Plastic Comparisons of Delrin, Acrylic, and Lexan

Delrin/Acetal (Polyoxymethylene) vs Acrylic/Lucite/PlexiGlass (polymethyl methacrylate) vs Lexan (Polycarbonate)

I work with Delrin, Acrylic, and Lexan alot and been trying to find strengths and weakness of the three types of plastics. Since plastics are all slightly different depending on it's use and make, I was wondering if the below is a good general assumption of the three:

Hardness
Acrylic > Delrin > Polycarbonate

Density
Delrin > Acrylic > Polycarbonate

Transmittance (Clearity)
Acrylic > Polycarbonate > Delrin

Refraction (Reflection)
Polycarbonate > Acrylic > Delrin

Yellowing (Yellowing Due to UV)
Polycarbonate > Acrylic > Delrin

Chemical Resistance
Delrin > Acrylic > Polycarbonate

Thermal Expansion (Retains Shape as Heated)
Delrin > Polycarbonate > Acrylic

Tensile Strength (Pull until break)
Polycarbonate > Delrin ~ Acrylic

Flex Strength (Bend until break)
Acrylic > Delrin > Polycarbonate

Compression Strength (Crush until break)
Delrin > Polycarbonate > Acrylic

Shear Strength (Tear until break)
Delrin > Polycarbonate > Acrylic

Modulus of Elasticity (Rigidity)
Delrin > Acrylic > Polycarbonate

Coefficient of Friction
Acrylic > Polycarbonate > Delrin

Corrections and additional plastics or comparisons are appreciated.

The comparison factors that are most of interest on this forum are:

1. Laser "friendliness" (toxicity/corrosiveness when heated)
2. Laserability (vector cutting)
3. Laserability (rastering)

The other factors you list may be of interest to the end-user, but any decisions involving them are usually made before they get to us.

Liana,

This type of comparison is probably more suited to forums that specialize in plastics molding, manufacture, etc. Lee hit the main points of interest to most here... unless I'm the designer (and that does sometimes happen as a laserer), those material specs are irrelevant. The person coming to you may ask if you suggest one plastic over another for a particular application, but if I'm the one they go to for help with choosing an appropriate coefficient of friction or tensile strength, they need to hire a designer first, not me.

Well , you can really only compare lexan and acrylic , deldrin is hardly used in the areas where these 2 are.
In essence lexan or polycarbonate is ONLY used where high impact resistance is required and is not really processable with our lasers so in reality one would almost exclusively use perspex or acrylic.
Apart from laserablity and properties , one has to bear in mind the stock thicknesses , sheet size and cost of the various plastics when considering which one to use.

I wasn't offering this information, I was asking if this information was correct. I was just trying to summarize everything I picked up from the boards and other sources.

I use a laser, and do a lot of engraving and cutting of plastics with it. I'm more of a hobbyist than a professional, and do a lot of projects for others and end up doing a lot of consulting. In my experience I had to find out what plastics does best with what purpose. I just thought other members of this board who worked with these materials a lot could correct me on the list or show some new insights on the usage. No one ever threw a project at you and you had to figure what materials is best suited for it?

For example, I use delrin for cutting gears and engraving stamps for embossing due to it's stiffness and low friction properties. In creating a display case, I use acrylic for it's clarity and etching properties. I use polycarbonate for building containers or cases that requires durability.

Liana,
From my experience the thinner materials 1/16 " and lower
Flex Strength (Bend until break) will be
Delrin > Acrylic > Polycarbonate
real thin delrin does not break unless I bend it back and forth many times.

Kim

Here is some information you might find useful:
http://www.crclarke.co.uk/Support/pdf/thermo.pdf

Quote:

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Originally Posted by Kim Vellore

Liana,
From my experience the thinner materials 1/16 " and lower
Flex Strength (Bend until break) will be
Delrin > Acrylic > Polycarbonate
real thin delrin does not break unless I bend it back and forth many times.

Kim

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Thanks good to know. Been using mostly 1/8" and above so far.

Quote:

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Originally Posted by Doug Griffith

Here is some information you might find useful:
http://www.crclarke.co.uk/Support/pdf/thermo.pdf

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Thanks so much! That's the kind of information that I was looking for. :)

I'm not sure If I read it on this board or not, but I remember someone once posted a general list of colored flames and smoke and smell from the different types of plastics when they were cut or engraved, especially to identify the more hazardous plastics like PVC. Tried a search and came up nothing and was also wondering if anyone remembers this?

Google plastic identification and you'll come up with several charts that show you what tests to run, from burning to dropping in water for a float test.

Liana, that might be the thread you're looking for http://www.sawmillcreek.org/showthread.php?t=114701

Andrea

Some of the mechanical comments are incorrect. My apologies for not editing them. Here are my observations:

Acrylic: Hard, strong, very clear, non-yellowing, great edge quality and easy to cut BUT brittle.

PETG: Strong, clear, not brittle, tricky edges, messy cut, soft surface. Nearly as good a polycarbonate. Takes cold bends.

Polycarbonate:strong, not brittle, less clear, nasty cut, soft surface.

Delrin: hard, slippery, strong, not brittle. Good cut but "melty". Almost like a metal, great for mechanical parts.

Nylon: close to Delrin but a terrible material to cut.