Thursday, August 2, 2018

CNC Programming Examples - Slot Milling

  Thanh A Tran       Thursday, August 2, 2018

Fanuc G71 Turning Cycle

G71 turning cycle is used for rough-material removal from a cnc lathe component. G71 turning cycle makes large diameter cutting easy. Cutting can be done in simple straight line or a complex contour can also be machined very easily.
Through G71 turning cycle parameters cnc machinists can control
  • Depth of cut.
  • Retract height.
  • Finishing allowance in x-axis and z-axis.
  • Cycle cutting-feed, spindle speed.

Programming

G71 U... R...
        G71 P... Q... U... W... F... S...

Parameters

First block
Parameter Description
U Depth of cut.
R Retract height.
Second block
Parameter Description
P Contour start block number.
Q Contour end block number.
U Finishing allowance in x-axis.
W Finishing allowance in z-axis.
F Feedrate during G71 cycle.
S Spindle speed during G71 cycle.


G71 Turning Cycle Overview

  • G71 turning cycle cuts the whole contour repeatedly which is given in P Q blocks.
  • Depth of every cut can be controlled by first-block U value.
  • Second-block U W are the finishing allowances which can be given if you want to make a finish cut with G70 finishing cycle.
  • F is cutting feed and S is spindle speed (given in second-block) which are used during G71 turning cycle.
Note – The F and S given inside P Q block will not be used during G71 turning cycle, they are used with G70 finishing cycle if later called.

G71 Turning Cycle Working

N60 G71 U10 R10
        N70 G71 P80 Q90 U3 W0 F0.25
        N80 G00 X60
        N90 G01 Z-75
When G71 turning cycle is run the whole operation will be done in following sequence,
First-cut
1 – Tool will move in x-axis U (depth of cut) deep with programmed feed from starting-point.
2 – Tool will travel with feed in z-axis (destination point in z-axis is given in P Q blocks )
3 – Tool rapidly retracts R amount in both x-axis and z-axis (at 45 degrees).
4 – Tool rapidly travel in z-axis to start-point
Later-cuts
5 – Tool rapidly moves to last cut depth.
6 – Tool moves with feed in x-axis U deep (first-block U depth of cut).
7 – Tool with feed moves in z-axis (destination point given in P Q blocks).
8 – Tool rapidly retracts in x-axis and z-axis R amount (45 degrees).
9 – Tool rapidly moves to start-point only in z-axis.
This whole sequence of operation keep on going, until the destination point in x-axis is met.
If finishing allowance is given tool will not make the exact diameter and length given in P Q blocks but will leave that much allowance, This finishing allowance can be later machined by calling G70 finishing cycle.

Fanuc G71 Turning Cycle

Fanuc G71 Example

Here is a cnc part-program which shows how G71 turning cycle can be used, this is the program for the drawing given above
N50 G00 X106 Z5 M3 S800
        N60 G71 U10 R10
        N70 G71 P80 Q90 U3 W0 F0.25
        N80 G00 X60
        N90 G01 Z-75
In this program G71 turning cycle will keep repeating the contour given inside P Q blocks shown below
N80 G00 X60
        N90 G01 Z-75
These two cnc program blocks tell us that we want to remove material till X60 deep and in Z-75 in length.
The depth of cut is given in first-block U10 retract amount is also given R10.
Finishing allowance in x-axis is U3 but there is no finishing allowance given in z-axis W0.

G70 Finishing Cycle

If you programmed G71 turning cycle with finishing allowances then that finish allowances can be removed with G70 finishing cycle.
G70 finishing cycle repeats the whole contour the G71 way, but in just one-cut removing the finishing allowances.

Why Use G70 Finishing Cycle

As material can be removed with G71 turning cycle, but if you want a different cutting-feed and spindle speed for the last cut, then it is recommended that you use G70 finishing cycle.
G70 finishing cycle use F and S values which are given inside P Q programmed blocks. (G71 use F S values which are given inside G71 second block.)

