How to achieve higher product performance tolerance in injection mold processing

What is the tolerance range?

Tolerance is an acceptable limit of variation: including physical properties or dimensions.

In the process of injection mold processing, the size of plastic parts depends on many variables, and it is not necessarily processed into accurate size like other manufacturing processes. The factors affecting the size change of plastic parts include: material, performance, design, machine and production process.

In the injection mold design stage, uncertainty of mold tolerance can lead to incorrect matching, product or function failure, production delay and unexpected extra cost.

In injection mold processing, the following four aspects will play a key role in getting the appropriate tolerance.

1. Injection mold product design

To control the tolerance of injection mold, the first step is to establish the tolerance range in the design phase. Tolerance ranges are critical to the function of most components. The establishment of tolerance range in the early stage of design will contribute to the manufacturability and repeatability of mold manufacturing. Improving manufacturability and repeatability will maintain quality throughout the life cycle of the program.

Key points of injection mold product design:

Shrinkage can vary according to material selection and product wall thickness. The thicker part may contract at a different rate than the thinner part. Changes in shrinkage affect the ability to maintain tight tolerances.

Part size also affects shrinkage. Small components have smaller shrinkage and are easier to maintain more stringent dimensional control. However, it may be more difficult to maintain tighter tolerances when larger parts contract over a larger distance.

It is helpful to analyze injection mold flow before production. Accurate prediction of gate location, filling rate, shear stress, build-up, cooling, and shrinkage will help determine the tolerance range. Avoid tight tolerances in areas prone to warpage, shrinkage or deformation.

2. Material selection of injection mold products

It is also important to select the right resin to achieve higher product performance tolerances. Different resins have different properties and characteristics. Injection molding is rising rapidly in manufacturing because different resins offer different possibilities.

The part environment may affect plasticity and may result in tolerance deviations. Plastics have a greater thermal expansion than many other materials. In a normal operating environment, test and measurement tolerances, as well as thermal expansion and part shrinkage, are critical to control tolerances.

Shrinkage affects tolerances as described during the design phase of the injection mold part. The geometry of the part may result in different shrinkage rates. Different resins also have different shrinkage. It is important to understand the properties of the resin and the complexity of the part to understand the shrinkage in order to align the appropriate tolerance area.

3. Injection mold processing

Parts requiring tight or tight tolerances shall be manufactured by robust and well-designed moulds. The mold also needs to provide consistent and repeatable heating and cooling. Otherwise, the shrinkage will be different and the tolerance will be difficult to achieve..

Complex parts need complex injection mold. As injection mold processing becomes more complex and additional components and functions are added, it is important to ensure that all components transfer heat correctly to allow acceptable resin and part cooling.

It is important to determine the proper gate position for the balance of melt flow. This will help to avoid unexpected shrinkage and warpage.

4. Injection mold processing control

Developing a repeatable production process is the key to achieving tight tolerance. From the start of production, proper process and documentation control will ensure that components do not experience unnecessary pressure, heat, or other factors that could damage the performance or application function of the resin.


About JasonMould Industrial Company Limited

Jasonmould is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: JasonMould Industrial Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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