How to Select the Right Engine-Driven Welder
Engine-driven welders are generally used when electric power is not available for arc welding. Usually these are outdoor applications. However, engine-drive welders are often used for indoor applications when it is not convenient to supply power to electric "plug-in" arc welders.
These indoor situations include everything from minor repair jobs to major plant shutdowns. When operating engine-driven welders indoors, vent the exhaust outside if at all possible, or use in large spaces with good ventilation.
The basic considerations when choosing an engine-driven welder are:
AC Generator Power
In trying to select an engine drive, the first thing to consider is the application. Ask yourself these questions:
Is this new construction or a repair job? Also, what is the size of the project?
Is there a particular welding process you would like to use? You may want to stick with a process with which you feel most comfortable, or there may be a certain process required on the job.
Is this a pipe welding project? The equipment chosen needs to produce an arc suitable for this type of work.
Will the job require arc gouging? Arc gouging is repair work usually done in industrial jobs.
What type of material needs to be welded? Most of the time the material will be a common mild steel plate. However, if it's aluminum, the welding will require different equipment.
Using this information, match it to the welding processes described below.
CC (constant current) stick welding is the most common choice for field work. Electrode (welding rod) diameters most commonly used are 3/32", 1/8" and 5/32". The simplest equipment will handle a wide variety of construction and repair applications. Output is measured in amps, and up to 200 amps is sufficient for the electrode sizes mentioned. Most equipment is DC (direct current) output for best arc stability. A 200-amp welder is usually able to get the job done.
Is most often done with stick electrodes. Look for equipment which specifies it will pipe weld, meaning that suitable arc characteristics are specifically provided for this process. Electrode diameters are typically 5/32" and 3/16", and 200 amps is sufficient for this process.
A process for removing metal. It is most commonly done in the stick mode. An arc is used with a carbon rod to melt metal and compressed air blows the molten metal away. Gouging is used to remove bad welds and to repair cracks. Most operators use equipment with 400 to 600 amps for higher productivity with 5/16" or 3/8" diameter carbon rods. However, smaller rods can be used with lower amperage. For example, a 5/32" carbon rod can be used with 150 amps. Usually a separate compressor supplies the air. A few engine-driven welders are manufactured with built-in compressors.
CV (constant voltage) wire welding requires a wire feeder. Wire welding's main benefit is greater productivity: more weld metal can be deposited than for stick during the same amount of time. Although wire welding is much less common compared to the above processes, the application is growing. The engine-driven welder must have a CV-wire capability. Since most engine-driven welder work is outdoors, self-shielded flux-cored wire (which requires no shielding gas) is highly recommended to keep the process simple. When welding under windy conditions, the shielding gas associated with gas-shielded processes (solid wire or gas-shielded flux-cored wire) may be blown away, resulting in poor quality welds. Output is measured in volts and amps. Wire diameters are typically .035" and .045", although 5/64" is often used for higher productivity. A welder with 30 volts and 300 amps is usually sufficient for many applications up to 5/64" wire.
A slower, but more precise type of welding well-suited for thin materials and unusual alloys. A TIG torch and shielding gas are required. If welding on aluminum, an AC weld output is required from the engine-driven welder and a high-frequency generator is attached to start and sustain the arc. Or, an AC TIG welder can often be powered from the engine-driven welder's AC generator, if at least 8,000 watts is available. Most TIG welding is done below 100 amps.
A metal cutting process which utilizes an arc and compressed air. The engine-driven welder's AC generator can often supply power to a plasma cutter. At least 8,000 watts of power is recommended.
After the application has been defined and the welding process has been selected, the next step is to choose the engine. Diesel, gasoline or liquid propane gas (LPG) are the choices. A diesel engine offers better fuel economy than a gasoline engine, and diesel fuel does not ignite as easily as gasoline. Refineries almost always require diesel-fueled machines rather than gasoline-fueled machines. Another consideration for large jobs is whether the fuel is being supplied at the job site. If so, it is usually diesel, but whatever the fuel, the cost savings will usually determine the engine choice.
Gasoline engines are sometimes preferred in cold weather climates because they start more easily without extra starting aids, such as ether start kits and winterized fuel for colder weather.
LPG is much less common, but becomes an important alternative choice when diesel and gasoline exhaust emissions are not permitted for indoor applications.
A spark arrester may also be required in forest and oil service areas.
Sometimes the need for portability will be the main factor in equipment selection. If an engine-driven welder needs to be carried or lifted to a work area, having a small gasoline stick welder will normally be the best answer.
AC Generator Power
AC power is sometimes required on the jobsite for grinding welds, or for lights when working at night. Normally, 3,000 watts of AC generator power is plenty of power for these applications. Ground Fault Circuit Interrupters (GFCIs) are recommended and may be required. An AC TIG welder or plasma cutter will require more power - typically 8,000 watts minimum.
For more information, contact our customer support team on 07 4659 0044
Contact us for the latest range of professional engine-driven welders and consumables or drop into our showroom at 500 Boundary Street Toowoomba.
At Toowoomba Welding Supplies we keep a range of engine-driven welders and generators in stock, ready to go. However, generally we like to order custom-built machines so that the engine-driven welder or generator you buy will suit your specific application and situation.