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What aluminum alloy should we use for anodizing/hardcoating load bars?

We are an anodizing/hardcoat job shop. Currently we use round copper bus bars. We would like to switch to aluminum square bus bars. Is there a recommended aluminum alloy for the load bars?

Jeff Nathan
Job Shop - Providence, Rhode Island, USA
2007

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First of two simultaneous responses -- 2007

Copper anode bars are better due to lower contact resistance. Copper also has a higher elastic modulus (x1.67) for less deflection under load, although rarely a factor with larger Al rods of equal conductivity.

Of common aluminum alloys, 6101-T61 (conductivity 57.2% of 101 copper) > 6063-T6 (51.5%) >> 6061-T6 (43%). Replacing a 1" diameter copper rod requires a 1.188" square bar of 6101, 1.25" of 6063 or 1.375" of 6061. Higher purity Al alloys (e.g., 1050, 1060, 1199, 1350) are more conductive (~61%) and etch more slowly, but have very low yield strengths (unless work hardened to near-brittleness). Use with supporting flight bars.

Al 1350 is the 99.5% Al, electrical conductivity (EC) grade for bus bars per ASTM B236; Al 6101 is the higher strength version per ASTM B317.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.

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Second of two simultaneous responses -- 2007

Jeff

6061-T6 will work fine. Allow for reduced conductivity when sizing. Consider powering from both ends.

Willie Alexander
- Colorado Springs, Colorado