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FANUC Series 30i/300i/300is-MODEL A. Machining Center System. User's manual - page 19

4.INTERPOLATION FUNCTIONS

PROGRAMMING

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Example

N10 G90 G01 X5.0 Z1.575 ;
N20 G02.3 X25.0 Z2.273 I3.0 J-45.0 K1.0 R1.238
F1000 Q1000 ;

r = 3.0

Z(0) = 1.4

J = 45

I = 3.0

U = 5.0

X = 25.0

B = 2.0

Xs: Start point on the

X-axis

Xe: End point on the

X-axis

The start point and end point of the Z-axis and the constant R are
obtained from the following expressions:

Start point on the Z-axis

(0)

)

tan(

End point on the Z-axis

(0)

)

tan(

)

tan(

−

Limitation
- Cases where linear interpolation is performed

Even when the G02.3 or G03.3 mode is set, linear interpolation is
performed in the following cases:

•

When the linear axis specified in parameter No. 5641 is not

specified, or the amount of movement on the linear axis is 0

•

When the rotary axis specified in parameter No. 5642 is specified

•

When the amount for dividing the linear axis (span value) is 0

- Tool compensation

The tool compensation functions (tool length compensation, tool
radius/tool nose radius compensation, and 3-dimensional cutter
compensation) cannot be used in the G02.3 or G03.3 mode.

CAUTION

The amount for dividing the linear axis for
exponential interpolation (span value) affects figure
precision. However, if an excessively small value is
set, the machine may stop during interpolation. Try
to specify an optimal span value depending on the
machine being used.

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4.12

SMOOTH INTERPOLATION (G05.1)

Either of two types of machining can be selected, depending on the
program command.

•

For those portions where the accuracy of the figure is critical,
such as at corners, machining is performed exactly as specified
by the program command.

•

For those portions having a large radius of curvature where a
smooth figure must be created, points along the machining path
are interpolated with a smooth curve, calculated from the
polygonal lines specified with the program command (smooth
interpolation).

In this manner, high-speed, high-precision machining can be
performed.

Format

G05.1Q2X0Y0Z0 ;

Starting of smooth interpolation mode

:
G05.1Q0 ;

Cancellation of smooth interpolation mode

Explanation
- Characteristics of smooth interpolation

To machine a part having sculptured surfaces, such as metal moldings
used in automobiles and airplanes, a part program usually
approximates the sculptured surfaces with minute line segments. As
shown in the following figure, a sculptured curve is normally
approximated using line segments with a tolerance of about 10

Enlarged

: Specified point

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PROGRAMMING

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When a program approximates a sculptured curve with line segments,
the length of each segment differs between those portions that have
mainly a small radius of curvature and those that have mainly a large
radius of curvature. The length of the line segments is short in those
portions having a small radius of curvature, while it is long in those
portions having a large radius of curvature. Because linear
interpolation controls the tool movement exactly as programmed so as
not to let the tool depart from the path specified by a part program,
machining is performed exactly along line segments with which a
sculptured curve is approximated. Consequently, when a curve with a
large radius of curvature and a moderate curvature change is machined,
the corners of line segments may become apparent. Such concave and
convex portions, produced as a result of machining performed exactly
as specified, are found troublesome when a smooth surface must be
obtained by finishing.

Profile

Portions having mainly
a small radius of
curvature

Portions having mainly
a large radius of
curvature

Example of machined
parts

Automobile parts

Decorative parts, such
as body side moldings

Length of line segment

Short

Long

Resulting surfaces
produced using
high-precision contour
control

Smooth surface even
when machining is
performed exactly as
specified by a program

Uneven surfaces may
result when machining
is performed exactly as
specified by a program

Example of uneven surfaces (polygon) resulting from machining that precisely follows the line segments.

In smooth interpolation mode, the CNC automatically determines,
according to the program command, whether an accurate figure is
required, such as at corners, or a smooth figure is required where the
radius of curvature is large. If a block specifies a travel distance or
direction which differs greatly from that in the preceding block,
smooth interpolation is not performed for that block. Linear
interpolation is performed exactly as specified by the program
command. Programming is thus very simple.

