Best Practices: Designing for Laser Cutting

Computer Numerical Control laser cutting is a versatile tool capable of creating intricate designs and features in various materials.

As with any process, understanding the nuances of CNC laser cutting can significantly impact the design and final result. This article presents valuable design tips for laser-cut parts, aiming to enhance your knowledge and improve the outcome of your laser cutting projects.

Overview of CNC Laser Cutting

CNC laser cutting is a subtractive manufacturing technology that utilizes a high-power laser beam to cut flat-sheet materials.

The process begins by designing a digital program in a CAD/CAM system that directs the laser cutter. This design file, typically a DXF or DWG file, outlines the desired shapes and dimensions of the parts to. The laser cutter, guided by the CNC system, then uses a concentrated beam of light to melt, burn, or vaporize the material along the programmed path.

The result is a clean, smooth, and accurate cut that can accommodate complex shapes and small holes, all with minimal waste.

Laser Cutting Design Tips

1. Use the thinnest sheet possible. On average, material cost represents 37% of the cost of sheet laser cut parts. This percentage is larger for simple geometries. Calculating the minimum thickness that can withhold the load saves you money.

2. The flatness of the sheets partly depends on the raw material. Your part will require a rework if the flatness is more than 0.1mm (per meter).

3. Brushing will be more cost-efficient than chamfering. Chamfering requires handwork or a complex setup on the machine. For that reason, brushing is the best post-processing method for deburring.

4. Avoid sharp internal corners. Add a hole at the corner of each sharp angle. It allows the stress to be distributed across the hole instead of at one edge point.

5. Expect distortions at bent parts. The distortion will be more visible in thick sheets. 

6. Keep a distance between the hole and the bending edge. The minimum distance from the edge of a hole to the adjacent edge of the blank should be at least stock thickness, but preferably it should be 1/2 to 2 times that.

7. Avoid some distortion by designing a window. Add a nonfunctional window at the bent corner if the distance from the hole to the edge is lower than recommended.

8. Expect misalignment before bending. Several alternatives can be considered:

• Drill the holes after forming. This is more expensive but provides excellent alignment.
• Use broad tolerances on the holes, or make one a slot, i.e., allow for misalignment if the function of the part permits.
• Include a pilot hole in the bottom of the U bend. This hole is located over a pin in the pad of the forming die that will consistently position the blank.

The thickness of the control stock is another requirement if your part needs close alignment. Although the material of close thickness tolerance commands a premium price, the extra cost may be more than offset by the savings realized by not having to perform the second operation.

9. Check the adequate number of threads for even minimum tightening ability. A rule of thumb for the minor thread diameter (tap-drill size) is that it not exceed twice the stock thickness for steel and brass and 1.5 times the stock thickness for aluminum, copper, and zinc.

10. Brush on both sides if parts are not bent. The bending tool marks affect your surface quality, and the surface can be brushed with lower quality and higher cost by hand.

11. Avoid tool marks. Define foiled sheets at your visual sides; the foil protects your part during machining and transport.

12. Define visual sides and no visual defects at the important surfaces. A perfect surface is not expected when not defined. Also it should be defined if no chips are allowed inside your laser cutted tubes.

13. Provide DXF files to save setup time. DXF files with your cut geometry to save time and prevent mistakes.

14. Keep the interior bend radii at least as large as the material thickness. To avoid distortion around the bend, parts should be designed with the interior bend radius to be the same size or greater than the material thickness.

15. Ensure the bend height is at least double the material thickness plus the bend radius. Small bend heights are more difficult to form and position in the press brake, which can result in deformation.

16. Use standard sheet thickness. For flat laser cutted parts, use the range between 1-10 mm. If the parts are bended, use 1-6 mm. Check in online shops if your raw material exists.

17. Avoid tiny cutting geometries. The minimum distance inside the geometry should be greater than the sheet thickness to minimize distortion caused by the beam.

18. Leave some space between the cutting geometry. Space the cutting geometry at least two times the sheet thickness to avoid distortion.

19. Avoid the distortions at the edge. If holes are placed too close to the edge, the possibility of the hole tearing or deforming is higher, especially if the part later undergoes forming.

20. Use the same radii with consistent bend orientations to reduce costs. Inconsistent bend orientations and varying bend radii mean the part will be need to be reoriented more often, which requires more time from the machinistoperator.

21. If using a bending tool, be sure to leave enough room so it can access the corners. The tool needs to come 90° from the bending corner.

Get Started with CNC Laser Cutting

CNC laser cutting is a powerful and versatile manufacturing method that, when utilized effectively, can yield high-precision components and minimize production costs. It is, however, essential to understand the process intricacies, from the impact of material thickness on cost to the importance of the bend radius on part distortion.

If you’re looking for design assistance – or need a high-quality CNC machining service, you can use the MakerVerse platform. Choose from a full range of materials and finishes for all your applications.