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Introduction to MIM Process of Metal Injection Molding
发布时间: 2020-12-04 08:49:03 次浏览 分享:

Ruilong Precision provides fully integrated manufacturing facilities for manufacturing precision, high-performance parts. The metal injection molding process includes the most advanced metal injection molding equipment and a complete complement of auxiliary operations. These facilities, combined with the capabilities of the MIM process, enable Ruilong Precision to manufacture highly precise parts to achieve close tolerances without the need for extensive machining (close to the final shape). We provide complete application development, including CAD/CAM and professional metallurgical services.

Process overview

Metal injection molding process 1. Raw material mixing and granulation


The first step in the MIM manufacturing process is to produce the raw materials to be used. It starts with the extensive characterization of very fine elements or pre-alloyed metal powders (usually less than 20 microns). In order to obtain the flow characteristics required by the injection molding process, the powder is mixed with a hot thermoplastic polymer (called a binder) to form a mixture in which each metal particle is evenly covered with the binder. Generally, the binder accounts for 40% of the raw material volume. Once cooled, the mixture is then pelletized into pellets to form raw materials for injection molding machines.



 


2. Forming


The next step is to mold the part in a conventional injection molding machine. The raw material particles enter the barrel of the machine by gravity from the hopper, and the heater in the barrel heats the binder to make the raw material reach the consistency of toothpaste. The reciprocating screw presses the material into a two-part mold through an opening called a gate. After cooling, the part is ejected from the mold and fully formed into its highly complex geometry. If necessary, other design features (for example, undercuts or cross holes) that are not feasible during the molding process can be easily added at this stage through machining or other auxiliary operations.



3. Removal of binder


The molded part is called a "green body", and it is still made of the same ratio of metal and polymer binder constituting the raw material, and all its dimensions are 20% larger than the finished product. Part of it will. The next step is to remove most of the adhesive, leaving only enough skeleton to be used as a skeleton to keep the size and geometry of the part completely intact. This process is often referred to as "degreasing" and can be done chemically (catalytically degreasing) or thermally. In some cases, the initial step may involve a solvent bath. The choice of degreasing method depends on the material being processed, the required physical and metallurgical properties and chemical composition. After degreasing, the part is called "brown part".



4. Sintering


In this process carried out in the highly controlled atmosphere of a batch heating furnace or a continuous heating furnace, the brown part is placed on the ceramic inlay in stages, and then the temperature profile is accurately monitored, which gradually rises to About 85% of the temperature. The melting temperature of the metal. Early in the cycle, the remaining adhesive is removed, then the holes are eliminated, and the fusion of the metal particles is eliminated when the part shrinks isotropically to its design size and transforms into a dense solid. The sintered density is about 98% of the theoretical value. The end result is a net-like or nearly net-like metal part whose properties are similar to those processed from rods. Of course, if necessary, post-sintering operations can be performed, such as imprinting, machining, heat treatment, coating,


The market includes:

Automotive-Aerospace-Medical-Commercial Machine

Computer Components-Hardware-Consumer Goods

Introduction to MIM Process of Metal Injection Molding(图1)

Manufacturing capacity

Forming machine: capacity up to 50 tons

Maximum part weight: 200 grams

Internal secondary operations/post-processing

Heat treatment

Steam treatment

Vibration deburring

CNC machining

Size/imprint

mirror reflection

Hair finishing/brushing

Passivation

Laser etching

PVD coating

Tool manufacturing/repair

Internal quality control and metallurgical inspection

ISO 9001: 2000, ISO/TS 16949

Complete mechanical testing facilities, including: optical metallographic equipment, vision system measurement center, CMM, optical comparator, microhardness and apparent hardness tester, gear checker, surface roughness tester, humidity chamber, conductivity meter .