Differences and precautions in processing copper busbars vs. aluminum busbars

When high and low voltage switchgear manufacturers or electrical panel factories use busbar machine (related: O que é uma máquina de barramento?) to process copper and aluminum busbars, if the technical engineers do not understand the physical properties (hardness, ductility, resilience) of the two metal materials, the finished product will be uncontrollable when punching, cutting and bending copper and aluminum busbars. This will result in obvious bright zone/shear zone, or even burrs, which will affect the quality and service life of the switchgear or electrical panel.

Copper busbars and aluminum busbars have significantly different physical properties, resulting in drastically different processing parameters and precautions. The following is a detailed analysis of the differences and specific precautions for machining these two materials in busbar machine processing:

When punching copper busbars, the cut surface is usually clean with few burrs. However, due to the hardness of copper, the punching die head wears relatively quickly, requiring regular checks of the punch’s sharpness.

When punching aluminum busbars, the soft and sticky nature of aluminum makes it prone to **Galling**, where aluminum shavings adhere to the punch or die. Therefore, the die must be cleaned more frequently to prevent shavings buildup that could cause punching deformation or die jamming. For aluminum busbars, the die clearance can be appropriately reduced to ensure a smooth hole wall.

When punching copper busbars, the cut surface is usually clean with few burrs. However, due to the hardness of copper, the punching die head wears relatively quickly, requiring regular checks of the punch’s sharpness.

When punching aluminum busbars, the soft and sticky nature of aluminum makes it prone to **Galling**, where aluminum shavings adhere to the punch or die. Therefore, the die must be cleaned more frequently to prevent shavings buildup that could cause punching deformation or die jamming. For aluminum busbars, the die clearance can be appropriately reduced to ensure a smooth hole wall.

Pontas: Requirements for die clearance when punching copper and aluminum busbars.

Copper busbars have high shear resistance and typically have a bright cross-section. However, one crucial point must be noted: ensure the shear blade is sharp. If the blade is dull, the copper busbar cross-section is prone to chipped corners or severe burrs.

Aluminum busbars, on the other hand, have low shear resistance but are easily deformed (flattened). During shearing, the pressure of the clamping foot (pressing device) must be moderate. Excessive pressure may leave indentations on the aluminum busbar surface, while insufficient pressure will result in a non-perpendicular cross-section.

This is the process with the biggest difference between the two, mainly in the **bending radius (R angle) and springback compensation**.

Copper busbars have good ductility and can usually use smaller R angle dies (e.g., R = busbar thickness), making them less prone to cracking. Their springback angle is smaller (usually around 3°-5°), making CNC control easier.

Aluminum busbars (especially hard aluminum) are extremely prone to cracking when stretched on the outside. This requires that **larger bending R angle dies must be used when processing aluminum busbars**, and **it is generally recommended that the R angle be ≥ 1.5 to 2 times the aluminum busbar thickness**. The springback rate of aluminum is also usually greater than that of copper (depending on the aluminum grade), and there is significant batch-to-batch variation. If the target angle is 90°, copper may only need to be bent to 92°, while aluminum may need to be bent to 95° or even more to spring back to 90°. It is recommended to set up a separate material library parameter for aluminum busbars in the CNC system.

• **Mold Protection (Recommended)**
  • Although copper and aluminum can use the same set of molds, to prevent **electrochemical corrosion** (copper-aluminum contact accelerates corrosion in humid environments), it is recommended to use separate molds for copper and aluminum whenever possible. If mixing is unavoidable, thoroughly clean any metal shavings from the molds before switching materials.
• **Surface Protection:**
  • Aluminum busbars are very easily scratched. When dragging aluminum busbars for positioning, avoid dragging them hard on the worktable. It is recommended to apply anti-abrasion rubber pads to the worktable of the busbar machine or use an auxiliary bracket with rollers.
• **Lubrication:**
  • When punching holes in aluminum busbars, apply a small amount of special lubricating oil or alcohol to the punch to reduce adhesion and improve demolding smoothness.

If you are conducting mass production, it is recommended to establish two independent parameter libraries (“Copper-Lib” and “Aluminum-Lib”) in the CNC system of the busbar machine, and to distinguish between copper busbar-specific dies and aluminum busbar-specific dies for the punching unit. It is crucial to record the different bending elastic coefficients and die radius selections for both. This way, when switching materials, you can simply call up the relevant parameters with one click, eliminating the need for repeated die trials.

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