This document provides design considerations for powder metallurgy parts. Key points include: - Part shapes should be simple and uniform to allow for easy ejection from the die without damage. - Tolerances and wall thicknesses are limited, with minimum wall thickness of 1.5mm. - Simple steps and perpendicular letters can be included but must be carefully designed. - Radii cannot be pressed directly, chamfers must be used instead. - Die design must create strong tooling that can withstand pressing forces of 700MPa.

1. Design Consideration for
Powder Metallurgy

2. ➢The shape of the compact must be kept as simple and
uniform as possible.
➢ Provision must be made for ejection of the green
compact without damaging the compact.
➢P/M parts should be made with the widest acceptable
tolerances to maximize tool life.
➢Part walls should not be less than 1.5 mm thick;
thinner walls can be achieved on small parts; walls
with length to thickness ratios above 8:1 are difficult to
press.

3. ➢Steps in parts can be produced if they are simple and their size
doesn’t exceed 15% of the overall part length.
➢Letters can be pressed if oriented perpendicular to the pressing
direction. Raised letters are more susceptible to damage in the
green stage and prevent stacking.
➢Flanges or overhangs can be produced by a step in the die.
➢ A true radius cannot be pressed; instead use a chamfer.
➢Dimensional tolerances are on the order of ±0.05 to 0.1 mm.
Tolerances improve significantly with additional operations such
as sizing, machining and grinding.

4. Die geometry and design features for powder-metal compaction.

5. Poor and Good Designs of P/M Parts

6. Design Features for Use with Unsupported Flanges or Grooves

7. ➢ Thin walls and projections create fragile tooling.
➢ Holes in pressing direction can be round, square,
D-shaped, keyed, splined or any straight-through
shape.
➢ Draft is generally not required.
➢ Generous radii and fillets are desirable to extend
tool life.
➢ Chamfers, rather the radii, are necessary on part
edges to prevent burring.
➢ Flats are necessary on chamfers to eliminate
feather-edges on tools, which break easily.

8. ➢Basic rules for the design of P/M parts
– Shape of the part must permit ejection from die
– Powder should not be required to flow into small cavities
– The shape of the part should permit the construction of strong
tooling
– The thickness of the part should be within the range for which
P/M parts can be adequately compacted
– The part should be designed with as few changes in section
thickness as possible

9. ➢Parts can be designed to take advantage of the
fact that certain forms and properties can be
produced by P/M that are impossible, impractical,
or uneconomical by any other method
➢The design should be consistent with available
equipment
➢ Consideration should be made for product
tolerances
➢Design should consider and compensate for
dimensional changes that will occur after pressing

11. Financial Considerations
Die design
must withstand 700 MPa, requiring specialty designs.
Can be very automated
➢1500 parts per hour not uncommon for average size part
➢60,000 parts per hour achievable for small, low complexity parts in
a rolling press.
Typical size part for automation is 1” cube
– Larger parts may require special machines (larger surface area, same
pressure equals larger forces involved)