This is an interesting little tale to me covering as it does two parts of my working life: tech and business and then the wider shores of the metals business which is what I do in my day job.
The video of the construction is from Apple itself:
That's all a bit fast to be able to see what is really being done but there's a great breakdown of it here. A step by step guide to what each of the video images is really about.
The one that caught my eye was the first step, the punching out of the case from a solid disk of aluminium (I assume it's an aluminium alloy actually, not pure Al).
The big story with the Mac Pro is deep draw stamping.
When uncle Phil said that Apple was using technologies that were new to them to make the Mac Pro, the brunt of his statement was focused on how the cylindrical case of the machine is formed. Here, Apple is using a process known as hydraulic deep draw stamping.
Most metal stampings go through one or two die tools to produce the final shape. With the Mac Pro though, the challenge is to produce a massive amount of plastic deformation without tearing, rippling or deforming the perfect cylindrical surface. To do this, the enclosure is drawn through a series of dies that progressively stretch the aluminum into something approaching the final shape of a Mac Pro.
Deep drawing is a process that very efficiently produces a "net shape" part. Apple could have just chucked a giant hunk of aluminum in a lathe and created the same part, but that amount of metal removal is extremely inefficient. Deep drawing efficiently creates a hunk of metal that is very close to the final shape of a Mac Pro in just a couple of operations. After that, the Mac Pro enclosure is lathe turned to clean up the surface and achieve desired tolerance, polished, placed back in a machining center to produce the I/O, power button and chamfer features and finally anodized.
The point is that absolutely none of these are in any way remarkable in the metals world. They are, some of them at least, rather odd to have in the manufacture of a computer case however.
Anodizing isn't unusual, that's how you get all of the different coloured metals (like the iPhone cases for example). But the one that stands out as being particularly unusual (the others pretty much flowing from this first decision) is that deep draw stamping.
There are conceptually four ways you could build an aluminium enclosure for Mac Pro. You could, for example, do what PC manufacturers have been doing for decades. Have a frame and pin sheets of aluminium to it. Cheap, functional and deeply boring. We could alternatively, if we wanted that cool cylindrical shape, wrap aluminium sheet into a roll and then pin it: say welding it or riveting. Not quite as cheap and a little more cool but not very.
We could, as mentioned above, take a rod of pure aluminiuim and simply lathe off all that which was not the tube that we wanted. Again a bit more expensive and definitely more cool: but not really the right way to go about this problem. You'd end up with huge amounts of scrap aluminium dross (the technical terms for the sort of shavings you'd get from the lathe) which you'd have to recycle, they would probably be contaminated with oil, just not what you really want to be doing.
Or you could do what the video shows them doing, using that deep draw stamping. While the machinery to do this isn't cheap the process as a whole is probably cheaper than hollowing out a solid block. The technology was originally developed to make seamless tube.
You can imagine having the same four methods as above to make a tube. And often rolling the sheet up and then welding it is the right way to go. However, there are some applications where you just don't want to do this. One example would be fire extinguishers or other containers to hold things under pressure. You'd much prefer for there not to be a possible weakness like that weld. Another might be the zircalloy tubes used to hold the fuel in a nuclear reactor. You would much prefer to pay the extra price of making your tubes out of a solid piece that you then deep stamp to make the tube than you would to have that possible failure point in the welds you've made.
What's happened over the years is that the technology of this stamping has become cheaper and cheaper: to the point that it's not exotic at all to make seamless tube in the manner that it used to be.
It is still, however, distinctly more expensive to make the Mac Pro this way than it would be to roll some sheet and stick it together. Well, expensive by the standards of the metals industry that is: certainly dollars more per part (this is an industry with low prices and tight margins). However, it most definitely wouldn't be quite as cool which is why Apple has gone the way it has. They are, after all, known for their sense of design: it's one of the things that enables them to charge the premium prices that they do.
My basic point here is that the techniques that Apple is using to manufacture the Mac Pro are well known and widely used. It's just that this is the first time that someone has decided to use them on the manufacture of a computer case.
