| abstract |
The moulding block has three cavities, connected to a common sprue. In the first operation material is injected via two shorter sprues to two parts of the moulding, any material flowing in to the third and longer sprue being discarded. The two part-mouldings are then extracted and placed together in the third cavity, there being a space between the two parts which butt together at a common shoulder. In the second injection operation, material flows along the third sprue to unite the two part-mouldings together, while at the same time it also flows along the two other shorter sprues to produce two more part-mouldings, to enable the process to be repeared. |