Laser, plasma, waterjet, and oxyfuel. What makes each of these metal-cutting methods unique, and what impact should that have on your selection?

In the previous post, we introduced the three T's for cutting metal—a simple formula that can help get the conversation started on determining the right fit for your project.

metal cutting equipment

In this post, we unpack more about what makes each of these metal-cutting methods unique, and what impact should that have on your selection.

We tap the expertise of advanced processing specialists who work with these technologies daily to find out more about the nuances that ultimately help the equipment make the best cut.

Our panelists: 

  • Jeff Pitzenberger, fabrication sales manager for Ryerson, based in Coon Rapids, Minnesota
  • Hugh Pruitt, senior account manager in fabrication sales for Ryerson, based in Little Rock, Arkansas
  • Chad Hart, fabrication sales manager for Ryerson, based in Little Rock, Arkansas
  • Tim Cowden, general manager with SFI Gray, part of the Ryerson Family of Companies.
 

Beyond the basics, what should customers be asking themselves before considering the equipment?

 
Pitzenberger: Is it necessary to hold very tight tolerances? Many times, customers specify tolerances that are tighter than they need to be. It’s always nice to recognize that there is a cost difference between plasma cutting or oxy-fuel cutting with a looser tolerance and laser cutting with a tight tolerance. Work with your partner to decide if your tolerance can be adjusted.
 
Cowden: The question you need to be asking, regardless of the equipment, is this: What is the intended use of the part?
 
Let’s say, for example, that the plan is for additional machining after the cut. Certain alloys develop a hardened edge when heated, which can ultimately disrupt the tooling when machined. Of course, you can anneal the alloy in order to eliminate that hardened edge, but that comes with an additional cost. So, in the case of oxyfuel, which uses a flame, you may run into an issue.

Each piece of equipment has its own nuances, what are some that stand out?

Pruitt: Alongside waterjet’s ability to produce precise cuts and tighter tolerances, it offers a cut with no heat-affected zone. This means the ability to cut without interfering with the inherent structure of the metal. You also have a relatively narrow kerf with a water jet. This leads to a reduction in the amount of scrap material produced, by allowing uncut parts to be nested closer together.

Cowden: With oxyfuel, you are talking about multiple torches used at once—eight heads to be exact. So, while oxyfuel may run slower than plasma or laser, you are running at a factor of eight, which can make it powerful.

But that use of heat can also be a drawback in certain instances. Steel expands and contracts when heated. Alternative methods like plasma or laser reduce the heat, which limits the movement of the metal. You may want to take that into consideration if you need tighter tolerances.

Pitzenberger: Technology advancements today allow us to cut faster, gain better quality in the cut edge, and save money on consumable costs. When you need to hold tight tolerances and don’t want to pay the added cost for machining, laser provides a good option. A typical tolerance on laser-cutting machines can be +/-.010 or better, but it really depends on the intended use of the part. 

Can any comparisons be made between the different methods?

Hart: Each cut process is different, but laser stands out because the quality is higher, and you can cut parts closer together. Also, there isn’t as much heat on the material which means it stays flat and doesn’t move around like on plasma or oxyfuel.

Cowden: It is often a debate on whether to use oxyfuel or plasma. With oxyfuel, you are using a torch rather than a laser, and while they will both cut a nice straight vertical line, the risk you run into with plasma is that it may create a bit of a bevel in the metal. 

Pruitt: Waterjet can handle both great thickness and a finer cut. The tolerance level of waterjet is very tight depending on the thickness of your cut. Compare this to plasma, for example: Typically, when you are out of the thickness range of plasma there are few choices other than waterjet. However, when you are in the thickness range of plasma, it would only be economical to use waterjet when a tighter tolerance is needed. Waterjet does often come with higher cost, which is due to the slow-burning speed.

Pitzenberger: Plasma cutters are the closest comparison to a laser, and the reason lasers stand out above plasma cutting is their high-cut quality, tight tolerances, and superior finish to allow for subsequent paint or coating operations.

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