufactured to confirm that Pentech had both the infrastructure and required skill to make a rotational mould of any sort. Then a medium size rotational mould of a steering wheel is manufactured. This case study is the key and longest stage in this project; it consists of the full process of mould subdivision followed by full mould manufacture, some subcontracting of parts and lastly full product testing. Finally, a part of a large size mould was manufactured for purpose of investigating all aspects around the subcontracting ofmould parts. In the first case study the clamping strategy used through out as an integral part of the subdivision strategy is proven. The second case study using the medium size rotational mould successfully demonstrates the subdivision concept, along with its material savings. This second case study also introduces the idea of including CNC lathe parts. Lastly, the third case study using a large size rotational mould proves the contractibility of the mould segments using NC files, despite certain industry leaders believing that machine shops would not be interested in accepting work on the basis ofNC files