Why do you need a mold?
Injection molds used for the manufacture of products of complex configuration from polymers, metal, rubber and other materials in batch or mass production.
The most important stage of the technological process making Press forms – design. For unification at the stage of project development, the use of universal blocks is envisaged, in particular, when small-scale or non-specialized production.
Mold design stages
- Development of drawings and 3D model creation …
- Optimization of the arrangement of parts in the tooling.
- Development of the design of the gating system – hot runner or cold runner.
- Preparation of a complete set of documentation for the mold (instructions for use and work, 3D models and drawings).
The advantage of the hot runner system is the absence of sprues that fall out with each cycle along with the finished product. The disadvantages are the high cost and complexity of maintenance. The cold runner system is reliable, easy to operate, but has disadvantages: hardened sprues and increased cycle times.
The procedure for constructive and technological calculations of molds for injection molding
The project contains the following calculations:
- Efforts (pressing the form, pressing, removing the part);
- The size and number of cameras;
- Gating systems;
- Number of nests (places);
- Column bushings and guides;
- The size of the fixtures used for the mold connector;
- Volume and tableting of loading chambers;
- Dimensions of the matrix, punch, signs and cross-sections of the sprues.
The design of the mold depends on the properties of the material, the type of product, and the volume of production. In direct pressing, the loading chamber, as it were, continues the cavity that forms the lower part of the part.
The material loaded into the die is heated to the desired viscosity and compacted with a punch. Full closure of the mold occurs during the final molding of the product. The advantage is high productivity.
A distinctive feature of injection molding is a completely closed mold before the injection of material coming from the loading chamber into the forming cavity through the sprues. The use of technological equipment makes it possible to obtain products of complex shapes with high accuracy, which do not require cleaning of flash.
Types of molds
Types of injection molds: with a loading chamber (work on a press without a loading chamber), without a loading chamber (work on an injection molding machine).
According to the type of operation, the molds are removable (extraction of the finished product with the removal of the mold) and stationary. Removable forms are rarely used (manufacture of products in a small batch), as they are ineffective. In stationary forms, the removal of products is carried out using pushers.
According to the number of simultaneously molded parts, the forms are subdivided: multi-seat and single. The use of multiple molds reduces the cost of the finished product and increases productivity.
According to the location of the parting plane, the forms are divided: with horizontal or vertical parting.
Mold making requirements
- channels for cooling or heating with a liquid should be cylindrical, straight with a turn at an angle of 90 degrees;
- the device for removing the casting is located on the side of the part of the mold having the largest number of protrusions. The parting surface is assigned taking into account the shrinkage of the material, as a result of which the casting fits around the rods and protruding parts, moving away from the walls;
- permanent fastening of the rods or the maximum reduction in the number of detachable parts. An increase in the number of removable parts leads to a decrease in the accuracy of the casting;
- when casting plastic products, the wear of the forming parts should be taken into account. The chrome signs are reduced in size and the covering parts are increased in size. The resulting mating products (for example, housing and lid) will not fit into each other with the required clearance;
- accounting for casting shrinkage of parts, size fluctuations with temperature drops;
- To create a design pressure in the chamber, an excess of material is required, since outflow occurs through the gap between the punson and the matrix in the flash. It is necessary to provide for a gap between the punch and the die from 0.3 mm for small and up to 0.6 mm for large (up to 1000 mm) parts.
Where to order a mold?
Design and manufacture of molds observing the required accuracy of future parts is a complex process that requires contacting a specialized company.
Our company has qualified personnel successfully working in this field, and high-tech equipment that allows us to solve complex technical problems. You can contact our division in Kiev or Kharkov and place an order for the required type of work.
The customer provides a drawing or a sample of the product and technical requirements for the product (intended material, production volume, operating conditions). Our specialists will fulfill the order within the agreed time frame with the required quality.