As used in thermal switches. Instead of in form of a bimetal strip and continuous curving with temperature, these are 0.5 inch diameter and make a definite flip from concave to convex at a specific temperature. About 1mm of abrupt movement gives a very positive transition for the switch contacts. Would it be possible to change the characteristic temperature by grinding back a spot/ring/radii? on one face? which face? or would it just destroy the action/activation force?
You might find one of the sort that used to be used in kitchen appliances, that could be inserted in a grill, waffle maker, cookpot, etc. These have adjustable settings, which (I assume) are varied by changing the pressure on the sensor.
According to patent "Laser adjusted set-point of bimetallic thermal disc" it is done at production , for precise adjustment, but no specific details of patterns/which surface/degree of variation. I'm more interested in adjusting otherwise useless batch made for set point of 16 degree C up to
50 or 60 degree C, with no great precision, +/- 10 deg C would be fine
If you could find the patent for the controller I described (it's a famous patent, from a man who patented many devices in the 50s and 60s), it might show how this is done.
Interesting , but no further forward. Looks as though these froststats will remain froststats. Surprising ping and bounce as much as six inches on change of state, the loud ping is somewhat damped when inside the casing. Need freezer spray to change the state of these discs (hysteresis and all that). When back to body temp I tried grinding a spot in the centre of the concave side, no change in set temp. Tried 4 diametrical marks on the concave side , no change in response. Tried deeper but small 8 cuts just on the perphery, now no ping but slowly migrates from one state to the other , still requiring freezer spray. I wonder how they "weld" these 2 materials together.
I don't think so (but I'm guessing). Grinding might change the deflection or force but probably not the transition temperature. Below some force level, it simply will not transition. My guess(tm) is that the transition temperature is controlled by the curvature which is rather difficult to modify.
Note that some discs are "manual reset" or "single operation" and act as thermal fuses.
Search Google for "bimetallic snap disk".
(etc...) I tried to find the vendor of the actual discs, which might include design information, but couldn't find anything useful.
Have you considered fire alarm heat sensors? They use a bimetal switch internally.
Gunner
"IMHO, some people here give Jeff far more attention than he deserves, but obviously craves. The most appropriate response, and perhaps the cruelest, IMO, is to simply killfile and ignore him. An alternative, if you must, would be to post the same standard reply to his every post, listing the manifold reasons why he ought to be ignored. Just my $0.02 worth."
(sorry for the digression.) huh! yesterday i was going to ask how they make copper clad stainless steel cookware but i thought it was too dumb and too trivial a question to ask. couple days ago i had a copper clad stainless pan delaminate the copper cladding and was stunned. made me wonder how they attach it in the first place. i'm guessing some sort of furnace brazing process(?). this pan is probably over 50 years old, i think this is one of the pans my mother got as a wedding present in the 50's. i've seen stuff (on tv and in books) about explosive welding but am totally assuming that's NOT how they make copper clad cookware.
probably in it's 50 years of use it might've been overheated, there's no specific recent incident that i'm aware of though. for months and months when i put the pot on the stove i could hear little "pops" of steam explosions in between the copper and stainless, i figured something was going on but i assumed it was a pin hole in the copper or something. i think it happened eventually over time, and it probably wouldn't've even come off completely except i stacked it inside another pot the same size and when i lifted the one pot out of the other the copper stayed behind (which startled me). maybe some long slow electrolytic reaction? once water started getting in there, that ultra thin gap, wicked in by capillary action, it just kept getting worse and worse? probably a combination of an overheating incident and water getting in there? i mean, this is not an earth shattering event but just when someone posted about laminated metal, and "explosive welding" it reminded me of something i wanted to post yesterday but thought was too uninteresting to bother you all with.
come to think of it, that's something i've wondered about too. even more. how in the heck do they make aluminum stick to stainless steel, and for thousands of heating cycles. it endures terrible abuse, fluctuations in heat thousands of times, probably like "shock cooling" too (i have no idea if that's an actual term)(ok, how about "quenching"?).
i tried to read that article and tried to understand it as best i can and it still amazes me they're able to reliably get aluminum to stick to stainless steel, and copper to stainless too (under/after thousands of heating cycles). the article talks about bringing the two metals together under great pressure, or putting them through a rolling mill. wow. weird. i wouldn't think putting them through a rolling mill would make them stick, more like probably resist to an even greater degree wanting to stick together, like work hardening them both. and so like they make a round disc of copper stick to a sheet of stainless, but they can accurately register it?!
hey, i guess for that matter, aren't some u.s. coins bimetallic?
i know they can get dissimilar metals to stick together using explosive welding, but how to they do it otherwise? that's, as far as i know, a very rare and extremely limited technique.
"William Wixon" wrote in news:3VOJm.11477$ snipped-for-privacy@newsfe07.iad:
US coins used to be explosively welded. I assuem that is still what they do. The use large thick sheets, and then roll them out thin. That way they get a lot of welded metal per bang.
This might be the correct answer, but there are fill-metal/reducing atmosphere/heat solutions that might do a kind of brazing for lower cost if you get the materials right. Explosive welding is used for US coins because it was possible to mimic the electromagnetic properties of silver well enough to keep lots of vending machines in service. I've gotta believe the requirements for a thermostat bimetal system are loose enough to allow for alloys that don't require explosive welds.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.