Laser CNC questions...

[ReaderScars]

If I had an alloy or steel hemisphere about 130mm OD, 2mm wall thickness, and I wanted to puncture it with a 5 axis laser, would I be able to have a number of .3mm perforations lasered through it?

I spoke to a laser outfit recently and the guy I spoke to told me that, generally, the laser diameter was determined by the wall thickness of the material.

Can anyone advise please?

[matjk]

Are you trying to make a burst disk or something? There are lots of different lasers for different jobs, some cut, some drill holes, some engrave. you will seldom find an outfit with multiple lasers in the UK. Sounds like you need holes drilling all the way through, or do you need blind holes? I can certainly point you in the right direction but I need more info.
Matt

[Jetblackonetenth]

generally the minimum size hole you can cut in a material is the same diameter as the thickness of the material ie. in a 2mm thick material the minimum hole diameter is 2mm

[ReaderScars]

matjk said:

Are you trying to make a burst disk or something? There are lots of different lasers for different jobs, some cut, some drill holes, some engrave. you will seldom find an outfit with multiple lasers in the UK. Sounds like you need holes drilling all the way through, or do you need blind holes? I can certainly point you in the right direction but I need more info.
Matt

Thanks for responding again, Matt. It's not for any kind of industrial application or anything. These hemispheres definitely need drilling all the way through rather than blind.

I was considering acrylic or stainless - or any other material that could be drilled through at about .3 to .5 mm diameter, but I still can't find a definitive answer to whether that size hole can be lasered through 2mm thick material.

This outfit: http://www.lasercuttingsheetmetal.co.uk/ states on their site:

"The minimum radius for slot corners is 0.75 mm (0.030 in). Unlike blanking, piercing, and forming, the normal design rules regarding minimum wall thicknesses, minimum hole size (as a percent of stock thickness) do not apply. The minimum hole sizes are related to stock thickness and can be as low as 20% of the stock thickness, with a minimum of 0.25 mm (0.010 in) for upto 1.9 mm (0.075 in). Contrast this with normal piercing operations with the recommended hole size 1.2 times the stock thickness.

(my bold)

So I just need to find out, is hole diameter in a 2mm thick material going to be limited to 2mm?

[Andy27]

Hi, do you have to use a laser? If not and you are making the hemisphere from S/S then a 5 axis EDM fast hole driller may suit, they can drill down to 0.3mm and it is none contact so doesn't stress the part. I am not sure who has the capability.

[ReaderScars]

Andy27 said:

Hi, do you have to use a laser? If not and you are making the hemisphere from S/S then a 5 axis EDM fast hole driller may suit, they can drill down to 0.3mm and it is none contact so doesn't stress the part. I am not sure who has the capability.

Thanks for the suggestion Andy - it doesn't have to be laser in all honesty so any options are good to hear. Will look into this for sure.

ps I can see you read more than you post, so thanks for taking the time to help - and by the way, top lurking!

[BGARK]

What is the application and will the back of the part end up being visible?

[ReaderScars]

Two hemispheres will be brought together, so the inside won't be seen. It's just going to be a decorative item, a sphere with a pattern drilled into/through it. It will literally just sit and do nothing.

[justinbaker]

Cut it flat, as a disk, then English wheel it, into the two hemi-halves.

[ReaderScars]

justinbaker said:

Cut it flat, as a disk, then English wheel it, into the two hemi-halves.

Sounds like a common sense approach, but it brings it's own complexities - the pattern across the sphere would need to be artworked in such a way to ensure it made sense once the discs were 'spherised' so to speak.

I'd much rather just find a 5 axis process which could drill .5mm diameter through 2mm stainless - even to the extent of considering buying one of these:

http://www.ebay.co.uk/itm/5-Axis-CNC-3040-Table-Co...

Anyone used/bought one of these or know of anyone who has?