In copper processing, the design and processing of R-angle (corner radius) directly affect the performance, service life, and process feasibility of the product. The following is a summary of its core role and key considerations:

1、 The role of R angle in copper processing

1. Optimization of mechanical properties

Reduce stress concentration: Copper materials (especially hard copper alloys) are prone to stress concentration at sharp corners, and the R-angle can disperse stress and prevent fatigue cracks.

Avoid deformation and cracking: When bending or stamping, a too small R angle can cause tensile cracking on the outer side of the copper material (such as beryllium copper) and wrinkling on the inner side (such as purple copper).

2. Improvement of processing technology

Protecting the tool: The R angle during cutting can reduce local wear of the tool and extend its lifespan (such as when milling brass, the R angle should be ≥ 0.3 times the tool diameter).

Improving stamping stability: R-angle ≥ 0.5 times the material thickness (such as 1mm thick copper plate R-angle ≥ 0.5mm) can prevent mold chipping and material tearing.

3. Functionality and safety

Uniform conductivity/heat conduction: Avoid high current density or heat flux density at sharp corners (such as the R-angle of high-frequency circuit copper foil should be ≥ 0.1mm).

Deburring and anti cutting: The R angle is easy to polish and eliminates sharp edges (such as copper handles and decorative parts).

2、 Precautions for copper R-angle processing

1. Material characteristic matching

Soft copper (such as T2 purple copper): has good ductility and can have a smaller R-angle (such as bending R-angle ≥ 0.2 times the material thickness).

Hard copper (such as C17200 beryllium copper): The R angle needs to be increased (such as stamping R angle ≥ 1 times the material thickness), and if necessary, annealing treatment should be carried out first.

2. Process parameter control

Cutting processing:

Tool radius ≤ R angle design value (if R1 requires a ball head knife with a diameter of ≤Φ 2mm).

The feed rate should be slow (such as copper precision machining feed ≤ 0.05mm/tooth) to avoid burrs.

Stamping/bending:

The R angle of the mold needs to be 5% to 10% larger than the design value (compensating for rebound, such as H62 brass rebound angle of about 2 ° to 5 °).

For thin plates (<0.5mm), it is recommended that the R-angle be ≥ the material thickness, and for thick plates, it can be appropriately reduced.

3. Design specifications

Minimum R-angle limit:

Recommended minimum R-angle for process (unless otherwise specified)

Cutting ≥ 0.3mm

Stamping ≥ 0.5 times the material thickness

Die casting ≥ 1.0mm

Tighten key areas: For example, the R-angle of high-voltage conductive parts should be ≥ 0.5mm and rounded and polished.

4. Common problems and countermeasures

Problem 1: Crack at the R corner

Countermeasure: Increase the R angle, switch to annealed copper material, or reduce processing speed.

Problem 2: Size deviation (rebound)

→ Countermeasure: Pre process the R angle of the bending die to a negative deviation (such as designing R1 and making R0.9 for the die).

Question 3: Surface roughness

→ Countermeasure: Use diamond cutting tools or electrolytic polishing during precision machining.

3、 Typical application cases

Copper bar (for conductivity):

R-angle requirement: Edge R ≥ 0.8mm, hole opening R ≥ 0.5mm (anti discharge corrosion).

Process: After laser cutting, deburring and passivation treatment are required.

Heat sink fins:

R-angle requirement: Root R ≥ 0.3mm (anti stress fracture).

Process: During extrusion molding, the R angle of the mold needs to be polished to Ra0.8 μ m or less.

Decorative copper parts:

R-angle requirement: Visible surface R ≥ 0.5mm (smooth feel).

Process: CNC machining followed by drum polishing for 30 minutes.

4、 Summary

Prioritize determining the R angle based on functional requirements: conductive components>structural components>decorative components.

Combining material and process adjustments: Soft copper can be aggressive, while hard copper needs to be conservative, and process validation should be conducted if necessary.

Testing focus: R-angle size (projector/profiler), surface cracks (penetration testing).

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