D/F Open-Arc Gasless Overlay Machine Barrel

Water-Cooled Gasless Overlay Torch

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D/F Machine Specialties Water-Cooled Gasless Overlay Machine Barrel on a BUG-OThe Open-Arc Water-Cooled Gasless Overlay Cladding Machine Torch is recommended for mechanized cladding applications where production demands the maximum durability and quality for multi-surfacing and rebuilding applications. This hardfacing torch is designed to last for years and is ideal for single-head machines or multiple-head machines used with hardfacing applications in up to 900 degree preheat like with the Welding Alloys Multi Surfacer: custom designed automated welding equipment. They feature dual replaceable Water Out & Power Cables to add to the durability and long life of the barrel assemblies. The Open-Arc Torch/Machine Barrel is primarily for hard/cored, metal-cored, & flux-cored wire diameters 7/64" & 1/8" (2.8mm & 3.2mm). The Open-Arc Machine Barrel offers a design that accommodates both slip-in, contact tips with a collet, and CrZr (chromium zirconium) heavy duty threaded current tips with a tip adapter nut. The suggested current level would be approximately 850 amperes (depending on application). Direct mounting is accomplished by utilizing interconnections to the welding head or wire drive.

An optional D/F Torch Rack #30418 can be used on any torch with an 8" long, 1.125" diameter water-cooled nozzle. The rack slips right over the water-cooled nozzle and is secured with 4 set screws. The rack can then be dropped into a BUG-O BUG-5188 Rack Holder. The rack has a 32 pitch gear, and with the rack holder makes torch head positioning very easy.

Engineered solutions for impact and abrasion challenges for hard automation, high deposition, and large wire diameters that require preheat and high amperages, a D/F heavy duty water-cooled weld automation gasless torch is ideal and has been used for metal build up, hardfacing and metal spray applications, open arc mechanized cladding applications for multi-surfacing and rebuilding applications, in the forging industry for the repair or reclamation of forging dies (also utilized in rams, sow blocks, die holders and die shanks when increased hardness is required), and in the steel mill industry for steel gears, arbors, shafts and couplings. D/F is a leading provider of hardfacing torches for impact and abrasion challenges, heavy steel fabrication in a wide range of industries, ideal for single-head overlay machines or multiple-head machines used with flux cored and metal cored large diameter wires.

The D/F torch is famous for the fact, that if it is chilled properly, the welder can grab the chrome front water-cooled barrel (not the copper gas nozzle/cup) of the torch with their bare hand and it will be cold to the touch seconds after welding. With the proper chiller, this can be done even after a 4 hour arc time. Make certain the cooling water supply is at least the minimum flow rate of 1 gallon per minute (for each inner body), at 40 psi (80 psi maximum) with a 6 gallon reservoir and a recommended 30,000 BTU/hr cooling capacity. Gun ratings are affected by shielding gas used, arc time, cooling time and inlet water temperature. Water outlet temperature should not exceed 27°C (80°F). The torch’s water out & power cable is not cooled until the coolant has gone through the torch and out the water out & power cable. If water is not flowing through the D/F torch for at least 1 minute prior to striking an arc, when you apply the power and water hits the “hot” water/out & power cable, you will generate steam. Steam can damage the torches internals in seconds causing a leak. It can also blow out the torches water/out & power cable. A flow switch can be installed after the return line ensuring that coolant is present at the return line prior to striking an arc. When High-Deposition GMAW, high current density, high amperages, preheat, or extended periods of arc time are used, a refrigerated liquid chiller with a larger reservoir is required. Precise temperature control maintains the cooling at a constant 13°C (55°F) temperature, thus prolonging the life of the welding equipment and more specifically extending the service life of the gas nozzle and current tip. D/F Machine Specialties does not manufacture or sell chillers, we only recommend them. Click here to see our recommended chillers.

Each D/F Machine Specialties welding gun is fully assembled and ready to install. In order to make the installation complete, the code number, wire size, wire feeder make/model (Lincoln wire feeders, Miller wire feeders, Tweco wire feeders, ESAB wire feeders, & EURO Quick Disconnect wire feeders), and inlet (as needed) must be specified when ordering. If special welding tools or accessories other than those listed previously are required, please consult with the factory. Get the right feeder adapter connection to fit your MIG wire feeder.


  • Greatly Reduces Maintenance and Downtime
  • Withstands Extreme Conditions - 1000° Preheat, 850 Amps
  • Water-Cooled Inner Body & Nozzle
  • Increases Tip Life up to 7-to-1
  • Heavy-Duty Construction for Long-Lasting Durability
  • Torch Longevity - Years vs. Months
  • Small Frontal Area for Hard-to-Reach Locations
  • Optional #40597 Mounting Bracket with Insulated Bushing for Remote Mounting
  • Optional Torch Holding Rack for Easy Mounting

Model Explanation

  • MWCG-D - Machine Barrel, Water-Cooled - Gasless - Dual Water-Cooled Power Cables

Model Specifications

MWCG90-D 850 amps 3.4 lbs 1 gallon/min .045"-1/8"

