First Al Ingot Today, Issues

[cg 2005]

I cast my first aluminum ingot today. The foundry worked well and the ingot looked good until I started to machine it in the mill.

The melt material was mostly aluminum floor drops, not cuttings or cans.

I used end mills, fly cutters, varied the speed and doc but all of the cuts looked bad. A lot of tool marks and ripped material. The fly cutter produced the best results, but not a mirror finish.

Is this what is expected from the DIY cast billets?

Any ideas?

 

[Charley Davidson]

Show us some pics. Cast aluminum makes the best cast aluminum

 

[cg 2005]

Show us some pics. Cast aluminum makes the best cast aluminum

 

[Ray C]

Maybe there's something you're able to see that doesn't show-up in the photos but, the finish looks pretty typical of a cut that was made without lubricant. A tiny squirt of WD-40 every 5-6 seconds will make aluminum look pretty good. How did you clamp that irregular surface?

 

[cg 2005]

Actually, the vise held it with no issues. I did mill it dry. I have some 16:1 Prime Cut mixed up already. I will give that a try. I did read that "unaged" cast aluminum is soft and gummy and difficult to machine. I think I just need to get a better technique.

Thanks

 

[Ray C]

I do believe that factory aluminum in various formulation and conditions is tempered. If memory serves for example with T6061-651, the 6061 specifies the composition (i.e. how much aluminum and other elements) and the 651 part specifies the condition (i.e. tempering/anealing treatment).

I could be way off on this because I am not into metallurgy (casting bullets 25 years ago and my uncle being a metallurgist doesn't count) but I'm guessing your ingot requires some form of post casting treatment.

I'm going to back off your thread because this is not an area I'm familiar. Only responded because I've been looking for heat-treating cookbooks lately and the issue of metallurgy keeps coming up.

Cool beans though.... I've got buckets full of aluminum scrap and swarf and keep thinking it would be nifty to cast it. I know my wife wants to because she's "artsy" and wants to do sand or wax casting.


Ray

PS: I'm not familiar with the cutting/lubing fluid you're using but, I'm telling you, a simple squirt of WD makes AL cutting look good.

 

[cg 2005]

I also posted this on a CNC forum. I was asked if I had pickled or artificially aged the casting before milling to harden it. The answer was no. So then I started researching and found that there is quite an involved process to harden cast aluminum. The two basic methods use either chemical treatment or heat treatment below the melting point for several hours.

I am going to continue as I am and work more on machining technique rather than treating the casting. At least for now. I need to try some fluids and see how that helps. Tomorrow is soon enough.

 

[Tony Wells]

If you want, you can age it in your kitchen oven, provided you clean it really well so as not to upset the domestic tranquility. Run the oven to 400° f for 8 hours. That is called condition T-51. It's not necessary, but it will improve machining characteristics.

 

[Ray C]

And as Tony suggests, in order to main domestic tranquility, consider getting a toaster oven. They're cheap enough and will heat using a lot less electricity. -But now that it's winder, running the house oven for 8 hours will simply offload work from the house furnace...

My wife really hates finding a handful of 7018 rods in the toaster oven -so I got my own for the shop.

If you want, you can age it in your kitchen oven, provided you clean it really well so as not to upset the domestic tranquility. Run the oven to 400° f for 8 hours. That is called considered condition T-51. It's not necessary, but it will improve machining characteristics.

 

[refinery Mike]

If you want to cook an aluminum billet at 400 degrees for 8 hours, i would suggest you look into a turkey roaster. One of those electric cook pots for turkeys. Throw the inner pan away and fill an inch and a half of silica sand in the cooker place your billet in the sand and then turn it on to 400. Put it in in the morning and turn it off when you go to bed. dig it out in the morning. I heat treat flint to 450 like that and it gives a real even slow up and down heat. Leave it in the center of a concrete floor, not on a wooden bench just in case.....Cheap to buy and cheaper to run than an oven all day. And no chance of disturbing the wife.