token
Structural
- May 31, 2009
- 5
Hello All,
I am working with a foundry in China and I am having difficulty settling on a lead-free alloy.
The casting is for use in a coffee machine and so must be lead-free, have good corrosion resistance to the mild saline water from the water softener and to the coffee acids at the operating temperature (170-200F). There is also significant secondary machining so a reasonable machinability rating would be preferable.
The alloy that I initially specified is a silicon bronze - C87850 but the foundry cannot supply it at a reasonable cost and suggest substituting H85 (which I presume is C23000) or H68As (presumably C26800 with Arsenic, although none is listed in the composition).
H85 Composition: Cu 84-86 Ni 0.5 Fe 0.1 Pb 0.03 Zn (balance) other 0.3
H68As Composition: Cu 67-70 Zn (balance) Pb 0.03 P 0.01 Fe 0.1 Sb 0.005 Bi 0.002 other 0.3
[single values are maximums]
Both of these specifications however are for wrought brasses and I can find no information about their casting properties. If the part can be cast from C23000 and the factory can perform the secondary machining, then I see no objections. However, I have so far failed to find any information about casting this alloy.
Any light shed on this would be greatly appreciated.
Many thanks,
Token
I am working with a foundry in China and I am having difficulty settling on a lead-free alloy.
The casting is for use in a coffee machine and so must be lead-free, have good corrosion resistance to the mild saline water from the water softener and to the coffee acids at the operating temperature (170-200F). There is also significant secondary machining so a reasonable machinability rating would be preferable.
The alloy that I initially specified is a silicon bronze - C87850 but the foundry cannot supply it at a reasonable cost and suggest substituting H85 (which I presume is C23000) or H68As (presumably C26800 with Arsenic, although none is listed in the composition).
H85 Composition: Cu 84-86 Ni 0.5 Fe 0.1 Pb 0.03 Zn (balance) other 0.3
H68As Composition: Cu 67-70 Zn (balance) Pb 0.03 P 0.01 Fe 0.1 Sb 0.005 Bi 0.002 other 0.3
[single values are maximums]
Both of these specifications however are for wrought brasses and I can find no information about their casting properties. If the part can be cast from C23000 and the factory can perform the secondary machining, then I see no objections. However, I have so far failed to find any information about casting this alloy.
Any light shed on this would be greatly appreciated.
Many thanks,
Token