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how to make injection molds
Thank you to all the mold enthusiasts for your continuous support of our company, Shanghai YunYan Prototype & Mold Manufacturing Factory. What are the general steps involved in manufacturing injection molds?
Generally speaking, it can be divided into five parts, as follows；
Mold Designing
Product analysis: Design the mold structure based on those factors such as the shape, size, precision requirements, and the batch of injection molding products. Using CAD/CAM software, construct a 3D model of the product, analyze the demolding method, parting surface, gate position, etc.
Generate drawings: After the design is completed, generate 2D engineering drawings, marking the technical requirements such as dimensions, tolerances, and surface roughness of each part.
Machining Process
Material preparation: Select suitable mold steel materials according to the mold design requirements, and check whether the hardness, organizational structure, etc. of the materials meet the requirements.
Rough machining: Using CNC, milling machines, lathes, drilling machines, and other equipment to perform rough machining on mold parts, removing most of the excess and leaving at least 0.5 mm of machining allowance for subsequent precision machining.
Precision machining: Using CNC machining centers and other equipment to ensure the dimensional accuracy and surface quality of parts, the machining accuracy of key dimensions can be controlled within ± 0.01mm, and the surface roughness reaches mirror level or Ra0.8-Ra1.6 μm.
Electric discharge machining: For some mold parts with complex shapes, the electric discharge machining method can be used to machine shapes that are difficult to achieve with conventional mechanical machining.
Heat treatment and surface treatment
Heat treatment: Quenching, tempering and other heat treatments are carried out on mold parts to improve the hardness, strength and wear resistance of the mold. For example, the commonly used P20 steel, the quenching temperature is generally between 850-870 ℃ and the tempering temperature is between 550-650 ℃.
Surface treatment: Nitriding, hard chrome plating and other treatments can be applied to the surface of the mold to improve its wear resistance, corrosion resistance and demolding performance. After nitriding treatment, the surface hardness of the mold can reach HV900-HV1200.
Mold Assembly
Cleaning parts: Clean the processed mold parts to remove impurities such as oil stains and iron filings, ensuring the surface of the parts is cleaned.
Parts assembly: Assemble the parts according to the mold design requirements. First, assemble the mold frame, and then install the mold core, mold cavity, slider, ejector pin and other parts in sequence to ensure that the fit gap between the parts meets the requirements. For example, the clearance between the guide post and the guide sleeve is generally 0.02mm.
Debugging and optimization: After assembly is completed, conduct trial mold debugging to observe the opening and closing actions of the mold, whether the ejection mechanism is smooth, the molding situation of the product, and adjust and optimize any existing problems.
Quality inspection
Appearance inspection: Check whether there are scratches, bumps, deformations and other defects on the surface of the mold, and whether the installation of the parts is firm.
Dimensional accuracy measurement: Use measuring tools such as coordinate measuring instruments to measure the key dimensions of the mold, ensuring that the dimensional deviation is within the tolerance range required by the design.
Trial mold inspection: Through trial mold testing, the demolding quality is checked, such as dimensional accuracy, surface quality, demolding situation etc so we can determine whether the mold meets production requirements.
The above is basically on our company Shanghai Yunyan Prototype & Mold Manufacturing Factory, Experience sharing during the injection molding process. For more technical questions about injection molds, please contact our engineers and our team will provide you with free quotation services.
