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| Introduction |
Due to the inherent material properties of ceramics, such as sturdy flexural strength, high resistance to corrosion, chemical inertness, electrical insulation and wear and tear, ceramic injection moulding (CIM) is regarded as the preferred net-shape manufacturing method for the production of making many precision engineering and electrical ceramic components.
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Advantages of CIM
- Precision Surface Finish – Employing the usage of sub-micron ceramic powder, CIM products possess high surface finish, very fine grain structures and close to theoretical densities, making them perfect for use in consumer products.
- Near Net-Shape Capability – With CIM, mass production of component parts of net shape straight off the manufacturing line provides you with savings in both time and cost.
- Precise Dimensional Control – With precise dimensional control, CIM gives rise to high throughput rates and consistency in quality.
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| Process |
The CIM process involves the mixing of selected ceramic powder with the appropriate binders to form a feedstock. This is followed by moulding the feedstock in a die cavity in order to form the required component shapes. Next, the shapes are then subjected to a debinding process, where the binders are removed by using either thermal evaporation or solvent washing. The resultant parts are then consolidated in a sintering furnace at temperatures up to 1800°C, under either oxidising or reducing atmospheres.
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1) Designing
The design formulation of the CIM components is the most critical stage. The final design is derived by using computer aided design software and involves close cooperation with customers. |
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2) Mixing
The ceramic powder is mixed with wax and various plastic materials, which are also known as a binder system, in order to form the feedstock. |
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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”. |
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4) Solvent Debinding
Solvent debinding removes the secondary binders and creates capillaries in the “green parts”, which are now ready for thermal debinding. |
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5) Thermal Debinding
Thermal debinding removes the remaining binder system through heating. The parts derived from this process are called “brown parts”. |
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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. |
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| Material Specifications |
With the increase in market demand and customers’ needs, the range of materials available in DYT has grown steadily in numbers. Among them are high purity oxides and carbides, such as Alumina, Zirconia, WC, SiC as well as toughened Alumina and toughened Zirconia.
Table 3: Typical Properties of Sintered Materials
| Material |
Composition |
Properties |
| Grain Size (μm) |
Density (g/cm³) |
Electrical R (Ω-m) |
Rupture Strength (MPa) |
Hardness (HV300gf) |
| Pure Alumina |
AI2O3 |
<3 |
3.95 |
>10¹³ |
400 |
2000 |
| 98% Alumina |
AI2O3 |
<5 |
3.88 |
>10¹³ |
275 |
1900 |
| Zirconia |
ZrO2 |
<0.6 |
6.05 |
>10¹² |
700 |
1200 |
| Toughened Alumina |
AI2O3+ZrO2 |
<1 |
4.15 |
>10¹³ |
550 |
1850 |
| Stabilized Zirconia |
ZrO2+Y2O3 |
<0.8 |
5.55 |
>10¹³ |
900 |
1350 |
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| 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.
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