Machining aluminum

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Mr Ron
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Machining aluminum

Post by Mr Ron »

I was watching a video on U-tube produced by Keith Rucker of vintage machinery, where he was machining a "mini pallet" for use for small items on a vertical mill. It involved end milling, face milling, drilling and tapping. For end milling, he was using a 4-flute, 3/4" HSS end mill and taking 0.250 deep passes. He didn't use any coolant, nor did he use any when drilling or face milling. He did use "rapid tap" only while threading. He didn't mention coolant and the end mill didn't show any signs of chip welding. He was running at 500 rpm. What is going on here? He didn't mention what alloy of aluminum he was using. If the alloy was 2024, it can be machined dry.
Mr.Ron from South Mississippi
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ctwo
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Re: Machining aluminum

Post by ctwo »

So we was using a new cutter, about 5 ipm feed, and 1/2" wide cut, 1/4" deep, off the side. He did say a 2-flute would be better, but he was using what he had. I think a lesser cutter might have given more problems.

Yeah, I try that and it would surely gum up and snap off, after the part cocked and got sucked into the cutter, ruining both, and probably tweaking my spindle too...
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Harold_V
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Re: Machining aluminum

Post by Harold_V »

The end mill was being operated at a relatively low speed, which can help reduce chip welding. In my opinion, way too slow, as that would border on the proper speed for steel.

A four flute for aluminum is generally not a good idea, as they don't provide anywhere near the amount of clearance for chips, to say nothing of the decreased relief angles. Even two flute end mills have reduced clearances, however. End mills ground for aluminum have polished flutes and greater relief angles. They are the best choice, but all will work to some degree of success.

Aluminum can be machined dry----as can steel. Providing lubrication tends to improve surface finish, and will often spell the difference between chip welding, or no chip welding.

Given the same setup, I'd have used lubricant, and higher spindle speed. My first choice would not have been a four flute, but if it was all I had at my disposal, yeah, I'd use it, too.

Harold
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SteveM
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Re: Machining aluminum

Post by SteveM »

If you are machining with inserts, there are special razor-sharp polished inserts for aluminum that reduce chip welding.

I had one on a parting tool and it parted at such high speed (first time I parted not in back gear) that it broke the bottom off the toolholder. There was no indication of trouble right up until the failure point because it was still cutting really well.

Steve
Carm
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Re: Machining aluminum

Post by Carm »

Sometimes how you do it is less important than just doing it.
oldvan
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Re: Machining aluminum

Post by oldvan »

Mr Ron wrote:I was watching a video on U-tube . . .
U-Tube is famous for taking advantage of those seeking YouTube by giving them malware infections. I hope you meant YouTube.
Mr Ron
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Re: Machining aluminum

Post by Mr Ron »

oldvan wrote:
Mr Ron wrote:I was watching a video on U-tube . . .
U-Tube is famous for taking advantage of those seeking YouTube by giving them malware infections. I hope you meant YouTube.
I wasn't aware there were 2 "U/you tubes".
Mr.Ron from South Mississippi
Richard_W
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Re: Machining aluminum

Post by Richard_W »

I agree with Harold's comment! Most likely he was cutting 7075 aluminum in the video.

Richard W.
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