Springback

Peter, sorry about taking so long. Once log in got fixed all I got was a scrambled site.

Spring back is the softness of the wire. You say several times that you have hard wire and your customers confirm this so let's look at a couple of things.

1- What is the purity and quality of your copper rod? Quality starts here! If you rod is all recycled material it is entirely possible that your problem starts there.

2- Here (USA) wire producers make rod and copper wire to ASTM specs and magnet wire producers make wire to NEMA specs. I had privilege of working at the same company as Marshall Yokelson and he showed us that there are areas around 1mm when the specs don't agree.

3- You are doing inline drawing. This machine is not designed to be a typical wire breakdown machine! The inline drawing machine should be supplied with soft wire and then reduced 30-80%. The inline drawing machine is designed to allow you stock fewer sizes of wire for enameling. Typically 3-4 supply sizes can be stocked and will allow you to enamel 8-12 sizes ( I am talking AWG sizes - obviously any number of specialty sizes can be made within the range of the machine).

4- in the late 60's or early 70's at GCC Buena Vista we tried a BICC inline drawing machine and years later I bought several package SICME systems for the company I worked for and later even built a couple for SICME in the USA.

5- One of the unique things about inline drawing is that when you supply it with good annealed wire, reduce it at least 30% and no more than 80%, the pre-annealer essentially becomes a wire cleaning device depending upon the number of passes you make through the enameling oven and the enameled wire will have good elongation, a higher tensile strength, and good spring back ( meaning softer)! This is because metallurgical the grain structure is near perfect. I can dig out my books for the particulars.

6- Any imperfection or reduction I rod quality will affect this as will over drawing or under drawing during the inline process.

Summary: First thought is that your problem is starting with the wire you are inputting.

Dear Richard Burke

Thank you very much for your information.

1. We use cooper rod to ASTM B49 .
2. We don't anneal the inlet wire. it is 1.400 mm. to produce 0.300 mm up to 1.300 mm.
3. We have good elongation . It is more than 30%
4. In our enameling process we make 10-12 passes through the enameling oven.
5. What do you think about our temperatures. Are all OK?

Mohsen Ajalloueian

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.

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.

Thank you so much

I got better results. i calculate elongation by below formula is that right?
E% = [( D/d)² -1] × 100%

This is our rod properties how do you evaluation?
- Twist test -ok
-Twist to break - 47
- ∆L% - 40 %
-IACD % - 100/3%
- Oxygen (ppm) - 396

Thanks

Dear Richard Burke

i reduce wire about 40 % but no difference. our wire always pass spring test but our customers say
that our wire is hard and difficult to insert in motor. Our rod cooper is the same as our competitors. i tested other wires
they have the same springback result.
What do you think about this?
Could you please explain me about drafts cooling the pre annealer, condensate in the annealer?.

Thank you