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The plastic parts made by these molding techniques have some characteristics. You can find
them on the parts used for this robot as well as other plastic parts around your house. Here,
the typical phenomena is explained in the case of injection molding.
・
Gate
In injection molding, there must be a gate to pour in the plastic. The solid plastic taken out of
the molds has the extra amount at the gate and it will be cut off to finish the part. Therefore,
the plastic part made by injection molding has a remain of the gate. Let’s try to find the marks
of the gates on the various plastic parts. Since cutting off the extra plastic at the gate makes a
mark on the plastic part, the gate is often located at the position, where it will not be noticed.
・
Parting line
The melted plastic will be pressed into the molds to spread all over the inside. Though the
molds are joined tightly, there will be partings between the molds, and the melted plastic will
get into there, making the line on the surface. This line is called the parting line. Since the
parting of the molds makes this line, it is usually designed to in such a way that the parting
lines will not be noticeable on the finished product.
2. Molded Plastic Parts
●
The characteristics of injection molding
A remain of the gate :
Melted plastic was poured in here.
Parting line
The part where the
molds meet.
・
Gate
・
Parting line
