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How much do you know about the basic knowledge of plastic mould design?


According to the specific needs and functions of plastic products throughout the products to determine which kind of the outside quality and specific size: the appearance belongs to the high quality requirements, precision plastic products, such as low toys; functional plastic products, strict requirement for the size and size requirements; the appearance of plastic products is very strict, such as a camera

Design basis

Accuracy of dimensional accuracy and its relative size.

According to the specific needs and functions of plastic products throughout the products to determine which kind of the outside quality and specific size: the appearance belongs to the high quality requirements, precision plastic products, such as low toys; functional plastic products, strict requirement for the size and size requirements; the appearance of plastic products is very strict, such as a camera.

Is the rake reasonable?.

The draft is directly related to the quality of plastic products and mould, which is related to the injection process, injection can be smoothly carried out: draft enough; slope should adapt to the plastic products in molding or die surface; it will affect the appearance and thickness accuracy;

Will it affect the strength of a part of a plastic product?.

Two. Design procedure

Analysis and digestion of plastic products, drawings, and solids (samples):

A, geometry of the product, B, dimensions, tolerances and design criteria;

C, technical requirements, D, plastic name, brand E, surface requirements

The number of cavities and the arrangement of cavities:

A, product weight and injection quantity of injection machine; B, the projection area of product and the clamping force of injection machine;

C, mold size and the injection mold mounting area, or the space between the rod of the injection machine

D, product precision and color; E, products with or without side shaft core and treatment method thereof;

F, production batch of products, G, economic benefits (production value per mold)

After determine the number of cavity, cavity arrangement, namely cavity position arrangement, cavity arrangement to die size, design of gating system, the balance of the gating system, core pulling mechanism design (slider), inserts and core design, the heat exchange system design, these problems with the parting surface and gate location selection, so the specific design process, to make the necessary adjustments, in order to achieve the perfect design.

Three. Determination of parting surface

Does not affect appearance;

It is advantageous to guarantee the product precision, the mold processing, especially the mold cavity processing;

It is beneficial to the design of gating system, exhaust system and cooling system;

It is good for mold opening (parting, demoulding), ensuring that the product is left on the side of the moving die during mold opening;

For metal patch arrangement.

Four 、 design of gating system

Determine the design of gating system including main channel selection, determine the shape and size of shunt gate and road section of the location selection, styles of gate and section size, when using point gate, in order to ensure the shedding of shunt should also pay attention to the design, from the gate device removal device nine chapter pouring gating mechanism.

In designing the gating system, the position of the gate is selected first.

Gate location is directly related to the quality of the molding process and the injection process. The selection of gate location shall follow the following principles:

The location of the gate shall be selected on the parting surface as much as possible so that the gate can be cleaned during the processing and use of the die;

The distance between the gate position and each part of the cavity should be consistent as far as possible, and the process should be the shortest;

The gate location should ensure that the plastic into the cavity, the spacious cavity, thick wall parts, in order to facilitate the smooth flow of plastic;

The gate position shall be located at the thickest part of the plastic section;

The plastic cavity is prevented from flowing into the cavity wall, the core or the insert in the flowing cavity, so that the plastic can flow into each part of the cavity as soon as possible, and the core or insert deformation can be avoided;

Try to avoid making the products produce weld line, or the weld line have not important place in;

The gate position and the inflow direction should make plastic, plastic into the cavity, can flow evenly along the direction parallel to the cavity, and is conducive to the discharge of gas cavity;

The gate should be set in most easily removed parts, as far as possible without affecting the appearance of the product.

Five 、 design of exhaust system

The exhaust system plays an important role in ensuring the quality of products.

A, using the exhaust slot, generally located in the exhaust slot cavity was finally filled with parts, exhaust the depth of the groove for plastic vary, basically does not produce plastic is determined by the maximum allowable gap of the flash, such as ABS0.04 to 0.02mm the following 0.02 saigang marl.

B, the use of core insert, push rod, such as clearance or special exhaust vent;

C sometimes the air pin must be set up to prevent the product from causing a vacuum deformation during ejection;

D and sometimes vacuum resist elements are designed to prevent vacuum adsorption between the product and the mold.

Six. Design of cooling system

The design of the cooling system is a complicated work, that is to consider the cooling effect and the uniformity of the cooling, and the influence of the cooling system on the overall structure of the die.

The arrangement of the cooling system and the specific form of the cooling system;

Determination of the specific location and size of the cooling system;

Cooling of key parts such as moving dies or inserts;

Side block and side core cooling;

Design of cooling element and selection of cooling standard components;

Sealing structure design