The main reasons for insufficient filling are as follows:
I. Insufficient resin capacity.
Ii. Insufficient pressure in the cavity.
Iii. Insufficient resin fluidity.
Iv. The exhaust effect is not good.

As improvement measures, we can mainly start from the following aspects:
(1)increase the injection time, prevent the short moulding cycle,cause the reverse flow of resin before curing the gate which lead barely fill the mold cavity.
(2) Increase injection speed.
(3) Increase mold temperature.
(4) Increase the resin temperature.
(5) Increase injection pressure.
(6) Enlarge the gate size. Generally, the height of the gate shall be equal to 1/2~1/3 of the wall thickness of the product.
(7) The gate is set at the place with the largest wall thickness of the product.
(8)Set exhaust slot (average depth 0.03mm, width 3-mm) or exhaust rod. It is more important for smaller workpieces.
(9)There is a certain buffer distance (about smm) between the screw and the injection nozzle.
(10) Select materials with low viscosity grade.
(11) Add lubricant.