Copper is a highly advantageous, high-conductivity, and high-thermal-conductivity precision material for CNC machining. Possessing excellent electrical and thermal properties, good plasticity, and low cutting resistance, it enables machining with high precision and superior surface quality. It serves as an ideal material for applications in electronics, power systems, thermal management, semiconductors, and microwave devices, and is widely utilized in the manufacturing of various precision conductive and thermal components.
Excellent Electrical and Thermal Conductivity: Second only to silver, making it the preferred material for electronic, electrical, and heat-dissipation components.
High Plasticity and Relative Softness: Exhibits low cutting resistance and high efficiency in CNC machining, while minimizing tool wear.
Facilitates High-Precision Machining: Capable of consistently achieving high dimensional accuracy and superior surface finishes.
Excellent Formability: Enables the fabrication of precision parts featuring complex cavities, thin walls, and intricate micro-structures.
Broad Range of Applications: Widely utilized in high-end precision manufacturing sectors, including electronics, electrical appliances, heat-dissipation assemblies, semiconductors, and microwave devices.
Features: Oxygen content ≤ 0.001%. Possessing extremely high purity, the material undergoes a specialized process to remove the vast majority of oxygen. It exhibits superior resistance to hydrogen embrittlement and excellent weldability, remaining highly resistant to brittle fracture in high-temperature or hydrogen-rich environments.
Applications: High-end welded assemblies, vacuum chambers, precision aerospace components, high-precision EDM electrodes, precision medical catheters, and other applications where exceptionally high standards of purity and stability are required.
Features: With an oxygen content of ≤0.003%, its purity and resistance to hydrogen embrittlement are slightly lower than those of TU1. Produced via a specialized process that removes the majority of oxygen, it offers superior cost-effectiveness. It is one of the most widely utilized grades of oxygen-free copper, suitable for structural components requiring moderate standards for welding and high-temperature operating conditions.
Applications: Moderate-requirement applications such as chemical valves, welded piping, and high-temperature heat exchangers; it also serves as an EDM electrode material for medium-to-high-end molds, as well as for precision medical components.
Features: The Cu+Ag content is ≥99.95%, with extremely low impurity levels (≤0.05%). It contains trace amounts of oxygen (typically ≤0.05%) and is virtually free of harmful impurities that would compromise its electrical and thermal conductivity. Classified as ultra-high-purity copper, it offers an excellent cost-performance ratio, making it ideally suited for high-end application scenarios.
Applications: Ultra-high-purity conductive applications, vacuum devices, as well as high-end sectors such as precision electronic components, high-frequency signal transmission parts for consumer electronics, copper busbars for PCBs, and conductive terminals.
Features: The Cu+Ag content is ≥99.90%, while the impurity content is slightly higher than that of T1 grade. It contains trace amounts of oxygen (typically ≤0.05%). This is currently the most versatile and widely used grade of pure copper in the industry, offering excellent electrical and thermal conductivity combined with high cost-effectiveness, making it suitable for applications across numerous fields.
Applications: General-purpose applications such as wires and cables, power busbars, heat exchangers, and standard electronic connectors; it also serves as an ideal material for EDM electrodes (copper "plugs") compatible with various types of molds, as well as for components such as automation fixtures and welding electrode tips.
Features: The Cu+Ag content is ≥99.70%, while the impurity content is relatively high. It contains trace amounts of oxygen (typically ≤0.05%). Its electrical and thermal conductivity are slightly inferior to those of T1 and T2 grades; however, due to its low cost, it is suitable for general structural components where performance requirements are not particularly stringent.
Applications: Simple structural components such as copper brackets, bases, standard piping, and mold positioning bushings—specifically in applications where high precision and superior electrical conductivity are not required.
To address the specific machining challenges associated with pure copper—namely its softness, high ductility, tendency to adhere to cutting tools, and difficulty in chip evacuation—CNC machining operations must prioritize four core areas: tool selection, cutting parameters, cooling and lubrication, and process control. This approach ensures optimal machining precision, surface finish, and efficiency. The specific requirements are outlined below:
Tool Selection and Parameter Optimization:
Cutting tools constitute the core of CNC machining for pure copper; priority must be given to tools specifically adapted for non-ferrous metal processing—characterized by anti-sticking and wear-resistant properties—while simultaneously optimizing their geometric parameters. Regarding tool selection, the preferred choices are uncoated YG6/YG8 tungsten-cobalt carbide tools (requiring a finely polished cutting edge) or PCD diamond tools; both offer excellent impact resistance and wear resistance, effectively preventing material adhesion to the tool. Conversely, the use of titanium-based coated tools—such as those with TiN or TiAlN coatings—is strictly prohibited, as these coatings tend to react with copper, thereby exacerbating the problem of material adhesion. Geometric parameters require specific, targeted adjustments: the rake angle should be maintained between 18° and 25° to minimize cutting forces and reduce adhesion; the chip breaker groove should feature a wide and shallow design to facilitate chip curling and evacuation; and the cutting edge radius must be kept under 0.02 mm to ensure edge sharpness and prevent tearing of the copper surface.
