ferrite machining?
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From: John Fields on 12 Jun 2010 13:30 On Sat, 12 Jun 2010 09:18:29 -0700 (PDT), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Jun 12, 2:47�am, BlindBaby ><BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: >> � It is closer to an epoxy bound sintered matrix than a ceramic. >> Ceramics get post sintering firings that harden them further. > >Regular ferrites aren't resin-bonded. --- What is it you don't understand about: "closer to?" >You can get resin-bonded soft >and hard ferrites and, but the resin dilutes the magentic material and >the magnetic performance is consequently poor. --- "hard ferrites and, but"??? "magentic"??? Maybe, in your state of perpetual torpor, you meant: http://magentic.net/en/ ??? JF
From: John Fields on 12 Jun 2010 13:40 On Sat, 12 Jun 2010 09:20:37 -0700 (PDT), MooseFET <kensmith(a)rahul.net> wrote: >On Jun 12, 11:48 am, BlindBaby ><BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: >> On Fri, 11 Jun 2010 20:24:34 -0700 (PDT), MooseFET <kensm...(a)rahul.net> >> wrote: >> >> >On Jun 12, 1:33 am, Bill Sloman <bill.slo...(a)ieee.org> wrote: >> >[...] >> >> Wrong. Permeability drops with rising temperature, and leakage flux >> >> rises. Ferrite cores don't have to get very hot before they become >> >> magnetically insignificant. Read the relevant data sheets for the >> >> material used to make your core on the manufactuere's web site. >> >> >This has nothing to do with the reason to watch the temperature rise. >> >It is just plain a mechanical issue. The material is brittle and a >> >bad >> >conductor of heat. >> >> And grinding it doesn't hurt it at all. It got heated when it got >> made. It is a sintered, stamped, baked manufacturing process. > >All sintered things are brittle. Watch the temperature. --- I don't believe that's right, since at least some (if not most) sintered metallic parts retain the mechanical properties of their parent metals or alloys. For example: http://www.lm-tarbell.com/machining_sintered_bronze.htm Take a look at the rejected bearing; if it was brittle the metal wouldn't have smeared like it did.
From: BlindBaby on 12 Jun 2010 14:03 On Sat, 12 Jun 2010 12:40:09 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Sat, 12 Jun 2010 09:20:37 -0700 (PDT), MooseFET ><kensmith(a)rahul.net> wrote: > >>On Jun 12, 11:48 am, BlindBaby >><BlindMelonChit...(a)wellnevergetthatonethealbumcover.org> wrote: >>> On Fri, 11 Jun 2010 20:24:34 -0700 (PDT), MooseFET <kensm...(a)rahul.net> >>> wrote: >>> >>> >On Jun 12, 1:33 am, Bill Sloman <bill.slo...(a)ieee.org> wrote: >>> >[...] >>> >> Wrong. Permeability drops with rising temperature, and leakage flux >>> >> rises. Ferrite cores don't have to get very hot before they become >>> >> magnetically insignificant. Read the relevant data sheets for the >>> >> material used to make your core on the manufactuere's web site. >>> >>> >This has nothing to do with the reason to watch the temperature rise. >>> >It is just plain a mechanical issue. The material is brittle and a >>> >bad >>> >conductor of heat. >>> >>> And grinding it doesn't hurt it at all. It got heated when it got >>> made. It is a sintered, stamped, baked manufacturing process. >> >>All sintered things are brittle. Watch the temperature. > >--- >I don't believe that's right, since at least some (if not most) >sintered metallic parts retain the mechanical properties of their >parent metals or alloys. > >For example: > >http://www.lm-tarbell.com/machining_sintered_bronze.htm > >Take a look at the rejected bearing; if it was brittle the metal >wouldn't have smeared like it did. I worked in an auto machine shop years ago and had to fit huge truck king pins and their steering knuckles together. The final tolerances were less than 5 ten thousandths of an inch. Those bushings had no brittleness. I had a bucket of smashed ones, and they make great shims under a hydraulic press, particularly due to their malleability and softness. More firm than raw brass, but certainly no rough granularity to it like bronze. It was a fine matrix.
From: John Ferrell on 12 Jun 2010 15:59 On Fri, 11 Jun 2010 05:42:19 -0700 (PDT), Yzordderrex <powersupplyguy(a)netzero.net> wrote: >Does anyone know of ferrrite can be turned on a lathe? > >I have a short 1" long by 1" dia. rod ( i know, i know, a personal >problem) and I would like to have a grove machined into it to accept a >few turns of wire. there will then be a bobbin slipped over that with >the secondary on it. > >I suppose this might be done with some type of grinder as well. > >Just curious to know what machining options are available for ferrite. > >regards, >Bob I made a simple fixture to hold a Dremel tool on the toolpost of my Jet 9X20 Metal lathe. Most of the 9X20's seem to have the same castings so there are a lot of them around. The cutting tool for this job would be the same as what I use for e-clips on rod stock: the tiny abrasive disk that shatters every time you use one hand held. It will last a while in this application. As for the tool post mount, think about a piece of angle, wood block & wood screws and hose clamps. light cuts don't need to be super rigid. A well positioned vacuum cleaner (use duct tape!) will save a lot on clean up. John Ferrell W8CCW
From: Archimedes' Lever on 12 Jun 2010 16:43
On Sat, 12 Jun 2010 15:59:17 -0400, John Ferrell <jferrell13(a)triad.rr.com> wrote: > the tiny >abrasive disk that shatters every time you use one hand held. The fibrous "concrete saw" type disc works better. "dado" two together for wider cuts. |