Machining Lexan

[plh]

I would like to here from anyone who has experience machining Lexan. Other than
leaving the paper cover on, what else can you suggest? This operation involves
milling and drilling, but nothing too fancy. In one station I will be using a 60
degree included angle "Wolverine" HSS tapered end mill. They have spiral as
opposed to straight flutes. There is also a .25 radius corner rounding operation
needed.
For end milling generally, carbide or HSS? There is also a need to drill .25
through the .50 thickness.
Coolant or no? Would coolant strip or degrade the paper covering?
Thank You,
-plh

[yourname]

I use HSS, but carbide may give you a better finish longer if the run is
long.
Lexan doesn't melt like plexi, but it is gooey and will move away and
into the tool. If you take a big rough cut it can pull a chunk right out
of the surface of the part, making it look like someone went at your
poart with an icepick. I run full flood , and you can save the paper
depending on the operation if you dry it off right afterward

Drilling will melt it if the drill is dull, so get in and out of the
hole fast.
Like all plastics, sharp tools, sharp tools, sharp tools.


rreminds me years ago trying to drill a 5/16 hole 3 inches deep in a 1/2
dia hdpe rod on my old monarch gear head. coudln't get out fast enough
to not melt it. got pissed off and was heavng the [150 lb] tailstock
into position and it slid on right into the part, and all the way
through. perfect hole. boy did I laugh

Post by plh
I would like to here from anyone who has experience machining Lexan. Other than
leaving the paper cover on, what else can you suggest? This operation involves
milling and drilling, but nothing too fancy. In one station I will be using a 60
degree included angle "Wolverine" HSS tapered end mill. They have spiral as
opposed to straight flutes. There is also a .25 radius corner rounding operation
needed.
For end milling generally, carbide or HSS? There is also a need to drill .25
through the .50 thickness.
Coolant or no? Would coolant strip or degrade the paper covering?
Thank You,
-plh

[Gary H. Lucas]

I've drilled hundreds of holes in Nylatron rods about 4 inches deep that way
on the old South Bend lathe.

Gary H. Lucas

[hamei]

Post by yourname
rreminds me years ago trying to drill a 5/16 hole 3 inches deep in a 1/2
dia hdpe rod on my old monarch gear head. coudln't get out fast enough
to not melt it. got pissed off and was heavng the [150 lb] tailstock
into position and it slid on right into the part, and all the way
through. perfect hole. boy did I laugh

Yeah, but if you do that all day long you'll go home one
tired-ass son of a bitch !

[Jan Nielsen]

Post by hamei

Post by yourname
rreminds me years ago trying to drill a 5/16 hole 3 inches deep in a 1/2
dia hdpe rod on my old monarch gear head. coudln't get out fast enough
to not melt it. got pissed off and was heavng the [150 lb] tailstock
into position and it slid on right into the part, and all the way
through. perfect hole. boy did I laugh

Yeah, but if you do that all day long you'll go home one
tired-ass son of a bitch !

Put the cart (tailstock) in front of the horse, and let the lathe do the
pushing.

[yourname]

well, back then I didn't need to go to the gym...

Post by hamei

Post by yourname
rreminds me years ago trying to drill a 5/16 hole 3 inches deep in a
1/2 dia hdpe rod on my old monarch gear head. coudln't get out fast
enough to not melt it. got pissed off and was heavng the [150 lb]
tailstock into position and it slid on right into the part, and all
the way through. perfect hole. boy did I laugh

Yeah, but if you do that all day long you'll go home one
tired-ass son of a bitch !

[Joe Osborn]

Lexan (Polycarbonate) is pretty easy to machine. It doesn't melt too easily
(like polypro) and doesn't chip too easily (like acrylic). Use sharp tools, HSS
or carbide. Pretty high chip load, mid range speeds, sharp tools. You should
have no problem. I would use coolant.

