Conventional release agents adhere very poorly or not at all to the surface of wires and insulated impregnated conductors. When conformal coating with resin, coils made of these conductors, usually a very strong adherence of the insulation to the resin occurs. If such a coil gets bent or twisted, the insulation may break, so that the coil becomes damaged or even useless.
This can easily be avoided by applying a PTFE-dispersion to the wire surface, using strong friction and an apt metering device. The water evaporates or is wiped away by the cord, the polymer is burnished onto the conductor surface, adhering to it very strongly. There will be no more adherence to the resin, and durability of coils will increase noticeably.
The coefficient of friction of aluminum wires could be improved from 0.35 to 0.11, the coefficient of cables with polyurethane insulation was enhanced from 0.5 to 0.3.
Paper given at the”American Welding Society Show” in Atlanta, USA (10/30/2006 – 11/02/2006)
This presentation is based on the principles of HELICORD® – a process for application to the manufacturing process of welding wire. Moreover, on the order of PTFE – dispersion, pointed to the use of HELICORD® abrasive cleaning and solvent-supported cleaning of aluminum wires, and for lubricating to improve the conveyance in a series of practical examples.
This presentation is available upon request to us.
The metering pump was developed to support the removal of soluble residuals of drawing agents from wire surface, so that ultrasonic cleaning could be replaced. It is also apt for applying liquid lubricants and anti-corrosives on welding and other wires, as well as for metering cutting oils, e. g. when using high speed cutters.
The amount to meter can be frequency controlled (e. g. using a stroke or pitch rate sensor) or pulse width modulated.
New at this exhibition: flat Helicords for treating stranded and large-core wire
The flat Helicords have been developed to avoid convergence of loops, and to meet extremely high surface purity requirements, e. g. for welding wire, stranded wire and cables by giving a bigger contact area. They are also applicable for copper clad optical fibers.
The composition of Helicords can be customized to meet different needs.
Demonstration of multi-stage abrasive treatment:
Solid impurities on the wire surface, e. g. powdery drawing agents like calcium stearate or graphite, can easily be removed by abrasive treatment. It requires several Helicord models NB55 and NB56 to be arranged in line.
The demonstration unit was set up of two NB55 devices, the first one using abrasive Helicord, the second one using an absorbing type of cord. Both devices were supplied with a fluid with low surface tension, so that formation of dust was minimized and the cleaning performance was maximized.
“The invention relates to a device for cleaning a wire or the outer surface of a tube, both preferably with a rounded cross section, using textile or textile-like material strands which move substantially parallel to and against the direction of travel of the wire or tube, the textile or textile-like material strands, surrounding the wire or tube in the form of at least one loop lying close thereto in a looping zone and optionally containing cleaning material, wherein the approach and exit angles of said material strands are flat with respect to the wire or the outer surface of the tube. When a plurality of loops is present, it can be said to lie in a spiral manner….”
Non-metallic impurities affect the weldability and feedability of welding wires. For smooth welding of high-alloy welding wires, a dead surface without drawing residuals have been proven beneficial. To achieve this, the wire should be cleaned after drawing. Using our Helicord system, impurities can be reduced by up to 70 %.
By lubricating the wire, the coefficient of friction is reduced and feedability is enhanced. Wax-like lubricants and oils with additives, that also enhance weldability, seem to be most valuable. Contrary to trials with other lubricating systems which did not achieve any satisfactory performance, Helicord met or even exceeded the requirements of several manufacturers of welding wire.
Surface treatment of silver-plated wire:
Loose metal particles and drawing residuals on silver-plated wire, e. g. for medical applications, cause problems during following production steps. Using a Helicord device NB55 and a dry Helicord, we achieved a cleaning performance significantly better than ultrasonic cleaning.
Cleaning steering conductors:
For military use of single-wire steering conductors, a minimum length of faultlessly insulated wire is required. Using Helicord, these requirements can be met more reliably than before. The amount of substandard products was decreased significantly.
Cleaning of high frequency communication and coaxial cables:
Copper deposits in the extruder nozzle often cause insulation faults of high frequency communication and coaxial cables. Using Helicord, the required minimum length of faultless insulation was achieved and no blow-out occurred during 8 hrs. production time, which had not been accomplished by any other technology so far.
Application of anti-corrosive lubricants on steel wire:
Rust and oxidation may decrease the windability, particularly of non-alloy steel welding wire. When lubricated with anti-corrosives (e. g. wax), rust-resistance may rise up to 400 %. Thick layers don’t absorb any dust, and the lubricant doesn’t diffuse into the filling of cored wire.
Cleaning aluminum wire for the food industry:
After drawing, aluminum wire to be used by the food industry has to be cleansed of drawing residuals (mineral oil) and should be lubricated. Using Helicord, residuals were decreased to 1 mg/m² and a wax-based lubricant was applied.
The main topic of our booth was the introduction of computer-aided process data documentation for our lubricating system HELILUB®.
Many producers of magnet wire need to log process data continuously as to be able to provide evidence of their quality and quality assurance. Using our process data documentation system, all settings, events, parameters and values of Helicord devices NB52, NB53 and NB54 can be recorded and compiled in an inspection sheet, so that all determining factors and basic conditions can be displayed later on.
We use a similar system to be able to trace back every single spool of our lubricant yarn used for lubricating magnet and winding wire.
In annex IIA of the VOC directive 1999/13/EC, which is valid in all countries of the European Community, the legal emission of volatile organic compounds resulting from the production of winding wire is limited to 5, respectively 10 g per kg of wire, depending on the wire diameter. The transition period for refitting existing plants will end on Oct. 31st, 2007.
Our Helicord system using the HELILUB® technique for emission free lubrication of magnet wire complies with all requirements of this directive. Especially when it comes to high speed production plants (up to VxD = 200), the Helilub technique alone allows very accurately and constantly measured, emission-free lubrication.