I have problems (breaks, and wear of drawing dies) in one machine with these characteristics:
-Tandem machine lubrication spray
-26% elongation
-initial diameter: 1.2 R
-final diameter: 0.25 mm
-V = 880 m/min
I test with concentrations 5-8% of several drawings oils emulsions, but the wire have "vibrations".
Anyone can help my?
First I am assuming you are talking about copper wire and that you are using a water based lubricant.
Second, since your finished size is so small (Smaller than 0.010 inches in diameter.) I assume that the wire has been annealed at least once since it started out as copper rod.
Third, I am going to assume from your description that this is not "checked wire" or what is commonly known as "crows feet". I am sure you are familiar with these very obvious chevrons on the surface of the wire.
Fourth, I am going to assume that this is not "cuppy wire" or what is known as "central burst defects". This often happens when a die is put in backwards.
This then leads us to "chatter marks" along the wire. Please confirm that this is what you are describing.
Here are the things that can lead to chatter marks on the surface of the wire:
- Hard wire and insufficient number of capstan wraps. Make sure the wire is not slipping on the finish capstan.
- Improper wire entry into the dies.
- Insufficient flow of drawing emulsion into the dies. Is the pump sized correctly and is the impeller in good shape?
- Too many capstan wraps.
- Too short a die bearing but since you have no problems with your other machines I presume that this is not a problem.
- Too old or too low a concentration of the fat in the emulsion.
- That the drawing dies fit properly in their die holders and that the holders are firmly attached to the drawing machine.
Likewise it is good practice to:
- Keep your capstans in good shape and make sure they are ground in sets so that you don't end up with a wrong size capstan.
- Keep your dies in string sets instead of just changing the occasional die when there seems to be a problem. This way your die shop will have tight control over your drawing dies.
Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
This message was edited by vettecoupe on 6-17-05 @ 4:09 PM
It´s copper wire indeed, with two intermediate annealed steps (8->3mm annealed, 3mm-> 1.2 annealed), it´s the same thing with other drawing machines I have.
I´ve been able to improve it with another drawing oil (more lubricant), but I have not solved the whole problem.
I think the lubricant wets through the dies, but this doesn´t wet the capstans well, and it may be getting stuck someway (and the wire doesn´t slip). The wire doesn´t goes straight through and vibrates.
Kindest regards,
Fermín Santana
e-mail: ferminsantana@eresmas.com
It may be very difficult to tell if the vibration is coming from the dies or the capstans so I suggest that you do the following:
(1) Check the % concentration of fat in your drawing emulsion. Make sure you have the right concentration for the gage size you are drawing. If not, top it up and make sure the emulsifier in the emulsion is not an issue. (An abnormally high concentration of copper fines stuck on the wire, even after annealing.)
(2) Metal Capstans - If your tandem drawing machine has metal capstans, make sure that they are all in good shape and BY MEASUREMENT make sure they are a proper set.
(3) Ceramic Capstans - As in (2) above, make sure they are smooth, polished and without damage.
(4) Put a new die string in the machine and see if this eliminates the problem.
(5) Make sure the drawing dies fit properly in their die holders, that the holders are firmly attached to the drawing machine and that the wire is properly guided to each die. (Remembering that the wire usually bows upwards in an arc when the machine is running.)
(6) Make sure you don't have too many wraps on the capstans (one, some, all) inside the machine thereby making wire fleeting across the capstans and capstan slippage difficult. After all a function of a capstan is to provide more metal at each die than is actually required and the excess disappears in capstan slippage.
(7) Make sure you are not taking a too large a draw at the entry die.
(8) Make sure the wire is not slipping on the finish capstan.
(9) Make sure there is adequate flow of drawing emulsion into the dies and on to the capstans if it is not a bathtub type machine. Make sure BY MEASUREMENT that the pump is sized correctly and that the impeller in good shape.
(10) Contact the lubricant manufacturer's technical department and tell them the problem you are having, that it is a tandem machine and let them know the type of drawing dies you are using. (Carbide, polycrystalline, synthetic diamond, natural diamond.) Then ask them for their % fat concentration recommendation.
(11) Check with the lubricant manufacturer to make sure that it is not time to change the drawing emulsion. (Send them a sample.)
(12) If you have mixed lubricants from two different suppliers then I doubt if either of them will help you much. Dump the system and start again!
Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
This message was edited by vettecoupe on 6-17-05 @ 4:13 PM
Your lubricant supplier should be best to tell you what % fat or what pH should be. A real simple test is to take a piece of clean, or ploished stainless steel rod 1/2" or 12mm in dia. works well by 10" or 25 cm in length. put some of your lubricant in a container - dip the rod into the lubricant and then remove it and hold nearly horizontal and observe how the lubricant reacts on the rod. If bare spots appear all over the rod then the same is probably happening on your capstan. If the lubrican "uniformily rolls" to the end of the rod and bare spots do not appear then you are getting better capstan coverage. You can doctor the sample in your lab and continue the wetness tests. As you chnage pH or %fat you will notice the change in the behavior of the lubricant on the rod.
As for %fat I would be less concerned with what it is than how it was performing, die life wire quality, machine cleanliness, etc.
Also the quality of the water is important. If the pH of your makeup water supply changes you may have problems. We once had a water supplier with 3 sources, deep well, cistern, and a spring. It nearly killed us since everytime it rained the pH changed often drastically.
Thanks for your input Richard.I agree with you 100% re the quality of the water used to mix up the emulsion. Moreover I forgot all about the pH. It's been a long time since I personally did any drawing emulsion testing. (Probably since 1970.) Luckily, the water at our plants was for the most part really good. pH was constant and never an issue. Likewise we never had any contamination from our rod.
Drawing machine cleanliness is always a given. If you remember the days when animal tallow was used, I'm sure you will agree that the drawing lubricants today are miraculous when compared to those. Early products like "Ironsides" and "Lusol" significantly improved the productivity of our plants and allowed us all to make some of the major productivity breakthroughs that came later.
Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
Drafting Information
Larger to Smaller Solid Wire AWG Diameters
If you go from a larger AWG solid conductor diameter to one immediately smaller AWG solid conductor diameter (This is a smaller to a larger AWG gage number just to make it a little more confusing and an example would be to go from 12 AWG to 13 AWG), the new size (13 AWG) would have 20.7% less cross-sectional area and 26.1% more length, hence the saying 26.1% elongation at each die in an AWG designed drawing machine using straight drafting.
Smaller to Larger Solid Wire AWG Diameters
If go from a smaller AWG solid conductor diameter to one immediately larger AWG solid conductor diameter (This is a larger to a smaller AWG gage number just to make it a little more confusing and an example would be to go from 13 AWG to 12 AWG), the new size (12 AWG) contains 26.1% more area and 20.7% less than the preceeding unit length.
If you want to learn more about the American Wire Gage (AWG) we suggest you go here:
http://www.stewart-hay.com/pshwire.htm
This message was edited by vettecoupe on 6-17-05 @ 11:43 PM