Sprue
In sand casting and injection molding of metal and plastic, the sprue is the part of the molded part that does not belong to the molded part. It is formed by the solidified into the supply channels to the mold melt and should have as little weight to drop to avoid.
When several injection molded parts are produced at the same time, the channel or sprue system must be designed in such a way that the molded parts are filled simultaneously and evenly with a melt of the same pressure and temperature .
The sprues are usually removed by hand by knocking off or shearing and cause a not inconsiderable part of the costs, since the rest of the casting process can be automated. It should be noted that the sprue always leaves a small flaw in the surface without expensive reworking. Sprues from thermoplastic injection molded parts from Hobby model making are often left on the parts and must be removed by the user.
If the material in the sprue also serves to compensate for shrinkage , it is also referred to as a feeder .
See also
literature
- K. Stoeckhert: Kunststoff-Lexikon, 7th edition, Hanser Verlag, 1981, ISBN 3-446-13088-8 .
- G. Menges: Introduction to plastics processing, 2nd edition, Hanser Verlag, 1979, ISBN 3-446-12863-8 .