In a Chinese precision machining shop, almost every structural aluminum part on a workbench is either 6061-T6 or 7075-T6. Both are heat-treatable, both anodize well, both are stocked in plate and bar. The choice between them changes the price by 30–60% and the weight, fatigue life, and machining behavior in subtle ways.
Quick Material Science Refresher
- 6061 is an Al-Mg-Si alloy. T6 temper means solution heat-treated and artificially aged. Tensile strength ~310 MPa, yield ~276 MPa, elongation ~12%.
- 7075 is an Al-Zn-Mg-Cu alloy (the same family as aircraft structural extrusions). Tensile strength ~572 MPa, yield ~503 MPa, elongation ~11%.
So 7075 is roughly twice as strong. But that is not the whole story.
Where 6061-T6 Wins
- Weldability — 6061 can be TIG welded; 7075 generally cannot without cracking risk.
- Corrosion resistance — 6061 holds up better in humid or mildly corrosive environments.
- Anodizing response — both can be hard-anodized to Type III, but 6061 takes color dye more uniformly.
- Cost — typically 30–50% cheaper per kg.
- Machinability — better chip formation, less tool wear.
For timing-belt clamp plates, jigs, fixtures, and most linear-motion brackets, 6061-T6 is the right choice. That is why we stock all 36 standard sizes in 6061-T6.
Where 7075-T6 Makes Sense
- High-cycle fatigue — robot arms under continuous load.
- Weight-critical parts — UAV frames, racing equipment, payload-limited robotics.
- Parts that will see impact loading or high stress concentrations.
- Defense and aerospace parts with strict certification requirements.
For Robot Joint Modules
Our standard joint housings are machined from 6061-T6 because the housing is mostly a structural shell — the load path is through the bearings and reducer, not the housing wall. If you need a custom joint housing for a high-cycle or weight-critical application, 7075-T6 is available as an option with the same anodized finish.
Material choice is rarely a single-parameter decision. Send us your duty cycle, environment, and weight budget and we will recommend the right alloy on the first revision.