We usually design disk gate if shape of a product is a trough hole sleeve like moldings, which need a mounting of the core at both ends. It Used in the case of single cavity, or when placing the gate directly to the base of the molded product. Residual strain tend to occur because the injection pressure will directly apply to the molded product. Mold construction is the simplest. The disk can be of a plane circular shape or a cone usually with 90° taper.
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1. Advantages and disadvantages of disk gate.
A. Advantages.
+ To prevent weld line of product.
+ Resin fill in molding cavity easily and have good quality.
B. Disadvantages.
+ Gate cutting is difficult.
+ Mold making is more expensive.
+ We lose many resin for runner and gate.
2. How to design disk gate?
+ When we use disk gate for mold design, the ratio between the length of the core and its diameter should be smaller than 5
L/D <5
+ If the core is longer, it has to be supported on the injection side to prevent shifting caused by a pressure differential in the entering melt. In such cases a ring gate should be employed.
Dimension of disk gate.
A. Disk gate type 1.
+ t: thickness of gate, t=0.1~0.17mm
+ T: Thickness of disk, T – 5~10 mm.
+ D: Inside diameter of through hole.
+ d: diameter of disk gate.
D-d = 2~10 mm
B. Disk gate type 2.
+ L: Length of gate, L < 1mm
+ T: thickness of gate, T = 1.5~3mm
C. Disk gate 90° taper.
S: Thickness of product.
You can read runner design at https://mechanicalengblog.com/plastic-injection-molding-runner-system/
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