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Century Star Turning CNC System. Programming Guide (V3.5 April, 2015) - page 3

3. Interpolation Function

X2_Z2_R1_;

X

X3_Z3_C2_;

C2

X4_Z4_

(X3, Z3)

A2

R1

(X4, Z4)

A1

(X2, Z2)

Z

Example

Φ 40

C10

Φ 15

Φ 80

Φ 70

Φ 80

%3329

N1 T0101

N2 M03 S400

N3 G00 X100 Z40

N4 X0 Z0

N5 G01 X0 Z-15 R15

;rounding

N6 G01 X60 Z-15C10

;chamfering

N7 G01 X60 Z-40

N8 G00X100 Z40

N9 M30

56

3. Interpolation Function

3.7.7 Chamfering then Rounding

Programming

G01 X_Z_C_

G01 X_Z_R_

G01 X_Z_

Explanation of the parameters

X_/Z_: Line location address;

R_: Rounding radius;

C_: Chamfer edge length;

Function

Round and Chamfering are inserted between two linear interpolation.

X

X2_Z2_C1_;

X3_Z3_R2_;

X4_Z4_

(X4, Z4)

(X3, Z3)

A2

R2

C1

A1

(X2, Z2)

Z

Example

Φ 50

R15

R15

Φ 10

Φ 90

C10

Φ 70

Φ 80

57

5. Coordinate System

5.1 Reference Position Return (G28)

Programming

G28 X(U)_ Z(W)_

Explanation of the parameters

X, Z

Coordinate values of the intermediate point in absolute command

U,W Coordinate values of the intermediate point with reference to the starting

point in incremental command

Function

The tool is moved to the intermediate point rapidly, and then returned to the reference

point.

X

Z

Figure 5.1 Reference Position Return

Note:

1) In general, G28 is used to change tools or cancel the mechanical error. Tool radius

compensation and tool length compensation should be cancelled when G28 is

executed.

2) G28 can not only make the tool move to the reference point, but also can save the

intermediate position to be used in G29.

3) When the power is on and manual reference position return is not available, G28 is

same as the maunaul reference position return. The direction of this reference

position return (G28) is set by the axis parameter - reference approach direction.

4) G28 is one-shot G code.

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5. Coordinate System

Example

Use G28, G29 command to program the track shown in. It moves from the starting

point A to the intermediate point B, and then returns to the reference point R. At last, it

moves from the reference point R to the end point C through the intermediate point B.

+X

200

R

100

B

A

C

+Z

250

Figure 5.2 Reference Position - Example

%3317

N1 T0101

N2 G00 X50 Z100

N3 G28 X80 Z200

N4 G29 X40 Z250

N5 G00 X50Z100

N6 M30

66

5. Coordinate System

5.3 Setting a Workpiece Coordinate System (G92)

Programming

G92 X_ Z_

Explanation of the parameters

X, Z

Coordinate values of the tool position in the workpiece coordinate system.

Functions

G92 can set a workpiece coordinate system based on the current tool position (X_

Z_).

Example

Use G92 to set a workpiece coordinate system.

+X

254

44

+Z

Origin on

Origin on

left end face

right end face

Figure 5.3 Setting a Coordinate System - Example

If the origin is set on the left end face,

G92 X180 Z254

If the origin is set on the right end face

G92 X180 Z44

67

5. Coordinate System

Example

Select one of workpiece coordinate system, and the tool path is Current point→A→B.

X

30

B

X

A

40

G59

O

30

Z

G54

O

30

Z

Machine Zero Point

Figure 5.4 Workpiece Coordinate System - Example

%3303

N01 G54 G00 G90 X40 Z30

N02 G59

N03 G00 X30 Z30

N04 M30

70

5. Coordinate System

Example

Move the tool from point 1 to point 2 through point 3, and then return to the current

point.

