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October 12, 2018

Dry Lubes: how to tell if you are using too much or too little

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If you don't see a thin shiny coating on the wire exiting a die using a dry lube, then there is a problem. The die and/or pressure die system has to be properly designed and kept in a functional state.

Too often, people use roller applicators to help push more lube along the wire, but if it is not melting properly all you will have done is wasted lots of lube. This is a primary indicator of poor lubricant practices, as the excessive lubricant dust will accumulate in the entire work area, fill the air and settle on building rafters, walls and all other nearby surfaces. The color of the wire exiting the lube box should be dark, not the same color as the lube in the box because that means you just have dust, not a properly melted lube! Below is some advice to consider.

  1. Use a die reduction angle where you have a contact of 50 to 75% of the drawn diameter. This traps enough lube between the moving wire and the reduction angle to cause it to melt. Again, the lubemust melt to be effective, and this action creates the pressure required to melt the dry lube.
  2. As a follow-up to 1, if you are using a pressure die system, the clearance between the incoming wire and pressure die should be decreased. The function of the pressure die is also to melt the dry lube, however it does this not by the wire temperature but by the pressure generated by compressing the dry lube between the pressure die and draw die along the reduction angle.
  3. The composition of the dry lube also matters. Calcium soap (lubricant) melts at a much lower temperature than do sodium soaps, so you have to remember that the melting range is not a specific point, but one that will vary depending on what kind of soap is used.
  4. Die geometry plays a critical role in lubricating, as does the design of the pressure die system. Some of the newer die constructions allow you to remove the carbide nib to reduce shipping costs, but that same design may result in wear on the nib holder, which can result in poor alignment and subsequently in poor lubrication. This is not immediately obvious, and that is a problem. The nibs fit snugly when die cases are new, but with use they become loose and this is when you lose the alignment. Unfortunately, the most cost in this die system is the casing, so it has to be put on an inspection routine. If a nib is set in the case and you can wiggle it with your finger, the casing either needs to be replaced or reworked to a larger nib size. An improved casing material may be a solution. Another factor is that most of these systems have a two piece screw together construction. Care must be taken when disassembling and reassembling, and it’s a good idea that the dies be cleaned of residual lube with ultrasonic bath before breaking them down.
  5. The pressure die system must be sealed. Normally, you first see a push out of lube from around the die holder, a turd backing out of the die box or at the exit end. The solution is to stop, pull the die assembly and clean the faces on a tapered holder and remove any burrs that may be preventing the two surfaces from sealing when they are pulled down against the taper. If you have leaks, then the pressure is reduced and you will not be getting the most efficient performance for the system.
  6. Finally, in terms of a “rule of thumb” to go by, if you are getting the right dark shiny look on the wire exiting a die, you should expect to be using 1.5 to 2 kg of soap per ton. A line producing a loose dusty wire might be going through about 10 kg of soap per ton, which unto itself is enough of a reason to re-assess your lube usage.

Additional Info

  • Company: Technical Consulting, LLC
Read 2 times Last modified on October 12, 2018
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