Precision Rectangular Tubing

[jmsayles]

I recently reverse engineered a relatively simple product and found a key component was a set of precision rectangular tubes that served as the structure for a telescoping actuator. The tubes were steel and used thin plastic bushings as the bearing surfaces between the tubes. They were nested in that the inside surface of one held the bushings that contacted the outside surface of the next tube. There was no observable play in the fit and the fit did not appear to change through the full travel length of about 1m. The tubing is thin wall and shows no signs of welding or machining. I am familiar with the drawn over mandrel process for round tubing. Is there a comparable process for rectangular tubing or how else might these tubes be fabricated? Thanks! John

 

[EdStainless]

Yes, you can DOM square tube.
Square die and square mandrel.

https://www.plymouth.com/products/shaped-tubing-2/

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P.E. Metallurgy, Plymouth Tube

 

[jmsayles]

Thank you EdStainless. I see the aspect ratio is limited to 1:1.16. The tubing I have is 1:1.5. Is the ratio a process limitation?

 

[EdStainless]

It depends on the size, some is and some isn't.

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P.E. Metallurgy, Plymouth Tube