FANUC Series 30i/300i/300is-MODEL A. Machining Center System. User's manual - page 121

22.5-AXIS MACHINING FUNCTION

 PROGRAMMING 

B-63944EN/03

 

 

- 924 - 

  - Block immediately before the offset cancel command (G40) 

In the block immediately before the offset cancel command (G40), a 
compensation vector is created from the movement vector of that 
block and the tool vector at the end point of the block as shown below. 

 

Tool center path (path after compensation)

Programmed path

V

M1

V

M2

V

T1

V

C1

V

C2 

V

T2

G40

 

 

Fig. 22.5.1.2 (f)   Block immediately before G40 

 
The compensation vector (VC2) of block 2 is created in a plane 
formed by the tool vector (VT2) at the end point of block 2 and the 
movement vector (VM2) of block 2.    VC2 is perpendicular to VT2. 
 

B-63944EN/03

 PROGRAMMING 

22.5-AXIS MACHINING FUNCTION

 

 

- 925 - 

  - Compensation performed when 

θ

 is approximately 0

°

, 90

°

, or 180

°

 

When the included angle 

θ

 between VMn+1 and VTn is regarded as 

0

°

, 180

°

, or 90

°

, the compensation vector is created in a different way.   

So, when creating a program, note the following points: 
 
<1>  Setting a variation range for determining 

θ

 to be 0

°

, 180

°

, or 90

°

 

 

When the included angle (

θ

) between the tool vector (VTn) and 

movement vector (VMn+1) becomes approximately 0

°

, 180

°

, or 

90

°

, the system regards 

θ

 as 0

°

, 180

°

, or 90

°

, respectively, then 

creates a compensation vector which is different from the normal 
compensation vector.    The variation range used for determining 

θ

  to  be  0

°

, 180

°

, and 90

°

 is set in parameter No. 19631.  For 

example, let the angle set in this parameter be 

∆θ

.  Then, the 

system regards 

θ

 as follows: 

 

(1) If 0 

≤

 

θ

 

≤

 

∆θ

 , 

θ

 is regarded as 0

°

. 

 

θ

∆θ

V

 

Tn

 

V

 

Mn+1

 

 

Fig. 22.5.1.2 (g)  Determination of 

θ

 = 0

°

 

 

(2)  If (180 - 

∆θ

) 

≤

 

θ

 

≤

 180, 

θ

 is regarded as 180

°

. 

 

θ

∆θ

V

 

Tn

 

V

Mn+1

 

Fig. 22.5.1.2 (h)  Determination of 

θ

 = 180

°

 

 

(3) If 

(90 

−

 

∆θ

) 

≤

 

θ

 

≤

 (90 + 

∆θ

), 

θ

 is regarded as 90

°

. 

 

θ

∆θ

V

 

Tn

V

Mn+1

θ

 

∆θ

V

Tn

V

 

Mn+1

 

 

Fig. 22.5.1.2 (i)    Determination of 

θ

 = 90

°

 

 

22.5-AXIS MACHINING FUNCTION

 PROGRAMMING 

B-63944EN/03

 

 

- 926 - 

<2>  Compensation vector when 

θ

 is regarded as 0

°

 or 180

°

 

 

At startup (when G41.3 is specified), alarm PS5408 is issued. 

 

This means that the tool vector of a block and the movement 
vector of the next block must not point in the same direction or in 
opposite directions at startup. 

 

At other than startup, the previously created compensation vector 
is maintained without change. 

 

If the included angles between VT2 and VM3, VT3 and VM4, 
and VT4 and VM5 are regarded as 0

°

, compensation vector VC1 

of block 1 is maintained as compensation vectors VC2, VC3, and 
VC4 of blocks 2, 3, and 4, respectively. 

