Content .. 147 148 149 150 ..

FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 149

B-64693EN-1/01

- 1146 -

7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

Decelerate the X axis

down to 354 mm/min

Decelerate the X/Y axis down to

250 mm/min

(The tangent direction feedrate is

354 mm/min.)

(Example)

If parameter FNW (bit 6 of No. 19500) = 1 and

permissible feedrate difference = 500 mm/min (on all axes)

Fig. 7.1.11 (l)

Speed control with acceleration in circular interpolation

When high-speed cutting is performed in circular interpolation, helical interpolation, or spiral
interpolation, the actual tool path has an error with respect to the programmed path. In circular
interpolation, this error can be approximated from the equation given below.

Fig. 7.1.11 (m)

)

(

)

(

⋅

∆

........................................................................................ (Equation 1)

In actual machining, permissible error

∆

r is given, so the maximum permissible acceleration a (mm/sec

)

in equation 1 is determined.
Expression 1 is an expression when type of acceleration/deceleration after interpolation is exponential
acceleration/deceleration. The radius error in the case of linear acceleration/deceleration after
interpolation is smaller than in case of exponential acceleration/deceleration by a factor of 12, excluding
any error caused by a servo motor time constant. The radius error in the case of bell-shaped
acceleration/deceleration after interpolation is a half of linear acceleration/deceleration after interpolation.
When a specified feedrate causes the radial error from an arc having a programmed radius to exceed the
permissible error, speed control with acceleration in circular interpolation automatically clamps the
arc-cutting feedrate by using parameter settings.
Let the permissible acceleration calculated from the permissible acceleration set for each axis be A. Then,
maximum permissible feedrate v with programmed radius r is expressed as follows:

⋅

.................................................................................................................................... (Equation 2)

If a specified feedrate exceeds feedrate v obtained from equation 2, the feedrate is clamped at feedrate v
automatically.
The permissible acceleration is specified in parameter No. 1735. If there is a difference in permissible
acceleration between two axes for circular interpolation, the lower acceleration is regarded as the
permissible acceleration.

B-64693EN-1/01

- 1147 -

7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

If the radius of an arc is small, too small value can be calculated as deceleration v. In such a case, the
lower feedrate limit can be set in parameter No. 1732 to prevent the feedrate from being decreased too
much.

Speed control with the acceleration on each axis

When consecutive small lines are used to form a curve, as in the example shown in the Fig. 7.1.11 (n), the
feedrate differences on each axis at the individual corners are not very large. Thus, deceleration with the
feedrate differences is not effective. Consecutive small feedrate differences, however, cause a large
acceleration on each axis, as a whole.
In such a case, deceleration can be performed to reduce the impact on the machine and the machining
error caused by too large an acceleration. The deceleration feedrate is determined to be the feedrate that
does not cause the acceleration on each axis to exceed the permissible acceleration set for parameter No.
1737.
The deceleration feedrate is determined for each corner. The actual feedrate is the smaller of the
deceleration feedrate determined at the start point of the block and that determined at the end point.
Depending on the specified figure, a very low deceleration feedrate may be calculated. In such a case, the
lower feedrate limit can be set in parameter No. 1738 to prevent the feedrate from being decreased too
much.

In the following example, the acceleration (gradient of the broken line in the feedrate graph) at too large
at corners N2 to N4 and N6 to N8 and, therefore, deceleration is performed.

X-axis
feedrate

Y-axis
feedrate

Tangent
feedrate

Time

Speed control with the acceleration is effective

Speed control with the acceleration is not effective

Fig. 7.1.11 (n)

The method of determining the feedrate with the acceleration differs depending on the setting of
parameter FNW (bit 6 of No. 19500).

B-64693EN-1/01

- 1148 -

7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

If parameter FNW is set to 0, the highest feedrate that does not cause the permissible acceleration set for
parameter No. 1737 to be exceeded is assumed to be the deceleration feedrate. In this case, the
deceleration feedrate differs depending on the travel direction even if the shape is the same, as shown in
the figure below.

