Brass C628

Brass C628 is a leaded brass alloy with excellent machinability and is commonly used in industrial applications requiring precision and high durability, such as automotive, plumbing, and electrical systems.

Introduction to Brass C628

Brass C628, also known as leaded brass, is an alloy primarily composed of copper, zinc, and lead, offering excellent machinability and strength. Compared to other brass alloys, Brass C628 stands out for its superior machinability, making it ideal for high-speed CNC machining. Its high lead content improves cutting efficiency and reduces tool wear, making it suitable for intricate, high-precision parts. Brass C628 is highly valued for its precision machining capabilities.

This versatile alloy is commonly used in CNC machined parts like valves, connectors, and bushings. Its excellent workability, combined with good corrosion resistance, makes it ideal for applications in the automotive, plumbing, and electrical industries.

Chemical, Physical, and Mechanical Properties of Brass C628

Chemical Composition (Typical)

Element	Composition Range (wt.%)	Key Role
Copper (Cu)	58.0–62.0%	Provides strength, conductivity, and corrosion resistance
Zinc (Zn)	37.0–41.0%	Enhances strength and material hardness
Lead (Pb)	2.0–3.0%	Improves machinability and lubricity
Iron (Fe)	≤0.5%	Minimal impact on properties

Physical Properties

Property	Value (Typical)	Test Standard/Condition
Density	8.4 g/cm³	ASTM B311
Melting Point	900–950°C	ASTM E29
Thermal Conductivity	120 W/m·K at 20°C	ASTM E1952
Electrical Conductivity	15% IACS at 20°C	ASTM B193
Coefficient of Expansion	19 µm/m·°C	ASTM E228
Specific Heat Capacity	380 J/kg·K	ASTM E1269
Elastic Modulus	105 GPa	ASTM E111

Mechanical Properties (Annealed Temper)

Property	Value (Typical)	Test Standard
Tensile Strength	280–350 MPa	ASTM E8/E8M
Yield Strength (0.2%)	180–250 MPa	ASTM E8/E8M
Elongation	30–40%	ASTM E8/E8M
Hardness	60–80 HB	ASTM E10
Fatigue Strength	~150 MPa	ASTM E466
Impact Resistance	Good	ASTM E23

Key Characteristics of Brass C628

Excellent Machinability

Brass C628 is highly machinable, thanks to its lead content, which improves tool life and reduces cutting forces. It is ideal for high-speed CNC operations.

Moderate Strength and Good Ductility

This alloy offers a good balance of strength and ductility, enabling it to be formed, bent, or stamped without cracking.

Corrosion Resistance

Brass C628 exhibits good resistance to corrosion in atmospheric conditions and fresh water, but it is not recommended for marine environments.

Good Electrical and Thermal Conductivity

With a substantial copper content, Brass C628 is effective in applications requiring good electrical conductivity, such as connectors and terminals.

Aesthetic Appeal

Brass C628 has a bright yellow finish that is highly valued in decorative applications like plumbing fixtures and jewelry, where appearance is important.

CNC Machining Challenges and Solutions for Brass C628

Machining Challenges

Chip Formation Brass C628 can produce long, stringy chips, which may cause issues in machining operations.
Solution: Use chip breakers to manage chip formation and improve chip removal during high-speed cutting.
Tool Wear Although it is a free-machining alloy, Brass C628 can still cause tool wear over time, especially at high cutting speeds.
Solution: Utilize carbide or ceramic cutting tools for increased durability and better cutting performance.
Surface Finish Quality Brass C628 tends to create rough edges during machining, making achieving a fine surface finish challenging.
Solution: Use high-speed cutting techniques and sharp tools with sufficient lubrication to obtain smooth surfaces.
Work Hardening Brass C628 may undergo work hardening if machining speeds or pressures are too high.
Solution: Use moderate cutting speeds and sharp tools to minimize the risk of work hardening.

Optimized Machining Strategies

Parameter	Recommendation	Rationale
Tool Material	Carbide or ceramic tools	These materials offer superior wear resistance and cutting performance.
Geometry	Positive rake, sharp edges	Enhances chip flow and improves surface finish.
Cutting Speed	150–250 m/min	Reduces heat buildup and prevents material deformation.
Feed Rate	0.10–0.20 mm/rev	Ensures smooth cutting and prevents burr formation.
Coolant	Flood coolant or air blast	Reduces heat and improves surface finish.

Brass C628 Cutting Parameters (ISO 513 Compliance)

Operation	Speed (m/min)	Feed (mm/rev)	Depth of Cut (mm)	Coolant Pressure (bar)
Roughing	150–200	0.15–0.20	2.0–3.5	25–35
Finishing	200–250	0.05–0.10	0.5–1.0	30–50

Typical Machining Methods for Brass C628

Machining Process	Function and Benefit for Brass C628
CNC Machining	Ideal for high-speed, precision machining of small components such as connectors and fasteners. Suitable for applications in the automotive and electrical industries.
CNC Milling	Perfect for creating slots, grooves, and complex shapes in components like valves and fittings. Widely used in the plumbing and aerospace industries.
CNC Turning	Used for turning cylindrical parts like bushings, gears, and mechanical components. Common in the automotive and industrial machinery sectors.
CNC Drilling	Ideal for precise hole creation for fasteners and mechanical parts. It is extensively used in the electrical and automotive industries.
CNC Boring	Ensures precise internal machining of parts like bearings and bushings. Popular in the manufacturing of industrial equipment and automotive systems.
CNC Grinding	Provides smooth finishes for parts exposed to wear and tear, like gears and shafts. Commonly used in aerospace and automotive applications.
Multi-Axis Machining	Ideal for producing complex, multi-featured parts for industries such as aerospace and automotive.
Precision Machining	Provides ultra-tight tolerances for components requiring high-precision performance. Widely used in the medical and aerospace industries.
EDM Machining	Used for creating intricate features and fine details in automotive and industrial parts. Common in precision tool manufacturing.

Surface Treatment for Brass C628 CNC Parts

Electroplating: Enhances corrosion resistance and gives a shiny finish for components like connectors and fittings.
Polishing: Achieves a high-gloss finish that improves both appearance and functionality for decorative parts.
Brushing: Creates a satin or matte finish for parts exposed to frequent handling or environmental stress.
PVD Coating: Adds a durable coating that increases wear resistance and enhances the part’s life.
Passivation: Improves the corrosion resistance, especially for parts exposed to chemicals.
Powder Coating: Provides a thick, protective finish ideal for parts exposed to UV light and harsh conditions.
Teflon Coating: Adds non-stick, chemical-resistant properties, ideal for high-performance mechanical applications.
Chrome Plating: Provides a glossy, durable coating that resists corrosion and adds an aesthetic touch to mechanical components.

Industry Applications of Brass C628

Aerospace Industry: Used for manufacturing connectors, bushings, and other parts subjected to high stresses.
Electrical & Power: Ideal for electrical terminals, connectors, and components that require high conductivity.
Automotive Industry: Commonly used for creating gears, fasteners, and connectors in automotive systems.
Medical Industry: Used for producing precise medical device and equipment components that require high reliability and performance.