Machining copper-tungsten, also known as copper-tungsten alloy or CuW, involves a series of techniques and considerations to ensure optimal results. Here are some key aspects to consider when machining this material:
Techniques
Tool Selection
- Use tools made of materials that can withstand the hardness and wear resistance of copper-tungsten. Carballoy, grade 883 or equivalent, is a suitable choice.
- Grind tools with specific angles and nose radii to ensure effective cutting. For example, use tools with 0-degree rake, 8-12-degree clearance, and a nose radius of 0.010″ to 0.025″, which can increase with the size of the work.
Turning and Boring
- For roughing, use a depth of cut of approximately 0.030″ and a feed rate of 0.020″ per revolution.
- For finishing, reduce the depth of cut to 0.002″ to 0.005″ and the feed rate to 0.001″ to 0.002″ per revolution.
- Maintain a turning speed of 300-500 surface feet per minute. It is generally not necessary to use lubricant or coolant during this process.
Shaping
- Use a tool speed of 43″ per minute for copper-tungsten 25% alloy.
- Apply a depth of cut of 0.030″ and a feed rate of 0.020″ per stroke.
Milling and Drilling
- High-speed steel drills and taps can be used for drilling copper-tungsten.
- For through tapping, ensure that the material is firmly held. Hand feed-lubricant and cutting oil are acceptable.
Grinding
- Rough grinding is best done with 80 grit resin bonded wheels of medium hardness.
- Use a pass depth of 0.015″ on copper-tungsten 25% alloy.
- Water or water-soluble oil coolant can be used during the grinding process.
Considerations
Material Properties
- Copper-tungsten alloys are hard and have high wear resistance, which can make machining challenging.
- They are also nonporous, so standard water-soluble coolants may be used if desired, but they are not required.
Machining Practices
- Each machine shop has its own individual machining or grinding practice. Therefore, the information provided should be used as a guide only.
- Machine shops may need to adjust their techniques based on the specific composition and hardness of the copper-tungsten alloy being machined.
Post-Processing
- After machining, consider additional processes such as cleaning, polishing, and coating to improve the surface finish and corrosion resistance of the copper-tungsten parts.
Safety
- Wear appropriate personal protective equipment (PPE) when machining copper-tungsten, such as safety glasses, gloves, and hearing protection.
- Ensure that the work area is well-ventilated to prevent the accumulation of dust and debris.
In summary, machining copper-tungsten requires careful selection of tools and techniques, as well as consideration of the material’s properties and machining practices. By following these guidelines, machine shops can achieve optimal results and produce high-quality copper-tungsten parts.