Close this search box.
Home » Blog » How does the injection molding machine produce finished products?

How does the injection molding machine produce finished products?

Molding conditions: speed, pressure, temperature, time, stroke, quantity.

1.Injection pressure (primary pressure): the pressure exerted on the plastic per unit area at the top of the screw during injection molding, P = cylinder diameter D0 / screw diameter D1 * hydraulic pressure.

2. Pressure retention (secondary pressure): molten raw materials in the cavity cooling, then a certain pressure must be applied to supplement its shrinkage part, increase the density, then the screw pressure on the plastic called pressure retention.

3. clamping force: (tonnage) clamping mechanism on the mold can be applied to the maximum clamping force.

F=K×P×A (K=0.4^ ~0. 7, the pressure loss coefficient. P: maximum oil pump pressure. A: clamping plate area. A: area of the locking template. *Generally, the setting does not exceed 80-100 kg/cm²).

4. Injection volume: The weight of plastic injected into the mold in one injection molding cycle. 

5. injection capacity: grams cm3, an injection molding machine screw for a maximum injection stroke can shoot the maximum amount of G = 3.14/4 * D2 * S * density (D: screw diameter, S: screw stroke. * production of a cycle injection volume should be less than or equal to 80% of the maximum injection volume of the machine). 

6. injection speed: screw in the material tube to move, the unit time to move the stroke called injection speed. V = S / T * 100%. S: screw travel in the material tube, T: screw injection time.

7. Backpressure: when adding material in the opposite direction of the screw back, add the pressure to the molten plastic.

The role of backpressure.

(1) to improve the temperature of the molten plastic.

(2) improve the density of the molten plastic.

(3) to improve the uniformity of the plastic color.

(4) to discharge the gas within the molten plastic. 

8. low-pressure protection: refers to the mold in the clamping of the resistance to a protective device, which can make the mold in the pressure of foreign objects by the most negligible harm to reduce the loss of compression mold. Its working principle is to set a particular time in the distance from the clamping low speed to the high clamping pressure of the mold. When the mold encounters a foreign object, plastic, or insufficient lubrication during the clamping process, the machine will generate an alarm and open the mold when the high-pressure switching point is not locked within the set time.

Share this post