Green Machining

This technique is commonly applied to as-pressed parts which are still in a “chalky” condition. Common metalworking machines are used to machine the part in this “soft” condition as greater material removal rates are possible than by post sintering operations such as diamond grinding.

As fired green machined components are subject to maximum tolerances of +/- 1%. To achieve tighter tolerances diamond grinding must be adopted.

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Injection Moulding

Injection Moulding

In a similar manner to extrusion, a plastic mix is prepared and heated in the barrel of the moulding machine until it is at the correct temperature at which the mix has a sufficiently low viscosity to allow flow if pressure is applied.

A plunger is pressed against the heated mixture forcing it through an orifice and on into the tool cavity. The moulded part is removed from the die and the organic binder slowly burnt out in a controlled atmosphere by means of a carefully controlled heating schedule, prior to sintering.

Low Pressure Injection Moulding

Technology has jumped forward in great leaps and bounds over the last ten years to arrive at a position were high volume ceramic components can be made using injection moulding techniques.

Injection moulding of ceramic components has several major benefits over more traditional manufacturing techniques such as die pressing and green machining.

Excluding the obvious; that it is a good technique for very high volume parts, injection moulding has also proved to be an excellent technique for making components such as turbo charger rotors and thrust bearings which would be too expensive if the parts were machined.

Low pressure injection moulding (LPIM) provides an excellent option for producing ceramic components using low cost tools in comparison to high pressure moulding techniques.

The LPIM process enables fabrication of very complex shapes as well as simpler components. The essence of the process is that parts can be produced with a higher level of integrated function to meet the customers needs then other process are able to achieve.

The main process features are:

Small diameter holes, LPIM is able to produce parts with hole diameters as small as 0.1 mm (0.004″) through walls as thick as 6.5 mm (1/4″). The hole geometry is not restricted to simple shapes but can be complex polygonal shapes.

Internal and External threads, LPIM is flexible enough to allow any configuration of thread to be moulded without any further machining.

Tolerances, through Statistical Process Control of raw materials it is possible to achieve “as fired” tolerance as small ±0.5%. Tighter tolerances can be achieved by machining the injection moulded blanks.

Process capabilities, minimum wall thickness 0.5 mm (0.020″) to a length of 12.5 mm (0.5″). Maximum wall thickness 6.5 mm (1/4″) and the maximum over all dimension must not exceed 150 mm (6″).

Isopressed Ceramics

Complete line of isopressed ceramic cylinders. Second only to diamonds in hardness (+9 Mohs), cylinders provide outstanding wear resistance.

Cylinders can be manufactured with inside diameters ranging from three to twelve inches with a minimum wall thickness of one-half inch. This design increases the wear life by limiting the number of parallel joints within the ceramic component.

We recommends that isopressed ceramic cylinders be installed with epoxy adhesive or high temperature mortar, when applicable.

Applications: bottom ash systems, dust collection, cyclones, valves, apexes.

Ceramic Injection Moulding (CIM)

For components requiring high precision and medium to high volumes we offer Ceramic Injection Moulding (CIM).

CIM is an innovative forming technique to manufacture a range of components, including those with a high geometric complexity, offering an economic solution for difficult production problems.

The CIM process begins with very fine ceramic powders. Using sophisticated mixing technology the powders are compounded with thermoplastic binders to produce a homogeneous pelletised feedstock.

The binders form a liquid medium which carries the ceramic powders into the mould during the injection stage. Using an injection moulding machine similar to that used in conventional plastic moulding, the molten feedstock is forced into a mould cavity forming a net shape part.

Moulds can be single or multi-cavity configurations.After forming the part it then goes through two thermal processes.

First is pyrolysis to remove the binder, followed by sintering in a high temperature kiln to form a fully dense ceramic component. During sintering the component shrinks uniformly by as much as 20% while retaining the complex shape. With good process control close tolerances can be obtained, therefore machining of the part after sintering is usually not necessary.

The benefits of Ceramic Injection Moulding

Provides unique, economic solutions to increasingly stringent material and product design requirements;

Excellent batch to batch repeatability and process capabilities achieving a tolerance of <0.3%;
High surface finish quality without the need for additional finishing processes;
Accommodates extremely complex geometric components;
Superior material performance, high hardness and mechanical strength, wear, corrosion and weathering resistant, dimension stable, high working temperature and good
electrical insulator also used for metallized applications.

 

Alumina ceramic machining

Alumina ceramic machining including molding & grinding.

Molding includes –
Extrusion for small tubes, slip casting for large tubes, isostatic pressing, hydraulic pressing, green body machining, & sintering.

Grinding includes –
Precision diamond machining, lapping, & polishing.