Barrel Dimensions

MWCG90-D 14.500" 1.125

Ordering Information

Complete Barrel Only

Model MWCG90-D Overlay Machine Barrel 30390D

Complete Assemblies

4 Ft. 5 Ft. 6 Ft. 7 Ft. 8 Ft. 10 Ft. 12 Ft. 15 Ft.
MWCG90-D 30390D-4 30390D-5 30390D-6 30390D-7 30390D-8 30390D-10 30390D-12 30390D-15
Add Footage Digit to Item Code Number for Length Required.
Example: Require 30390D with 3 Ft. Utilities: 30390D-3

Manuals & Downloads

Instruction Manuals


CAD Files & Drawings

MWCG90-D 30390D 30390D 30390D

Other Documents

Torch Connection Options
Gasless Overlay Machine Barrel

Utility Station #45188

45188 Utility StationThe D/F Utility Station is required for all D/F torch installations. Typical modern torch setups utilize a unitized cable assembly with a power pin. D/F torches take an alternative approach to the setup. The torches use a separate gas hose, water-in hose, Water Out & Power Cable, and casing/conduit. When one cable goes bad it is simply replaced instead of attaching an entire new unitized cable assembly; a huge cost saver! This is also where the D/F Utility Station comes into play. The gas hose, water-in hose, and Water Out & Power Cables are interfaced with the customer's existing lines via the Utility Station. The D/F torch leads plug into the front (see right) of the Utility Station. Into the back (see below) of the Utility Station go the customer's utilities. Read more on the D/F Utility Station product page.

For more information on proper use of the D/F Utility Station, and to see the various torch connection options, please download the Torch Connection Options one-sheet.

D/F Utility Station #45188D/F Utility Station #45188

Torch Rack #30418 and Rack Mount

An optional D/F Torch Rack #30418 can be used on any torch with an 8" long, 1.125" diameter water-cooled nozzle. The rack slips right over the water-cooled nozzle and is secured with 4 set screws. The rack can then be dropped into a BUG-O BUG-5188 Rack Holder. The rack has a 32 pitch gear, and with the rack holder makes torch head positioning very easy. See the images below right. See the Torch and Rack Mount product page for more information

For more information on proper use of the D/F Utility Station, and to see the various torch connection options, please download the Torch Connection Options one-sheet.

D/F Torch RackD/F Torch Rack


Hardfacing is gaining more and more importance in the most varied fields of modern engineering. In the case of wear, corrosion and other types of surface attack, the application of hardfacing permits the economical reconditioning of many structural members. Reconditioning may comprise work pieces subjected to metal-to-metal wear. Such as rollers, crane wheels, shafts, rails or which are subjected to metal-to-mineral wear, like building machinery, conveyor screws, excavator bucket edges, etc.

The possibilities of hardfacing not only lie in the field of reconditioning, but more and also in the manufacture of new tools and components. In this manufacturing process, a non-alloyed or low- alloy steel is used as carrier material to which are imparted special properties by welding on a suitable high quality weld metal. Decisive factor in hardfacing is the knowledge of the wear conditions, that is, whether it is a frictional wear caused by metal or minerals, corrosion, cavitation, erosion or temperature. The selection of the welding consumable to be used will depend on these conditions. Besides this, it is most important to know the composition of the base metal to be surfaced, because of the measures likely to be taken, such as preheating and/or post weld treatment.

Depending on the use of the workpiece to be hardfaced, the weld metal shall meet the most varied demands. These can be cited as follows:

  • Hardness in the as-welded condition
  • Red hardness under thermal loads
  • Resistance to metal-to-metal wear
  • Abrasion resistance to frictional and grinding wear
  • Impact strength
  • Corrosion resistance
  • Resistance to scaling

In some cases, more than one of these modes of load may occur simultaneously, so that the weld metal must posses the respective properties. Hence, a conscientious selection of the proper weld metal will be a must. Of course, there doesn’t exist a weld metal possessing all these properties in full measure. Nevertheless, in most cases it will be possible to find a satisfactory compromise in practice.

Hardfacing Tools
An interesting field of application in hardfacing is reconditioning of hardened tools, such as shear blades, punching dies, cutting edges, deep-drawing tools, etc. For this purpose, the so-called “step hardening weld method” has proven a success. Welding is carried out in the delayed transformation range which is situated between the perlite and bainite zones of TTT-curves of the steel in question. Thereby, the hardenability of the steel is taken into account. Generally, the temperature range in which welding shall be carried out is from 400°C to 600°C. This means, that step welding is based on the fact that in such steels the transformation of austenitic is clearly delayed within a certain temperature range.

The sequence of operations is as follows:

  1. Slow heating of the workpiece to its hardening temperature. At this temperature the structure becomes austenitic.
  2. Cooling to step temperature; that is, to the range in which the delay in austenitic transformation (according to TTT-diagram) is most pronounced.
  3. Welding the workpiece at this temperature.
  4. Cooling the workpiece to room temperature in still air or better in oil (50°C to 150°C).
  5. Tempering to the respective temperature which in the case of high-speed steels lies in the range of 550°C to 570°C.
  6. Machining the weld area.

For the solution of the many cladding and hardfacing problems, D/F offers a complete line of welding Torches & consumables for flux cored wire electrodes, solid wire electrodes, gas metal arc welding and submerged arc welding fluxes.