Plastic Chair Backrest Molding For Office Chair

The calculation of clamping force in the injection molding machine

1. Empirical Formula 1

Clamping force (T) = clamping force constant Kp * product projected area S (CM * CM)

Kp experience value:

PS/PE/PP – 0.32;

ABS – 0.30~0.48;

PA – 0.64~0.72;

POM – 0.64~0.72;

Add glass fiber – 0.64~0.72;

Other engineering plastics – 0.64~0.8;

For example, a product has a projected area of 410 cm² and the material is PE, calculate clamping force.

Calculated by above formula: P = Kp * S = 0.32 * 410 = 131.2 (T), 150T machine tool should be selected.

2. Empirical Formula 2

350bar*S(cm^2)/1000.

As above, 350*410/1000=143.5T, choose 150T machine.

3. Two important factors in calculating clamping force

Projected area (S) is the largest area viewed along with mold opening and closing.

Determination of cavity pressure (P)

Cavity pressure is affected by the following factors:

* Number and location of gates

* Gate size

* Wall thickness of product

* Viscosity characteristics of plastics used

* Injection speed