Machinability and manufacturing cost in low-lead brass

Abstract

Today, commercially used brasses commonly contain 2 to 4 wt% lead. As the availability of low-lead and lead-free brass increases, there are environmental incentives for investigating the consequences of replacing the lead-containing brasses with lead-free equivalents. Generally, lead-free brass is expected to have a lower machinability than its lead-alloyed counterpart, implying a higher manufacturing cost. Thus, the aim of this study has been to quantify the added manufacturing cost by replacing a standard brass alloy with a low-lead alternative. This was done through a case study performed at a Swedish SME which replaced CuZn39Pb3 (3.3 wt% Pb) with low-lead CuZn21Si3P (< 0.09 wt% lead) for a select part. Since CuZn21Si3P is almost twice as expensive as CuZn39Pb3, the material cost was found to have a substantial influence on the manufacturing cost. Additionally, the lower machinability implied a longer cycle time and higher losses while machining CuZn21Si3P, resulting in a 77% overall increase in manufacturing cost when using the low-lead material. Arguably, the difference in material cost, and thus manufacturing cost, may decrease over time making production of low-lead and lead-free brass products a viable option, especially when considering the environmental incentive for decreasing the amount of lead in circulation.

Machinability of CuZn21Si3P brass

“…In order to evaluate the industrial viability of replacing common lead-containing free-machining brass with CuZn21Si3P, a case study was performed at a Swedish SME. 18 The study consisted of a comparison of the manufacturing cost between CuZn39Pb3 and CuZn21Si3P at a Swedish SME producing indoor heating components. For the product in question, a part of a thermostatic radiator valve assembly, it was found that the material accounts for roughly 70% of the total manufacturing cost.…”

Machinable Leaded and Eco-Friendly Brass Alloys for High Performance Manufacturing Processes: A Critical Review

“…From a purely manufacturing-economic standpoint, substitution of lead-containing brass with a lead-free alternative does not appear to be an economically viable option, but it is technically possible, satisfying the requirements of the enforced legislation [19]. As such, efforts were made into incorporating soft second phase particles (SPPs) in the microstructure of copper-base alloys to attain the positive effects of Pb.…”

A Study of the Morphological Changes and the Growth Kinetics of the Oxides Formed by the High Temperature Oxidation of Cu-32.02% Zn-2.30% Pb Brass

“…Leaded brasses consist mostly of a two phase structure, namely the alpha and the beta phases, with the lead particles randomly distributed at the grain boundaries 4,5 . However, depending on the amount of zinc, brass as an alloy can exist with a single alpha-phase 6 .…”