B10alia said:
I don't think that machining in the US is going to help anything in terms of wear. Poor-quality metal is poor-quality metal. Not to say that the Chinese aren't capable of making good steel or cast iron, they certainly are, but good metal is more expensive to make. The assumption nowadays is pretty much that rotors get junked with pads, because they're so cheap.
There is a lot of helpful background info at the Centric site. It's heat-treating that is often inadequate in China, not just machining. I probably didn't go into enough detail. It's not specifically 'poor-quality metal' to start. I've looked into this in the past.
Rotors a decade or two ago had heat treatment extending about .050 inches or so into the depth of the metal. This ensured a hard surface for wear longevity, and you could get 1-2 turns out of the rotor before discarding. They also have a stamping in them for the minimum rotor width, something like 229 mm.
What has happened in recent years is that many overseas sources only heat-treat them to a depth of about .010 inches. This means that they can wear out quickly, and once the hard surface is gone, the soft metal below is cut into easily. That's one reason why some rotors only last 10K -20K miles. The other failure that can happen is that this thin surface sometimes chips away (I have experienced this), and you'll get flaking rotors, which cause vibration and poor braking power, and can damage the pads.
In addition, whether deliberately or a misinterpretation, the "Minimum 229 mm" specification, which was meant that this is the thickness at which it is discarded, has been replaced by product which comes out of the box
new at 229 mm. Therefore, as soon as you begin using it, it's below the minimum thickness, can't heat-sink as well, and will wear out faster and fade more for that reason.
Combine the two, and you have the $11 junk that we often find in the stores today.
If Centric or others can get a blank that's thicker than 229 mm, they can heat-treat it and machine it to perform as originally intended.