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Anonymous Poster #1

How to Calculate Exact CNC Turning Time From Drawing

01/19/2016 3:25 AM

Dear All,

I need some help in calculating cnc turning time from drawing ,we have engineering standard in which we have used mean dia for all calculations with rpm constant, while cnc machine works on fix Vc(cutting speed) & variable rpm & feed to improve tool life & tool wera & quality of job.Is there Any method to calculate cycle time just like cnc machine works?with constant vc(cutting speed) .

Thanks,

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#1

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 3:32 AM

Arithmetic is usually taught in elementary school. Find a local one and sign up.

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#2

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 3:53 AM

Take the time at the beginning of the operation. Take the time at the end of the operation. Simply subtract the earlier time from the later time.

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#13
In reply to #2

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 4:15 PM

Say I start at 4:00PM on Monday and finish at 4:00PM on Tuesday.

4:00PM-4:00PM=0

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#14
In reply to #13

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 5:15 PM

<...The supply of fools will always outstrip the demand.....>

Quite.

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#3

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 4:22 AM

You can make s decent estimate if you know the Vstart , Vend , Vmax , Acceleration , Deceleration and length for each vector of the tool path.

If you are really pressed for performance you can optimize the tool path by re-sequencing the cuts and keep moves time to a minimum.

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#4
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Re: how to calculate exact cnc turniung time from drawing

01/19/2016 5:14 AM

Ooh, that's too hard. It entails arithmetic, as suggested by that meanie in post 1.

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#5
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Re: how to calculate exact cnc turniung time from drawing

01/19/2016 5:20 AM

What <...meanie...>?

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#6

Re: how to calculate exact cnc turniung time from drawing

01/19/2016 6:22 AM

Not so complicated - To do any calculation you need coordinates.

What file format are your tool path / output of your drawing in ? (NCI, NC . . . . )

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#7

Re: How To Calculate Exact CNC Turniung Time From Drawing

01/19/2016 8:47 AM

Get a stop watch and a stool and park your butt by a machine and time some cuts.

You can develop your own formulae, maybe.

Cutting speed has many variables. I'll give you two to start you on the road to knowledge. The rest you can ask a machinist about, if you actually have any machinists on staff.

Ready?

1. Type of material.

2. Cutter diameter.

Of course, a reasonably intelligent person might perform an internet search for help.

Milling Speed and Feed Calculator - CustomPart.Net

Calculation for Cutting Speed, Spindle Speed and Feed ...

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#9
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Re: How To Calculate Exact CNC Turniung Time From Drawing

01/19/2016 11:34 AM

And add tooling to the list of variables. If you're looking at high volume production, you can make custom inserts that have a significant impact to cutting time... well, depending on what you're cutting.

Example, CNC cutting of premium and semi-premium threaded connections on OCTG utilize custom-designed inserts... 1) because of the proprietary profiles, and 2) to reduce cutting time.

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#11
In reply to #9

Re: How To Calculate Exact CNC Turniung Time From Drawing

01/19/2016 1:04 PM

It's going to be one hell of an equation!

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#12
In reply to #9

Re: How To Calculate Exact CNC Turniung Time From Drawing

01/19/2016 1:08 PM

If they're looking for 'Exact" results, my opinion is that this company's (profit) margins are way too tight.

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#17
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Re: How To Calculate Exact CNC Turniung Time From Drawing

01/20/2016 1:04 AM

Indeed. The word "exact" in the post title is a dead giveaway that the person in question does not know such concepts as error bands.

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#19
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Re: How To Calculate Exact CNC Turniung Time From Drawing

01/20/2016 7:13 AM

What's error bands?

ohh,.. and an off topic remark, too..... That's good right?

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#23
In reply to #7

Re: How To Calculate Exact CNC Turniung Time From Drawing

01/30/2016 11:50 PM

pl send me any method for turning from drawing

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#8

Re: How to Calculate Exact CNC Turniung Time From Drawing

01/19/2016 10:44 AM

I'd be surprised if the software that operates the CNC machine couldn't tell you that when you enter the STEP file and the type and size of the raw material along with the specified feed rates for the various tools, RPM, and so on. Or use a stop watch for the first one.

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Anonymous Poster #1
#22
In reply to #8

Re: How to Calculate Exact CNC Turning Time From Drawing

01/30/2016 11:47 PM

Sir,

I am working in engineering ,we are receiving lot of drawing every day for time study,so we have never made job before,to confirm the order marketing ask us for time estimation for quotation.exact or accurate estimation can help organization making profit other wise loss.

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#10

Re: How to Calculate Exact CNC Turning Time From Drawing

01/19/2016 12:57 PM

Experience helps,

actually running the geometry through CAM programming software is better (after the operation variables in the software have been put in)

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#15

Re: How to Calculate Exact CNC Turning Time From Drawing

01/19/2016 7:02 PM

Just show your drawing and time requirement to the experienced machinist who will be making the part.

Once he gets done laughing/slapping you around take his time estimate and a go with that.

When you need a precision part made you have two options.

One you can have it done in a specific time constraint or two you can have it done correctly.

As for who an experienced machinists going to see your drawing and time numbers to him its just a sheet of paper with some suggestions on it.

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#16

Re: How to Calculate Exact CNC Turning Time From Drawing

01/19/2016 10:40 PM

You can take the weight of the finished product and subtract it from the weight of the starting block...then figure the weight of swarf produced per minute by calculating the chip load for the bit and speed you will be using....

"Chip load - The distance a bit moves forward as a single flute cuts into a material. The amount that each flute cuts during a single revolution of a cutting tool. The formula for chip load is CL = (feed rate / no. flutes) / RPM. The TOTAL chip load is defined as the distance a bit moves forward during a single revolution (TCL = feedrate / RPM) and is given in inches (or millimeters) per revolution."

chip load calculator...

http://zero-divide.net/index.php?page=fswizard

The final figure may need some tweaking...

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Anonymous Poster #1
#18
In reply to #16

Re: How to Calculate Exact CNC Turning Time From Drawing

01/20/2016 4:59 AM

Dear Sir,

Thanks for your support,in case of turning & facing is this software can work ?

Thanks

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#21
In reply to #18

Re: How to Calculate Exact CNC Turning Time From Drawing

01/20/2016 8:05 AM

No, not from just a drawing. If you write a program for it, there is software that will estimate the turning time.

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#20

Re: How to Calculate Exact CNC Turning Time From Drawing

01/20/2016 7:51 AM

<Don't feed the trolls>

<Ban Anonymous Posters!>

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