EuroWire May 2016

Feature Wire cleaning & treatment High frequency solution

A unique partner for wire cleaning Candor Sweden AB specialises in advanced wire cleaning and plating plants for various applications. Founded as a chemical supplier, its combination of know-how in chemical processes and advanced equipment for cleaning and plating of wire makes it a good choice in the market.

The request for cleaning processes in the wire industry is continuously increasing, along with the need for increased quality requirements. Cleaning is used for stainless steel, low and high carbon steel, aluminium alloy, and copper wire to remove calcium and sodium stearate lubricant coming from the dry drawing machine, lubricant oil from a wet drawing machine or forming process, etc. Ultrasonic cleaning has become popular and has been adopted by many wire producers worldwide. Ultrasonic cleaning uses high frequency sound waves. During the activity, called cavitation, micro-size bubbles form, grow and implode due to alternating positive and negative pressure waves. Just prior to the bubble implosion, there is a tremendous amount of energy stored inside the bubble itself. The implosion event occurring near a hard surface changes the bubble into a jet which travels at a speed of approximately 400km/h towards the hard surface. Because of the inherent small size of the jet, ultrasonic cleaning has the ability to reach into small crevices and remove entrapped soils very effectively. The basic components of an ultrasonic cleaning system include some ultrasonic transducers, an electrical generator and a tank containing the cleaning solution. The ultrasonic generator converts a standard electrical frequency of 50 or 60Hz into the high frequencies required. The higher the frequency, the smaller the bubbles during the cavitation will be.

The transducers are constituted of PZT elements (Pb-Zr-Ti) which converts the electrical energy in mechanical vibrations by piezoelectric action. Generally speaking, for the majority of the applications in the wire industry, alkaline solutions are preferred to remove oily matter, and phosphoric acid-based solutions preferred to remove stearate soaps. Higher temperatures result in higher cavitation intensity and better cleaning. However, if the solution temperature closely approaches the boiling point of the solution, the liquid will boil in the negative pressure areas of the sound waves, reducing or eliminating the cavitation effect. Working around 60°C (140°F) offers an excellent compromise. Sirio recommends that the baths be made of polypropylene, with one reservoir and one overflow bath in order to avoid any inflexion of the wire. One vertical pump transfers the solution from the reservoir to the overflow bath. ▲ ▲ View of air wiping and the rinsing device

It has a wide selection of wire cleaning plants to offer, such as hot water spray cleaning, ultrasonic cleaning and electrolytic cleaning. Which technology to use is a balance between wire speed, cleaning requirements, type of lubricant used and environmental aspects. In many cases, especially for high- speed applications, the processes can be combined as separate steps after each other in a plant. By this way a hot water cleaning unit can be dedicated to remove sodium-based lubricants and an acid ultrasonic or electrolytic process can make the fine tuning of the already pre-cleaned wire if required. Candor Sweden AB – Sweden Website : www.candorsweden.com ▲ ▲ A Candor MIG wire cleaning plant with the Candojet HW as pre-cleaning followed by an ultrasonic acid treatment for an effective cleaning at high speed up to 15-20m/s

SirioWire Srl – Italy Website : www.siriowire.it

Over the past few years, Boockmann‘s still relatively new Helicord® technology for wire and cable surface processing has been implemented successfully in industrial production lines. Particularly noteworthy applications are welding wire finishing, removal of misprints from cable, removal of metal particles from strands, removal of drawing lubricants and metal particles before extrusion, and various cleaning and lubricating applications in special wire such as for food or medical use. The main advantages of Helicord as compared to other technologies are the multiple 360° contact between wire and cleaning medium, a constantly refreshed cleaning medium, and efficiency of the process being independent from wire speed. Helicord machines can be equipped with a pump and heating, and are available as one-step (NB57) or two-step (NB58) models, allowing for up to two subsequent processes (eg abrasive cleaning and subsequent finish application). Special models for low tensile forces, ie small wire diameters, are also available. Extraordinary results

NB57W and NB58W models were designed for installation directly before the winder. A traversing process zone that can be connected to the traverse of the winder allows for minimum space requirements and avoids stress on the wire after the finishing process. The most promising application is welding wire finishing with simultaneous coating and re-

▼ ▼ Helicord® technology has been successfully implemented in industrial production lines

moval of particles. New types of fully impregnated finishing cords used to transfer active components (such as lubricants, corrosion inhibitors and arc stabilisers) have been a huge success. Boockmann Engineering GmbH – Germany Website : www.boockmann.com

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May 2016