Joe

Joe Osborn

OMW Corporation
"Custom Precision Machining
in all Metals and Plastics"
21 Pamaron Way, Ste. G.
Novato, CA 94949
WWW.OMWMETAL.COM
EMail: ***@AOL.COM
An ISO 9000 Registered Company

[plh]

Thank you for replying. Also, thank you "yourname".
Are there any speed and feed references available for Lexan? I was unable to
find any on line. (How many SFM is "mid-range"? What's a "pretty high chip load"
in Inches Per Tooth?)
Thanks,
-plh

Post by Joe Osborn
Lexan (Polycarbonate) is pretty easy to machine. It doesn't melt too easily
(like polypro) and doesn't chip too easily (like acrylic). Use sharp tools, HSS
or carbide. Pretty high chip load, mid range speeds, sharp tools. You should
have no problem. I would use coolant.
Joe
Joe Osborn
OMW Corporation
"Custom Precision Machining
in all Metals and Plastics"
21 Pamaron Way, Ste. G.
Novato, CA 94949
WWW.OMWMETAL.COM
An ISO 9000 Registered Company

[yourname]

err hell who the heck knows. start like aluminum and start winding the
feed up . very part dependant you may need to lower chip load to stop
deflection or raise it to lessen heat.

Post by plh
Thank you for replying. Also, thank you "yourname".
Are there any speed and feed references available for Lexan? I was unable to
find any on line. (How many SFM is "mid-range"? What's a "pretty high chip load"
in Inches Per Tooth?)
Thanks,
-plh

Post by Joe Osborn
Lexan (Polycarbonate) is pretty easy to machine. It doesn't melt too easily
(like polypro) and doesn't chip too easily (like acrylic). Use sharp tools, HSS
or carbide. Pretty high chip load, mid range speeds, sharp tools. You should
have no problem. I would use coolant.
Joe
Joe Osborn
OMW Corporation
"Custom Precision Machining
in all Metals and Plastics"
21 Pamaron Way, Ste. G.
Novato, CA 94949
WWW.OMWMETAL.COM
An ISO 9000 Registered Company

[Sam Hytovick]

I agree fully with both previous poster, but add the following.

- if you are having chipping or cracking problems with the drill, get one with
a 60 degree drill point. Most industrial suppliers don't have these, but your
plastics supplier may be able to get them for you, I get mine from Piedmont
Plastics.

- We use water soluble vegetable oil based coolant, and have never had any
issues. I'm not sure of the effects a petroleum based coolant.

- Razor sharp cutting edges are definely a plus. Polished flutes help
tremendously with chip evacuation.

Sam

[d***@lakefield.net]

Lexan.... PolyCarb... Acrylic !!! Oh boy, here we go !<G>

I at one time cut a lot of Acrylic for Vacuum jigs. The ultimate
cutters we found were single flute cutters, but specifically those
sharpened for acrylic along the lines of Signmakers bits. After all,
Sign Guys cut a LOT of Acrylic. Very clean without coolant, almost
clear edges with coolant.

A great place to dig around is http://www.antaresinc.net/
They have D-blank tooling and engraving bits. Try one, you'll like it.

There are some fact sheets on that site that are useful for cutting any
plastic....
"Crown" is another company with this type of cutter.

Chris L

[Cliff]

Post by d***@lakefield.net
Lexan.... PolyCarb... Acrylic !!! Oh boy, here we go !<G>

<G>

Post by d***@lakefield.net
After all, Sign Guys cut a LOT of Acrylic.

Where's Ricky & Michael or poor jb?

[Peter Renolds]

I've done a lot of machining 6mm thick Lexan sheet and fixturing is
important to hold it from moving/flexing etc. I also had great success
with zero helix carbide tools ranging from .25" down to 1/16" from
Mcmaster Carr e.g. P/N 8881A17 My problem was the material lifting due
to the the spriral helix of conventional tooling and the parts always
being undersized. Some areas of my parts have to be reduced to 1mm
thick. These tools solved that problem - but I still had some trouble
with deburring. Using KoolMist #77 mist cooling reduced the deburring
time by about 75%. Also, I change the tools early to keep the edges
sharp - that also helps.

The other big thing I found was that I got way better results with
genuine GE brand Lexan than some of the other brands of polycarbonate
http://www.matweb.com/reference/polycarbonatemfr.asp I tried? I found
Hyzod (not in the list) to be quite problematic and gummy. Yuck!

Interestingly, my GE Lexan sheet comes with plastic covering that I have
to remove - else it gets in the way.

Cheers, Peter