Specifying G5.1 Q2 also enables AI contour control to be turned on at
the same time. The automatic velocity control by AI contour control
reduces impacts on the machanical system. Specifying G5.1 Q0
cancels the smooth interpolation mode. The AI contour control mode
is also canceled at the same time.

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Interpolated by smooth curve

(Example)

N17

N16

N15

N14

N13

N12

N11

N10

Linear interpolation

N17

N16

N15

N14

N13

N12

N11

N10

- Conditions for performing smooth interpolation

Smooth interpolation is performed when all the following conditions
are satisfied. If any of the following conditions is not satisfied for a
block, that block is executed without smooth interpolation then the
conditions are checked for the next block.
(1) The machining length specified in the block is shorter than the

length specified with parameter No. 8486.

(2) The machining length is other than 0.
(3) The modes are:
G01

Linear

interpolation

G13.1

: Polar coordinate interpolation cancel

G15

: Polar coordinate command cancel

G40

: Tool radius/tool nose radius compensation cancel

(except for 3-dimensional cutter compensation)

G64

Cutting

mode

G80

Canned

cycle

cancel

G94

Feed

per

minute

(4) Machining is specified only along the axes specified with

G05.1Q2.

(5) The block is judged to be unsuitable for smooth interpolation, as

performed with the internal algorithm of the CNC.

- Commands which cancel smooth interpolation

(1) Auxiliary and second auxiliary functions
(2) M98, M99 : Subprogram call

M198

: Calling a subprogram in external memory

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PROGRAMMING

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- Checking the smooth interpolation mode

Diagnostic data (No. 5000#0) indicates whether the smooth
interpolation mode is enabled in the current block.
If the smooth interpolation mode is enabled, "smooth interpolation on"
bit is set to 1.

Limitation
- Controlled axes

Smooth interpolation can be specified only for the X-, Y-, and Z-axes
and any axes parallel to these axes (up to three axes at one time).

Example

N10 X-1000 Z350 ;

N11 X-1000 Z175 ;

N12 X-1000 Z25 ;

G91 ;

N13 X-1000 Z- 50 ;

G05. 1 Q2 X0 Y0 Z0 ; N14 X-1000 Z- 50 ;
N01 G01 X1000 Z-300 ; N15 X-1000 Z50 ;
N02 X1000 Z-200 ;

N16 X-1000 Z200 ;

N03 X1000 Z-50 ;

N17 X-1000 Z300 ;

N04 X1000 Z50 ;

G05. 1 Q0 ;

N05 X1000 Z50 ;

N06 X1000 Z-25 ;

N07 X1000 Z-175 ;

N08 X1000 Z-350 ;

N09 Y1000 ;

Interpolated by smooth curve

(Example)

N17

N16

N15

N14

N13

N12

N11

N10

Linear interpolation

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4.13

NANO SMOOTHING

Overview

When a desired sculptured surface is approximated by minute
segments, the nano smoothing function generates a smooth curve
inferred from the programmed segments and performs necessary
interpolation.
The nano smoothing function infers a curve from a programmed
figure approximated with segments within tolerance. If the spacing
between adjacent inflection points or programmed points is not
constant, this function can generate a smoother curve than the
conventional smooth interpolation function.
The interpolation of the curve reduces the segment approximation
error, and the nano-interpolation makes the cutting surface smoother.
The interpolation of the curve reduces the segment approximation
error, and the nano interpolation makes the cutting surface smoother.
Nano smoothing 2 allows the basic three axes (X, Y, and Z) or their
parallel axes as well as two rotation axes to be specified. This enables
five-axis machining (including rotation axes) to produce very smooth
finished surfaces and so finds applications such as machining of
smooth workpiece side faces.
In addition, this function can be used with tool center point control
(type 1 (G43.4)). This eliminates the necessity of modifying a
program when the tool length is changed.
For this function, the AI contour control option is required.
For nano smoothing 2, the nano smoothing option is required.

