The measured solidification range for the bismuth-containing alloy was approximately 90[degrees]F (50[degrees]C) greater than the leaded alloy
solidification range and approximately 81[degrees]F (45[degrees]C) smaller than the lead/bismuth free alloy The liquidus of the bismuth containing alloys was lower than both the leaded and lead/bismuth free alloys.
substitutes are more prone to spots or cracks.
Chicago Faucet Co, a green sand foundry pouring a copper-base leaded alloy
, employs a reclamation system that reclaims sand and recovers alloy for remelting.
So, the brass scrap stream now contains leaded alloys
and lead-free alloys that contain new elements not before present on a significant scale.
Besides the solder pot heater and pot materials, there are thermal switches, pumps, floats (remember, Pb-free is less dense than leaded alloys
) and myriad other little "gotchas." To avoid problems, talk to an expert on your specific machine, model, and option configuration; do not trust generalities.
Cross contamination with leaded material is detrimental and is a major concern if bismuth alloys get into leaded alloys
In most cases, few pattern changes are required when switching from leaded alloys
. Melting and pouring procedures will not vary greatly from the leaded alloys
While some existing gating and risering techniques designed for traditional leaded alloys
, such as C83600, were successful without modification, other casting geometries required larger ingates.
also are more castable than their no-lead counterparts.
As new environmental legislation limits the lead content in castings, especially in water applications, more users are demanding non - leaded alloys
for other applications.
Copper-bismuth alloys were developed to behave in the metalcasting process and have properties similar to existing leaded alloys
. However, no-lead alloys can be more difficult to cast than their leaded counterparts, so metalcasting facilities may need to make some changes in their practices when using them.
PANEL: Case Studies in the Use of Solidification Modeling to Transition Away From Leaded Alloys