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# inverse time

Solution Partner Pioneer

Does someone know when we use INVERSE TIME (G93)? In only 5 axes continues motions?

8 REPLIES 8

# Re: inverse time

Legend

yes, when you have rotary axis involved in cutting to calculate 'rotary' feedrate from you given linear feedrate.

# Re: inverse time

Solution Partner Pioneer
The inverse time it works for RTCP or not.

# Re: inverse time

Legend
Could you please explain what RTCP means to avoid any wrong assumptions from my side?

# Re: inverse time

Phenom

(Rotary Tool Center Point)

I bookmarked this article a few years back. It explains fairly well. Article is for (G43.5 vector programming), instead of the (G43.4 rotary value programming), but still gives a good explanation of (Rotary Tool Center Point).

You are basically programming relative to the part, the machine will calculate the proper feedrates, regardless of where the part is on the table.

Imagine you had two identical programs, part and machines, but one setup had a distance further from center of rotation. The setup that is further from "center of rotation" would require the linear axes to move further due to the larger swing, and would have an actual different (faster) feedrate. The speed of tool relative to parts would still be identical on both setups though.

Glenn Balon
Production: NX 12.0.2 MP10 Primarily CAM

# Re: inverse time

Siemens Phenom

In principle the Inverse Time feedrate can also be used when not using RTCP. It simply tells how long the controller should take to move to the end position of that line, regardles of the mode you are in.

This is higly dependent on the controller you are using.

Regards,

Gerrit Koelewijn

# Re: inverse time

Phenom
You can use inverse time with RTCP, but you should not have to if machine is configured correctly. Feedrates should work as programmed without inverse time when using RTCP.

Glenn Balon
Production: NX 12.0.2 MP10 Primarily CAM

# Re: inverse time

Siemens Phenom

@TechniCsNC

Remember that when there is not a linear motion in your NC block, so only a rotary motion, you have to define your  feedrate either in:

• Degrees/Min
• Inverse Time
Regards,

Gerrit Koelewijn

# Re: inverse time

Phenom

@GerritKoelewijn

Correct, the post outputs Degrees/Min (DPM) on a rotary only move. Fortunately DPM is still the same no matter how far you are from center of rotation. It's the linears that end up having to do the feedrate compensating.

Glenn Balon
Production: NX 12.0.2 MP10 Primarily CAM