Injection Molds Design Process

Injection molds are an indispensable tool in the modern manufacturing industry, especially in the fields of automotive, electronics, medical, and so on. The quality of injection molds design directly affects production efficiency, product accuracy, and manufacturing costs. A sound injection molds design process not only ensures efficient production of parts but also reduces subsequent mold adjustments and maintenance.

Requirements Analysis and Product Design Evaluation

Demand Analysis

Before starting the injection molds design, we need to clarify the specific needs and requirements of the customer. Including the product’s function, appearance, precision, tolerance, and other aspects of the requirements. In addition, factors such as production quantity, material selection, and usage environment should also be fully considered in the demand analysis stage.

Product Design Evaluation

Product design evaluation is the first step in the injection molds design process. The mold designer needs to evaluate the drawing or 3D model of the part provided by the customer and analyze whether it is suitable for the injection molding process. The evaluation includes part geometry, dimensions, wall thickness, draft slope, and so on. If necessary, the designer will suggest product design improvements to simplify the mold structure and ensure smooth production.

Material Selection and Process Analysis

Material Selection

Different plastic materials have different characteristics such as fluidity, thermal expansion, shrinkage, etc. Therefore, it is necessary to select mold materials suitable for the required plastics in the mold design. Common plastic materials include ABS, PP, PC, etc. The mold materials usually use steel (such as P20, 718H, H13, etc.) or other wear-resistant materials to ensure the durability and precision of the mold.

Process Analysis

Injection molds design involves not only the structural design of the mold itself but also comprehensive consideration of the entire injection molding process. The designer will carry out process analysis, including flow analysis, cooling analysis, and shrinkage prediction to ensure the stability of the injection molding process and the quality of the final product.

Injection Molds Structure Design

Design of Parting Surface

The parting surface is the contact surface when the injection mold opens and closes, and it is also the main channel for products to take out of the mold. When designing the parting surface, we need to make sure that it will not affect the appearance and accuracy of the product, and at the same time, we need to consider the convenience of demolding. The selection of parting surface should be simplified as much as possible to reduce the problem of flying edge in later production.

Pouring System Design

The pouring system is the channel to introduce the molten plastic into the mold cavity, mainly including the main flow channel, manifold and gate. An optimized pouring system ensures uniform distribution of the melt and reduces injection molding defects such as bubbles, warpage or shrinkage. Common types of gates include point gates, side gates, latent gates, etc. The design requires the selection of the appropriate gate form according to the shape, size and material of the product.

Cooling System Design

The cooling system is an important part of the injection molding cycle and product quality. Reasonable design of cooling waterways can help accelerate the cooling process of the mold, shorten the production cycle, and avoid product defects caused by local overheating of the mold. Usually, water pipes or cooling circuits are used to take away the heat from the mold quickly and keep the temperature of the mold uniform.

 Ejector System Design

The ejector system is used to remove the molded product from the mold cavity smoothly. Ejector pins, push plates, and other common ejector devices should be designed to ensure that the ejector force is uniform to avoid deformation or damage to the product. At the same time, the ejector mechanism should be coordinated with the opening and closing movements of the mold to ensure production efficiency.

Mold Design Simulation and Optimization

CAE Analysis

After the injection molds design is completed, mold flow analysis is usually performed to simulate the flow process of molten plastic in the mold. This process can identify potential problems in advance, such as uneven material flow, poor cooling, stress concentration, etc., to optimize the design stage and reduce the cost of adjustments after the mold is manufactured.

Structure Optimization

According to the results of mold flow analysis, designers can further optimize the injection molds structure. For example, adjust the runner or gate position, modify the cooling system layout, and improve the strength and stability of the mold. Through optimization, the productivity of the mold and the quality of the parts can be improved.

Mold Manufacturing and Testing

Mold Manufacturing

After detailed design and optimization, the mold manufacturing process begins. The machining of the mold usually adopts CNC milling, turning, electrical discharge machining, and other high-precision machining methods. The injection molds manufacturing process requires strict control of the accuracy of each processing step to ensure that the mold is consistent with the design drawings.

Mold Testing

After the mold manufacturing is completed, the trial injection molds must be carried out. The purpose of mold trial is to verify the functionality and stability of the mold to ensure that the parts produced meet the design requirements. During the mold trial, some minor problems may be found, such as dimensional errors, surface defects, etc. At this time, the designer needs to make further adjustments and improvements to the mold.

Mass Production and Maintenance

Mass Production Preparation

When the mold passes the test and meets all the requirements, the mold can be put into mass production. At this time, the design and process parameters of the mold will be finalized, and the mold will enter the normal production use stage.

Regular Maintenance

To ensure the continuous and stable operation of the mold in production, regular maintenance and repair is very important. Maintenance includes cleaning the mold, checking the wear and tear of key parts, lubricating the moving parts, etc., which can effectively extend the service life of the mold and reduce production failures.

The design process of injection molds are complex process involving multiple links, from demand analysis to mold manufacturing to post-maintenance, each step affects the quality of the final product and production efficiency. Through scientific design and strict process control, not only can improve the product qualification rate, but also reduce production costs, to win a greater competitive advantage in the market.