1.Injection volume
It is defined as the maximum weight of PS plastic injected into the air. When the material of the plastic product is different from PS, the injection volume is converted to: m=cb/1.05 (where b is the density of the plastic and c is the injection volume expressed in PS plastic). The total weight of the product is best controlled within 85% of the injection volume. For non-crystalline plastics, the maximum value can be taken, and for high-viscosity plastics, a smaller value should be taken.
2.Clamping force
It is defined as the final clamping force of the mold plate on the mold when the molten material is injected into the mold cavity at the end of mold closing. The clamping force is usually calculated by multiplying the average pressure in the mold cavity by the projected area of the mold cavity. The average pressure in the mold cavity is generally 20-40Mpa.
3.Injection pressure and injection rate
The injection pressure in the specification parameters of the injection molding machine is the maximum pressure in the barrel during injection, not the maximum pressure of the injection system oil pressure. The relationship between the injection pressure and the oil pressure is inversely proportional to the ratio of the screw cross-sectional area to the injection cylinder area.
Injection rate refers to the amount of molten material ejected from the nozzle per unit time. Its theoretical value is the product of the cross-sectional area of the barrel and the speed.
4.Mold thickness and maximum mold opening stroke
The specifications of injection molding machines generally include maximum mold thickness and minimum mold thickness, which represent the mold thickness that the injection molding machine can accommodate.
The mold removal stroke of the injection molding machine is limited, and the mold opening distance required to remove the part must be less than the maximum mold opening stroke of the injection molding machine. For a single-parting surface injection mold, the mold opening stroke is S>=H1+H2+5~10 (mm), H1 is the demoulding distance (usually equal to the height of the mold core), and H2 is the part height (including the pouring system). For a three-plate double-parting surface injection mold, the mold opening distance needs to increase the separation distance between the fixed mold plate and the gate plate.
5.Relevant dimensions of mold installation part
The length and width of the mold must be compatible with the size of the injection molding machine template and the tie rod spacing to ensure that the mold can be smoothly installed on the template through the tie rod spacing. When positioning, it should be considered that: the center of the main channel of the mold coincides with the center line of the barrel nozzle;
The size of the locating ring on the mold should be consistent with the size of the locating hole on the fixed platen of the injection molding machine and a clearance fit should be used; the spherical radius of the injection molding machine nozzle should match the spherical radius of the beginning of the main channel of the mold in contact; the size of the mold feet of the front and rear molds should match the arrangement of the threaded holes on the fixed mold of the injection molding machine.
6.Ejection stroke
The ejector stroke should be reasonably selected according to the appearance of the product and the design structure of the mold. Generally, the ejector stroke of the machine is fixed. When ordering a machine, the ejector stroke should be larger so as to suit a wider range of products.
