How to Choose the Parting Surface in an Injection Mold?

In injection mold design, the selection of parting surface is a key decision, which will directly affect the quality of the product, the difficulty of manufacturing the mold and the production efficiency. The parting surface is the interface between the mold cavity and mold core in the mold, and its design needs to consider various factors.

What does Parting Surface Design Affect?

• Product Quality: The location and design of the parting surfaces are directly related to the appearance, function, and accuracy of the product. For example, unreasonable parting surfaces may lead to obvious flying edges or shrinkage marks.
• Mold Processing Complexity: Complex parting surface design may increase the cost and time of mold manufacturing.
• Difficulty of Demolding: Good parting surface design can simplify the demolding process and improve productivity.

Principles of Parting Surface Selection

Product Structure Characteristics

• Give preference to the natural demarcation line of the product as the parting surface, such as the outer contour of the part, a raised part, or a recess.
• Avoid setting parting surfaces on high gloss or decorative surfaces, so as not to affect the appearance quality.

Mold Structure Optimization

• Ensure that the part surfaces are easy to machine and assemble, reducing machining difficulties and errors.
• Consider the opening direction of the moving and fixed molds, and avoid complicated mechanisms such as slider and slanting top.

Smooth Demolding

• The parting surface should help the product to be demolded smoothly and avoid the jamming phenomenon.
• For products with inverted structure, the parting surface should be consistent with the ejection direction, or solved by adding a slider mechanism.

Gate Design Requirements

• The parting surface should provide enough space and flexibility for gate and runner design.
• Ensure uniform flow of melt in the runner to avoid gas retention or uneven cooling.

Reduced Cycle Time

• The selection of parting surfaces should minimize the assembly process and post-processing of the mold.
• Optimize the layout of cooling channels to improve the heat dissipation efficiency of the mold.

Common Types of Parting Surface Design

Flat Part Surface

• Characteristics: Simple and easy to process, suitable for products with more regular shapes.
• Advantage: Low processing cost and short manufacturing cycle.
• Application Scenario: Such as electronic shells, simple containers, etc.

Curved Molding Surface

• Characteristics: Used for products with complex and irregular shapes.
• Advantage: It can better match the product shape and improve the appearance quality.
• Application Scenario: Such as automotive interior parts, complex home appliance housings, etc.

Stepped Part Surfaces

• Characteristics: Used in the case where the product requires multi-directional mold opening.
• Advantage: Solve complex mold design problems and ensure smooth demolding.
• Application Scenario: Such as multi-cavity molds or products requiring multiple sliders.

The selection of the part surface in the injection mold design is crucial, it needs to consider the product structure, mold processing and production requirements, and other factors.

Through the reasonable choice of part surface, you can significantly improve product quality, reduce mold manufacturing costs, and optimize production efficiency. If you need mold design service, please feel free to contact our professional team!

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