There are a lot of applications within the automotive industry, where MIG/MAG is in use for so-called fillet edge welding. Generally, fillet edge welding is accounting on over 80% of the total joints performed with arc technology in automotive industry. Mainly, for structural components, chassis, frames, cradles, shock absorbers, various types of brackets, bumpers, etc.
MIG welding technology has been widely reknown for many years by metal products manufacturing industries as the most broadly used process for welding. However, MIG/MAG welding process is relatively slow, requires extensive use of filler wire, and is practically inapplicable for lap/overlap welding, as it necessitates seam finding capability for automated welding systems and produce extensive heat distortion at work piece. Super-MIG® provides solution to all above impediments.
Main difficulties related to the finding of the welded edges, post welded treatment due to the high level of heat deformation, relatively slow processing speed, high ratio of consumables.
Also, there are several applications within the structural components for Plasma Arc welding. Mainly for so-called overlaps; using special holes with further melting around these halls. As it is evidential, the above process requires precise indexing for co-axial positioning of the torch with respect to the hole; high scrap because the issue of the variable gaps, slow processing speed, complicated tooling, etc.
More prominent method of overlap joining is Laser welding. However, precise surface preparation, expensive tooling, high capital equipment cost, high running cost, relatively low up-time causes very limited applications of Laser.
Welding of Zn-coated materials either in overlap or fillets configurations, represents utmost difficult case for any of the above described welding technologies.
PLT’s unique concept of combination between MIG and plasma arc is the best qualitative and cost effective solution for lap and fillet edges welding of steel and Zinc coated steel joints.
Super-MIG® is a new and innovative technology that provides extensive amount of opportunities for the development of unique and very needed by the market, off the shelf and customized solutions for welding applications.
Super-MIG® technology is also based on combining two existing power source technologies (MIG/MGAW and Plasma) into one operational welding system that results in collective advantages and benefits of both the technologies it is comprised of. It improves the welding fusion and increases by 3-4 times welding penetration depth, productivity and quality. Super-MIG® provides welding capabilities not available by each of the two welding technologies alone, without any grooving or any other edge preparation technique. Any other existing welding machines and prior arts for augmentation of plasma-MIG technology inventions cannot provide similar welding capabilities and quality.
As stated already before, traditional MIG/MAG process incorporates automatic feeding of a continuous, consumable electrode that is shielded by externally supplied gas. Of a special importance is the metal transferred from electrode to the work piece, which may be done in three basic modes:
Short circuiting transfer is characterized by the lowest range of welding currents and electrode diameters. The metal is transferred only while the electrode is in contact with the weld pool. No metal is conveyed across the arc gap. This mode is suitable mostly for joining thin sections and for bridging large root openings. Processing speed and resulting overall process productivity is very low, and penetration is shallow.
Globular transfer is characterized by a drop size with diameter greater than that of the electrode. This mode typified by insufficient penetration, excessive reinforcement and big spatters. This significantly limits the use of the globular transfer mode in production applications.
Spray transfer is possible in argon-rich shielding gas. Leads to a highly directed stream of discrete drops, accelerated by arc forces up to velocities that overcome the effects of gravity. The spray transfer mode is possible if the arc current is higher than so-called transition current, the value of which depends on wire diameter and type of material. Operating in spray transfer mode is highly recommended.
However, the typically high deposition rate may produce a weld pool too large to be supported by surface tension in vertical and overhead positions. Deposition rate progressively increases at a higher rate as welding current increases. This leads to excessive electrode melting and excessive consumption of filler metal.
All the above limits welding speed and thickness of material welded by one pass. Hence, it eventually leads to the necessity of multi-pass welding with different groove types. In addition, the high volume welding pool produces high level of welding distortion.
Notionally, if heat input in base metal may be accelerated without increasing filler metal deposition rate, penetration depth and welding speed can be dramatically increased.
The combination of commonly used MIG welding with the plasma welding improves the welding fusion and increases its productivity.
The above goal is achieved through enhancing the benefits offered by both methods:
· Plasma arc’s high power density and deep penetration, and
· MIG (GMAW)’s high arc efficiency and ability bridging big gap.
This we propose to obtain by combining in one processing torch both consumable electrode and non-consumable electrode, in the way that the axes of both non-consumable electrode (plasma arc) and consumable electrode (MIG-GMAW) will have an acute angle facing the work-piece, and the above axes will be placed in a plane that crosses the work-piece nearby weld line. In our patented Super-MIG®, we intensify major advantages of the plasma arc on the one hand, and high arc efficiency and metal transfer of the MIG-GMAW on the other hand. This we reach by means of interaction of plasma arc and MIG arc.