MIC-6 stock for making parts

Jay Fleming · Oct 10, 2016

I'm familiar with MIC-6 being used for fixture plates and molds but can it be used for parts that aren't just decorative? There are plenty of cast aluminum parts in all markets so it got me wondering. Any input is appreciated.

Jay

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extropic · Oct 10, 2016

For any part, material selection is based on many factors. Material properties, material cost & availability as well as compatibility with cost effective manufacturing are some of the factors.

If MIC-6 suits your needs, why not use it?

Jay Fleming · Oct 10, 2016

I understand that but I've just never seen anything on here about using it for anything beyond fixtures and molds.

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sfriedberg · Oct 11, 2016

Sands Machine goes through tons of Mic-6 making large slewing bearings. The last time they updated their "drops" page, they claimed to have over 100 tons of drop material.

Apparently they use it because it doesn't warp when they cut out rings of relatively thin and flimsy cross-section.

gkoenig · Oct 11, 2016

MIC-6 is great for tooling, but it anodizes like shit compared to 6061 or 7075.

Since 90% of aluminum parts in the world get sent to anodizing, MIC-6 doesn't float around for production parts very often.

AARONT · Oct 11, 2016

gkoenig said:
MIC-6 is great for tooling, but it anodizes like shit compared to 6061 or 7075.

Since 90% of aluminum parts in the world get sent to anodizing, MIC-6 doesn't float around for production parts very often.

90%? Where did you come up with this number?

morsetaper2 · Oct 11, 2016

We use MIC-6 for parts that we have stringent requirements for flatness and stability over large surfaces (after machining) in our laser systems. Relative to 6061 it has about 1/2 the tensile strength so its relatively soft. We finish it w/ a chem conversion coating. Don't think we have ever anodized it?

I don't like to use it because its so soft, threads can get damaged, etc. One of our vendors F-ed up some tapped/helicoil holes because they had a newb installing the STI's one time. But it has its place.

JNieman · Oct 11, 2016

MIC-6 is also a cast plate rather than rolled/extruded, etc.

It will not tolerate forces that 6061 plate will. You're more likely to need to use shrink-fits than press-fits if you need something of the sort in a MIC-6 plate (though it's not an ideal situation to start with)

We mainly just use it for jig plates, grid plates, and we'll often ask customers if they'll accept it as a substitution for parts requiring challenging flatness but seem to have no really tough structural concerns. Not sure if you mistyped or not, but "parts that aren't just decorative" confused me. I would not say jig plates and molds are 'just decorative'.

D Dubeau · Oct 11, 2016

AARONT said:
90%? Where did you come up with this number?

87% of statistics are made up on the spot.

We use mic 6 all the time for "parts". The "parts" we are making are not "structural", or require any special physical properties other than being "aluminum". We have a lot of mic 6 scrap so we try and use it when and where we can.

gkoenig · Oct 11, 2016

AARONT said:
90%? Where did you come up with this number?

Jesus Christ, are you my college professor demanding footnote citations?

It's an internet forum, not a fucking Alcoa investor note; consider it shorthand for "The vast VAST majority of aluminum barstock going through American machine shops is 6061."

Jay Fleming · Oct 11, 2016

JNieman said:
Not sure if you mistyped or not, but "parts that aren't just decorative" confused me. I would not say jig plates and molds are 'just decorative'.

I was just trying to say parts that are actually stressed rather than simple incidental parts.

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Jay Fleming · Oct 11, 2016

Thanks for the info everyone. The first thing I had in mind is engine mounts but they are highly stressed and experience a lot of oscillating stresses. Probably a better job for 6061 or 7075.

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EPAIII · Oct 11, 2016

I have a couple of those drops from Sands. Thanks for the information on their properties. Seems I need to be careful with tapped holes. They still seem good for my intended purpose. And I have no intention to anodize them.

AARONT · Oct 14, 2016

gkoenig said:
Jesus Christ, are you my college professor demanding footnote citations?

It's an internet forum, not a fucking Alcoa investor note; consider it shorthand for "The vast VAST majority of aluminum barstock going through American machine shops is 6061."