(Example) If a circular shape with a radius of 10 mm is specified with small

line blocks

Parameter FNW (bit 6 of No. 19500) = 0
Permissible acceleration = 1000 mm/s

(on all axes)

The feedrate is
higher in these
directions.

Tangent feedrate

Time

F6000

Fig. 7.1.11 (o)

If parameter FNW is set to 1, the feedrate is determined with not only the condition that the permissible
acceleration on each axis is not exceeded but also the condition that the deceleration feedrate is constant
regardless of the travel direction if the shape is the same.
If this parameter is set to 1, the deceleration feedrate determined with the feedrate difference or
acceleration may be up to 30% lower than that determined if this parameter is set to 0.

(Example) If a circular shape with a radius of 10 mm is specified with

small line blocks

Parameter FNW (bit 6 of No. 19500) = 1,
radius = 10 mm, permissible acceleration = 1000 mm/s

(on all axes)

The tangent
feedrate is
constant.

Tangent feedrate

Time

F6000

Fig. 7.1.11 (p)

NOTE

In circular interpolation, the tangent feedrate is constant regardless of the setting
of the parameter.

When this function is effective, the feedrate might be clamped as well as the travel distance in the block is
small even if the travel distance in the block is long. Speed control with the acceleration is invalidated in
the block longer than the block length set to parameter No. 19518 if bit 1 (HNG) of parameter No. 19517
is set to 1.

Smooth speed control

In speed control with acceleration, the smooth speed control function recognizes the entire figure from
preceding and following blocks including blocks read ahead to make a smooth feedrate determination.
When a curve is specified with successive minute straight lines, programmed values are rounded to the
least input increment before issued, so the machining profile is approximated with a broken line.

B-64693EN-1/01

- 1149 -

7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

When the feedrate is determined with acceleration in an ordinary manner, an optimum feedrate is
automatically calculated exactly for a programmed figure, so a large acceleration may result depending on
the command, which can lead to deceleration.
In such a case, the use of smooth speed control enables speed control by recognizing the entire figure,
which provides smooth speed control while suppressing local deceleration, therefore increasing the
feedrate.

Large acceleration

: Programmed path

: Recognized figure

Fig. 7.1.11 (q)

Also for a part of a programmed figure in which a large acceleration would be required, the acceleration
is obtained based on the figure recognized from multiple blocks, and the feedrate is determined so that the
acceleration is within the permissible acceleration set in parameter No. 1737.

Tangential feedrate

Deceleration with acceleration
in ordinary manner

Smooth speed control

Time

Command with large acceleration

Fig. 7.1.11 (r)

Smooth speed control obtains the acceleration by using the figure recognized from the preceding and
following blocks including blocks read ahead, so smooth speed control is enabled even in parts in which
the acceleration increases.
Smooth speed control is enabled under the following conditions:
(1)  Speed control with acceleration is enabled in the AI contour control II mode.
(2)  Successive linear interpolation commands are specified.
(3)  Bit 0 (HPF) of parameter No. 19503 is set to 1.

CAUTION

When smooth speed control is used, the feedrate in a certain figure such as a
corner may become larger than the feedrate obtained by ordinary speed control
with acceleration. For corners, set parameter No. 1783, which is the permissible
feedrate difference parameter for speed control with the feedrate difference at
corners, to perform appropriate deceleration by speed control with the corner
feedrate difference.

When this function is effective, the feedrate might be clamped as well as the travel distance in the block is
small even if the travel distance in the block is long. Smooth speed control is invalidated in the block

B-64693EN-1/01

- 1150 -

7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

longer than the travel distance set to parameter No. 19518 if bit 1 (HNG) of parameter No. 19517 is set to
1.

Deceleration with the cutting load

Usually, the cutting resistance produced when machining is performed with the bottom of the cutter as the
tool lowers along the Z-axis is greater than the cutting resistance produced when machining is performed
with the side of the cutter as the tool rises along the Z-axis. Therefore, deceleration is required.
In AI contour control II, the tool travel direction on the Z-axis is used as a condition for calculating the
machining feedrate.
This function is enabled when parameter ZAG (bit 4 of No. 8451) is set to 1.

