Understanding Laser Focus

When laser cutting, understanding laser focus is critical in ensuring that the maximum amount of available energy produced by the tube reaches the work piece.

If you are “out of focus” then the machine will not cut as effectively, as you are lessening the effect of the beam on the part.

A good way to think of the focal point is to draw an imaginary triangle from the nozzle to the work surface:

Understanding Laser Focus

If the focal point is set too low or too high then the energy density onto the work piece is lessened – this is due to the triangle being intersected at somewhere other than the apex.

Imagine you are trying to put a stake into the ground; if you use a large, blunt stake it takes a massive amount of force to punch through the soil – use a nice sharp point, and it’s easy to push in by hand.

A similar principle can be applied to the focus point, if you are “out of focus”, you are not using the sharp tip of the triangle to punch through the material so it will take more energy and the cut will be nowhere as neat or clean.

This very basic principle is fine for very thin materials, it becomes a bit more complex as you increase the material thickness. Ideally you want the focus point to be in the centre of the material so that you get a nice even cut on the top and bottom of the material, rather than a large taper on the cut face.

We will go into more detail at a later date, however it serves the purpose to illustrate that getting the focal distance correct is important in getting both the best performance from your machine, and the best results in your parts.

There are a number of ways to set up the focal distance on your machine, it can be done manually (this normally involves sticking your head in the machine and using a focusing jig – which can quickly become tiresome) or, you can have the machine do it for you at the touch of a button.

If you plan to cut a range of different material thickness’ or even engraving on the tops of different height items then repeatedly having to reset the focus manually is a pain in the neck – its also pretty time consuming.

The Autofocus system is by no means fool proof, and there is scope for accidents to happen if you do not follow basic machine maintenance rules. But, if you look after the machine and it’s a great tool that will allow you dramatically reduce the set up time between jobs.

So, time to hand you over to our tame superuser, for an in-depth rundown of the best tips and tricks when using your autofocus setting.

As always a big thanks to Russ for all the work put into the production of these tutorials.

If you are unsure about any of the topics covered in our blogs or in these tutorials, please request a call back or, talk to one of our laser marking specialists by going to our contact page – link below.

Contact Us for Laser Engraving, Marking & Cutting Advice (thinklaser.com)

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