Who shit in your coffee? I just asked where you got that ridiculous number from.

Tonytn36 · Oct 14, 2016

Mechanically, MIC 6 has a Tensile strength of 166 Mpa vs 310 Mpa for 6061-T651. Yield strength is 105 Mpa vs 276 Mpa for 6061. Elongation at break is 3% vs 12% for 6061. Brinell is 65 vs 95 for 6061.

All aluminum is cast, but 6061 is a wrought alloy that is post-cast rolled or formed. There is also significant differences in the alloy composition as indicated by the Mpa numbers above.

Mn = 0.09-0.5 for MIC, Max 0.15 for 6061
Cu = 1.7-3 for MIC, 0.15-0.4 for 6061
Si = 0.05-0.15 for MIC, 0.4-0.8 for 6061
Fe = 0.26-1 for MIC, Max 0.7 for 6061
Zn = 1.8-5.3 for MIC, Max 0.25 for 6061
Mg = 0.9-1.9 for MIC, 0.8-1.2 for 6061

Basically, it is softer but more brittle (although not has hard, it still pretty much breaks before it bends - which is why it isn't used in structural applications). But it doesn't move around during machining or during heat / cool cycles as much though.

Jay Fleming · Oct 14, 2016

Tonytn36 said:
Mechanically, MIC 6 has a Tensile strength of 166 Mpa vs 310 Mpa for 6061-T651. Yield strength is 105 Mpa vs 276 Mpa for 6061. Elongation at break is 3% vs 12% for 6061. Brinell is 65 vs 95 for 6061.

All aluminum is cast, but 6061 is a wrought alloy that is post-cast rolled or formed. There is also significant differences in the alloy composition as indicated by the Mpa numbers above.

Mn = 0.09-0.5 for MIC, Max 0.15 for 6061
Cu = 1.7-3 for MIC, 0.15-0.4 for 6061
Si = 0.05-0.15 for MIC, 0.4-0.8 for 6061
Fe = 0.26-1 for MIC, Max 0.7 for 6061
Zn = 1.8-5.3 for MIC, Max 0.25 for 6061
Mg = 0.9-1.9 for MIC, 0.8-1.2 for 6061

Basically, it is softer but more brittle (although not has hard, it still pretty much breaks before it bends - which is why it isn't used in structural applications). But it doesn't move around during machining or during heat / cool cycles as much though.

Very good info. Thanks Tony.

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specfab · Oct 15, 2016

As others note, and as seen from Tonytn36's succinct post, there are well-defined differences in the mechanical properties of MIC-6 vs. wrought aluminum materials. In the optics biz, we use a fair amount of cast tooling plate for parts that aren't going to see a lot of mechanical stress but do need good stability as a machined part. It works well in the right circumstances.

In regard to press-fits, they are quite feasible, as long as you aren't trying to press-fit a 1/4" dowel into a hole with .0025 interference .093 from the edge of the part. Use good engineering judgement for all such decisions.

As far as anodizing goes, you need to let your plater know that it IS cast material, and requires a very light touch with pre-anodize etching. If your shop hasn't worked with MIC-6 previously, they will need some experience before running your parts. Or the WILL look like crap.

Jay Fleming · Oct 15, 2016

Thanks specfab. As I mentioned before, I was thinking about using it for some engine mounts but seeing as how it won't be suitable, I may use it for some fixtures I plan to make in the near future.

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Punkinhead · Oct 15, 2016

I specify jig plate a lot in applications where I require flatness but can accept the as-purchased thickness. Saves the shop having to face both sides. Now that I think about it, I really ought to compare the material cost versus having the shop face 6061. I always just assumed it was saving money.

nofxz · Oct 15, 2016

I find threads in my Mic6 fixture plates to be weaker then 6061. So if your parts require threaded features be careful.

MIC-6 stock for making parts

Hot Rolled

Stainless

Hot Rolled

Diamond

Titanium

Stainless

Diamond

Titanium

Hot Rolled

Titanium

Hot Rolled

Hot Rolled

Diamond

Stainless

Diamond

Hot Rolled

Titanium

Hot Rolled

Cast Iron

Aluminum

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