Tin-Bronze Moulded Parts With Lead-Free Chip-Breaking Machinability
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Solution Overview
Problem
Current copper alloys used in water-conducting systems face challenges in machining due to long chip formation, which affects cost-effectiveness and safety due to lead content regulations, and existing lead-free alloys lack economic efficiency and mechanical properties.
Innovation Solution
A copper alloy with a composition of 2 to 4% Sn, 0.1 to less than 1.5% Zn, 0.05 to 0.45% S, and less than 0.25% Pb, without Al, Si, Pb, Sb, Te, Se, C, and Bi, that enables hot forming and subsequent machining with high mechanical strength and corrosion resistance, using sulfur as a chip breaker without lead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lead is added to red brass to improve machinability, then chip breaking is enhanced and machining becomes economical, but lead leaching into drinking water occurs which is harmful to health
Solution Approach 1:
The invention extracts and removes lead from the copper alloy composition while introducing alternative elements (sulfur, zinc, tin) that provide chip-breaking functionality without the harmful leaching effects. The alloy is specifically designed to be lead-free or contain minimal lead (less than 0.25 wt.%) to comply with drinking water safety regulations.
Solution Approach 2:
The invention uses sulfur as a substitute for lead as a chip breaker. Sulfur forms brittle sulfide inclusions that break chips effectively during machining, replacing the function of lead without the long-term health hazards. This substitution allows economical machining of drinking water components.
2Object-affected harmful factors
If lead-free copper alloys are used to comply with health regulations, then health safety is improved, but the alloys form long chips during machining which reduces productivity and increases costs
Solution Approach 1:
The invention introduces sulfur as an intermediary element that mediates between the health safety requirement (lead-free) and machining efficiency requirement. Sulfur forms sulfide inclusions that act as chip breakers, enabling efficient chip evacuation during machining of lead-free copper alloys used in drinking water systems.
Solution Approach 2:
The invention changes the chemical composition parameters of the copper alloy by adding specific amounts of sulfur (0.05-0.45 wt.%), zinc (0.1-1.5 wt.%), and tin (2-4 wt.%) to create a lead-free alloy that maintains good machinability through controlled chip formation rather than producing long continuous chips.
3Reliability
If homogeneous copper alloys are used to ensure corrosion resistance, then corrosion protection is improved, but long chip formation occurs during machining which worsens manufacturing efficiency
Solution Approach 1:
The invention applies local quality by creating a non-homogeneous microstructure with distributed sulfide inclusions throughout the copper alloy matrix. These localized sulfide regions serve as chip breakers during machining while the overall alloy maintains homogeneous corrosion resistance properties. The sulfide inclusions are dispersed throughout the material to provide consistent chip breaking functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The alloy allows for the production of molded parts with high mechanical strength, dimensional accuracy, and corrosion resistance, enabling economical machining and compliance with lead content regulations without compromising mechanical or corrosion properties.
Implementation Method 1
Lead acts as a chip breaker in the alloy, allowing machining on CNC machines and conventional automatic lathes
Implementation Method 2
copper possesses bacteriostatic properties and also offers excellent corrosion resistance
Implementation Method 3
copper possesses bacteriostatic properties and also offers excellent corrosion resistance
Data Source
AI summary
The present invention relates to a tin-containing copper alloy, its use and a method for producing molded parts, as well as the molded parts produced therefrom.