Investment Casting for High Strength

Lestercast delivers high-strength components with precision, quality and aesthetics for demanding applications.

CUSTOMER
Investment casting for a crane manufacturer.

PRODUCT & FINISH
Rope guide retainer casting. A product specific to the company’s crane hoist design. This high-strength rope guide retainer casting keeps the cable in-line with the scrolls of the barrel it wraps.

MATERIAL
PB2 (Phosphor Bronze)

HISTORY
The part has always been investment cast in HTB3 (a high tensile brass) due to the requirement for high strength and aesthetics. However, HTB3 is susceptible to forming surface oxides that can alter the appearance of the component. In addition, larger oxides may develop during manufacturing, which can compromise the casting’s mechanical strength. As a result, the customer requested an investigation into alternative casting materials for their part.

IDENTIFYING AN ALTERNATIVE MATERIAL
Lestercast identified two alternatives to HTB3 (high tensile brass), which would offer higher corrosion & wear resistance, whilst retaining the aesthetic look of a copper-based alloy, in line with their corporate branding colours. The alternatives were: PB1 and PB2 (Phosphor bronze).

TESTING THE MATERIAL
Lestercast manufactured the castings in the new materials. The castings were then subjected to CMM surface point inspection to confirm dimensional accuracy, due to the swap of material. This is critical as one material will shrink at a different rate to another during the cooling process.
Once inspection was complete, the parts were sent to the customer so that they could perform their own field tests under controlled conditions. Tests were performed on both PB1 and PB2 castings over several days to measure wear.
PB2 was chosen as the new material for the rope guide retainer.