Here is a simple run through of the different stages of laser marking manufactured parts, of how it works, what you see and why we do each stage. What we put in to the computer to start with and the image we get out of the laser on the finished product.
‘In’ and ‘Out.’
1. Putting the design into computer.
Each job needs to be created within the laser job editor.
There are tools within the editor that allow a simple function, like text, to be added, serial numbers sequences to be generated or simple forms such as boxes, circles or lines to be generated.
In some cases the customer will provide artwork that can be imported into the editor and used. Once the job file is created and finished laser parameters are allocated based on material type.
2. Placing the part in the laser machine.
Depending on the part format we would use either a standard jig or customer specific jig for part location.
The jig locates on a datum base plate.
A jig’s primary purpose is to provide repeat-ability, accuracy, and interchangeability in the manufacturing of products. We use the jigs to locate the parts relative to the laser for repeatable positioning. This means we do not have to adjust the job files each time we run the parts for marking. The datum plate is another form of jig. The datum is a fixed point, in this case two sides perpendicular to each other, against which everything else is measured from.
There is also no force applied during the process so no clamping or holding is required.
3. Laser marking the part and what you see.
Once the start button is activated the information in the editor is converted to machine code and sent to the controller that then controls the beam steering mechanics.
These steer the beam across the process area reproducing the information held within the editor.
The beam is invisible so the light you see is the surface materials being vaporised. This is also what makes the noise.
Sometimes you will think you see more than one spot. This is due to the laser being switched on and off very quickly as it scans across the process area.
4. Smoothing the design over.
In most cases images are created by creating vectors and placing them very close to each other. This leaves a scalloped edge to the image, not always visible to the human eye.
In order to smooth this off we would draw the image outline at the end of the process. This is the purple outline you see.
5. The effects on the Material.
When processing anodised aluminium, as shown here, we have to use a reasonable amount of power in order to get through the anodised surface.
This may result in a darkening of the exposed aluminium due to the heat generated by the laser energy.
To clean this up we then provide a second pass that lightens up the surface.