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injection molds

Quality, stability and productivity should be considered in the design of each plastic piece. It is a mistake to assume that shapes can be molded successfully without any defects. In any molding process, 100% of the final product characteristics may not be achieved. To improve the injection molding process, the quality of the plastic injection mold must be carefully checked.


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We at Pars Company share some tips based on our 10 years of experience in injection mold production. We hope that if you have a new project that requires plastic parts, we can help you design and manufacture injection mold parts.

Effective factors in the form of plastic injection

wall thickness

The wall thickness of plastic parts is usually about 0.80-3.00mm, if it is too thick, it is easy to shrink and produce bubbles in the part, it is also difficult to produce very thin part, the thickness of larger products is thicker and smaller products Thinner, generally 1.0-2.0mm thick product is used for most products and the thickness of products is as uniform as possible, in case of special design, part of the product may be thicker or thinner.

Plastic injection mold is required for the principle of injection process. If the thickness of the product is less than 0.3 mm, it is difficult to completely fill the injection mold, but softer plastics can be used in some cases.

Injection mold ribs

Most plastic products require ribs that can greatly increase their overall strength without increasing the product’s overall shell thickness, especially for large products, while also preventing product deformation. The thickness of the ribs is usually 0.5-0.7 times the overall thickness, if it is more than 0.7 times, it is easy to shrink. When the height of the ribs is high, the tension angle of the ribs should be at least 0.5-1 degrees. If the height of the ribs is less than 15 mm, there is no need for the tension angle of the ribs.

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Stretch angle

Plastic products have a stretch angle, but their height is generally below 4mm, and they have special conditions, except when the side wall is not large, the stretch angle is usually 1-5 degrees, depending on the size, height, special shape, able to Molding is successful and does not affect the principle of operation. The front mold is usually 0.5 degrees larger than the back cavity mold so that the product can stay in the back cavity.

R corner

In order to reduce the plastic flow stress, the edge of injection molding plastic parts should be designed to be rounded R0.3-0.5mm, except for special conditions and for special performance.

Holes on molded parts

From the mold processing point of view, it is better to make the hole in a simple circular hole shape, as far as possible not to create complex shape holes, the hole size should not be too small, the hole depth and hole diameter should not be too large. The distance between the hole and the edge of the product is preferably more than 1.5 times the diameter of the hole and the distance between two holes is preferably more than twice the diameter of the hole so that the product has good strength.

Insert molding

When an existing metal or plastic part is re-inserted into the mold, the existing part is called an insert. When the design of the plastic product has insert parts, it is necessary to consider the insert in the mold, which must be able to be fully, accurately and reliably positioned, but also consider that the insert part must be connected with the solid forming part. Therefore, when the thickness of the wall around the insert parts is too thin, the inserts will not be firmly fixed. Also, keep in mind that the plastic around the inserts does not leak.

The surface of the molded parts

The surface of the molded plastic piece can be smooth or engraved. When the engraving or other patterns on the surface are too deep, we need to increase the draft angle in the mold design.

Types of plastic injection molds


Plastic cap mold and PET preform mold

Types of plastic lid molds, mineral water bottle lid molds, juice lid molds, spray lid molds for different bottle sizes. We can also make multi-cavity PET preforms from 30ml to 5 gallon bottle capacity.

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If you have a new investment plan in the water packaging industry, contact us, we can supply high-quality plastic production line, including bottle cap injection molding line, PET preform injection molding line, as well as blow molding line. Bottle. We are a direct manufacturer of plastic injection molding and blow molding machines, and we can offer favorable prices with good services.

Plastic household appliance injection mold

The experienced team for household appliance molds (such as refrigerators, washing machines, air conditioners, etc.) of Pars Company can provide complete solutions for household appliance molds with high precision according to the ideas of customers, from feature analysis Molds, product design optimization, mold design improvement and plastic parts production, which ensures smooth surface of home appliances and complete assembly.

We are still developing our technology in home appliance molding to provide better and better solutions for home appliance molds.

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Buy plastic injection mold

To order and buy all kinds of plastic injection molds and inflatable plastic molds to produce all kinds of simple and complex plastic products, contact our technical experts.

Pars company provides all kinds of plastic industry machines and various and high quality molds.

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