Selection of powder metallurgy binders, metal powder injection molding technology is the product of the integration and intersection of plastic molding technology, polymer chemistry, powder metallurgy technology and metal materials science. The mold can be used to injection mold the blank and pass it through Sintering can quickly produce high-density, high-precision, three-dimensional complex-shaped structural parts. It can quickly and accurately materialize design ideas into products with certain structural and functional characteristics, and can directly mass-produce parts. It is a new change in the manufacturing technology industry.
Process features:
This process technology not only has the advantages of conventional powder metallurgy processes such as fewer steps, no or less cutting, and high economic benefits, but also overcomes the shortcomings of traditional powder metallurgy products such as uneven materials, low mechanical properties, and difficulty in forming thin walls and complex structures. It is especially suitable for mass production of small, complex and special metal parts. Process flow: binder → mixing → injection molding → degreasing → sintering → post-processing.
Powder metal powder:
The particle size of metal powder used in the MIM process is generally 0.5~20μm; theoretically, the finer the particles, the larger the specific surface area, making it easier to shape and sinter. The traditional powder metallurgy process uses coarser powders larger than 40μm.
In themetal injection molding MIM, the binder plays a very important role, it directly affects the mixing, injection molding, degreasing and other processes, and has a great impact on the quality, degreasing and dimensional accuracy of the metal powder injection molding blank, alloy composition, etc. Its role is to bond the metal powder particles, so that the mixture is heated into a material with rheological characteristics in the barrel of the injection machine, that is, it becomes a carrier to drive the flow of powder. Therefore, the choice of binder is the key to the formation of the whole powder injection. Requirements for binder:
- small amount, that is, to ensure that the mixture has better rheology while using as little binder as possible;
- No reaction, i.e. no chemical reaction with metal powder;
- Easy to remove, no residue in the product.
The soul of binder powder metallurgy MIM process, its addition and removal is the key technology of MIM, and the degreasing process used in the binder system is a key research topic at home and abroad. The binders used in MIM include thermoplastic systems, thermoset systems, water-soluble systems, gel systems and special systems, each of which has its own advantages and disadvantages. Thermoplastic binder system is the mainstream and precursor of MIM binder, and people focus on improving the rheological properties of feeding grains,A lot of research has been carried out to reduce degreasing deformation and shorten the degreasing time, and some special agents including polyacetal binders have been developed。The special system has enabled the further development of thermoplastic binder system. But the research and development of binders lacks with powders
Affinity, mixing of powders and binders, rheological and thermodynamic properties of binders and feeds under various conditions,The influence of binders on degreasing and product properties provides universal principles and theoretical basis for the selection of binders, which is undoubtedly unique It has a very positive meaning. The development of a new and efficient binder system is also the focus of MIM technology .
Post time: Jun-23-2022