Machining Center Programming & Operation

Dr. Juma Yousuf Alaydi

By

Program Zero:

The Key To Making Axis Movements

Program Zero Allows ALL Program Coordinates To

Be Taken From A Common Location.

Program Zero Can Be Compared To The

Origin Of A Rectangular Coordinate System

Y

X

Y Z

With CNC, Points Are Plotted In Space

Y

X

Y Z

With CNC, Points Are Plotted In Space

Y

X

Y Z

With CNC, Points Are Plotted In Space

Y

X

Y Z

With CNC, Points Are Plotted In Space

Y

X

Y Z

With CNC, Points Are Plotted In Space

Y

X

Y Z

With CNC, Points Are Plotted In Space

X+

Y+

X-

Y-

XY Plane 1.5 R

X+

Y+

X-

Y-

XY Plane

X1.5 Y0

X+

Y+

X-

Y-

XY Plane X1.0607 Y1.0607

X+

Y+

X-

Y-

XY Plane X0 Y1.5

X+

Y+

X-

Y-

XY Plane

X-1.0607 Y1.0607

X+

Y+

X-

Y-

XY Plane

X-1.5 Y0

X+

Y+

X-

Y-

XY Plane

X-1.0607 Y-1.0607

X+

Y+

X-

Y-

XY Plane

X0 Y-1.5

X+

Y+

X-

Y-

XY Plane

X1.0607 Y-1.0607

Front View

Z Zero

X+ X-

Z+

Z-

Front View

Z Zero

X+ X-

Z+

Z-

Z.1

Front View

Z Zero

X+ X-

Z+

Z- Z-.5

Program Zero Can Be Located Anywhere - As

Long As All Programmed Coordinates Are Taken

From Program Zero

Where Do You Place The Program Zero Point?

Where Do You Place The Program Zero Point?

This Decision Is ALWAYS Based On How The Print Is

Dimensioned.

In X & Y:

0

0

.5 1.0

2.5

3.0

5. 75.

1.75 2.0

In X & Y:

0

0

.5 1.0

2.5

3.0

.5 75.

1.75 2.0

Program Zero

In X & Y:

0

0

.5 1.0

2.5

3.0

5. .75

1.75 2.0

Program Zero

X.5 Y.5

In X & Y:

0

0

5. 1.0

2.5

3.0

.5 .75

1.75 2.0

Program Zero

X.5 Y2.0

In X & Y:

0

0

.5 1.0

2.5

3.0

.5 .75

1.75 2.0

Program Zero

X3.0 Y2.0

In X & Y:

0

0

.5 1.0

2.5

3.0

.5 .75

1.75 2.0

Program Zero

X3.0 Y.5

In X & Y:

.5

2.0

.5 3.5

.75 1.5

.75

1.0

In X & Y:

.5

2.0

.5 3.5

.75 1.5

.75

1.0

Program Zero

In X & Y:

.5

2.0

.5 3.5

.75 1.5

.75

1.0

Program Zero

X.5 Y-.5

In X & Y:

.5

2.0

.75 3.5

.75 1.5

.75

1.0

Program Zero

X4.0 Y-.5

In X & Y:

.5

2.0

.5 3.5

.75 1.5

.75

1.0

Program Zero

X4.0 Y-2.5

In X & Y:

.5

2.0

.5 3.5

.75 1.5

.75

1.0

Program Zero

X.5 Y-2.5

In X & Y:

45 deg.

3.5 dia.

Drill .375 (8 holes)

eq. spaced

In X & Y:

45 deg.

3.5 dia.

Drill .375 (8 holes)

eq. spaced

Program Zero

In Z:

Plan View

Front View

X+ X-

Z-

Z+

X+ X-

Y+

Y-

In Z:

Plan View

Front View

X+ X-

Z-

Z+

X+ X-

Y+

Y-

Z Zero

When Working From Program Zero, You Are Programming In The ABSOLUTE MODE.

G90 Specifies The Absolute Mode.

INCREMENTAL MODE: The Old Way To Program

Movements.

G91 Specifies The Incremental Mode

In The Incremental Mode, Movements Are Given From The Tool's

LAST POSITION.

X+

Y+

X-

Y-

XY Plane

Current Tool Position

X+

Y+

X-

Y-

XY Plane X-.4393 Y1.0607

X+

Y+

X-

Y-

XY Plane X-1.0607 Y.4393

X+

Y+

X-

Y-

XY Plane

X-1.0607 Y-.4393

X+

Y+

X-

Y-

XY Plane

X-.4393 Y-1.0607

X+

Y+

X-

Y-

XY Plane

X.4393 Y-1.0607

X+

Y+

X-

Y-

XY Plane

X1.0607 Y-.4393

X+

Y+

X-

Y-

XY Plane

X1.0607 Y.4393

Where Is Program Zero?

