Shortly after the founding of the first construction equipment rental company, the great debate began: Is it better to rent or buy? Decades later, the debate continues, as contractors and engineering firms constantly re-evaluate how to best deploy their capital and weigh this against their equipment needs.

Equipment needs can be divided into three subcategories:

1. Utilization rates, or how often do you need to use the equipment?
2. Volume, or how many welders do you need?
3. Technology requirements, or what welding technology do you need to use for optimum productivity?

Utilization Needs
In the construction industry, a general rule of thumb is that if you don't utilize a piece of equipment at least 60 to 70 percent of the time, you should consider renting.

However, if your utilization rate exceeds a certain threshold, consider purchasing or leasing the equipment. Another factor that weighs in favor of the purchase option is this: if you don't have the right equipment immediately available, are there significant cost consequences? For example, would your service trucks be unable to perform a field repair without welding or generator power, thus idling a critical piece of equipment and disrupting the job schedule?

Because they are used so frequently for both welding and generator power, most contractors choose to purchase gas engine drives like Miller's Bobcat 250 (250 amps of multiprocess CC/CV welding output and 10.5 kW of Accu-Rated generator power).

Volume Needs
Volume requirements may dictate supplementing equipment you own by renting additional welders. For example, building a power or processing plant, or working on a scheduled plant shutdown, may easily demand 100 to 300 arcs. To meet this sudden increase, most contractors prefer to rent rather than incur the capital expenses to purchase such a large fleet of equipment.

Note that two trends have emerged to meet high volume arc needs, whether you chose to buy or rent. The first is running an inverter off an engine drive with strong simultaneous welding and generator power. This enables a two-man team to work from a single engine drive, cutting all costs associated with the second engine drive (note: Miller recommends using the Trailblazer Series or PipePro 304 units in this application for best performance). The second trend, when work is confined to a smaller area, is to power a 4- or 8-arc XMT or CST inverter rack off an 80 or 100 kW generator. This will lower costs compared to using four separate diesel engine drives (see Fig. 1. However, note that if you need to run hundreds or thousands of feet of welding lead from a multi-arc welder, separate engine drives may be more cost effective).

Fig. 1: Powering a 4-arc XMT inverter rack off an 80 or 100 kW generator will lower costs compared to using four separate diesel engine drives.