The choice of plastic mold structure is the most important in the process of mold development

1、 Structure of plastic mould

1. Gating system

The channel leading plastics from injection machine nozzle to mold cavity is called gating system, which is composed of main channel, shunt channel, inner gate, cold material hole, etc., and is composed of casting sleeve and pulling rod of parts

2. Molded parts

It is a variety of parts that directly form the shape and size of plastic parts, and is composed of core (internal shape of molded plastic part), cavity (external shape of molding plastic), molding rod, insert block, etc

3. Structural parts

All kinds of parts that constitute the part structure play the role of installation, guiding, mechanism action and temperature regulation in the mold. Guide parts: guide pillar, guide sleeve. Assembly parts: positioning gap, fixed mold bottom plate, fixed template, moving template, moving mold base plate, die foot cooling and heating system

2、 Selection principle of parting surface of plastic mould

1. General principles of parting surface selection

(1) Ensure the quality of plastic parts. This is the most basic one. The quality of plastic parts must meet the predetermined requirements

(2) Easy to demould. Easy to demould, can improve productivity, plastic parts are not easy to deform, improve the quality rate

(3) Simplify the mold structure. For the same plastic part, due to the different selection of parting surface, the complexity of the structure is very different. Reasonable selection can simplify the mold structure

3、 How to select parting surface

1. The parting of long components is shown in the figure below. If the length of the plastic part is long, such as tubular, cylindrical and rod-shaped plastic parts, if the cavity is placed in a template, the stripping slope will be too large (Fig. a). If the cavities are arranged in the movable and fixed molds respectively (Fig. b), the demoulding slope can be reduced, so that the size difference between the two ends of the plastic part will not be too large

Structure of plastic mould and selection principle of parting surface

(1) The parting with too large demoulding slope;

(2) To reduce the parting angle

2. The parting surface of the cover part is selected according to figure a; for the plastic part with insert, the core is wrapped tightly because the insert will not shrink, and the parting surface can be selected according to figure B. if the core of the plastic part is symmetrically distributed, the parting surface can be selected according to figure B, It should be divided according to the drawing, forcing the plastic part to stay on the moving mold; if the plastic part with side hole, the type should be divided according to the figure D, so as to avoid the fixed mold core pulling Structure of plastic mould and selection principle of parting surface

(1) Cover shaped plastic parts;

(2) Plastic parts with inserts;

(3) Symmetrical core plastic parts;

(4) Plastic parts with side holes

3. The parting surface to ensure the appearance quality of plastic parts is shown in the figure below. The appearance quality of plastic parts needs to be guaranteed. Careful consideration should be given to the selection of parting surface. For example, no parting surface should be set on the smooth surface or arc surface. Figure a is the parting that keeps the surface smooth, and figure B is the parting that can reduce flash, Figure C shows the parting which can reduce the overflow. The structure of plastic mould and the selection principle of parting surface of plastic mould

(1) To make the surface smooth;

(2) Reduce the type of flash;

(3) Reduce the type of overflow

4. The parting surface is often used as an exhaust channel in injection mold. In order to exhaust smoothly, the parting surface should be set at the end of melt flow, and there should be no obstruction at the end. The structure of figures B and D is more reasonable than that of figures a and C Structure of plastic mould and selection principle of parting surface

5. Many plastic parts have the requirement of coaxiality, which should be ensured in the mold design. Generally, the parts with coaxiality requirements in the plastic parts should be designed in the same moving template to meet the accuracy requirements. Figure a can meet the requirements of coaxiality, while figure B is not accurate in mold closing, so it is difficult to meet the requirements of coaxiality. (1 moving die 2-fixed mold) Structure of plastic mould and selection principle of parting surface

(1) Ensure the type of coaxiality;

(2) It is difficult to ensure the type of coaxiality

6. The parting with side holes is shown in the figure below. When selecting the parting surface, the side core pulling or parting should be avoided as far as possible. If necessary, the following principles can be referred to. Fig. a sets the side core on the moving die to facilitate core pulling, while it is more difficult to pull the core if it is set on the fixed die; FIG. C shows that the long core pulling distance is placed in the opening direction, while the one with small core pulling distance is placed on the side, which is more reasonable, It is difficult to demould

Structure of plastic mould and selection principle of parting surface

7. For example, the parting of figure a ensures the accuracy of thread, while the parting of figure B cannot guarantee the accuracy of thread by passing through the thread axis; The classification of figure C ensures the integrity and smoothness of the circular surface, while D has an obvious seam line around it, which affects the appearance and use

Structure of plastic mould and selection principle of parting surface

(1) Ensure the accuracy of thread parting;

(2) It can not guarantee the thread accuracy;

(3) Ensure the smooth appearance of plastic parts;

(4) Can not guarantee the smooth appearance of plastic parts

8. The parting of thin-walled plastic parts with uniform wall thickness is shown in the figure below. In order to make the wall thickness uniform, the common plane is not used as the parting surface, as shown in Figure B, but the conical stepped parting surface shown in figure a is adopted Structure of plastic mould and selection principle of parting surface

(1) Conical stepped parting surface;

(2) Plane parting surface

To sum up, if you still have any doubts about the mold, you are welcome to enter the line to consult us, we will have professional personnel to answer your doubts for you