Steps of Plastic Mold Design

Accept the assignment
The specification of molded plastic parts is usually proposed by the part designer, and its contents are as follows:
1. Approved and signed drawings of formal parts, and indicate the brand and transparency of plastics.
2. Instructions or technical requirements for plastic parts.
3. Production output.
4. Samples of plastic products.
Generally, the mold design specification is proposed by the plastic part technologist according to the specification of plastic parts, and the mold designer designs the mold based on the specification of plastic parts and the specification of mold design.

Collect, analyze and digest original data
Collect and sort out relevant data on product design, molding process, molding equipment, machining and special processing for use in mold design.
1. Digest the drawing of plastic parts, understand the purpose of the parts, and analyze the technical requirements such as the processability and dimensional accuracy of plastic parts. For example, what are the requirements for the appearance, color transparency and service performance of plastic parts, whether the geometric structure, slope and insert of plastic parts are reasonable, the allowable degree of forming defects such as weld lines and shrinkage cavities, and whether there are post processing such as painting, electroplating, bonding and drilling. Select dimensions with high dimensional accuracy of plastic parts for analysis to see whether the estimated molding tolerance is lower than the tolerance of plastic parts, and whether qualified plastic parts can be molded. In addition, we also need to know the plasticizing and molding process parameters of plastics.
2. Digest the process data, analyze whether the molding method, equipment model, material specification, mold structure type and other requirements proposed in the process specification are appropriate and can be implemented.
The molding materials shall meet the strength requirements of plastic parts and have good fluidity, homogeneity, isotropy and thermal stability. According to the use of plastic parts, the molding materials shall meet the requirements of dyeing, metal plating conditions, decorative properties, necessary elasticity and plasticity, transparency or opposite reflective properties, bonding or weldability.
3. Determine the molding method
Direct pressing method, casting method or injection method shall be adopted.
4. Select molding equipment
The mold is made according to the type of molding equipment, so you must be familiar with the performance, specifications and characteristics of various molding equipment. For example, for the injection machine, the following contents should be understood in terms of specifications: injection capacity, mold clamping pressure, injection pressure, mold installation size, ejector device and size, nozzle hole diameter and nozzle spherical radius, gate bushing locating ring size, mold large thickness and small thickness, mold stroke, etc. See relevant parameters for details.
The overall dimension of the mold shall be preliminarily estimated to determine whether the mold can be installed and used on the selected injection machine.
5. Specific structural scheme
（1） Determine mold type
Such as pressing die (open type, semi closed type, closed type), casting die, injection mold, etc.
（2） Determine the main structure of the mold type
The choice of ideal mold structure lies in the determination of necessary molding equipment and ideal cavity number, which can make the work of the mold itself meet the requirements of the process technology and production economy of the plastic parts under absolutely reliable conditions. The technological requirements for plastic parts are to ensure the geometric shape, surface finish and dimensional accuracy of plastic parts. The production economy requires that the cost of plastic parts be low, the production efficiency is high, the mold can work continuously, the service life is long, and the labor force is saved.