Tool center path

(path after compensation)

Programmed 
path 

V

M

V

M

V

T1

V

C

V

C

V

T2

V

M

3

V

T3

V

M

V

C

V

C

V

M

V

M

V

T4 

V

C

V

T5

 

Fig. 22.5.1.2 (j)    When 

θ

 = 0

°

 is determined 

 

If the included angles between VT2 and VM3, VT3 and VM4, 
and VT4 and VM5 are regarded as 180

°

, compensation vector 

VC1 of block 1 is maintained as compensation vectors VC2, 
VC3, and VC4 of blocks 2, 3, and 4, respectively. 

Tool center path

(path after compensation)

Programmed 
path 

V

M

V

M

V

T1

V

C

V

C

V

T2

V

M

V

T3

V

M

V

C

V

C

V

M

V

M

V

T4

V

C

V

T5 

 

Fig. 22.5.1.2 (k)  When 

θ

 = 180

°

 is determined 

<3>  Compensation vector when 

θ

 is regarded as 90

°

 

 

If the previous compensation vector (VCn-1) points in the 
opposite direction ((VMn 

×

 VTn-1) 

×

 VTn-1 direction) to VMn 

with respect to VTn-1, the current compensation vector (VCn) is 
created so that it also points in the (VMn+1 

×

 VTn) 

×

 VTn 

direction. 

Tool center path

(path after compensation)

Programmed 
path 

V

M

V

M

V

T1

V

C

V

C

V

T2

V

M

V

T3

V

M

V

C

V

C

V

M

V

M

6

V

T4 

V

C

V

T5

 

Fig. 22.5.1.2 (l)  When 

θ

 = 90

°

 is determined 1 

 

If the previous compensation vector (VCn-1) points in the same 
direction (-(VMn 

×

 VTn-1) 

×

 VTn-1 direction) as VMn with 

respect to VTn-1, the current compensation vector (VCn) is 
created so that it also points in the -(VMn+1 

×

 VTn) 

×

 VTn 

direction. 

Tool center path

(path after compensation)

Programmed 
path 

V

M

V

M

V

T1

V

C

V

C

V

T2

V

M

V

T3

V

M

V

C

V

C

V

M

V

M

V

T4 

V

C

V

T5 

 

Fig. 22.5.1.2 (m)  When 

θ

 = 90

°

 is determined 2 

B-63944EN/03

 PROGRAMMING 

22.5-AXIS MACHINING FUNCTION

 

 

- 927 - 

22.5.1.3 

Tool tip position (cutting point) command 

 

Overview 

For machines having a rotary axis for rotating a tool, this function 
performs 3-dimensional cutter compensation at the tool tip position if 
a programmed point is specified with a pivot point. 
When this function is used, the programmed point (pivot point) is 
converted into a tool tip position (cutting point) and a vector of 
3-dimensional cutter compensation is calculated for the position 
obtained by the conversion.  Then, the programmed point (pivot 
point) is compensated for with the vector of 3-dimensional cutter 
compensation. 
If the tool side offset (G41.2/G42.2) of 3-dimensional cutter 
compensation is performed, the operation of this function is as 
follows: 
 
(1)  If parameter No. 19632 is 0 

The vector of 3-dimensional cutter compensation is calculated at 
the programmed point (pivot point). 

(2)  If parameter No. 19632 is not 0 (this function) 

The vector of 3-dimensional cutter compensation is calculated at 
the tool tip position (cutting point). 

 

22.5-AXIS MACHINING FUNCTION

 PROGRAMMING 

B-63944EN/03

 

 

- 928 - 

Explanation 
 - Operation explanation 

This function calculates a vector at the tool tip position for the 
3-dimensional cutter compensation function as described below. 
 
(1)  Convert the programmed coordinates from a programmed point 

(pivot point) to a tool tip position (cutting point).    Parameter No. 
19632 is used to store the distance from the programmed point 
(pivot point) to the tool tip position (cutting point). 

(2)  Calculate a vector of 3-dimensional cutter compensation at the 

tool tip position (cutting point). 

(3)  Add the cutter compensation vector to the programmed point 

(pivot point). 

