machining aluminum question

Newbie questions:

  • What process is required to create the fillet on the top surface of, for example, macbooks? Is it achieved through milling from a single block of aluminum?

Thanks in advance!

  1. radius cutter.

  2. custom profile cutter. Often done where volume and costs allow.

  3. Multi-axis profile cutting. Time consuming, requires post finishing.

Yes, with a corner rounding endmill.

I think the one on the MB is 3 or 5 axis profiled with a ball end mill. The transition around the corners doesn’t look linear the way it would be if it had been cut with a custom radius tool.

It’s one old guy and he cuts them by hand with a hack saw and then sands them down with a brick.


It’s one old guy and he cuts them by hand with a hack saw and then sands them down with a brick.

That was before they discovered that they could be simply mined out of the earth and graded for size…

I think this is right. Obviously a radius tool can’t go to a perfect tangent, whereas if the ball-end bit travels back and forth over that edge it can make any sort of perfectly smooth radius or splined fillet. Very time consuming.

They might be using a near-net forging (or die casting, etc.), so the machining pass could be really quick. Even if they’re starting with a rectangular billet, they aren’t actually taking away that much material when you look at it. A fast roughing pass followed by a finish pass shouldn’t take much time.

While we’re at it, anyone care to guess what the MB finishing process is? Sandblast then anodize, perhaps?

This came up in another thread, but I don’t think there’s anything other than a longish etch dip during anodizing. The edges are too crisp to have been blasted or abraded in any way.

I thought it looked like (fine) bead-blasting, but I’m not super knowledgeable about anodizing.

What’s been stumping me lately is the ipod touch (specifically 2nd gen). It has to be a sheet process, because milling would be way too expensive (especially out of stainless), and there are no parting lines around the edge to indicate MIM.

[7] “When metal, the housing can be formed using conventional collapsible core metal forming techniques well known to those skilled in the art.”

Awesome, thanks!