Special Laser cut Help

[fever16]

Hello all,
Iam not very good with the laser tech.just have idea of lasers and what they are capable of.
i have a requirement,where i need to cut a special sticker material which is of 2 layers.the laser shld cut only the top layer(green layer).this process has to be very accurate.so iam not sure whether such operation is possible with laser or not.

need some desperate help here.
Regards.

 

[rog8811]

What colour is the backing sheet?

I ask as it may effect the laser that you use, different wavelengths have different charecteristics with different colours.

Regards rog8811

 

[Deleted member 8382]

You are almost not giving any info at all?

What materials are those layers? what are you tring to do? How many cash can you spend on this?

 

[HIMNL9]

machines that already cut custom-shaped stickers with CO2 laser already exists, but they are usually based on a combination of speed and power, for cut the sticker layer and not the paper support layer ..... as far as i know, there is no working units that do this basing on colors.

Just as principle, you can try to obtain this with a resonant unit, focused at levels involving microns, using a wavelenght that is the same identical one of the maximum absorption line of the layer that you are trying to cut (as example, red for the greem color layer), but also you need that the other layer be the complementar color, with the maximum reflection at the same wavelenght ..... and this is just an idea, cause there are a lot of things that can go wrong.

Other than this, you need a power high enough to work for ablation, instead than for burning ..... said in poor words, the beam must be able to "vaporize", literally, the material of the first layer, in times so short that no thermal can be transferred to the second layer, deforming or changing it ..... i see all that as a very hard challenge, imho

 

[fever16]

thans for the responses.
the top layer is RED film and the button is just regular transparent plastic sheet.
this is some thing like vinyl cutting.but here the depth of cut accuracy is high.

if this process is possible,then iam planning to build a small X-Y table using servos.to achieve good IPM's.
and isn't possible in lasers to control the depth of cut precisely.

 

[Benm]

You might be able to whip something up, using red laser diodes. The transparant backing is a big help here, since the lower layer will hardly be affected. If you get the focus close to the laser module, you can 'aim' it within the upper layer too.

That said, it will take a lot of thinkering. If you're doing it on a budget, finding the optima for focal distance, power and scan speed will be largely experimental. At these power levels the best you can expect is melting the upper layer to the point it breaks easily - to actually ablate it much larger power levels combined with high speed motion are needed.

 

[fever16]

ok i will git it a try.
how many mW you think i need here.
and as this is budget project,can u suggest some economical laser modules.

 

[millirad]

Shortest wavelength is the best. It is "easier", not easy at all really, to focus at the smallest spot, the shortest wavelength I.E. ultraviolet/blu-ray. Good luck!