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Laser tube cutting is a process in which a laser beam is focused on the outside surface of a metal tube to perform a cutting operation. The tube is fed in various patterns beneath the focused laser beam, where the tube wall is melted through. In medical applications with smaller tube diameters, the laser’s beam width is approximately .10 mm (.004”). Our machines are equipped with fiber lasers.

 

 

 

 

Close-up of Laser Tube Cutting Process

 

In the case of most laser machines, the laser is stationary and aimed directly toward the center of the tube. The tube that is being cut is fed through a stationary guide bushing—a “slip-fit” mechanism which stabilizes the tube while keeping it aligned and at a proper distance under the focused laser beam.  Behind the guide bushing, the tube is held firmly by a programmable 360-degree indexing collet. This device can rotate the tube and has the ability to simultaneously push and pull the tube axially through the guide bushing. The CNC controller delivers the programmed instructions to these mechanisms, which cuts out the desired shapes and configurations from the tube.

 

 

 

Additional Details of Laser Tube Cutting Process

 

 

 

 

Photo of finished “laser cut” part from above examples

2 + 2 Axis Laser Cutting

Marshall’s laser tube cutting machines offer 2 + 2 axis. Two axis rotate the tube and axially move the tube. The additional two axis can be programmed to move side to side, and up and down. 

 

 

 

 

 

 

2+2 Axis Diagram:  When Y-Axis is utilized and the tube is not rotated, the laser beam cuts an off-center rectangle through the wall of a tube—and a vertical cut is produced on the longitudinal edge of the cut.

 

 

 

 

 

 

3 Axis Diagram: When there isn’t an active Y-Axis and the tube is rotated—and the laser beam is directed towards the center of the part when cutting a rectangle through the wall of a tube—a bevel (trapezoid) is produced on the longitudinal edge of the cut.

This video link (starting at 0:34 seconds to 00:52 seconds) demonstrates the laser tube cutting operation using only three of the four axis available. The laser remains stationary in the video, continually focused at the center of the part. The raw tube length is 3,660 mm (10 feet), and after the cutting process is completed, the finished part is severed from the initial tube. As each part is manufactured, the raw tube becomes shorter, until a new tube is loaded into the machine. The guide bushing is pictured immediately to the right of the laser beam, and the indexing collet system is on the far right of the picture.

In this example, the material diameter is 2 mm in diameter (.78”), and the finished part is approximately 11mm (.433”) in length. The wall thickness of the part is .10 mm (.004”). As you can see from the video, the tube has a multitude of cut features. Lasers can run wet or dry, and in the accompanying video, water is forced through the end of the tube. This prevents slag from building up on the through-cut-edges of the part—as well as eliminating slag on the wall opposite of the cut. 

Minimal “Heat Affected Zone” (HAZ)

The heat affected zone is the area of the tube which doesn’t melt, but is affected by the heat of the laser, which alters the microstructure and mechanical properties of the tube. The heat affected zone is minimal when considering the following:

  1. The very small laser beam-width of .10 mm (.004”)
  2. The thin wall of the medical hypo tube
  3. The feed rate of the material
  4. The forcing of water through the tube. 

Marshall can accommodate tube diameters ranging from .5 mm to 8 mm (.020” to .315”). Maximum wall thickness is approximately .5 mm (.020”) with most materials.

Laser Tube Cutting Services: Providing Repeatability & Accuracy

At Marshall, our laser tube cutting machines can generally hold tolerances of +/- .013 mm (.0005”), at very high repeatability levels. These machines are set up at Marshall to manufacture medium to high volumes with faster cycle times—and lower to medium volumes with slower cycle times. Be sure to connect with us for more insight into our full capabilities for laser tube cutting.