Many jobs require the addition of holes to bolt two or more pieces or parts together, so hole production is an important part of most cutting operations. Punching, drilling, plasma, waterjet, and laser are all used depending on need and equipment availability. Ideally, fabricators prefer to use a single process for hole cutting – waterjet for example – in order to reduce material handling time and save on floor space.
Traditionally, fabricators would cut the outside of a part using plasma, and then move that part to a second station to cut the holes. This was done because of the less-than-perfect quality of typical plasma-cut holes. They often had a fairly severe taper, in which the bottom of the hole was much smaller than the top, as well as “dings” and “divots” – essentially, notches in the inside of the hole.
Fortunately, today there are ways to nearly eliminate the taper, and the dings and divots, enabling the cutting of “bolt-ready” holes. If using plasma on an X-Y table, an operator can manually change the machine speeds and height control settings and modify the machine codes for a particular hole size, material thickness and power level. Owners of a Hypertherm high definition system, such as our HyPerformance® HPRXD, have the added benefit of True Hole® technology, which automates much of the manual work. Cutting holes by hand using a handheld plasma torch is also possible using tools like a circle cutting guide.
Examples of where hole cutting is used:
- Cutting holes for bolting a cut piece to another plate or part
- Cutting multiple holes in a large plate, pipe, or drum for hoses and wire to pass through
- Fabricating holes for gauges on an instrument panel