Introduction
Metal injection moulding (MIM) is a hybrid technology which integrates the shaping capabilities of plastic injection moulding with the material flexibility of conventional powder metallurgy.

MIM is ideally suited to the mass production of intricate and complex-shaped components of a variety of materials, resulting from its ability to achieve 95% to 98% of its wrought material properties at a much lower cost, compared to traditional machining methods.
Advantages of MIM
  • Greater Design Freedom – With MIM, parts can be designed and manufactured without any design restrictions. All design changes are also possible within the shortest development cycle and turnaround time.
  • Miniaturisation – MIM technology allows for the mass production of miniature parts at a much lower and economic cost.
  • Complex and Intricately Shaped Parts – MIM is ideal for producing complex-shaped components, as well as parts that require assembly or multiple steps to put together.
  • High Production Rate – MIM is most beneficial in high volume production of small precision parts with complicated design geometry. The process lends itself to automation, resulting in high throughput rate and consistency in quality.
  • Material Design Flexibility – With our technology and expertise, we are able to customize material compositions according to your specific needs. We can produce parts from a long list of materials that can achieve up to 98% density of wrought material properties.
Process
The initial stage of MIM involves material selection and preparation. The appropriate combinations of metal powder and plastic binders are mixed to produce an injection mouldable feedstock. Using an injection-moulding machine, the feedstock is then subjected to a binder removal process. Solvent & Thermal Debinding are used in DYT to remove the binder. Upon debinding, the parts will undergo a sintering process in order to ensure that they are of the right material composition, physical properties and geometry.
1) Designing
The design formulation of the MIM components is the most critical stage. The final design is derived by using computer aided design software and involves close cooperation with customers.

2) Mixing
The metal powder is mixed with wax and various plastic materials, which are also known as a binder system, in order to form the feedstock.
3) Moulding
To form the shape of the part, the feedstock is injected into the mould cavity. Parts that are injected in this stage are also known as “green parts”.
4) Solvent Debinding
Solvent debinding removes the secondary binders and creates capillaries in the “green parts”, which are now ready for thermal debinding.
5) Thermal Debinding
Thermal debinding removes the remaining binder system through heating. The parts derived from this process are called “brown parts”.
6) Sintering
At this stage, the parts undergo high temperature sintering. Voids are closed and shrinkage occurs, resulting in a density of 96% - 98% and achieving near net-shape components.

Material Specifications
Due to the flexibility of MIM technology, DYT is able to customize material compositions according to specific attributes required by the customers.

Table 1: Material Compositions
Material Chemical Compositions (wt%)
C Cr Ni Mn Mo Si V W Co Cu Nb+Ta Fe
17-4PH <0.07 15-16 4-5 <1 - <1 - - - 3-4 <0.45 Bal.
304L <0.03 18-20 9-13 <2 - <1 - - - - - Bal.
316L <0.03 16-18 12-15 <2 2-3 <1 - - - - - Bal.
317L <0.03 18-20 13-15 <0.5 3-4 <1 - - - - - Bal.
430L <0.03 16-18 <1 <0.5 - <1 - - - - - Bal.
440C 0.9-1.2 16-18 <0.6 <1 <0.75 <1 - - - - - Bal.
F75 <0.1 27~30 <1 <1 5~7 <1 - - Bal. - - <0.75
4140 0.38-0.45 0.9-0.12 - - 0.2-0.3 - - - - - - Bal.
8620 0.18-0.25 0.4-0.6 0.4-0.7 - 0.2-0.3 - - - - - - Bal.
Low <0.2 - - <1 - <1 - - - - - Bal.
Medium 0.2-0.5 - - <1 - <1 - - - - - Bal.
High >0.5 - - <1 - <1 - - - - - Bal.
Fe-Ni2 0.6-0.8 - 1.8-2.2 - - <1 - - - - - Bal.
Fe-Ni8 0.4-0.6 - 7.5-8.5 - - <1 - - - - - Bal.
Fe-Ni50 <0.1 - 49-51 - - <0.5 - - - - - Bal.
Kovar <0.015 <0.5 29-30 <0.2 - <0.3     16-17 - - Bal.
M2 0.8-1 3.5-4.5 <0.3 <0.4 4.5-5.5 <0.5 1.8-2.2 5.5-6.5 - <0.25 - Bal.
SKDII 1.4-1.6 11-13 <0.5 <0.6 0.8-1.2 <0.4 0.2-0.5 - - <0.25 - Bal.
Tungsten Alloy WHA <0.03 - 4.8-5.2 - - - - 93-94 - - 1.8-2.2

Table 2: Typical Physical Properties of MIM Materials
Material Density (g/cm³) Mechanical Properties ( Minimum value)
0.2% Yield Strength
(MPa)		 UTS (MPa) Elongation (%) Hardness (HV300gf)
17-4PH 7.6 550 950 6 320
304L 7.8 205 515 35 120
316L 7.85 210 510 40 120
317L 7.85 240 540 35 150
430L 7.55 205 415 30 120
440C 7.55 1900 1970 2 550
F75 7.6 427 724 14 260
4140 7.4 400 650 3 130
8620 7.4 400 650 3 190
Low 7.7 150 250 25 80
Medium 7.6 250 400 5 130
High 7.4 400 700 2 320
Fe-Ni2 7.6 150 250 25 90
Fe-Ni8 7.7 200 350 15 100
Fe-Ni50 8.05 250 400 20 120
Kovar 7.7 - - - 150
M2 8.05 1000 1100 1 520
WHA 18 - - - 450
 
Applications
Both MIM and CIM technologies are breakthroughs in the field of traditional manufacturing and machining methods. Besides greatly reducing the cost of production, MIM and CIM technologies allow for large production volume of complex and intricate components.

The applications for both MIM and CIM are virtually boundless. It can be found from the Medical, Telecommunications, Avionics, Automotives, Electronic, Industrial, chemical plants, weaponry to home appliances, tools, instrumentation, optical, orthodontics, watches and textiles industries.


 
 
 
For further enquires, please contact us at tel (65) 6444 0218. fax (65) 6444 8273.
Alternatively you can email us at marketing@douyeetech.com or engineer@douyeetech.com.