Programmed point (pivot point)

Workpiece 

Tool center 

Tool side

Distance from programmed point
(pivot point) to cutting point
(parameter setting) 

Vector from programmed point (pivot
point) to cutting point 

Cutting point 

Vector of three-dimensional cutter compensation conforming to this specification 

Tool 

Vector of conventional three-dimensional
cutter compensation conforming 

Vector of 
three-dimensional cutter 
compensation conforming 
to this specification 

 

Fig. 22.5.1.3 (a)    Basic operation (for G42.2) 

 

B-63944EN/03

 PROGRAMMING 

22.5-AXIS MACHINING FUNCTION

 

 

- 929 - 

 - Operation example 

For a machine configuration in which the tool axis direction is along 
the Z-axis and the rotary axes are the B and C axes (Fig. 22.5.1.3 (b)) 
LC: Parameter (No. 19632) specifying the distance from the 

programmed point (pivot point) to the tool tip position (cutting 
point) 

b: Specified B-axis value, c: Specified C-axis value 
Q = (Qx,Qy,Qz): Programmed point (pivot point) 
P, R: 

 Programmed points (pivot points) in the preceding and 

succeeding blocks 

QT = (QTx,QTy,QTz):  Tool position (tool tip position (cutting point)) 

resulting from conversion 

PT, RT:  Tool positions (tool tip positions (cutting positions)) in the 

preceding and succeeding blocks 

Then,  
<1>  Convert programmed points (pivot points) P, Q, and R to tool tip 

positions (cutting points) PT, QT, and RT. 
      QTx = LC 

×

 sin(b) 

×

 cos(c) + Qx 

      QTy = LC 

×

 sin(b) 

×

 sin(c) + Qy 

      QTz    LC 

×

 cos(b) + Qz 

      (The same applies to PT and RT.) 

<2> Calculate vector VD of 3-dimensional cutter compensation from 

tool tip positions (cutting points) PT, QT, and RT and tool 
gradient VT. 

<3> Add cutter vector VD to programmed point (pivot point) Q and 

set the result as the end point position. 

Cutter compensation vector (VD') is calculated on a compensation plane perpendicular to
the tool axis direction.
The cutter compensation vector (VD') on the compensation plane is converted to the
original Cartesian coordinate system, and the resulting vector is regarded as the cutter
compensation vector (VD).

P’

R’

Q’

VD

VD’

e2

e3

e3

e2

V

T

Coordinate system of compensation plane

Tool tip position

LC

Tool radius

e1

 

Fig. 22.5.1.3 (b)    Operation 

22.5-AXIS MACHINING FUNCTION

 PROGRAMMING 

B-63944EN/03

 

 

- 930 - 

 

NOTE  

1  This function is disabled for leading edge offset. 
2  With a command for a rotary axis only, this function 

does not calculate a cutter compensation vector. 

3  This function cannot be used in the 

three-dimensional coordinate system conversion 
mode. 

4  In addition to the cautions given here, the cautions 

on the 3-dimensional cutter compensation function 
apply to this function. 

 

B-63944EN/03

 PROGRAMMING 

22.5-AXIS MACHINING FUNCTION

 

 

- 931 - 

22.5.2 

Cutter Compensation in Table Rotation Type Machine 

 

Overview 

Cutter compensation can be performed for a 5-axis machine having a 
rotary table as shown in Fig. 22.5.2 (a). 
Shown below is a 5-axis machine that has table rotation axis A on the 
X-axis and table rotation axis B on the Y-axis. 
This machine configuration is used as a sample configuration in the 
following explanation unless otherwise noted: 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

B

A

Z 

X 

Y

X 

Y

Z

Machine coordinate system

Indicates the direction of machine operation. 

This machine configuration is used as a sample 

configuration in the explanation. 

The table coordinate system is rotated according to the 

table rotation.    It is possible to specify whether to create 

a part program in the workpiece coordinate system or in 

the table coordinate system, using an appropriate 

parameter. 

Table coordinate 

system 

Workpiece 

coordinate system 

 

Fig. 22.5.2 (a)    Machine having a rotary table