Fig. 7.1.11 (s) During ascent on the Z-axis

Fig. 7.1.11 (t) During descent on the Z-axis

The descent angle

during descent on the Z-axis (angle formed by the XY plane and the tool center path)

is as shown in the Fig. 7.1.11 (s). The descent angle is classified into four areas, and the override values
for the individual areas are set for the following parameters:

Parameter No. 8456 for area 2
Parameter No. 8457 for area 3
Parameter No. 8458 for area 4

For area 1, however, no parameter is available, and an override of 100% is used at all times. The feedrate
obtained according to other feedrate control is multiplied by the override value of the area to which
descent angle

belongs.

Area1

0º

≤

< 30º

Area2

30º

≤

< 45º

Area3

45º

≤

< 60º

Area4

60º

≤

< 90º

The feedrate can be overridden with an inclination by setting bit 1 (ZG2) of parameter No. 19515 to 1. In
this case, specify the override value for area 1 in parameter No. 19516.

B-64693EN-1/01

- 1151 -

7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

XY plane

Area1

Area2

Area3

Area4

Fig.7.1.11 (u)

CAUTION

1 The speed control with the cutting feed is effective only when the tool is parallel

with the Z-axis. Thus, it may not be possible to apply this function, depending on
the structure of the machine used.

2 In the speed control with the cutting feed, the travel direction on the Z-axis is

determined with the appropriate NC command. If, therefore, manual intervention
is performed on the Z-axis with manual absolute on, or if a mirror image is
applied on the Z-axis, the direction on the Z-axis cannot be determined. When
using the speed control with the cutting load, do not use these functions.

3 When performing 3-dimensional coordinate system conversion, determine the

descent angle on the Z-axis using the converted coordinate system.

4 Speed control with the cutting load is enabled for all interpolations in the AI

contour control II mode. This function, however, can be made valid only for linear
interpolations by setting bit 4 (ZOL) of parameter No. 19503 to 1.

Ignoring feedrate commands

In a block in which AI contour control II is enabled, all feedrate commands (F commands) can be ignored
by setting parameter NOF (bit 7 of No. 8451).
The term feedrate commands, as used here, refer to the following commands:

(1) Modal F commands before the block in which AI contour control II is enabled
(2) F commands and modal F commands in the block in which AI contour control II is enabled

When the feedrate commands are ignored, it is assumed that the upper feedrate limit specified for
parameter No. 8465 is specified.
When a rotation axis is singly specified, it is assumed that the upper feedrate limit specified for parameter
No. 8466 is specified.
Note, however, that any issued F commands and modal F commands are stored within the CNC.
Thus, in a block in which AI contour control II changes from the enabled state to the disabled state, the
modal values of the F commands described in (1) and (2) described above are used as modal F commands,
instead of the modal values of the F commands calculated by AI contour control II.

Another example of determining the feedrate

If a specified feedrate exceeds the upper feedrate limit of AI contour control (in parameter No. 8465, or
parameter No. 8466 (when a rotation axis is singly specified))), the feedrate is clamped at the upper
feedrate. The upper feedrate limit is clamped at the maximum cutting feedrate (parameter No. 1432) for
acceleration/deceleration before interpolation

B-64693EN-1/01

- 1152 -

7. FEEDRATE CONTROL/ACCELERATION AND

DECELERATION CONTROL

Status display

Depending on the control mode, one of the status indications shown below blinks at the lower right of the
screen.

Table7.1.11 (b)

AI contour control I

AI contour control II

Status display

AICC 1

AICC 2

In the case of AI contour control I, the character string to be displayed can be changed using
parameter Nos. 3241 to 3247.

In the case of AI contour control II, the character string to be displayed can be changed using

parameter Nos. 3251 to 3257..

