TPT May 2009

P roduction & P rocessing of A utomotive T ube

Unique solution for multi-void tube spraying

Corrosion of heat exchangers for automotive air conditioning units can be a major problem. The unit is often located near the front grille of the vehicle and is exposed to a severely corrosive environment. Road salts, rain and high temperatures all contribute to high corrosion rates. Arcsprayed zinc offers resistance to corrosion, lower production costs and reduced pollution, compared to other processes. Multi-void aluminium tubing is used in the production of serpentine type condensers, which are widely used in air conditioning systems. The voids in the tubing provide a route for the cooling medium to extract heat from the incoming air. The coating of the tubing and the corrugated fins is generally carried out by flux brazing or zincate nocolok brazing processes. In either case, problems are inevitable. Whether the air is extracted from the top or the bottom of the air conditioning unit, cleanliness is critical to the process, as is production reliability. The advantages of zinc sprayed tubing include improved productivity and zinc deposited at a pre- selected rate. In addition, a zinc diffusion pattern equally uniform to the zincate process is produced. Spraying with zinc also means highly corrosive flux, zincate treatment and waste treatment are not required and post brazing cleaning processes can be eliminated.

The zinc coating is carried out in line with the extrusion press. The plant can be installed on to either new or existing lines. The number of individual arcspray pistols required depends on the number of extrusions being produced by the press. The pistols are located on adjustable mounts, angled to allow even coverage and can accommodate single of multi strand extrusions. Metallisation has over 145 units in use around the world, with some companies opting for 1.2mm wire to produce a very fine coating finish for specialist surface protection. The Metallisation Arc 528E is a heavy duty, high performance arcspray pistol, which features a unique constant geometry head. This proven head ensures reliable alignment of the wire for long periods, giving consistent spray quality and ease of  The Arc 528E is a heavy duty, high performance arcspray pistol

 A diagram of the system layout

variable wall tubes used in making cylinder blank tube for power steering assemblies, SUV and truck axles, as well as instrument panel beams and automobile fuel tank filler tubes. Mitchell is also the world leader in producing hydraulic tube push pointers in capacities ranging from 5,000lb up to 1,000,000lb, for materials from aluminium to zirconium, for the tube drawing industry. With over 600 push pointers produced and delivered worldwide in the past 48 years, no other company on the globe can match Mitchell’s push pointing expertise and machine design. George A Mitchell Company – USA Fax : +1 330 758 7263 Email : sales@mitchellmachinery.com Website : www.mitchellmachinery.com maintenance. The electric drive, electronic control system and constant geometry spray head combine to give a wide range of deposition rates to match the job size. The Arc 528E supplies pack and wire feed includes power cables, air hose and control cable. For multi-void mills, a quick release option is also available, as this dramatically reduces the complexity of the system and pistol changeover time. The S250 Energiser is a reliable, consistent, low current power supply, which has been specifically designed for arc spraying. With a PLC control it offers reliability and ease of maintenance. For added reliability, its control electronics panel is sealed to reduce dust ingression, has easy access energiser panels and an external fuse bank for reduced mean time to repair. Metallisation Ltd – UK Fax : +44 1384 237196 Email : sales@metallisation.com Website : www.metallisation.com

Variable wall tube drawing line for truck and SUV tubes

George A Mitchell Company is the manufacturer of variable wall tube drawing systems that can accommodate drawing of tubular shapes, such as square, rectangular and hexagonal cross sections. These are used for products such as automobile crush tips and frame tubes,

as well as truck and SUV axle tubes, all of which are produced in North America for the automotive market by Mitchell’s customers. Mitchell and its customers have long standing relationships that extend over the

past 25 years, where many special forming processes have been jointly developed to enhance the tubular products fabricated for the automotive industry, sporting goods and tubular parts industries. Mitchell is a leader in providing production equipment to produce

 A Mitchell variable wall tube drawing line

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M ay 2009

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