? ? ?

No Matter How Program Zero Is Assigned, Its Position Must Be

Determined

The Distance Between Program Zero And The Machine's Zero Return Position In Each Axis

MUST Be Found.

No Matter How Program Zero Is Assigned, Its Position Must Be

Determined

The Distance Between Program Zero And The Machine's Zero Return Position In Each Axis

MUST Be Found.

No Matter How Program Zero Is Assigned, Its Position Must Be

Determined

One way to determine this position is to measure it

Zero Return Position

The Zero Return Position Is A Very Accurate Location Along Each Axis. It Is Usually Very Close To The Plus Limit For

Each Axis.

Zero Return Position

Machine shown at Zero

Return position (plus

end of each axis)

The Program Zero Measurement Method

Depends On The Workpiece Configuration.

The Program Zero Measurement Method

Depends On The Workpiece Configuration.

Square

Control Operator area

Program zero

Y+

X+

Zero return position

Control Operator area

Program zero

Y+

X+

X program value Zero return position

Control Operator area

Program zero

Y+

X+

X program value

Y axis

value

Zero return position

Control

Program zero

Y+

X+

Zero return position

X00.0000 Y00.0000 Z00.0000

FANUC 10M

Edge Finder

Control

Program zero

Y+

X+

Zero return position

X-24.9287 Y-14.3887 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-24.4544 Y-14.3887 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-00.0000 Y-14.3887 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-00.1000 Y-14.3887 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-00.0000 Y-14.3887 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-15.3433 Y-22.4674 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-15.3433 Y-22.2344 Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-15.3433 Y00.0000

Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-15.3433 Y00.1000

Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X-15.3433 Y00.0000

Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X24.0974 Y22.1233

Z-18.3283

FANUC 10M

Control

Program zero

Y+

X+

Zero return position

X24.0974 Y22.1233

Z-18.3283

FANUC 10M

X&Y program

zero assignment

values

What About Z?

What About Z?

The Program Zero Measurement In Z Depends

On How Tool Length Compensation Is Used.

Spindle Nose

Program Zero

Z Axis At Zero Return Position

Spindle Nose

Program Zero

Z Axis At Zero Return Position

Z Measurement

X12.3232 Y11.2357 Z13.0294

FANUC 10M

X11.4843 Y7.4637 Z13.0294

FANUC 10M

X11.4843 Y7.4637 Z1.2544

FANUC 10M

X11.4843 Y7.4637 Z00.0000

FANUC 10M

X11.4843 Y7.4637 Z11.7750

FANUC 10M

Final Note About Program Zero Measurements

Final Note About Program Zero Measurements

If You Know How Your Work Holding Tooling Is Located, You May Not Need To Take

Measurements.

Lesson Summary:

Why Program Zero Must Be Assigned

How Program Zero is Measured For Rectangular Workpieces

How Program Zero Is Measured For Round Workpieces

How Program Zero Is Measured In Z

Older Controls Require That Program Zero

Be Assigned In The Program (With G92).

Older Controls Require That Program Zero

Be Assigned In The Program (With G92).

Newer Controls Allow Program Zero To Be Set With

Fixture Offsets.

No Matter Which Of These Two Ways You Use To Assign Program Zero,

The Measured Values Discussed In The Last Lesson Will Be Used.

Assigning Program Zero In The Program

Control Operator area

Program zero

Y+

X+

Zero return position

Control Operator area

Program zero

Y+

X+

Zero return position

+

+

Z Measurement

+

A G92 Command Is Used With Which To

Assign Program Zero In The Program.

Example:

Measured Values:

In X: 12.3412

In Z: 9.5423

Command:

N005 G92 X12.3412 Y11.2364 Z9.5423

In Y: 11.2364

O0001 N010 G90 S1000 M03 N015 G00 X1. Y1. N020 G43 H01 Z.1

N025 G01 Z-.75 F4.5 N030 G00 Z.1

N035 G91 G28 X0 Y0 Z0

N005 G92 X12.3412 Y11.2364 Z9.5423

N040 M30

Major Problem With Assigning Program

Zero In The Program:

All Axes MUST Be In Their Planned Positions BEFORE The

Cycle Can Be Activated!

Z Measurement

Z Measurement

O0001 N010 G54 G90 S1000 M03 N015 G00 X1. Y1. N020 G43 H01 Z.1

N025 G01 Z-.75 F4.5 N030 G00 Z.1

N035 G91 G28 X0 Y0 Z0

N005 G92 X12.3412 Y11.2364 Z9.5423

N040 M30

N003 G91 G28 X0 Y0 Z0

Assigning Program Zero With Fixture

Offsets

Control Operator area

Program zero

Y+

X+

Zero return position

Control Operator area

Program zero

Y+

X+

Zero return position

-

-

Z Measurement

- (minus)