Increasing laser power and high acceleration motion technology has improved cutting speeds to 60 feet per minute and more and created a new process called high speed laser cutting. High speed cutting requires a highly dynamic, stable machine and a modern CNC with high resolution. With nitrogen assist gas, the speed limiting oxidation process encountered when using oxygen assist gas can be overcome. This process demands higher laser power (> 3 kW), even in thin mild steel (> 16 gauges) as well as substantially higher assist gas consumption (1000 SCFH and more).

Today between 85% and 90% of all laser cutting applications are in flat sheet metal cutting. Additional exchange tables, automatic loading/unloading systems and pallet towers can increase automation and productivity optimization.

3D applications account for the other 10 to 15% of laser cutting, used primarily  by the automotive industry which utilizes large systems that perform cutting on large parts such as whole car bodies. Because of the large size of 3D laser processing systems and their restricted dynamics, high speed cutting is not available or necessary. Historically, programming these large 3D systems using the teach-in method has been costly because the machine is not productive during the programming time. However, today's new programming software allows for off-line programming of 3D machines directly from CAD files. This new technology opens new opportunities in the 3D cutting market.

Traditional fabrication job shops are currently using laser cutting to fabricate flat sheet metal parts, before the part is formed. In the past, cutting the part after it's formed was complicated due to the expense of the equipment. Also, programming was difficult and required the machine to be off-line. That is the reason 3D or 5/6-axis lasers are used almost exclusively in the automotive industry for prototyping or low volume production.

Today's new laser systems are designed for both flat sheet and three-dimensional cutting, which offer job shops the diversification that can give them a competitive edge. Offering 3D cutting, which is still a niche market and demands a premium, is a good way for job shops to realize greater profits. For example, 3D cutting can simplify a multiple operation job which requires cutting, bending and possibly machining since the bending operation will distort the hole if it was flat cut with a laser. With a 3D laser cutting system, the sheet metal could be bent first and the parts cut out after the forming process. This eliminates the machining and a complicated bending process.

These new 2D/3D systems open new opportunities for laser job shops including: laser cutting of small 3D parts; bevel cutting on 2D sheet metal and 3D parts; efficient 3D trimming of small deep drawn parts; and processing holes and cut outs in hydro formed parts.

Adding an optional rotary axis further expands the system's processing capabilities such as cutting of tubes and profiles and bevel cuts in tubes for better fits.

One example of an application for these hybrid systems is in the automotive industry, which demands highly efficient processing of hydro formed parts. For such applications, high speed cutting is the answer. By adding an increased Z travel, a 3D cutting head and a modern 6-axis CNC with fast processors to a flat sheet high speed, high power laser cutter, high speed 3D laser cutting becomes a reality.

Another interesting application for the 3D head in flat sheet metal is bevel cutting. Especially thick sheet metal parts need to be bevel cut to prepare them for welding. With conventional laser cutting, this represents a complicated, time consuming process. With 3D cutting, this bevel is realized during the initial profiling process, which eliminates an entire process step thus reducing time and cost. 

Bevel cutting is normally started with vertical piercing. The laser head is subsequently tilted in order to realize the necessary bevel angle. The tilt beam also allows  for production of more complex parts, such as slanted teeth for a helical gear or simple beveled holes for countersunk screws. An optional rotary axis will further increase the system's versatility.

Besides the automotive industry, which is a major user of 3D laser cutting, other  markets that tilt beam technology lends itself to include agricultural, construction equipment, military and lightning (spin form parts).

This article was written by Thomas Burdell, vice president, sales and marketing and Pieter Schwarzenbach, vice president, laser technology, both with Prima Laser Tools.

prima-na.com