The advanced preview feed forward function when the AI contour control
mode is off

The advanced preview feed forward function is enabled when bit 1 (FEED) of parameter No. 2005 for
enabling the advanced preview feed forward function is set to 1 and a value is set in parameter No. 2092,
regardless of whether AI contour control is turned on or off.
By setting bit 2 (AOFF) of parameter No. 1611 to 1, the advanced preview feed forward function is
disable when command for turning on AI contour control is not specified yet.

Example of the advanced preview feed forward function turned on/off

(1) Bit 0 (SHP) of parameter No. 1604 is set to 0

When bit 0 (SHP) of parameter No. 1604 is set to 0, the AI contour control mode is not turned on if
the command for AI contour control ON is not specified. Program operation in this state is explained
below.
O0001;
N01 G90 G01 X50.0 Y50.0 F1000. ;
N02 G05.1 Q1 ;
N03 X100.0 Y100.0 ;
N04 G05.1 Q0 ;
N05 X150.0 Y150.0 ;
N06 M02 ;

(a) When bit 2 (AOFF) of parameter No. 1611 is set to 0

The advanced preview feed forward function is enabled in the N01, N03, and N05 blocks.

(b) When bit 2 (AOFF) of parameter No. 1611 is set to 1

The advanced preview feed forward function is enabled in the N03 block.
The advanced preview feed forward function is disabled in the N01 and N05 blocks.

(2) Bit 0 (SHP) of parameter No. 1604 is set to 1

When bit 0 (SHP) of parameter No. 1604 is set to 1, the program operates in the same way as when
G05.1Q1 is specified at automatic operation start time (from the reset state). Program operation from
the reset state is explained below.
O0001;
N01 G90 G01 X50.0 Y50.0 F1000. ;
N02 G05.1 Q1 ;
N03 X100.0 Y100.0 ;
N04 G05.1 Q0 ;
N05 X150.0 Y150.0 ;
N06 M99;

(a) When bit 2 (AOFF) of parameter No. 1611 is set to 0

The advanced preview feed forward function is enabled in all movement blocks of N01, N03,
and N05.

B-64693EN-1/01

- 1153 -

7. FEEDRATE CONTROL/ACCELERATION

AND DECELERATION CONTROL

(b) When bit 2 (AOFF) of parameter No. 1611 is set to 1

Immediately after automatic operation is started, the advanced preview feed forward function is
enabled in the N01 and N03 blocks and the advanced preview feed forward function is disabled
in the N05 block.
If N06 specifies M99 to return to the start of the program, the advanced preview feed forward
function is disabled in the N01 block because N04 turns off the AI contour control mode.

(3) When none of the AI contour control is specified

G05.1Q1 cannot be specified. This state is equivalent to the state where G05.1Q0 is specified, that is,
AI contour control is off at all times. Program operation in this state is described below.
O0002;
N01 G90 G01 X50.0 Y50.0 F1000. ;
N02 X100.0 Y100.0 ;
N03 X150.0 Y150.0 ;
N04 M02 ;

(a) When bit 2 (AOFF) of parameter No. 1611 is set to 0

The advanced preview feed forward function is enabled in the N01, N02, and N03 blocks.

(b) When bit 2 (AOFF) of parameter No. 1611 is set to 1

The advanced preview feed forward function is disabled in the N01, N02, and N03 blocks.

Limitation

Conditions for temporarily canceling the AI contour control mode

If one of the commands listed below is issued in the AI contour control mode, the AI contour control
mode is canceled temporarily.
If the system becomes ready for AI contour control after it is canceled, the AI contour control mode is
restored automatically.
-

Positioning (rapid traverse)

Single-direction positioning

Spindle positioning

Rigid tapping

Threading cycle (threading and multiple repetitive threading)

Electronic gear box

Superimposed control

When no move command is specified

One-shot G code other than the following:
Tool offset
Cutter compensation vector retention
Cutter compensation corner rounding
Exact stop

Content .. 147 148 149 150 ..