Φ25

Φ15

Φ50

3

2

1

30

4

40

1

2

Figure 5.5 Absolute and Incremental Programming - Example

Absolute Programming

Incremental Programming Absolute and Incremental

%0001

%0001

%0001

N 1 T0101

N 1 M03 S460

N 1 T0101

N 2 M03 S460

N 2 G91 G01 X-35

N 2 M03 S460

N3 G90 G00 X50 Z2

N 3 Z-32

N 3 G00 X50 Z2

N4 G01 X15

N 4 X10 Z-10

N 4 G01 X15

N 5 Z-30

N 5 X25 Z42

N 5 Z-30

N 6 X25 Z-40

N 6 M30

N 6 U10 Z-40

N 7 X50 Z2

N 7 X50 W42

N 8 M30

N 8 M30

73

5. Coordinate System

Example

Use Diameter programming and Radius programming for the same path

+X

254

160

44

Figure 5.6 Diameter and Radius Programming - Example

Diameter Programming Radius Programming

Compound Programming

%3304

%3314

%3314

N1 G92 X180 Z254

N1 G37 M03 S460

N1 T0101

N2 M03 S460

N2 G54 G00 X90 Z254

N2 M03 S460

N3 G01 X20 W-44

N3 G01 X10 W-44

N3 G37G00 X90 Z254

N4 U30 Z50

N4 U15 Z50

N4 G01 X10 W-44

N5 G00 X180 Z254

N5 G00 X90 Z254

N5 G36 U30 Z50

N6 M30

N6 M30

N6 G00 X180 Z254

N7 M30

75

5. Coordinate System

5.9 Inch/Metric Conversion (G20, G21)

Programming

G20

G21

Explanation of the parameters

G20: Inch input

G21: Metric input

The units of linear axis and circular axis are shown in the following table

Table 5-1. Unit of Linear axis and Circular axis

Linear axis

Circular axis

Inch system (G20)

Inch

Degree

Metric system (G21)

Mm

Degree

Function

Depending on the part drawing, the workpiece geometries can be programmed in

metric measures or inches.

76

6. Spindle Speed Function

Example

Use the constant surface control command

40

31

27

R15

Figure 6.1 Constant Surface Control - Example

%3318

N1 T0101

N2 G00 X40 Z5

N3 M03 S460

N4 G96 S80

N5 G46 X400 P900

N5 G00 X0

N6 G01 Z0 F60

N7 G03 U24 W-24 R15

N8 G02 X26 Z-31 R5

N9 G01 Z-40

N10 X40 Z5

N11 G97 S300

N12 M30

82

7. Tool Function

7.1 Tool Offset and Tool Wear Compensation

The trajectory of the turning machine programming is the tool nose movement

trajectory. But actually, the geometry size and installation position of different cutting

tool is varied, the cutter point relative to the tool center position is also different.

Therefore, it needs to measure the tool nose position in order to compensate for the

tool offset during the machining process. So there is no need to consider tool shape

and install position causing the position consistency of tool tip to simplify programming.

There are two types of tool offset compensation.

7.1.1 Tool Offset

1. Absolute compensation mode

As it is shown in Figure7.1, the absolute offset means the workpiece origin relative to

the directed distance of the tool nose position on the cutter frame, when the machine

returns to workpiece origin. When executing tool offset compensation, tools use this

value to set the coordinates. Therefore, although the cutter frame is on the machine

origin, the distance of tool position relative to workpiece origin is different caused by

the different sizes of the cutters. These set coordinates coincide with the workpiece

coordinates (programming).

Workpiece origin

No.1 tool offset

on axis Z

Z₁

No.2 tool offset

Z₂

on axis Z

X

2/2

X₁/2

Workpiece origin

No.2 tool offset

on axis X

Figure 7.1 Absolute tool offset compensation

As it is shown in Figure7.2, when the machine is reached the machine origin, the

value of machine coordinate system is zero, and the point on the cutter frame is

regarded as the ideal point. Thus, when the tool is aligned, it is considered that the

machine origin is on the cutter position. The system can automatically calculate the

distance of workpiece origin relative to the tool position by the input trial diameter and

length. The procedure is as followed:

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7. Tool Function

1) Press “Tool Offset” function key;

2) Input the workpiece coordinates value of the tool on axis Z in the trial face

cutting of the workpiece. Input 0 if the workpiece origin is set at the front face

of workpiece (no movement on axis Z before setting zero). The system would

automatically calculate the distance of the workpiece origin relative to the tool

position on axis Z.

3) Input the workpiece coordinates value of the tool on axis X in the trial

cylindrical surface cutting of the workpiece. It is the diameter of workpiece

after trial cutting (no movement on axis X before setting zero). The system

would automatically calculate the distance of the workpiece origin relative to

the tool position on axis X.

4) Change a tool and use another tool to repeat the above steps 2~3. The

absolute tool offset of this tool can be get, and automatically input to the table

of tool offset.

Machine origin

Zw

DM/2

ZM

Dw/2

workpiece

D_M′/2

origin

ZM′

Figure 7.2 Setting the absolute tool offset compensation

2. Relative compensation mode

As it is shown in Figure7.3, one tool is set as a standard tool when aligning tool, and

the coordinates is set based on the position A of this tool tip. When the other tools are

at the machining position, the position B of tool tip relative to position A would arise

the offset, and the original coordinates would not be applicable. Thus, the offset △x

and △z are used, and the tool tip is moved from position B to A. The compensation is

implemented by controlling the movement of machine carriage in this system.

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