The right welder/generator

Engine-driven welder/generators are synonymous with service trucks. The fabrication process of joining, fixing and re-engineering materials and metals is an essential component to servicing landscape and construction equipment. Choosing the right engine drive for your truck prepares you for whatever repairs you encounter in the field. Take into account the following factors and you’ll never be caught shorthanded on a critical repair.

Choosing the right engine drive for your truck prepares you for whatever repairs and fabrication you encounter in the field.

Cutting/gouging

The first step in repairing a broken piece of steel is cutting out the damaged portion. An oxy-fuel torch can be found on most trucks, but choosing the right engine drive gives you two additional options: plasma cutting and carbon arc gouging.

Plasma cutting is an arc cutting process that creates a constricted arc that melts a small work area and then removes it with a constricted flow of a hot, ionized gas (standard compressed air). This process cuts all metals that conduct electricity. Plasma cutters offer lightweight portability and can cut steel up to 3/4-inch with 10,000 watts of power from an engine drive.

Carbon arc gouging is a cutting process by which metals are melted by the heat of an arc using a carbon electrode. Molten metal is then forced away from the cut by a blast of forced air. It is available on most engine drives; machines that offer at least 300 amps of power at a high-duty cycle work best for gouging. If you need to remove a lot of metal, look for an engine drive with a peak output of at least 500 amps. This lets you run 3/8-inch diameter carbons, so you’ll get the job done faster.

Welding

Selecting the right machine is based largely on the type of welding and consumables required to do the job. One of the most common welding processes is stick welding, a method that joins metal by heating it with an arc between a covered metal electrode and the work piece. Filler metal is deposited by the electrode and shielding is provided by the electrode’s covering. The key factor when stick welding is the electrode diameter. A 1/8-inch electrode welds at about 145 amps while a 5/32-inch rod experiences optimal performance at 180 amps. An engine drive with a 40-percent duty cycle at 250 amps offers more than enough welding power to fill most stick welding needs.
Flux cored welding is also popular in the field because the wire is self-shielded and offers less chance of contamination than a solid wire with shielding gas. Like MIG welding, flux cored welding joins metal by heating it with an arc between a continuously-fed filler metal electrode and the work piece. Flux cored electrodes, however, contain a flux within the electrode that provides atmospheric shielding and other process benefits. An engine drive with constant voltage (CV) output provides superior wire welding performance over a constant current (CC) machine. Amperage requirements vary based on the type and diameter of wire used, but a 250- to 300-amp machine is sufficient for most applications.

Power generation

Engine drives offer power generation capabilities ranging from 5,000 to 20,000 watts. Choosing the right one for your truck depends on the type of tools you run and if you need to simultaneously weld and run other tools. Knowing the wattage needed to run tools such as grinders (1,800 watts), cut-off saws (up to 2,400 watts) and air compressors (8,200 starting watts) will help you pick the right unit. Some engine drives even have two generators – one for welding and one dedicated to running other tools. This allows two people to work off the same machine without any concerns over generator power usage interfering with the welding arc.

Compared to a separate welder-generator and air compressor, the multi-function Trailblazer® Air Pak™ from Miller requires about 50 percent less truck space, uses less fuel and simplifies equipment management.

Space and weight 

The size and weight restrictions of your truck may also determine the type of engine drive you choose. Smaller units have a very small footprint and can weigh as little as 345 lbs while still offering 6,500 watts of generator power. Larger units even combine an air compressor with the welder and generator. This saves space but such units can weigh up to 2,000 lbs. Other units are designed especially to direct airflow out the top of the machine, eliminating the chance of airflow being blocked when the unit is truck mounted. This reduces overheating and extends the life of the machine. Know your weight, size and mounting restrictions so that you can make an educated choice that fits your truck’s needs.

Fuel

What type of fuel do you need or prefer? Most engine drives are available in gasoline, diesel and even LP. Gas engines offer a lower product cost, reduced weight and a smaller size while diesel engines use 20 to 35 percent less fuel, have longer engine lives and are required on some sites. Choose whichever fuel option best suits your needs and work environment.

Courtesy of Compact Equipment magazine, March 2009