Cutting Parameter Settings:
Cutting parameters must be appropriately matched to the specific machining process, adhering to the principle of "high spindle speed, medium feed rate, and shallow depth of cut" in order to minimize the accumulation of cutting heat and the risk of tool adhesion. Reference parameters for machining pure copper using carbide tools are as follows:
| Process | Cutting Speed Vc (m/min) | Feed per Tooth Fz (mm/tooth) |
| Rough Milling | 100–150 | 0.06–0.10 |
| Finish Milling | 150–200 | 0.03–0.06 |
| Turning | 80–120 | 0.08–0.12 |
Cooling and Lubrication Requirements:
Dry cutting is strictly prohibited during the CNC machining of pure copper. The core principles of cooling and lubrication in this process are "adequate cooling, prevention of tool adhesion, and avoidance of corrosion." It is essential to select sulfur-free or low-sulfur emulsions—or semi-synthetic cutting fluids—maintaining a concentration between 5% and 10%. These fluids should be applied via a high-flow direct stream aimed at the cutting zone to ensure thorough cooling at the interface between the cutting edge and the workpiece, thereby mitigating tool adhesion caused by excessive cutting temperatures. Simultaneously, the use of chlorine-containing extreme-pressure additives must be avoided to prevent corrosion of the pure copper surface. When necessary, compressed air assistance may be employed to blow away chips, preventing chip accumulation from scratching the workpiece surface and ensuring smooth chip evacuation.
Process Control:
Appropriate process control can effectively minimize workpiece deformation and surface defects while enhancing machining precision. Regarding tool entry strategies, climb milling is the preferred method; this reduces cutting forces and prevents surface tearing in copper materials, thereby avoiding workpiece damage caused by direct vertical plunging. For thin-walled pure copper components, the use of soft jaws and auxiliary supports is essential to minimize clamping forces and prevent deformation under stress. Roughing and finishing operations must be strictly separated: roughing serves to rapidly remove the bulk of the material, leaving a finishing allowance of 0.3–0.5 mm; for the finishing pass, a sharp, new cutting tool should be utilized to ensure the required surface roughness and dimensional accuracy. During programming, specific routines for frequent tool retraction and chip evacuation should be incorporated to prevent long chips from entangling the cutting tool, thereby safeguarding both machining efficiency and surface quality.
Pure Copper Terminal
Pure Copper Connector Terminals
Pure Copper Heat Sink
Pure Copper Screw
Pure Copper Conductive Post
Pure Copper Terminal
CNC Machining of Copper Parts
CNC Machining of Copper Parts
A: The root causes are tool dullness, insufficient cooling, and excessive cutting temperatures. Since copper is highly ductile and prone to adhesion, it easily bonds with the tool, leading to built-up edges or direct tool sticking. The solutions involve promptly replacing the tool with a sharp one, increasing the pressure of the cooling system to ensure the cutting fluid is directed straight into the cutting zone for effective cooling, and—simultaneously—appropriately reducing the cutting depth to minimize heat accumulation.
A: This is primarily caused by an excessively low feed rate or a poorly designed chipbreaker geometry on the tool, which prevents chips from curling and evacuating smoothly. You can address this by appropriately increasing the feed per tooth and adjusting cutting parameters to better suit the specific machining characteristics of pure copper. Additionally, switch to a tool featuring a wider, shallower chipbreaker design to promote chip curling and detachment, thereby preventing entanglement.
A: These issues are often caused by inappropriate cutting parameters (such as an excessively high feed rate) or tool vibration, which leads to instability at the cutting edge. Solutions include reducing the feed per tooth and appropriately increasing the cutting speed to optimize parameter matching. Furthermore, check for and correct any tool runout, verify that the tool is securely mounted, and minimize tool vibration to ensure a smooth cutting action, thereby preventing surface tearing and burr formation.
A: These problems typically stem from excessive cutting forces, overly tight clamping, or thermal expansion of the workpiece during the cutting process. You can resolve this by optimizing the clamping method—specifically, by reducing clamping force (using soft jaws and auxiliary supports for thin-walled parts)—and by reducing the cutting depth to lower cutting forces. Additionally, increase the flow rate of the cutting fluid to provide ample cooling for the workpiece, thereby minimizing the impact of thermal expansion on dimensional accuracy.
A: The primary causes are an inappropriate selection of tool material, excessive cutting parameters, or insufficient cooling, all of which lead to premature tool wear due to overheating. The recommended solution is to prioritize the use of PCD diamond tools or YG6/YG8 tungsten-cobalt carbide tools, while avoiding the use of high-speed steel tools. Additionally, optimize machining parameters by appropriately reducing the cutting speed and depth of cut; simultaneously, increase the flow rate of the cutting fluid to ensure adequate tool cooling and minimize high-temperature wear.
A: This issue is primarily caused by the selection of unsuitable cutting fluids, a failure to clean the workpiece promptly after machining, or storage in a humid, sulfur-rich environment. To prevent corrosion, opt for sulfur-free or low-sulfur cutting fluids. After machining, immediately wipe the workpiece to remove any residual cutting fluid. For short-term storage, apply a rust-inhibiting oil; for long-term storage, place the workpiece in a dry, sulfur-free environment. If slight oxidation has already occurred, it can be removed by wiping the surface with a soft cloth and a specialized copper polishing agent.
