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How to design injection mold
Learn expert tips on how to design injection molds for plastic manufacturing. Discover key considerations, design processes, and best practices for efficient mold production.
Designing injection molds requires a combination of product characteristics, material properties, and production requirements. The process can be roughly divided into the following steps:
There is five steps in roughly as below to explain the process;
Preparation before design
1. Product analysis: Clarify the structure, dimensional accuracy, materials (such as PP, ABS, etc.), surface quality requirements of the plastic parts, and determine whether there are complex structures such as inverted buckles and thin walls. Feasibility assessment should be conducted in advance.
2. Determine the molding scheme: Based on the size and batch size of the plastic parts, select the injection molding machine model, determine the number of cavities (single cavity or multiple cavities), and the injection method (such as gate position and type).
Die structure design
Design of mold cavity and core: Based on the shape of the plastic part, design the mold core that forms the inner cavity of the plastic part and the mold cavity with the outer contour, taking into account the demolding slope (to facilitate the removal of the plastic part) and shrinkage rate (to compensate for material cooling shrinkage).
Pouring system: including main channel, diversion channel, and sprue, responsible for introducing molten plastic into the mold cavity. The design should ensure smooth flow and uniform filling.
Cooling system: The mold is cooled by circulating water channels to control the molding temperature, ensuring rapid shaping and stable size of the plastic parts. The water channel position should be close to the mold cavity.
Demolding mechanism: such as ejector pins, top plates, etc., used to push plastic parts out of the mold after molding, ensuring smooth demolding and no damage to the plastic parts.
Guidance and positioning mechanism: such as guide columns and guide sleeves, to ensure precise alignment when opening and closing the mold, avoiding collision of parts.
Detail design and verification
Verify the strength and stiffness of the mold to ensure that it does not deform or damage under injection pressure.
Check whether the movement of each mechanism is smooth, such as the stroke of the demolding mechanism and the sealing of the cooling system.
Consider exhaust design to avoid defects such as bubbles and material shortages in plastic parts caused by the inability to exhaust gas from the mold cavity.
Drawing and processing
Output detailed 2D part drawings and 3D assembly drawings, annotate dimensions, tolerances, materials, and other information.
Process molds according to the drawings, such as milling, grinding, electrical discharge machining, etc. Key parts need to undergo heat treatment to improve hardness and wear resistance.
Trial molding and adjustment
After the mold processing is completed, a trial mold is conducted to observe the quality of the plastic parts through actual injection molding, such as dimensional accuracy, surface defects, deformation, etc.
Adjust the mold based on the trial results, such as modifying the gate size, adjusting the cooling water channel, optimizing the demolding mechanism, etc., until the plastic part meets the requirements.
The entire process needs to be optimized repeatedly based on product requirements and actual production conditions to ensure that the mold can produce qualified plastic parts stably and efficiently. For more information Please contact us at info@ymolding.com of Shanghai Yunyan Prototype & Mould Manufacture Factory.
