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Author Topic: pecking to machine plastic and rubber  (Read 1787 times)

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pecking to machine plastic and rubber
« on: February 27, 2017, 10:59:51 AM »
Hello Chaps
I machine a lot of plastics and polyurethane. As you know the swarf control is a problem.

It is nessessary to turn at high speed (1200 rpm plus) to get the swarf to fly away from the tip
and I find that a hefty cut also helps to keep the swarf moving.

I have a strong vacuum positioned near the cutting tip but sometimes (in fact quite often)
the swarf wraps around the workpiece and this is a BU

Could the pecking cycles under the canned cycle section be used to momentarily stop the
cutting tip so that the swarf is "broken" into short lengths making it easier to control?

Or what about some other ideas??

Hope you can help
think of the trees-- use both sides of the computer paper

Offline Davek0974

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Re: pecking to machine plastic and rubber
« Reply #1 on: February 27, 2017, 02:11:59 PM »
A "chip-breaking" peck cycle should help break the stringers up, may be called chip-break, partial-retract pecking etc.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: pecking to machine plastic and rubber
« Reply #2 on: February 28, 2017, 02:58:37 AM »
thanks dave- could you suggest an example??

fred
think of the trees-- use both sides of the computer paper

Offline Davek0974

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Re: pecking to machine plastic and rubber
« Reply #3 on: February 28, 2017, 03:08:19 AM »
I just choose chip-break drill cycle in my CAM application, what software do you use?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: pecking to machine plastic and rubber
« Reply #4 on: February 28, 2017, 03:32:32 AM »
I am using mach3
think of the trees-- use both sides of the computer paper

Offline Davek0974

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Re: pecking to machine plastic and rubber
« Reply #5 on: February 28, 2017, 05:40:59 AM »
But where does your G-code come from - could be an application like SheetCam, Aspire, Fusion360 or are you manually writing your code?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: pecking to machine plastic and rubber
« Reply #6 on: February 28, 2017, 06:05:15 AM »
sorry - yes I am manually writing the code
think of the trees-- use both sides of the computer paper

Offline Davek0974

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Re: pecking to machine plastic and rubber
« Reply #7 on: February 28, 2017, 06:24:22 AM »
Ok, pecking is simple - here is a chunk of my code from Vectric, it drills a hole at X0 Y0 to 4.5mm deep with a rapid retract to +0.5mm each peck.

Code: [Select]
N100 G00 G21 G17 G90 G40 G49 G80
N110 G71 G91.1
N120 T2 M06
N130 (T2 - 5mm Carbide YG)
N140 G00 G43 Z20.000 H2
N150 G00 Z20.000
N160 S12500 M03
N170 M07
N180 (Toolpath:- Drill 1)
N190 ()
N200 G94
N210 F550.0
N220 G00 X0 Y0 Z20.000
N230 G00 X0 Y0 Z2.000
N240 G01 X0 Y0 Z-1.500 F300.0
N250 G00 X0 Y0 Z0.500
N260 G01 X0 Y0 Z-3.000 F300.0
N270 G00 X0 Y0 Z0.500
N280 G01 X0 Y0 Z-4.500 F300.0
N290 G00 X0 Y0 Z20.000
N300 G53 G0 Z0.000
N310 M05
N320 M09
N330 G54
N340 M30

Obviously you need to feed in your speeds and feeds.

This code is more of a deep-hole full-retract type drilling, for a simple chip-breaker, modify the retract lines to just pull the Z back up maybe 0.5mm from the last cut depth, this maybe enough to break the stringers, may need a little more retract.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: pecking to machine plastic and rubber
« Reply #8 on: February 28, 2017, 07:15:47 AM »
this is really good of you thanks verymuch
I will try it tonite when i get home
Obviously for drilling the motion will be directly along the Z axis
What about making and angled cut ( eg g01 x0z0 then g01 x2z2)
will it peck back at the angle--?
regards fred
think of the trees-- use both sides of the computer paper

Offline Davek0974

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Re: pecking to machine plastic and rubber
« Reply #9 on: February 28, 2017, 08:08:57 AM »
That would snap the drill ??

Theres no secret, the code is basic in-out, in-out in whatever axis you like, it just goes a little further each time- pecking away at the material.

For deep holes you might want the full retract, especially in sticky muck like aluminium so the drill flutes have time to clear, then you dive back in and drill some more and then retract again to clear.

I think for your plastics, a simple short retract might work so...

G1 Z-1.5 - in to 1.5mm
G0 Z-1.0 - back 0.5mm
G1 Z-3.0 - in to 3mm
G0 Z-2.5 - back 0.5mm
G1 Z-4.5 - in to 4.5mm
G0 Z-4.0 - back 0.5mm

Clearly as the hole gets deeper it gets slower if using a full retract but the short version only goes back a little way so is faster.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives