Steel material that is magnetic and stable when machined?
Steel material that is magnetic and stable when machined?
(OP)
Hello-
I am designing a series of inspection plates for a family of aluminum parts. Each inspection plate will hold an array of 25 machined, cylindrical (2-3 in. o.d., .375 in. tk.) aluminum parts. The plate will hold each part in a 3 pt. kinematic seat machined into the surface of the plate. The part will lay flat on the plate, and the kinemtic seat in the plate will hold the part on a critical (datumed) plane. The part will not be constrained diametrically, but will be loosely clocked using a locator pin to mate up into one of the tapped holes of the part. A bar will span the part, contacting the part near the "i.d." so as not oil can the bottom surface of the part as it will be constrained axially by a screw that runs through the bar and part and threads into a machined hole in the plate (not pictured).
I want the plate to be steel so that it won't wear when switching out batches of parts. I don't really need a super hard steel, just as long as it’s tougher than aluminum. I would like the steel to be stable when machined and magnetic, so that a grinder can be used to achieve the .0004in./3.0X3.0in. flatness tolerance that I need. Right off the top of my head, 416 SS is the only steel that would work, but its pretty pricey. I had considered 01 tool steel, but I couldn't confirm whether or not it is magnetic, and I know it would be harder to machined than the 416 SS.
What other steel is magnetic and will stay stable when machined?
The part in the picture is just a concept test that holds one of the aluminum parts.
Thanks!
I am designing a series of inspection plates for a family of aluminum parts. Each inspection plate will hold an array of 25 machined, cylindrical (2-3 in. o.d., .375 in. tk.) aluminum parts. The plate will hold each part in a 3 pt. kinematic seat machined into the surface of the plate. The part will lay flat on the plate, and the kinemtic seat in the plate will hold the part on a critical (datumed) plane. The part will not be constrained diametrically, but will be loosely clocked using a locator pin to mate up into one of the tapped holes of the part. A bar will span the part, contacting the part near the "i.d." so as not oil can the bottom surface of the part as it will be constrained axially by a screw that runs through the bar and part and threads into a machined hole in the plate (not pictured).
I want the plate to be steel so that it won't wear when switching out batches of parts. I don't really need a super hard steel, just as long as it’s tougher than aluminum. I would like the steel to be stable when machined and magnetic, so that a grinder can be used to achieve the .0004in./3.0X3.0in. flatness tolerance that I need. Right off the top of my head, 416 SS is the only steel that would work, but its pretty pricey. I had considered 01 tool steel, but I couldn't confirm whether or not it is magnetic, and I know it would be harder to machined than the 416 SS.
What other steel is magnetic and will stay stable when machined?
The part in the picture is just a concept test that holds one of the aluminum parts.
Thanks!





RE: Steel material that is magnetic and stable when machined?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Steel material that is magnetic and stable when machined?
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RE: Steel material that is magnetic and stable when machined?
My recommendation would be as KENAT said, cast iron. If flatness is an issue, it is possible to get it surface ground and scraped (if necessary).
RE: Steel material that is magnetic and stable when machined?
RE: Steel material that is magnetic and stable when machined?
Regards,
Mike
RE: Steel material that is magnetic and stable when machined?
You're right, Mike. I'm looking for magnetic so that a surface grinder can be used.
RE: Steel material that is magnetic and stable when machined?
If it has to be stainless steel, you're looking for ferritic or martensitic SS.
Contact your suppliers to see what they have in stock.
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RE: Steel material that is magnetic and stable when machined?
The only reason to use stainless is if you need the corrosion resistance, otherwise you are just adding unnecessary costs.
Grey Cast Iron is a pretty good choice if you're looking for long term dimensional stability during use and over environmental changes.
Otherwise using a common tool steel such as O1, A2, etc.. is probably your best bet. A rough machining pass, heat-treat (temper for best stability, not highest hardness), then finish grinding, whether surface or jig, to get within your tolerances is the process I would use to make this tooling.
This looks like a pretty easy job for a tool and die shop.
Nick
RE: Steel material that is magnetic and stable when machined?
RE: Steel material that is magnetic and stable when machined?
Pardon my ignorance here, but why are you saying i'd want to heat treat? I really don't think I need the plates to be that hard, but I just need something tougher than the aluminum parts that will be inspected. Is it just for dimensional stability? I like that you mentioned grinding after the first machining of the surface. I was wondering if that would be a good idea.
RE: Steel material that is magnetic and stable when machined?
If you use the continuous cast gray Iron I don't think you'd necessarily need it.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?