So the read/write head floats only a few nanometres from the disc. How is this assembled in a factory to such precision? Is the entire process done by machines? How can a machine position something so precisely?
So the read/write head floats only a few nanometres from the disc. How is this assembled in a factory to such precision? Is the entire process done by machines? How can a machine position something so precisely?
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Manufacturing machines do not position the head and disc platter to that level of precision. It is not practical, and not physically feasible.
This precise spacing is achieved through harnessing magnetism. The head and the disc platter are made with same polarity, and a spring/suspension mechanism applies down pressure to push them together. The same magnetic poles repel, and the head will skim the surface of the disc platter by the smallest of distances, without touching.
The effects of magnetism gets stronger the closer you push the magnets together, and they forces get weaker the further you position them. So for a certain (predictable, calculatable and designable) downforce that the spring/suspension mechanism applies, you can calculate the strength that the magnetic field needs to be, for the read/write head to repel against the surface of the disc platter.
It’s deep engineering, and one of the wonders of the modern age. And yet, these days, hard disc drives are considered to be inferior devices compared to solid state storage (M.2 and SSD drives). Technology and engineering are absolutely incredible, if you think about it.