On Thursday, 4 January 2018 22:14:06 UTC, Jon Elson wrote:
tabbypurr wrote:
On Wednesday, 3 January 2018 16:11:52 UTC, Clive Arthur wrote:
On 09/09/2017 03:11, wrote:
I've always wondered how they paint on the colored stripes. I put "how
do they paint the stripes on resistors" on google, but all I got was
links explaining how to READ color codes.

Has anyone ever heard anything about this process?

Resistors are made from a clay-like material containing carbon or other
conductor in various amounts. Colourants are added, and the material is
rolled and layered into large 'pats', so for example a 4k7 resistor pat
might have cream, yellow, cream, violet, cream, red, cream, gold, cream
coloured layers. This is rolled to the correct thickness corresponding
to the final resistor length, then hollow punches form the resistor
bodies, usually several thousand from one pat. The better quality ones
are rolled for smoothness and low noise. The wire ends are fitted, the
resistors are baked and often varnished. For high accuracy resistors,
the depth of one wire end is adjusted on test before the baking stage.

Cheers

You're surely pulling someone's leg.
Oh yes, I'm sure of it! All the resistors I've used in the last 30 years or
so had a ceramic core, with ends fuest to the core, and then either metal
film or carbon film deposited onto that. Then, they use an air/abrasive
just to cut a helical groove in the film for higher resistance values.
Then, they are painted overall with that manufacturer's base color (often
tan or light blue) and then the color code is applied. I'm guessing they
have a machine with a row of some kind of rollers each with the right paint
color, and they paint all the stripes in one pass. But, I've never seen
pictures of such a machine.

If they were made as described above, the color would go all the way through
the resistor. I've broken enough over the years to know the inside is
always white for film resistors, and black for carbon composition.

Jon

Quite. Even in the carbon comp days they weren't made that way.


NT