Analysis of Precision Mould Forming Requirements and Characteristics

In comparison to ordinary moulds, precision moulds have higher requirements in their production process. They must strive for excellence in their raw materials, design, processing, precision, dimensions, and more. The machining process must involve highly precise manufacturing techniques. Specifically, engineers from Huanke Precision have collected relevant information to present the requirements and characteristics of precision moulds.

I. The six forming requirements of precision moulds.

1. The product specifications have high precision, with small dimensional tolerances, and high precision specifications;

2. The product has high repeatability standards with reliable size accuracy on a daily, monthly, and yearly basis;

3. The mould material is excellent, with sufficient rigidity, high precision in the outer dimensions of the concave mould, smoothness, and high accuracy between the templates;

4. High precision plastic machines are used instead of basic plastic machines;

5. High precision forming processes are used;

6. Raw materials that integrate high precision forming are selected.

The focus of the machining process of precision moulds is undoubtedly on precision. The requirements for dimensional tolerances of precision moulds are extremely high, usually +/–0.005. Many of the main specifications of precision moulds do not allow any inclination, but during mould production, low inclination will be flexibly applied using tolerance levels, such as installing column heads on transmission gears. In the design drawings of precision moulds, the machinability and controllability of the machining process must be considered to ensure smooth production.

II. The four characteristics of precision moulds

1. Wear resistance

When the blank undergoes plastic deformation and rotation in the concave mould of the injection mould, it flows and rolls along the surface of the mould cavity, causing intense friction between the mould cavity surface and the blank, which can lead to the ineffectiveness of the mould due to damage. Therefore, material corrosion resistance is one of the most basic and important characteristics of moulds.

The strength of the mould parts is the primary factor that harms wear resistance. Generally, the higher the strength of precision mould parts, the lower the wear rate and the higher the wear resistance. In addition, the wear resistance of materials is also related to the type, number, shape, size, and distribution of the permeable carbon structure in the data.

2. High ductility

The operating standards of moulds are mostly extreme, with some often subjected to heavy shock loads, leading to brittleness. To avoid sudden brittle fracture of mould parts during work, high-precision metal moulds must have high hardness and ductility.

The ductility of moulds mainly depends on the carbon content, grain size, and structural characteristics of the raw material.

3. Fatigue cracking performance

In the working process of mould parts, fatigue fractures are usually caused by long-term cyclic pressure. Types of fatigue fractures include low-energy repetitive impact fatigue fractures, tensile fatigue fractures, contact fatigue fractures, and bending fatigue fractures.

The key to the fatigue cracking characteristics of moulds lies in their compressive strength, ductility, strength, and the composition of impurities in their raw materials.

4. High-temperature properties

When the precision mould operates at high temperatures, its strength and hardness decrease, leading to initial damage to the mould or causing plastic deformation and ineffectiveness. Therefore, the steel used for precision metal moulds should have high reliability to resist quenching to ensure that the mould has high strength and compressive strength at environmental temperatures.

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