Format

G5.1 Q3 Xp0 Yp0 Zp0 [

0] [

0] ; :

Nano smoothing mode on

G5.1 Q0 ;

Nano smoothing mode off

Xp  : X-axis or an axis parallel to the X-axis
Yp  : Y-axis or an axis parallel to the Y-axis
Zp  : Z-axis or an axis parallel to the Z-axis

: Rotary axis

NOTE

1 Specify G5.1 alone in a block. (Avoid specifying

any other G code in the same block.)

2 Specify position 0 for the axis programmed in the

nano smoothing mode on block. The specified axis
is subjected to nano smoothing, but no movement
is made even in the absolute programming mode.

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PROGRAMMING

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Nano smoothing 2 enables specification of the basic three axes (X-, Y-,
and Z-axes) or their parallel axes as axes on which to perform nano
smoothing, as well as two rotary axes.
If executing nano smoothing 2 simultaneously with tool center point
control (type 1 (G43.4)), enable tool center point control (G43.4) first
and then enable nano smoothing 2 (G5.1 Q3). To cancel them, cancel
nano smoothing 2 (G5.1 Q0) first and then cancel tool center point
control (G49).

Example :

O0010
…
G43.4 H1 P0;
G5.1 Q3 X0 Y0 Z0 B0 C0;
…
G5.1 Q0;
G49;
…
M30;

Nano smoothing 2

Tool center point control

- Nano smoothing mode

Specifying G5.1 Q3 selects the nano smoothing mode. An axis of
nano smoothing is specified in the same block. The basic three axes
(X, Y, and Z) and their parallel axes can be specified as the axis of
nano smoothing. In the nano smoothing mode, nano smoothing is
performed in a block which satisfies the conditions described below.
Nano smoothing is cancelled in a block which does not satisfy the
conditions.
Specifying G5.1 Q3 also enables AI contour control. The automatic
velocity control by AI contour control reduces impacts on the
mechanical system.
Specifying G5.1 Q0 cancels the nano smoothing mode. The AI
contour control mode is also cancelled at the same time.
Making a reset also cancels the nano smoothing mode.

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- Conditions to enable nano smoothing

Nano smoothing is enabled when the following conditions are
satisfied. Nano smoothing is cancelled in a block which does not
satisfy the conditions. A decision is made to perform nano smoothing
from the next block.
In the programmed block length and the difference in angle between
adjacent programmed blocks in the conditions listed below, only the
basic three axes (or their parallel axes) are considered, and the rotation
axes are excluded. When the nano smoothing mode is canceled in a
block when these conditions are satisfied, nano smoothing for the
rotation axes is not performed, either.

<1> The programmed block length is shorter than the length specified

in parameter No. 8486.

<2> The programmed block length is longer than the length specified

in parameter No. 8490.

<3> The difference in angle between adjacent programmed blocks is

smaller than the value specified in parameter No. 8487.

<4> The current mode is one of the following:

•

Linear interpolation

•

Feed per minute

•

Tool radius compensation cancel

•

Canned cycle cancel

•

Scaling cancel

•

Macro modal call cancel

•

Constant surface speed control cancel

•

Cutting mode

•

Coordinate system rotation / 3-dimensional coordinate system

conversion cancel

•

Polar coordinate cancel

•

Normal-direction control cancel

•

Polar coordinate interpolation cancel

•

Programmable mirror image cancel

•

Polygon turning cancel

<5> No one-shot G code is specified in the block.
<6> Buffering is not suppressed in the block.
<7> A movement just on the axis of nano smoothing is specified in

the block.

- Checking the nano smoothing mode

Diagnostic data (No. 5000) indicates whether the nano smoothing
mode is enabled in the current block.
If the nano smoothing mode is enabled, the "smoothing on" bit is set
to 1.

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