MIM process of 440C stainless steel feed mixing and high hardness scissors

Stainless steel has the characteristics of high strength, high wear resistance, corrosion resistance and not easy to rust, so it is
widely used in the national economy and people’s livelihood in various industries, including chemical industry, machinery
manufacturing, household appliances manufacturing, and decoration industry. And with the development and progress of
the forming technology of stainless steel products, stainless steel is being used in more and more fields, and the market
prospect is huge.
Scissors is closely related to People’s Daily life of a common hardware tools, high hardness scissors are generally forged
from stainless steel materials. As we all know, the traditional production method of scissors is forging, which is time-
consuming and laborious, and the production of scissors is a labor-intensive work.
With the introduction and continuous promotion of MIM metal injection molding process, the production of scissors by this
process can completely replace the traditional forging method, especially in the production of high-hardness stainless steel
scissors can be formed in one time, and after forming the scissors density compact, hardness and other mechanical
properties better.
Stainless steel according to the different microstructure can be divided into austenitic stainless steel, martensite stainless
steel, generally also known as non-magnetic stainless steel and magnetic stainless steel. The material of choice for high
hardness scissors is 420 and 440 martensitic stainless steel. Because the hardness of this stainless steel material is greater
than 58 HRC, it has high wear resistance and good corrosion resistance, which can meet the general use needs of scissors.
Using MIM process to produce stainless steel scissors, the first thing we need to do is to prepare stainless steel feed. The
440C stainless steel powder and a water-soluble binder are combined to make the feed that can be used for injection
through mixing machine, granulator and other equipment.
Then inject the injection material through the injection machine into the cavity of the previously designed scissors mold to
get the blank of scissors. When the binder of the blank is removed, it is carried out in two steps. PEG components in the
scissor blank are extracted with water first, and PMMA in the blank is decomposed by heating.
After degreasing, the furnace temperature is rapidly increased to sintering temperature. After 40 minutes of insulation, the
blank is cooled to room temperature by different cooling methods, and then the blank is heat-treated.At this point, high-
performance stainless steel scissors are truly finished.
Looking at the whole production process, the production of stainless steel feed is the key step of its basic function, because
the subsequent debonding sintering and the final performance of products will be affected by stainless steel powder and
binder. Therefore, attention should be paid to the feeding production link when using MIM process to produce stainless
steel scissor, scissor and other products.