Stronger Material Than Acrylic

[Drew Montell]

I am just getting started making stuff on our new laser (Trotec 80W CO2), and have had some success with Acrylic. However, I have noted some of the pieces that I am making are quite brittle simply due to the nature of the material.

Does anyone have suggestions on similar but stronger material that can be cut as easily as the acrylic? The edges being "polished" are nice, but not necessary.

I am well aware that PETG, PolyCarbonate, PVC are not viable options.


Thanks in advance!

[Dave Sheldrake]

How much stronger do you need Drew? in what method? (compression,tension,torsion?)

Cast acrylic tends to shatter but extruded can be a little tougher (so long as you don't hit it with the beam too hard) if you are doing a lot of thin section work them you will probably need to look at some of the specialist plastics but many of those are expensive and not easy to laser cut. Invasive machining always causes stress issues it just depends on what limits you need?

cheers

Dave

[Mark Sipes]

Transparent aluminum? AION

ALON is optically transparent (≥80%) in the near-ultraviolet, visible and near-infrared regions of the electromagnetic spectrum. It is 4 times harder than fused silica (http://en.wikipedia.org/wiki/Fused_silica) glass (http://en.wikipedia.org/wiki/Glass), 85% as hard as sapphire (http://en.wikipedia.org/wiki/Sapphire) and nearly 15% harder than magnesium aluminate spinel (http://en.wikipedia.org/wiki/Spinel). The material is stable up to 1,200 °C (2,190 °F).[1] (http://en.wikipedia.org/wiki/Aluminium_oxynitride#cite_note-r3-1) It can be fabricated to transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques

[Rich Enders]

Drew,

I know nothing of laser engraving, but acrylic in the rest of the world is not what one would normally class as brittle. Cast (thermoset), and extruded (thermoplastic) acrylic both are used in outdoor signage that has to withstand hail etc. Perhaps there is something in the laser cutting process that affects the chemistry, or the notches created during cutting. Something as simple as avoiding notches by rounding all intersections may solve the problem.

You also mentioned PETG, PC, and PVC not being viable. Can you say why? I have seen threads where others are using PVC with proper ventilation.

If you can answer Dave's question regarding strength and your other requirements (clarity?) there should be an answer.

[Bert Kemp]

Transparent aluminum? AION


Didn't Scotty invent this?

[Bert Kemp]

Drew,

I know nothing of laser engraving, but acrylic in the rest of the world is not what one would normally class as brittle. Cast (thermoset), and extruded (thermoplastic) acrylic both are used in outdoor signage that has to withstand hail etc. Perhaps there is something in the laser cutting process that affects the chemistry, or the notches created during cutting. Something as simple as avoiding notches by rounding all intersections may solve the problem.

You also mentioned PETG, PC, and PVC not being viable. Can you say why? I have seen threads where others are using PVC with proper ventilation.

If you can answer Dave's question regarding strength and your other requirements (clarity?) there should be an answer.
Cutting PVC with a laser really isn't an option because the fumes it releases causes damage to the laser.

[Rodne Gold]

You get various grades of acrylic - ask your supplier for a High impact version , you can gut thin sheet with thin sections and it wont snap or break. Normally called something like UHI acrylic (Ultra High impact)
http://control.visionscape.com.au/SiteFiles/specialisedwholesalecomau/pdfs/3863_Acrylic%20Technical%20Data%20and%20Informatio n%20Sheet.pdf
http://www.maizey.co.za/signage-materials/sheet-materials/rigid-media-other/item/256-high-impact-acrylic-sheet-uhi.html

[Rich Harman]

The extruded acrylic that I have cut is very brittle, you bend it a little and it snaps. I am quite surprised to see Dave say that extruded is tougher than cast. I have had extruded shatter but not cast. The cast acrylic on the other hand is much, much less brittle. As I have learned from a customer that build aquariums, there are many different grades of acrylic, they use a particular type for the parts that must bond well enough to hold saltwater in someone's living room. I don't know exactly what flavor it is (they supply it) but it is very tough. For example, a 1/4" thick strip can be bent almost 180 degrees into a "U" before it breaks.

There is also a high impact acrylic that is almost like polycarbonate, it cuts well but leaves a sticky edge.

I'm out of town now so I can't go look and see exactly what types of acrylic these are.

ABS cuts fairly well and is pretty tough.

