topic Re: How accurate are the times shown in toolpath statistics? in PowerMill Forum

How accurate are the times shown in toolpath statistics?

liam.carr59V7G — Fri, 22 Sep 2017 18:58:44 GMT

Does anyone know how accurate the toolpath statistics time calculations are? I ran a program today that said it would take about 4 hours and it ended up running for at least double that? Am I doing something wrong or is there a setting somewhere I need to change? Any insights would be much appreciated.

Regards

Liam

Re: How accurate are the times shown in toolpath statistics?

iamcdn79 — Fri, 22 Sep 2017 19:16:47 GMT

Powermill doesn't take into consideration the slowdowns when it goes into a corner, that time is based on continuous cutting feedrate which we never get on our machines

I always multiply the actual time by 1 1/2 times to get a more accurate time.

So in your case, if you have a 4 hr prgm I would multiply 4 by 1.5 which would give us a more realistic time of 6 hrs

Re: How accurate are the times shown in toolpath statistics?

TK.421 — Fri, 22 Sep 2017 19:54:53 GMT

I am actually sitting here tweaking my time macro right now. I took the actual time for a few rouging toolpaths, and actual time for a few finishers and I will find a factor for each of them to get a good average and have two separate macros

Re: How accurate are the times shown in toolpath statistics?

Anonymous — Mon, 25 Sep 2017 08:35:57 GMT

I have HAAS VF2 - when PM say 4 hours - it is always be as 4 hr +5 min

(this 5 min added when operator is paused program for check how it work)

3 years im working near HAAS VF2 - it is always say correct time!

im loaded into him NC programs 40 Megabytes - and all is ok

but all speed settings must be 100% of course

also im sometime make programs for Dekkel Maho 50V

it is always say incorrect time - from +30 to +80 % much more time.

So - i think it depends from your CNC controller and machine tool.

Re: How accurate are the times shown in toolpath statistics?

Pijetro — Mon, 25 Sep 2017 11:21:34 GMT

Does anybody know what value Powermill puts in for Rapid moves?

Re: How accurate are the times shown in toolpath statistics?

TK.421 — Mon, 25 Sep 2017 11:37:47 GMT

You are able to find all parameters under help-documentation-reference. There is something in there for rapid moves

Re: How accurate are the times shown in toolpath statistics?

TK.421 — Mon, 25 Sep 2017 12:13:04 GMT

Re: How accurate are the times shown in toolpath statistics?

Pijetro — Mon, 25 Sep 2017 13:29:00 GMT

Thanks...

That's a given..

However, my skim moves are calculated as G1s...I use those when needed, however, I default to Rapid moves, since my post creates G00 moves for them.

My Rapid moves on my mills are only at 750 IN/MIN..If I could somehow tell Powermill that all dotted red lines have a value of 750 IN/MIN, then except for machine dwell, Powermill calculates to within 10% for most of my needs..

Re: How accurate are the times shown in toolpath statistics?

TK.421 — Mon, 25 Sep 2017 13:42:15 GMT

I found it under the reference docs:

Re: How accurate are the times shown in toolpath statistics?

GlennM.MCAM — Tue, 26 Sep 2017 09:58:36 GMT

Same for me. Machining time vs calculated machining time has a lot of difference for me. I guess that tool changes, spindle speed up or slowing down, slowing down in corners, ... are all steps that PM doesn't add to the machining time of the project.

This could easily be solved when we would have a box to fill in the tool change time, spindle speed up time, etc....

Re: How accurate are the times shown in toolpath statistics?

NanchenO — Tue, 26 Sep 2017 14:23:06 GMT

I found on the former Delcam forum some piece of code to generate +/- correct times, which you should run before generating the setup sheet in order to get imes in HH:MM:SS :

FOREACH ent IN folder("NCProgram\Cincinnati") {
            ACTIVATE NCProgram $ent.Name
            ACTIVATE WORKPLANE FROMENTITY NCProgram ;
            ROTATE TRANSFORM TOP
            KEEP SNAPSHOT NCPROGRAM ; CURRENT
            TEXTINFO ACCEPT
            UNDRAW TRANSFORM
			$nombre = $nombre +1
			REAL $Time = 0
			$Time = $Time + $entity('ncprogram',$ent.Name).statistics.LeadsandLinks.Times.plunge
				$Time = $Time + $entity('ncprogram',$ent.Name).statistics.LeadsandLinks.Times.ramp
				$Time = $Time + $entity('ncprogram',$ent.Name).statistics.LeadsandLinks.Times.rapid
				$Time = $Time + $entity('ncprogram',$ent.Name).statistics.LeadsandLinks.Times.others
				$Time = $Time + $entity('ncprogram',$ent.Name).statistics.cuttingmoves.Times.arcs
				$Time = $Time + $entity('ncprogram',$ent.Name).statistics.cuttingmoves.Times.linear
				// Include the correction factor
				$Time = $Time*$CorrectionFactor
				$temps = $temps + $Time
				$Time = 0

If you add a test with the tool number (same or not) at every toolpath, you can add the tool change's duration at every tool change, but it's definetly machine dependent.

I don't see other ways to estimate the accelerations/decelerations than counting the leads and links and applying some correction factors according to the machine and the type of toolpath and the difference between machining feeds and leads/links feeds ...

A lot of work, but the result could be +/- correct at the end...

Olivier