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.
Leaded alloy 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 also.
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.
Leaded alloys 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 (10-160)