Brinell hardness vs. Rockwell hardness

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knifer-one

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I bought some Fortal aluminum a while back.From what i can understand from the chart,it has a Brinell hardness of 150. I found a conversion chart and it looks like it has a Rockwell hardness of 70. Very difficult to machine. HELP! I can't do anything with it!
 
We need to know what scales you have there. Rockwell is measured in several, depending on several factors, and so is Brinnell. At times they overlap. Is your Rockwell A, B, C, D, E, or F. Or perhaps the Rockwell Superficial Scale 15-N, 30-N, 45-n, or 30-T. Is the Brinell measured with a 500Kg load, or a 3000Kg load?

What kind of tooling?
 
Fortal® is an aircraft-quality aluminum with applications in many industries. Available exclusively from Superior Die Set Corporation, Fortal® is lightweight with excellent machining properties. In addition, Fortal® is also stronger than 1020 steels, and provides superior energy absorption, with a modulus of elasticity that is one-third that of steel. Fortal® provides high corrosion resistance and is delivered free of tensions and stresses giving you the consistency of a product that rarely deforms during machining or use. These benefits lead to higher productivity and lower tooling costs, which add up to a competitive edge for you
 
Interesting. I spent a lot of time in the aircraft industry and never heard of Fortel. The specs look almost too good to be true. It's stronger than 7075 but has better corrosion resistance than 6061 and the machinability is excellent. I can't wait to try some.

Tom
 
I wish they'd just use the R.C. scale for measuring hardness of hardened and tempered steels. When the hardness of a lathe bed is said t be 300 Brinnell,I have to get out info to find out that 300 Brinnell is (IIRC) about 52 R.C.,or as hard as a good piece of blue spring(1095) steel. Which,by the way,is not hard enough to suit me for a lathe bed. I want it file hard(so a new,fine tooth file won't cut it),which is more into the 60's of RC.

By the way,a fine tooth,new USA file will cut harder steel than the same file in a coarser tooth. Always use a new,fine tooth file for testing hardness.
 
Thanks for the responses.I guess its just me,but it does seem to cut differently from 6061. What type of end mill should I be using? Would I be better off with carbide? Keep in mind that I am a mere freshman in this hobby machining stuff.
 
TLGriff said:
Interesting. I spent a lot of time in the aircraft industry and never heard of Fortel. The specs look almost too good to be true. It's stronger than 7075 but has better corrosion resistance than 6061 and the machinability is excellent. I can't wait to try some.

Tom
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I bought this from ebay. they have a store there and have about any size you want
 
knifer-one said:
Thanks for the responses.I guess its just me,but it does seem to cut differently from 6061. What type of end mill should I be using? Would I be better off with carbide? Keep in mind that I am a mere freshman in this hobby machining stuff.
Click to expand...

Looking at the specs, it will cut differently than 6061. Instead of the long stringy chips you get from 6061, these will break off and will likely require coolant to keep from loading up the end mill. Try a little WD-40 on the end mill to keep it from sticking. This type of aluminum is also harder than 6061 so you'll get more flex in the end mill especially so if it is starting to get dull. Dull end mills and aluminum of any kind are a bad combination. They generate so much heat that the chips stick to the flutes plugging them up which generates even more heat.

The only time I'll use carbide on aluminum is with a long, small diameter end mill and I need the rigidity of the carbide. Normally, carbide is not necessary or even desirable on aluminum.

Tom
 
Why is a fine file easier to file harder metal with? Food for thought. Perhaps the teeth are sharper,or there are more teeth to engage the metal.
 
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