First step is to make a casting pattern, which typically has two parts (upper and lower pattern). The pattern is made e.g. from wood, aluminium or polystyrene, depending on the wear and accuracy demands. A single pattern is attached normally to a moulding plate, and around it is put a mould frame (flask) for the mould making purpose. The frame is filled with sand, which is compacted tight and dense through a vibrating process. Into the upper main mould is also put the feeding and gating systems and risers.
Another possibility is to make just one-piece mould. In this method the mould frame is filled in two steps. The mould frame is opened for casting pattern removal after the upper part sand has hardened. Single-use styrox-pattern can be burned without opening the mould.
When the cast part includes hollow shapes there is needed a mould core, which is hardened and if needed coated. After the mould sand is hardened the patterns are released from the moulds. The mould parts are coated, possible cores are put in place and the upper and lower mould are attached to each others. After this the molten metal is poured into the moulds. After the metal has cooled down the mould frames are dismantled and the sand moulds are broken away. After cast part final cooling down the feeding and gating systems are fettled away. In the end the cast parts are sand blasted and the necessary machining and coatings are done.
Typical products and part sizes
Typical products from our factory partners are e.g. rock crushers and other equipments frames and wind mill hubs. The part weights can be from 30 kilos to 30 tons.
Iron and steel grades
The most common grades are ductile iron = nodular cast iron (GJS=GRP) and grey iron (GJL=GRS) and various steel grades.