Kerf cut: Cutting technique for bending applications

Cutting Techniques for
Material Flexibility

Adding curves and flexibility to rigid sheet materials using a Trotec laser cutter

By cutting a 'bending cut geometry', otherwise known as a kerf cut, rigid sheet materials including wood and acrylic can be bent. There are many different shapes and geometries that result in differing flexural behaviour. We at Trotec decided to test different materials, including wood and acrylic (3 - 5mm), to see how effective this technique would be. Here, you can find all the appropriate graphic templates ready for downloading.


So, what kinds of cutting techniques are there?

Kerf 1: Straight Cut Lines

Straight cutting lines will form a sturdy, stable radius. The further apart the cuts are, the larger the bending radius will be. Depending on the graphic and material you are using, a distance of up to .5mm between each line can be selected. It’s a good, simple technique.

Kerf 2: Small Waves

These tiny waves are all interconnected and make the material look extremely flexible. The cutting technique is suitable for materials that are 3mm thick or less. The bending radius is very large here, which can be a desirable trait depending on your application.

Kerf 3: Large Honeycombs

When using large honeycombs, the curves are tapered at each end and cut out of the sheet. This is a technique often used in model making. Wooden boards up to 5mm thick can be made very flexible. This is because the honeycombs can be easily pulled apart and pushed back together. These properties can also be combined with connections.

Kerf 4: Wavy Cut Line

As with Kerf 1, this cutting pattern consists exclusively on straight cut lines. However, it does differ in its bending properties quite significantly. It is much more flexible than Kerf 1, so it can be used for a wider range of applications. It’s also a bit sturdier.

Kerf 5: Honeycombed Cut Line

This specifically arranged cutting pattern allows extreme flexibility in all directions, as opposed to just up or down. This can make numerous creative applications possible. For example, you can try your hand at creating some laser cut bags made completely from acrylic or wood. The sky is your only limit!

Kerf 6 & Kerf 7: Narrow / Wide Waves

These two cuts can work with almost any application and are appropriate to use with almost any material. The shape of the individual lines supplies your work with a fair amount of stability and flexibility. You won't have to worry about your completed product breaking or over-stretching because the technique is quite sturdy and safe. Give it a go if you're unsure of which technique is appropriate for your current application.

Kerf 8: Triangular Shape

This is a very effective as well as aesthetically pleasing pattern. It can be bent in all directions and the pattern tends to be used as a graphic element. The triangular shape of this technique is suitable for materials approximately 3mm in thickness or less. From about 5mm and up, the bend will become rigid and inflexible.

Download

Here, you can find the graphics for all the kerf cuts outlined above. Get creative and have some fun with these techniques.

Download the Kerf Cut Graphic Templates

Kerf Cuts & Wood

Wood is generally a great material to use alongside these cutting techniques. However, be mindful of the type of wood you are using. The following distinctions must be observed:

  • Plywood - Plywood is suitable for these kinds of bending applications. By gluing each sheet, the wood becomes very flexible in all directions and can even be bent at a very narrow angle.
  • Solid Wood - When using solid wood boards with a material thickness of 5mm or above, cutting techniques with recesses (Kerf 6) are much more flexible than a straight cutting line pattern (Kerf 1). Here, it is very important to always cut in the direction of the wood grain. If the cut lines run across the grain, flexibility will be reduced drastically, and the wood won't be very sturdy.
  • MDF - Akin to plywood, MDF is very easy to work with. Due to the mixture of grains within the wood, it is not necessary to align the cut lines in a certain direction.

Kerf Cuts & Acrylic

The cutting techniques that are associated with acrylic usually work best with rigid bends. This includes boxes or cases where the bending radius is very rarely changed (see the picture to the right). With a continuous load of the cutting pattern, the webs can easily break. 

When you process acrylic:

  • We suggest using a 2" lens for the bending cuts. Since acrylic melts, the focal length must be carefully considered. If it is too small, it may cause the corresponding area to instantly stick together, thus taking away any intended flexibility and increasing the risk of damage.
  • We also suggest a cutting distance of about 1 - 1.5mm. If the material melts, despite the correct lens being used, you simply need to increase the distance between each of the individual lines. However, don't make the new distance too large! Otherwise the flexibility of the bend will, inevitably, decrease.

Important Points for Your Desired Result:

Conclusively, the following points must be observed when creating a design:

  1. Material properties
  2. Direction of the grain
  3. Distances of the cuts
  4. Material thickness

Need More Information?

If you need any extra help regarding material processing or laser applications, please feel free to contact us at any time. Our laser experts will be happy to assist you. Additionally, ask us about our Trotec Academy courses. They offer training in many laser technology topics. We would be happy to arrange a training appointment with you.

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