Hayden offers an in-house, full-service welding facility. Technicians and operators in our welding department have been trained and certified in a variety of MIL-SPEC applications, as well as the complete array of Hayden hardfacing procedures. Manually-applied hardfacing requires a level of operator skill and judgment that comes only with experience, and Hayden is proud to have the team of craftsmen necessary to provide this service.
Shielded Metal Arc Welding (SMAW, STICK)
- Journal Buildup and Repair
Shielded Metal Arc Welding, or SMAW, is perhaps the most commonly taught welding method. Its application requires practice, and a good welder will develop a certain finesse with the rod that tends to get lost in more automated processes. As with all welding methods, metal is heated to a molten state and joined together, forming a chemically structural bond, an alloy usually using tools like a Hypertherm powermax 45 xp. SMAW accomplishes this by striking a high-temperature electric arc between the base metal, to which the coating is being applied, and the tip of the rod of the coating material. The localized hot arc liquefies both the substrate metal and the rod, and, as the two pool together and cool, the resultant bead is an alloy of the two metals. To protect the weld pool from contamination and oxidization, the protective jacket that surrounds the rod melts around the pool. When the weld cools, the residue left from the covering, called slag, hardens over the weld and may be chipped off.
SMAW, being a long-running method of welding, affords a wide range of available materials. An experienced welder can apply significant amounts of material rather quickly, allowing for heavy buildup with short turnaround. And with practice, a fairly consistent surface can be built up using a weaving pattern of sequential passes.
Gas Metal Arc Welding (GMAW, MIG)
- High-Volume or High-Deposition SMAW Candidates
Gas Metal Arc Welding, more commonly referred to as MIG (Metal Inert Gas) welding, uses a torch-style electrode attached to a spool of wire and a wire-feeding mechanism. Like SMAW, GMAW uses an electric arc between the work and the applied stock to generate heat for the weld pool. In GMAW systems, however, the torch maintains a standard distance from the work while a mechanism, typically mounted away from the torch on the power supply, feeds the weld material (in wire form) into the weld pool. As the tool standoff is constant, less effort is typically required to evenly apply a GMAW weld than a SMAW weld for which the operator must continually adjust the distance from his hand to the work surface as the rod burns away. GMAW also eliminates the need to continually stop and replace electrodes since welding can continue as long as there is wire on the spool. The primary physical difference between the two processes, and the one responsible for its name, Gas Metal Arc Welding, is the use of a constant flow of inert (non-reactive) gas around the weld pool. This is used instead of molten slag to protect the integrity of the weld. The use of gas rather than molten slag also makes for faster cleanup of the weld.
Due to the thin size of the filler wire, compared to the gauge of SMAW rod, heat input into the base metal can be significantly reduced. Nevertheless, to avoid deformation of the part, cracking, warping, or other heat damage, a MIG overlay is typically applied with a technique called “skip” welding. In this process, material is applied in short intervals along the surface to be coated, leaving equal spaces of unwelded material between each weld. These unwelded areas are then filled during a second pass across the part.
Powder Welding (Puddle Weld)
- Repair Applications
- Spray and Fuse Touch-Up
The powder welding process uses an oxy-fuel torch to heat the substrate metal, and adds a stream of powdered filler metal introduced into the oxygen jet just above the torch tip. The result is a pooling of the substrate metal and the molten powder particles at the weld interface.
Powder welding provides an excellent method for puddling in small patches of a material fairly quickly. For this reason, the torch is usually used for repair work, to build up small gouges and cracks, and to apply small amounts of material. There are some materials currently available exclusively in powder welding format. These are applied with a powder torch in production if no other comparable material can be found for another, faster process.
Gas Tungsten Arc Welding (GTAW, TIG)
- Repair Applications
- Fine or Thin Work
Also called TIG (Tungsten Inert Gas) welding, gas tungsten arc welding most closely approximates oxyacetylene welding. It is an electric arc process, but the arc is struck between the substrate and an essentially nonconsumable tungsten electrode. Filler metal is introduced separately by adding the tip of a bare filler rod into the molten pool and hot plasma arc. A flow of inert gas, like that used in GMAW, protects the weld from impurities and oxidization. TIG power supplies typically include a foot control for adjusting the heat of the arc. This feature, combined with the small arc size and independent filler feed, allows for much greater control of the weld pool than with most other methods.
Maneuvering the TIG arc and filler requires a fair amount of practice, and the small scale of the weld pool can make large jobs too time-consuming to be effective with TIG. The process is better suited to repair and patching, especially on delicate substrates where other processes might quickly burn through.