- About me
- 40 years in the magnet wire industry with positions that include processing, product, equipment start up, design and construction and plant management. Corporate training, development for a college.
- Richard Burke replied to the topic 'conductor elongation tester standard specification' in the forum.A quick simple test would be to run the tester until the elongation indicator displays a number that is approximately 5 cm. Read what is indicated as accurately as you can. Measure the physical distance of the items where you previously measured 24.9. Subtract the 24.9 from the measured distance. Divide that distance by 24.9. Does sit equal the number shown on the elongation indicator. If it does you really don't have a problem as you are getting a fairly accurate elongation measurement.
- I have minimal experience with drawing aluminum but I once worked for a company that also made coilers and had one at a major aluminum processor in upper NY. This I learned: The higher the tensile strength of the aluminum alloy the greater the horsepower required to draw it. This company had a huge rod break down machine and will drawing the softer aluminum alloys could reach speeds of 5-7,000 fpm however with the higher tensile alloys operating the 800HP! motor at 110% electricity they could only get up to about 1,200-1,500 fpm! They were running about 7 awg and lubrication was critical as die wear was much worse than with the lower tensile alloys.
- If you are having spring back problems within a batch of wire, I would suspect the quality of the rod was not uniform. When I had a sample fail, I would then scrap several pounds (Kg) off that spool and retest it. Do this several times to see if the problem comes and goes. If it does I think it would indicate a lack of purity of the conductor. At the same time you need to make sure that the temperature of the pre annealer and oven is snot varying. If you have some samples that pass and some that fail, do a metallurgical analysis to determine the structural and chemical differences between the samples.
It is also important to know that there are not outside influences affecting the pre annealer or oven such as drafts cooling the pre annealer, condensate in the annealer, etc.
- I'm sorry I've tried responding a couple of times and it doesn't show up.
While it varies with applicator design, typically for large wire on vertical systems the enamel dies should have some free floating ability. This will help the wire to be centered in the die opening and provide a uniform coating . It also depends upon the die design. As the wire is wetted by the enamel or varnish and enters the die, there is a build up of pressure in the die. This hydrostatic pressure will cause the die to move. You don't care so much that if moves but that it stays straight? It cannot cock to one side or bounce up and down (chatter). If the die is fixed in a rigid position and cannot move at all it places greater emphasis on the alignment of the wire into the die. Enameling does have the benefit of the wire making multiple passes through the applicator and there is some rotation of the wire as it makes the various passes during the process so it tends to even out the concentricity of the coating.
- Spring back failure indicates a lack of flexibility. You can have minimal elongation and poor spring back. I have never seen good spring back and failing elongation. First I would ask my rod/wire supplier to provide me proof of quality. check your equipment supplier directions. The supply wire should be soft of annealed. You should reduce it at least 30-40% but no more than about 80%. This should, if your copper wire is good, result in a product that has good elongation, good spring back , and increased tensile strength.
The best finished Eire comes from the highest quality rod or rod that is made from "virgin" copper as opposed to reprocessed copper.
- Cleaning aluminum wire for enameling can be challenging but not impossible. Some use an ultra sonic machine. Other use their regular pre annealer. Some use a combination of the two. Challenge with typical preannealer is to get the wire hot enough that the quench water dries before it gets to the applicator. Aluminum wire is very soft so it is essential that you have a separate enamel supply and drain for the first pass. If you try to run all base coat passes throught the same applicator and enamel supply you run the risk of contaminating the enamel with aluminum dust and this will cause the wire to fail dielectric testing.