The problems that can occur in the case of pin point gate structure are the following.

These are the problems that a mold designer has to solve whenever adopting a pin point gate.
Some technical measures for solving these problems are described below.

Fig. 1 shows the structure of a general pin point gate. This is the shape when the gate design is made without any special considerations.
On the other hand, Fig. 2 is a design in which measures have been taken to solve the above problems.

Key factor 1: Gate land length L

If the gate land length is longer than necessary, at the time of cutting the gate part, it is possible that the gate gets cut in the middle thereby leaving a projection on the molded product.
As a rule of experience, it is recommended that the gate land length L is in the range of about 1 to 2 times the gate tip diameter d.

Key factor 2: Gate opening angle A

As an opening angle, a gate is provided with a conical shaped taper. If it has a conical shape, at the time of cutting the gate, the possibility becomes high that the gate is always cut at the minimum cross-section part where the gate and the molded product meet.
In addition, even releasing from the mold becomes easier. Generally, the value of A is about 15 to 30. Although the cutting becomes definite when the value is large, there is also a trend that the wear of the tip part progresses faster.

Key factor 3: Recess

If the gate is made to penetrate more into the molded product by forming a recess at the surface where the gate meets the molded product, even if there is a projection at the cut part, it will not project beyond the surface of the molded product.
For providing a recess, it is always necessary to get the permission in the drawing for the change in the specifications from the designer of the molded product.

Key factor 4: Dimple

A dimple is a spherical shaped depression provided on the side opposite the gate of the same extent as the ordinary wall thickness of the molded product so that the molten plastic can flow in a stable manner.
Even for providing a dimple, it is always necessary to get the permission in the drawing for the change in the specifications from the designer of the molded product.

In the above manner, if considerations are given in the design aspects, and also, if the gate has been machined accurately using electric discharge machining, etc., there is a very high probability that the above problems are solved.