Plastic mold design process

- May 30, 2018-

                                 Plastic mold design process?

(1) accept the letter of appointment

   The instructions for forming plastic parts are usually put forward by the designers of the parts, and their contents include: the formal part making drawings approved and signed, with the mark and transparency of the plastics used;Specification or technical requirements for plastic parts;Production capacity;Plastic sample.

   Usually the design plan descriptions of the mold by plastic parts engineer put forward according to the specification of molding plastic parts, mold designers to molding plastic parts specification, mold design specification as the basis to design the mold.

(2) collect, analyze and digest raw materials

   To collect and sort out the materials of parts design, forming process, forming equipment, mechanical processing and special processing for use in mold design.

   Digesting the plastic parts drawing, understanding the use of the parts, and analyzing the technical requirements of the plastic parts.Such as plastic parts in appearance shape, color, transparency, the use of performance requirements, the son of structure and slope, insert, such as whether reasonable, welding scar, degree of molding defects such as shrinkage cavity allows, with or without coating, electroplating, after cementing, drilling and other processing.The size with the highest precision of plastic parts was selected for analysis to estimate whether the forming tolerance was lower than that of plastic parts, and whether the plastic parts could be formed in accordance with the requirements.In addition, we need to understand the plasticizing and forming process parameters of plastics.

   Digesting the process data, analyzing whether the forming method, equipment model material specification, mold structure type and so on proposed in the process specification are appropriate and can be implemented.

   The forming material should meet the strength requirement of plastic parts. It has good fluidity, uniformity, isotropy and thermal stability.According to the use of plastic parts, molding materials meet the conditions of dyeing, metallized, decorative performance, necessary elasticity and plasticity, transparency, or reflection performance, glue joint or welding requirements.

(3) determine the molding method

Direct pressure method, casting pressure method or injection method.

(4) select molding equipment

   Mould design is carried out according to the type of forming equipment. Therefore, the performance, specifications and characteristics of various forming equipment must be well known.For injection machine, for example, should know the following content: in terms of specifications, clamping pressure, injection pressure, injection capacity mold installation size, ejection device and size, nozzle hole diameter and the nozzle radius of sphere, shallow mouth sleeve positioning ring size, mould maximum thickness and the minimum thickness, templates, travel, etc., specific ^ related parameters.

   To preliminarily estimate the size of the mold, determine whether the mold can be installed and used on the selected injection machine.

   The specific structural scheme is described below.

Determine the mold type.Such as the press mold (open, semi-closed, closed), prayer mold, injection mold, etc.

   Determine the main structure of mold type.Choose the ideal mold structure is to determine the necessary molding equipment, the ideal cavity number, under the condition of absolute reliable can make the mold itself the job satisfaction of the plastic parts processing technology and production and economic requirements.The technical requirements for plastic parts are to ensure the geometric shape, surface roughness and dimension precision of plastic parts.The requirement of production economy is to make plastic parts cost low, production efficiency high, mould can work continuously, service life long, save labor.There are many factors influencing the structure of the mould and the individual system of the mould.

Cavity layout: the number and arrangement of the cavity are determined according to the geometric structure, dimension precision, batch size, difficulty in mold manufacturing and mold cost.

    Determine parting surface: the location of parting surface should be conducive to mold processing, exhaust, demoulding and molding operations, plastic parts surface quality and so on.

    Determine the casting system (shape, location, size of the main runner, runner and gate) and the exhaust system (method of exhaust, location and size of the outlet).

Select the jacking method (jacking rod, jacking tube, pushing plate and combination jacking), and decide the side concave treatment method and core pulling method.

Determine the shape, position and installation of heating elements of cooling, heating and cooling grooves.

   According to the mold material, strength calculation or experience data, determine the thickness, shape size, shape structure and all connections, positioning and guide parts.

Determine the structural form of the main forming parts and structural parts.Considering the strength of each part of the mould, calculate the working dimension of the molding part.

If the above problems are solved, the structure of the mould will be solved naturally.At this point, you should begin to sketch the mold structure and prepare for the formal drawing.

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