Diamond is amazing. We had this benchtop wheel grinder to shape and sharpen steel turning tools, and somebody had tried to grind a piece of aluminium on it. A diamond-tipped wheel dressing tool went through it as if it was butter. It's kind of amazing to see a grinding wheel yield so easily to a tiny piece of diamond.
Jeroen Belleman
Probably gummed it up pretty badly, too. Some alcohol makes a big difference cutting Al.
Cheers
Phil Hobbs
Yes, that was the reason for dressing the wheel. People shouldn't try to grind aluminium on these things. It irritates the mechanic. We hate people who don't clean files, too.
Jeroen Belleman
Grinding non-ferrous materials with any grinding wheel not specifically rated for non-ferrous not only gums up the wheel, it risks grinding wheel shattering from crack initiation by metal jammed into the wheel pores. I once worked with a shop foreman who made sure everyone knew this by relating an incident where someone was killed when a large wheel shattered while someone was grinding aluminum on it. Grinding wheels rated for use with non-ferrous materials are readily available but rarely found installed on bench grinders, probably because grinding soft materials which can easily be filed rarely makes sense.
Glen
Putting my machinist cap one. It is not particularly hard to lap the two surfaces, that virtually no air gap result. This is used to construct parallel gauges, they are so flat that the cohesion holds it together.
Whether it holds up with thermal stress,I don't know.
Groetjes Albert
It may be less attractive if you include the cost of shipping.
You need not have a diamond for this. Steel wheel dressers are used before that. It works by removing the top layer of the wheel, where the dull grains are, by hitting it.
Groetjes Albert
Lapping a fet and its heat sink will seriously reduce theta, but it's a lot of work. Grease is easier. But the thermal conductivity of aluminum is still a bottleneck.
Heat sinks and machining are both expensive, and mosfets are cheap. It often makes sense to use several fets, distributed about a heat sink, to avoid hot spots.
I assume that heat sink vendors test theta by applying a big, uniform heat source. Real parts tend to be small spots, and local heating makes theta go way up.
We have several new products that use copper CPU coolers on the board, to cool mosfets. They are magic.
It's cheap and thin, but AlN conducts heat about 200x better.
1 mil thick hard anodize is really good, up to 100 volts or so.
Like many things the cost of shipping is ofen more than the cost of the item.
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