In the MIM process, each link will eat up the tolerance of the product, so the initial mold precision must be very high to ensure the size of the subsequent process.

Mold design is not a simple job, and the MIM designer must always have the spirit of "keeping improving" for the mold cause, and never have the concept of "almost". Not only are the tolerance requirements strict, no flash, smooth surface, etc., but also complex details need to be paid attention to. I talked with a "sweeping monk" from Lianyungang Fuchi Intelligent Manufacturing Technology Co., Ltd. who has been working on MIM mold for 30 years. The mold industry is like climbing an iceberg, which is very difficult. Very few people can stick to it. Most of them have changed their careers at the same time. But he has stuck to it. Now he is an influential mold master in China, and has trained a large number of talents for the mold industry.

First of all, MIM die design should have a good plan, which is the basis and key to success or failure. High quality dies can improve the forming quality and comprehensive performance of parts. The mold shall include excellent cooling water circuit layout and parting line locking device to prevent misplacement of the mold during processing and production, a pair of mold bases that can well support the mold cavity and core sidewall, and a method suitable for demoulding specific parts. The basic structure of the MIM mold is similar to the injection mold, with some exceptions. These include the selection of mold cavity and core steel, the design of clamping angle fittings and sliders, the runner system to enable material flow, and the correct selection of coating for cavity and core details. The detailed design of the MIM mold includes the selection of mold part materials, mold and cavity tolerances, surface quality and coating, gate and runner dimensions, exhaust port locations and dimensions, and pressure sensor locations. In the successful manufacturing of metal injection mold, demoulding and cooling become the key problems.

High quality die should start with material selection, usability and safety of die structure, maintainability of die parts, etc. Because the mold is a tool composed of several different mold parts, there are some vulnerable parts that need to be replaced frequently. Therefore, mold manufacturers need to pay special attention to mold maintainability design.

The selection of MIM mold materials should meet the customer's quality requirements for the products as much as possible, while taking into account the material cost and material strength. The selection of MIM mold materials requires that mold materials with less affinity to products should be selected as far as possible according to the properties of powder materials to be injection molded by customers, so as to prevent mold sticking from aggravating the wear of mold parts, thus affecting the quality of molds and the demoulding effect of products.

In addition to working hard on materials, to improve the quality of the MIM mold, attention should be paid to the maintainability of the mold from the mold structure design. When designing the die structure, try to be compact and easy to operate, and ensure that the die parts have sufficient strength and stiffness.

When the die structure allows, the corners of each surface of the die parts shall be designed as fillet transition as far as possible to avoid stress concentration; For female die, cavity and part of punch and core, combined or inlaid structure can be used to eliminate stress concentration. For slender punch or core, appropriate protective measures shall be taken in structure.

For injection molds, devices (such as spring pins, compressed air, etc.) should be configured to prevent blocking of parts or wastes. At the same time, we should also consider how to reduce the impact on the quality of the mold caused by the wear of sliding fit parts and frequently impacted parts in long-term use.

In the design, it is necessary to reduce the scope of disassembly and assembly for maintenance of a certain part, especially for replacement of wearing parts, so as to reduce the scope of disassembly and assembly as much as possible.