What issues should be noted when designing MIM artifacts?

MIM is one of the more popular production processes in China in recent years, and many precision components are made by this process. So, what issues should be paid attention to when designing MIM workpieces?

1. Meat thickness: When designing MIM workpieces, it is best to ensure that the meat thickness of each part is consistent, so that the flow performance is evenly adhered to the model cavity during injection. This way, during the degreasing process, inconsistent shrinkage rates will not result in workpiece defects. For example, during degreasing, the size expansion of workpieces with different thicknesses varies, which can affect the stability of the final product.

2. Draft angle: When the workpiece has blind holes and a depth greater than 1cm, demolding defects are prone to occur. This is because the contact area between the mold workpiece and the ejected workpiece is too large, and the resistance caused by its friction force is easy to tear the contact surface. This issue requires increasing the draft angle appropriately based on the draft depth.

3. Sintering support: When certain parts of the workpiece cannot be supported, it is easy to cause sagging due to gravity during the degreasing or sintering process. Therefore, in the design process, the support seat should be directly designed to ensure that the workpiece can be placed smoothly, in order to avoid deformation of the workpiece caused by product tilting during the sintering process.

4. Fusion line: For example, when designing some circular parts, it is necessary to avoid the pattern design on the circular workpiece. It is important to consider that the workpiece enters the back mold cavity from the gate and overlaps with the other end. Due to the low temperature before the front injection, the two ends are not easily melted due to different temperatures when they overlap, often forming a fusion line.

5. Hole direction: MIM workpieces can have holes along the X, Y, and Z axes simultaneously. Among them, holes along the Z axis are easy to form, while holes in other directions require slider forming. Therefore, it is best for the holes to be straight and have the same switch direction as their axis to avoid increasing production costs.

Due to the fact that the design of MIM workpieces is related to the difficulty of the machining process and the quality of the workpiece, it is necessary to fully refer to the performance and design structure of the finished product during the design process, in order to ensure the quality of MIM workpieces.