Design flash gate will be applied to the plate shaped molded product. This type is effective at preventing deformation by suppressing residual strain. It appears a litter in mold design.
1. Advantages and disadvantages of flash gate.
+ Flash gate usually use with big product and thickness is thin. If resin of product is acrylic, we usually use flash gate.
+ To prevent bending of product.
+ Melt plastics easy to fill in molding cavity.
+ To prevent weld line.
+ Lose more time to cut gate.
+ After removed gates, appearance of product after gate position is not good.
2. How to design flash gate?
Recommended dimension is approximately 0.2 mm to 0.6 mm in thick, the land area (parallel runner) is also been kept small approximately 0.6 mm – 1 mm depend on the large and weight of product.
Dimension of flash gate can calculate by picture above.
S: Thickness of product.
H: Thickness of film gate.
L: Length of flash gate, L= 0.5~0.2 mm.
D: Diameter of runner where connect between flash gate and main runner. It calculates by the formula.
D= (S~4*S/3) + k
k=2 When a product has small length, k=4 with a product has long length.
You can read runner design at https://mechanicalengblog.com/plastic-injection-molding-runner-system/