Injection mold design: injection gate

The injection gate is the channel through which the plastic melt enters the mold cavity in the injection mold, which is also the inlet of the mold during injection molding.

The design of the gate is crucial to ensuring the quality and production efficiency of the finished product. The type and location of the gate will affect the molding cycle, appearance quality and mechanical properties of the plastic part.

How to design injection molding gate? Universe Plastic Engineer recommends learning and referring to the following points:

Injection gate design categories and characteristics

1. Point gate

The gate mark is small and easy to hide. It is suitable for small and precision parts and has a beautiful appearance.

2. Side gate

The most common type of gate, usually located at the edge of the mold, is often used for large parts and is simple in design, easy to manufacture and maintain.

3. Latent gate

The gate can be hidden inside the part, giving it a high-quality appearance. Suitable for products with higher appearance requirements. Automatically cut off the gate to reduce post-processing work.

4. Sector gate

For thin-walled, flat injection molded parts. The gate is wide and the material has good fluidity, which reduces injection molding problems. Provides even filling and pressure distribution.

5. Ring gate

It is mostly used for circular or annular plastic parts. The material enters the mold cavity evenly from the annular gate to reduce internal stress and warpage.

6. Hot runner gate

There is no need to cool and solidify the gate, the material always remains in a molten state, reducing material waste, and is suitable for mass production. But the cost is higher and maintenance is complicated.

7. Strip gate

Suitable for long or thin-walled parts, the gate is wide and thin to provide even material distribution.

8. Multiple gates

Gates are opened at multiple locations on the product to inject plastic from multiple directions. Suitable for large, complex or products that need to withstand multi-directional stress.

9. Film gate

It is a very thin gate. The cooling speed of plastic at the gate is very fast and the design is difficult. It is usually used in situations where high transparency and surface quality of products are required.

10. Combination gate

It is a combination of multiple gate types used to meet the processing needs of specific products. The design of the combined gate needs to be flexibly adjusted according to the actual situation of the product to ensure the best processing effect.

Injection molding gate design steps and suggestions

1. Determine the gate location

Try to design the gate at the center of the product and avoid designing the gate at a location with large thickness changes. The gate position should have sufficient draft angle. Ensure uniform material flow, smooth product demoulding, reduce internal stress, and prevent uneven cooling and sink marks.

2. Select gate type

Each gate type has its specific application scenarios, advantages and disadvantages.

The selection of the gate needs to be comprehensively considered based on the geometry, material properties, appearance requirements and production conditions of the part.

3. Gate size design

The width and thickness of the gate directly affect the material flow and cooling rate. Rectangular or trapezoidal cross-sections are usually selected to reduce flow resistance. Larger gates can reduce injection pressure but may increase cooling time. Shorter gates reduce the residence time of material in the gate, reducing degradation and internal stress.

4. Gate quantity design

A single gate is suitable for small or symmetrical parts and is simple to design.

Multiple gates are suitable for large or complex parts to ensure even filling of material, but care needs to be taken to balance gate flow.

5. Gate cooling and removal

Make sure there are adequate cooling channels in the gate area to prevent overheating. Design latent gates or use automatic cutting devices to reduce subsequent processing work.

6. Calculation and Simulation

Use computer-aided engineering (CAE) software to conduct flow analysis to predict material flow behavior and the effects of gate location. Optimize gate design based on simulation results to ensure optimal material flow and cooling.

The influence of injection gate on injection molding

1. Increase material flow

Reasonable gate design can reduce flow resistance, ensure that the material evenly fills the mold cavity, and reduces the formation of cavities and bubbles.

2. Optimize cooling effect

Proper gate size can help achieve uniform cooling and ensure part quality. Failure to do so may result in deformation, warping or dimensional instability of the part.

3. Improve injection molding quality

Appropriate gate location and type can reduce gate marks and improve the appearance quality of injection molded products.

4. Improve production efficiency

Proper gate design can reduce mold filling time and cooling time and optimize the injection molding cycle. It can also reduce the workload of post-processing and improve production efficiency.

5. Reduce material waste

Proper gate design can reduce the volume of gate residue, reduce material waste and production costs. Hot runner gating systems are particularly effective in minimizing material waste.

Summarize

In actual projects, designing a suitable injection molding gate requires considering a variety of factors, including product geometry, material properties, mold processing capabilities, injection molding machine parameters and mold structure, etc.

Dongguan Universe Plastic Company has 15 years of experience in injection mold design services. The injection gates of each set of molds will be continuously optimized by engineers and completed through various computer simulations.

If you have injection mold manufacturing needs or injection gate design questions, please leave a message to contact us.