HAZ on laser cut aluminum .025" thick and less

[KirbyWan]

Howdy all,

I would like to have the details for and aircraft part laser cut from aluminum sheet stock (.025" thick and .010" thick), but I have a process specification issue. STP 51-310 requires that I do a test with the same alloy, gage, thickness and heat treat to determine the extent of the heat affected zone, and have that HAZ removed in subsequent processing.

What is the size of the HAZ for laser cut thin aluminum? Specifically I'm cutting 7075-T6 .010" thick and .025" thick chem milled (in places) to .012/.014.

Since all of these parts are adhesivly bonded the edge of the sheet does not carry significant load so the HAZ (If it's as small as I think it is) should not make any difference anyway.

Has anyone dealt with this issue before and have suggestions? The spec was last updated in 1996 so what may have been a new process at the time is now old news with no current issues.

Thanks for your help.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[tomwalz]

We figure the heat affected zone in saw steel is about 0.005" to 0.007".

In steel we get a phase change and a fair amount of slag on the edge of the cut.

The amount of slag depends on what gas they use, of course.



Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[KirbyWan]

Tomwalz,

When you say saw steel do you mean as used in band saws? How thick are the blades? ~.020"? You talk about slag build up depending on the gas used. I didn't think a laser cutter needed gas. Is this just an inert gas for keeping the head clean? What are the gas choices?

Thanks for your help.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[tomwalz]

Band saws, round saws up to maybe .125".

The lasers I am familiar with use the laser to melt the steel then a gas to blow the metal out. Compressed Air, Nitrogen, Argon, CO2 are some. There may be more.



Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[GRoberts]

Some aluminum alloys have cracks in the melted portion of a thermal cut. The specification was most likely written so guarantee that any potential cracking is removed. Even if your part is adhesively bonded, the pre-existing cracks on a thermally cut edge can act as a stress riser that could lead to fatigue crack prorogation over the years in aircraft parts.