Page 159 - Module DMV20173

8.0 POWDER PROCESSING

Table 8.2 Advantages and limitations of each process

Process Advantages Limitations
Slip casting Large parts Low production rate
Complex shapes Limited dimensional accuracy

Low equipment cost
Extrusion Hollow shapes and small diameters Parts have constant cross-section
High production rate Limited thickness
Dry pressing Close tolerances Density variation in parts with high

High production rates [with length-to-diameter ratios
automation) Dies require abrasive-wear
resistance
Equipment can be costly

Wet Complex shapes Limited part size and dimensional
pressing High production rate accuracy
Tooling costs can be high
Hot Strong Protective atmospheres

pressing High-density parts required
Short die life
Isostatic Uniform density distribution Equipment can be costly
pressing

Jiggering High production rate with Limited to antisymmetric parts
automation Llimited dimensional accuracy
Low tooling cost
Injection Complex shapes Tooling can be costly

moulding High production rate

8.3.6 DRYING

I) GREEN MACHINING

1. The final shape of ceramic product cannot always be achieved by the

original shaping processes.
2. It is often obtained by secondary operations before the sintering process
that is Green machining process.
3. Green machining refers to shaping operations of the dried unfired ceramic
product. Due to the lower strength in green ceramic product, refinement of

BPLK 191 DMV 20173