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The design basis of the main process of mold design

2021-06-22

The design basis of the main process of mold design

The main basis of mold design is the plastic product drawing and sample provided by customers.The mold designer must check the product

Detailed analysis and digestion of drawings and actual samples are carried out. At the same time, all the following items must be checked one by one when designing the mold:


1. Dimensional accuracy and the correctness of related dimensions

According to the plastic products in the whole product on the specific requirements and functions, to determine the quality of its appearance and specific size belongs to which

Type.Generally speaking, there are three kinds of situations, the first kind is the appearance of high quality requirements, low dimensional accuracy requirements of plastic products, such as the shape of toys, its appearance must be beautiful, in addition to the specific size of the assembly size, the rest of the size as long as the fit is good, shape force

Really can.The second kind is functional plastic products, the size requirements are strict, its size must be within the allowable tolerance range, otherwise

Can affect the performance of the whole product, such as plastic gear products.The third is the appearance and size of the requirements are very strict plastic system

Such as plastic parts for cameras, plastic optical lenses, etc.For strict sizes, if certain sizes are male

The difference has exceeded the standard requirements, it is necessary to carry out a specific analysis, to see whether the appropriate adjustment can be made in the process of mold test to meet its requirements.

2. Whether the demoulding slope is reasonable

Demoulding slope is directly related to the demoulding and quality of plastic products, that is, related to the injection process, whether the injection is smooth

Leon.Therefore, plastic products are required to have sufficient demoulding slope.The direction of the demoulding slope should be with the plastic products in the forming of the points

The type or mold parting face is suitable, otherwise it will affect the appearance of the product and the precision of the wall thickness size, and even affect the plastic products

The strength of some parts.

3. Product wall thickness and uniformity

The wall thickness of plastic products should be appropriate, and should have a certain uniformity.The wall thickness is too thick or the uniformity of the wall thickness is poor

It directly affects the forming quality of products and the deformation after forming, lengthens the forming cycle, and even increases the cost of products.

4. Types of plastics

Different kinds of plastics have their commonalities, but also have their own characteristics.The plastic characteristics of the mould must be taken into account when designing the mould

The influence and requirements of the design in order to adopt the corresponding scheme.Because this must fully understand plastic name, brand, manufacturer

And shrinkage rate, for example, in the molding of plastic containing glass fiber reinforced, the mold cavity and core should have a high hardness

And wear resistance, and in the molding of flame retardant plastics, its cavity and core must have corrosion resistance, to prevent injection

The corrosive gas volatilized in the process corrodes the mold.In addition, different manufacturers of plastic produced by its color and shrinkage

The rates are also different.

5. Surface requirements

The surface requirements of plastic products refer to the surface roughness and surface striation requirements of plastic products.The roughness of the molding surface of the mold

Roughness is different for forming transparent and opaque products. Forming transparent products requires surface roughness of the cavity and core

The same.For forming opaque products, cavity, core surface roughness can be different, forming decorative surface mold

The parts should have high roughness requirements, and for the non-decorative surface, the mold surface can, without affecting the demoulding

Some rough

The surface roughness requirements of plastic products should be determined according to the surface quality requirements of products.

Plastic products on the surface of the skin grain requirements, should be provided by professional manufacturers of plastic skin grain sample to choose.Have tables in the design

When the mold is required by the skin grain, special attention should be paid to the influence of the side skin grain on the demoulding of the product. The demoulding slope of the side should be 2 degrees to 3 degrees

6. The color of plastic

In general, the color has no direct effect on the mold design, but in the case of thicker wall thickness and larger products,

It is easy to produce uneven color, and the darker the color, the more obvious the defects of the products are exposed.

7. Whether there is post-treatment after plastic products are formed

Some plastic products need heat treatment or surface treatment after forming.The molding size of the products to be heat treated is calculated

, the effect of heat treatment on its size should be considered.Products requiring surface treatment, such as products requiring surface plating, such as products

When the quantity is small and large, it is necessary to consider setting up an auxiliary flow channel to connect the products together until the electroplating process is completed

Separate the product from the auxiliary runner.

8. Quantity of products

The production volume of products is one of the important basis for mold design, so customers must monthly batch, annual batch, total batch

Provide a range, in order to design the mold, mold cavity number, mold size, mold material selection, mold life, etc

Face can be adapted to batch.

9. Specifications of injection machine

When receiving the order from the customer, the customer must put forward a clear specification for the injection machine used in order to be used as the mold design

According to.The following shall be included in the specifications of the injection machine provided

(1) Injection model number and manufacturer;

(2) Maximum injection volume (maximum injection volume) of the injection machine;

(3) Mold locking force of injection machine

(4) Spherical radius and nozzle aperture of the injector;

(5) Diameter of positioning hole of injection machine;

(6) Internal spacing of the pull rod of the injection machine;

(7) Volumetric modulus of injection machine (allowable maximum and minimum closure height of mold);

(8) the ejection method of the injection machine (hydraulic ejection or mechanical ejection, ejection point position and ejection rod diameter);

(9) Mold opening stroke and maximum opening distance of injection machine;

(10) If necessary, the jacking stroke and the jacking output of the injection machine should be provided.

10. Other requirements

When the customer puts forward the order, in addition to providing the necessary design basis, some customers even put forward some tools for the mold

Body requirements, such as the number of cavity and the type of molded products in the same mold, gate form, mold form (two plate mold or three plate mold), ejection

Mode and ejection position, operation mode (manual, semi-automatic, automatic), the surface roughness of the cavity core, and even the alignment

The grade and hardness of the steel used in the cavity core are required.

Above these contents, mold designers must carefully consider and check, in order to meet the requirements of customers