Cutting methods have evolved over the past decade as work requirements have changed.

TEDM once was widely used, as was stamping, but those processes have been affected by alternative processes such as laser and abrasive waterjet.

“Customers look at other ways to cut various materials, and many choose laser, a good tool for production on parts up to ½ in. Thicker parts and hardened steel can't take the heat, so in many applications abrasive waterjet is most versatile as it cuts all types of materials with no heat and high-precision,” Nick Giannotte, vice president of MC Machinery Systems' Waterjet & EDM sales and marketing, said.

MC Machinery Systems is a company of Mitsubishi Corp. (www.mitsubishi-world.com). Mitsubishi also manufactures EDM/laser systems to address the growing needs of the industry.

As the uses of exotic metal alloys and composite materials have increased in a wide variety of applications, laser and abrasive waterjet cutting alternatives have increased while the some uses of CNC machining and stamping methods have declined.

CNC-based industrial laser and abrasive waterjet cutting methods can play an important role in cutting high-tech and exotic materials, according to LAI International. LAI International provides precision engineered components and assemblies for aerospace, power generation, defense and other advanced technology industries.

Tom Sterner, operations support manager for LAI, at its Westminster, Md., facility, said when it comes to determining the best cutting method application, there are several factors to take into consideration.

The first is the material type.

“Generally, just knowing the material type that is to be used eliminates one or the other process,” Sterner said. For example, lasers are absorptive with some materials and reflective with others.

Material thickness is also a consideration.

“There's a definite limit to how thick lasers can cut, High-powered lasers, which have their cutting power at the focal point, can cut up to 1 in. thick materials, but ½ in. thickness for practical applications. We've cut very thick materials — up to 14 in. — using waterjet which has a much less defined threshold. If the material is too thick, it eliminates laser as a process right away,” Sterner said.

Both laser and waterjet cutting technologies produce small kerfs, so the processes allow close nesting of parts that can be a significant cost saving for expensive materials.

Compared to a kerf width of 0.875 mm (0.035 in.) for waterjet cutting, the typical kerf width for laser is 0.250 mm (0.010 in.).

However, laser cutting becomes very limited when material thickness increases, according to LAI. The company also offers NADCAP certified non-conventional machining and welding processes, and has made the effort to have its five fabrication facilities certified to ISO 9001:2000 and AS9100 standards.

“Complexity of geometry also can come into play as a factor when deciding which process to use,” Sterner said.

Both abrasive water jet and laser can cut geometric shapes, but as thicknesses approach laser's ½ in. threshold, thermal conduction can create edge finish problems.

For applications in which a heat-affected zone can't be tolerated, waterjet cutting is best because it produces no heat-affected zone.

Laser, on the other hand, produces a heat-affected zone, but it is localized near the cutting zone.

Additionally, according to LAI, laser processing is more sensitive to material quality than abrasive waterjet cutting.

Hot-rolled steel presents serious quality problems in laser cutting because of surface scale that tends to melt into the metal to create an undesirable surface finish.

Surface texture must be smooth, otherwise the assist gas and laser focus can be altered, affecting the quality of the cut. These problems do not affect and are not affected by abrasive water jet cutting.

Laser cutting also creates more stresses in material than abrasive water jet cutting. Titanium, for example, is very combustible so the heat from a laser could destroy the part if it is cut with oxygen.

“Waterjet is displacing laser in titanium and Inconel applications in which you're concerned with temperature on the edge and a recast layer,” Sterner said.