Fanuc G70 Example

N50 G00 X106 Z5 M3 S800
        N60 G71 U10 R10
        N70 G71 P80 Q90 U3 W0 F0.25
        N80 G00 X60
        N90 G01 Z-75 F0.15
        N100 G00 X200 Z100
        N110 G92 S1200
        N120 T3 G96 S150 M03
        N130 G00 X106 Z5
        N140 G70 P80 Q90
        N150 G00 X200 Z100
        N160 M30

G70 G71 Example


G71 Rough Turning Cycle Example
O0004
        G00 X200 Z10 M3 S800
        G71 U2 R1 F200
        G71 P80 Q120 U0.5 W0.2
        N80 G00 X40 S1200
        G01 Z-30 F100
        X60 W-30
        W-20
        N120 X100 W-10
        G70 P80 Q120
        M30

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Fanuc G71 G72 G70 Canned Cycle CNC Lathe Internal Machining Example (Boring & Facing )

Fanuc programming example which shows the use of multiple fanuc canned cycle in cnc programming, Following canned cycle are used in this cnc lathe programming example
  • G71 Rough Turning Cycle
  • G72 Facing Cycle
  • G70 Finish Cycle
Contents
  • Fanuc G71 for Boring Opertaion
  • Fanuc Programming Example

Fanuc G71 for Boring Opertaion

This programming example also illustrate how G71 turning cycle can be used for internal machining (boring operation). So if you want to remove extra stock from inside of a component, you can use Fanuc G71 turning cycle for internal stock removal as well.

Fanuc Programming Example


Fanuc Canned Cycle Example
G28 U0 W0
            G50 S1500
            N1 T0101 M8 (OD FACING)
            G96 S180 M3
            G0 X255.0 Z5.0
            G72 W2.0 R0.5
            G72 P100 Q200 F0.25
            N100 G0 Z0 G41
            G1 X-2.0 F0.18
            N200 G0 Z5.0
            G40
            X255.0
            G28 U0 W0
            N2 T0404 M8 (ID ROUGH)
            G96 S180 M3
            G0 X50.0 Z5.0
            G71 U2.0 R0.5
            G71 P500 Q600 U-0.5 W0.1 F0.25
            N500 G0 X202.0 G41
            G1 Z0 F0.12
            X200.0
            Z-10.0
            X100.0
            Z-30.0
            X60.0
            Z-45.0
            N600 X50.0
            G40
            G0 Z5.0
            G28 U0 W0
            N3 T0505 M8 (ID FINISH)
            G96 S220 M3
            G0 X50.0 Z5.0
            G70 P500 Q600
            G0 X50.0 Z5.0
            G28 U0 W0
            M5 M9
            M30
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Fanuc G73 Pattern Repeating Cycle CNC Program Example Code

CNC programming example for Fanuc G73 pattern repeating cycle.
Fanuc G73 Pattern Repeating Cycle has already been described here
CNC Fanuc G73 Pattern Repeating Cycle
You might like other Fanuc G73 pattern repeating cycle examples
CNC Fanuc G73 Pattern Repeating Cycle CNC Program Example
Fanuc G73 Pattern Repeating Canned Cycle Basic CNC Sample Program

Fanuc G73 Pattern Repeating Cycle Programming Example

This cnc program example also shows how cnc machinists can use ‘W’ instead of ‘Z’ for z-axis movements.

Fanuc G73 Pattern Repeating Cycle Program Example
N010 G00 X260.0 Z80.0
                N011 G00 X220.0 Z40.0
                N012 G73 U14.0 W14.0 R3
                N013 G73 P014 Q020 U4.0 W2.0 F0.3 S0180
                N014 G00 G42 X80.0 Z2.0
                N015 G01 W-20.0 F0.15 S0600
                N016 X120.0 W-10.0
                N017 W-20.0 S0400
                N018 G02 X160.0 W-20.0 R20.0
                N019 G01 X180.0 W-10.0 S0280
                N020 G40
                N021 G70 P014 Q020
                N022 G00 X260.0 Z80.0
                N023 M30


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CNC Programming Example with Fanuc G71 Rough Turning Cycle and G70

Here is another cnc programming example, this cnc programming example shows the use of G71 Canned Cycle and G70 for Fanuc CNC Control.
Contents
  • G71 Turning Cycle
  • Program Example

G71 Turning Cycle

Although I already have posted about the G71 Turning Canned Cycle(Rough Turning Cycle), but that blog post just illustrates the use of G71 and G71 parameters.
This cnc programming example shows a complete contour cutting with G71 and finish cut on contour with G70.
G70 finishing cycle for fanuc cnc control can also be used with G72 Facing cycle for fanuc control. Usage of G70 Finishing cycle with G72 Facing cycle is same as shows here in the following example.

Program Example


CNC Programming Example with Fanuc G71 Rough Turning Cycle and G70
N10 G00 G90 X142 Z171
                    N20 G71 U4 R1
                    N30 G71 P40 Q110 U4 W2 F0.3
                    N40 G00 X40
                    N50 G01 Z140 F0.2
                    N60 G01 X60 Z110
                    N70 G01 Z90
                    N80 G01 X100 Z80
                    N90 G01 Z60
                    N110 G01 X140 Z40
                    N120 G70 P40 Q110
                    N130 G00 X200 Z220
                    N140 M30
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