Delrin cuts okay, bad fumes and expensive but very strong - pretty much impossible to glue.

[Drew Montell]

As far as "stronger," I cannot specify exactlywhat i am looking for, because i don't have a specific application at this time. I make a lot of jigs, prototype parts, inlays, etc... and I want to use the Laser as much as possible due to it's ease and speed. Therefore, for future use, i was hoping to source some other materials besides the acrylic.

I recently made a jig that is approximately .25" x 6" x 8" that looks like a picture frame. It was bumped off of a 3' table, and cracked in half wen it hit the ground. I made another piece in minutes (becuase the laser was setup), but if the jig I make cannot withstand accidental small falls/bumps like this, I may resort back to machining polycarbonate.

Rodne: The UHI acrylic seems interesting....I'll look into that!

Rich: As for the other materials I listed, I have tried some, and know not to use the others due to the harmfull gasses (to user and laser), as well as the fact they are just too tough to laser at thickness or at all due to melting.

Thank you all for your input!

[Glen Monaghan]

Depends on how long you need the fixture to last/how durable you want it, and what you have available. An old corrugated cardboard box can be cut up to make quickie fixtures for short term. I usually use 1/8" birch ply for long-term fixtures. Most of what I've done uses a single layer, but a couple of fixtures are made from two identical layers glued together. When I needed an even thicker fixture to hold and position some knife sheaths, I built it up from 4 layers of 1/8" ply because I wouldn't have been able to easily cut something 1/2" thick on my lasers and, by building it up, I was able to modify the cuts in each layer to account for the belt loop and thickness taper in the sheath to level the top surface for engraving.

[vic casware]

I recently made a jig that is approximately .25" x 6" x 8" that looks like a picture frame. It was bumped off of a 3' table, and cracked in half wen it hit the ground. I made another piece in minutes (becuase the laser was setup), but if the jig I make cannot withstand accidental small falls/bumps like this, I may resort back to machining polycarbonate.

I know what you mean, before i got my laser i cur my acrylic on either the router or the rotary engraver and of course a cutter gives a radius cut corner, now i use the laser and with it's sharp corners the acrylic snaps just as you look at it so i now add a small radius to all my inside corners and no more breakages

[Chuck Stone]

I don't understand .. I've been using .220" extruded acrylic for ages, and it doesn't
snap even when it's cut most of the way through. It never cracks or shatters.. (and I've
thrown a few pieces at the brick wall) I've got a 3' x 2' x 2' box that I throw the scraps
in and after two years, no broken pieces in there. Cut, yes. Broken, no.

[Kevin C. Johnson]

thank you all for the advice, not sure what I'm going to do. But gives me good food for thought. Have thought about just having them outsourced and have him blind shipped.

Thanks again

[Jim Dawson]

cast acrylic > extruded acrylic

[Mike S White]

have you tryed Delrin

[Drew Montell]

I have been told that Delrin is also a difficult one to laser due to density (and perhaps toxins). However, I have not tried lasering yet.

[Doug Griffith]

I cut Delrin all the time and it cuts great. Working with it is similar to teflon except that it can be laser cut. Delrin is the trade name for acetal.

[Kev Williams]

Last month I laser engraved a bunch of Delrin microphone housings, I was surprised how well they turned out. As for cutting, I had to experiment...

This is a one cut pass, full power, one step from my lowest possible speed, NO air assist, piece of 3/8" diameter black Delrin-

http://www.engraver1.com/erase2/burn.JPG


The result-- this is the beginning side of the cut--

http://www.engraver1.com/erase2/leading.JPG


this is the trailing edge

http://www.engraver1.com/erase2/trailing.JPG


This is 3 passes at "2" speed, again no air (I had a hole drilled in one end)

http://www.engraver1.com/erase2/noair.JPG


This is WITH air, and quite a bit I might add...

http://www.engraver1.com/erase2/withair.JPG


=====================

The air definitely helped! I would think cutting smaller thicknesses of this stuff should work out well.

[Dave Sheldrake]

http://ensinger-inc.com/downloads/support/msds/DuPont%20Delrin%20150%20NC010%20MSDS.pdf

if you don't mind Formaldehyde it's fine. I tend to value my lungs though ;)

cheers

Dave

[David Somers]

Dave?

Lungs stored in a gallon or two of Formaldehyde last a reallllllllly long time! What's your point?

<silly grin.....been a really long day>

Dave