METHOD FOR FORMING VACUUM-SEALED MOULD

摘要

Method for forming a communication hole or sprue in a vacuum sealed mould comprises placing a hole forming pattern(3) in a mould cavity(5) and applying a 1st. shield member(4) over the cavity forming and hole forming patterns. The mould is then formed by charging the cavity with particulate material(7) while the applied vacuum forces the shield members(4,8) into contact with the charge. The two shields are then welded along the periphery of the top of the forming pattern. The material is then cut along the joint line and the hole forming pattern is removed. Method reduces the cost of the mould forming process and avoids the risk of damage to the main mould body when the communication hole is formed.