Wzmii u08 Aufgabe Brs English

Chair of Machine Tools

Prof. Dr.-Ing. Christian Brecher

Exercise 8 Machine Tools II

Topic: Manual programming of NC machines

Assistant

responsible:

Dipl.-Ing. Sebastian Bauer

[email protected]

WZL, 53B R424

Tel.: 0241 / 80-28478

Index

1 Basics of manual NC programming 1

1.1 Introduction 1

1.2 NC programming 1

1.2.1 Writing NC programmes 1

1.2.2 Structure of a NC programme 4

1.2.2.1 Coordinate systems and reference points 4

1.2.2.2 Presentation of information 7

1.2.3 Tool offset compensation 8

1.2.3.1 Cutting-edge radius compensation 9

1.2.3.2 Milling cutter radius compensation 10

1.2.4 Additional commands for programme input 10

1.2.4.1 Combined contours 11

1.2.4.2 Sub-routines 13

1.2.4.3 Cycles 14

1.3 References 14

2 Exercise 15

2.1 Programming exercise 15

2.2 Solution 17

Exercise 8, WZM II

2.3 Programming key 22

2.4 Coding sheet 23

3 Bonus task 25

3.1 Introduction 25

3.2 NC programme for test part 29

Manual programming of NC machines, WZM II

1

1 Basics of manual NC programming

1.1 Introduction

Numerically controlled (NC) machine tools are used to increase the level of

automation in the field of one-off and small-batch manufacturing (batch sizes

approximately 1-100 pieces). Compared to automatic lathes NC-machine tools have

the advantage of greater flexibility. Especially for manufacturing complex geometries

NC machines are superior to conventional machines.

The following sections describe the fundamentals of manually programming NC

machines. Semi-automatic and automatic (computer-based) programming methods

will not be covered here.

1.2 NC programming

Programming NC machines means to assemble control information which contains

precise working instructions for the machine tool in the correct order.

The control information is usually transmitted to the machine in ASCII format via

floppy disc or DNC (Distributed Numerical Control) these days, in recent years USB-

connected storage devices have come into use as well. The punched paper tape

formerly used as a data medium is now employed only on very old machines.

The control information must have an agreed systematic structure so that the

numerical control can interpret it.

1.2.1 Writing NC programmes

In conventional manufacturing, the machine operator translates the production task

into control instructions for the machine (technical drawing data � manual switching

and motion events). In NC manufacturing, by contrast, this work is transferred to the

programming department (technical drawing data � switching and traversing

instructions as control information).


2

The various programming methods in practical use may be classified as

� manual methods (direct programming)

� semi-automatic programming and

� automatic (computer-aided) programming.

The choice of method will depend primarily on the type, quantity and complexity of

the manufactured parts and on the percentage of repetition parts. For example,

choosing a computer-aided approach necessitates that hard- and software be

purchased for automatic programming with programming systems like APT or

EXAPT. In consequence, this method is only used when the number and scope of

NC programmes which have to be prepared seems to economically justify this extra

cost or when it is essential because the complex geometry of the work pieces does

not permit manual programming. This exercise deals solely with manual NC

programming.

Geometry:

- rawpiece geometry

- workpiece geometry

- tolerances

- workingsteps

Technology:

- material

- cutter's material

- surface quality

- vc, Qc, ...

Production facilities:

- workspace

- clamping devices

- tools

- torque

- maximun rpm

- maximum speed

- preciseness

- auxiliary devices

Fig. 1: Information needed to generate a NC-Programm

Manual programming requires detailed planning of each individual machining step by

the programmer, based on given requirements (Fig. 1). Starting from the technical

drawing of the part, the programmer has to choose a suitable machine tool and

determine the clamping position of the work piece. The machining sequence is

recorded in a working plan and the required tools are stored in a tool plan. Because

of the part geometry must be converted into a tool path curve, the most time-

consuming task is determining the geometrical dimensions. If there are large


3

differences in volume between the blanks and the finished parts, determining the

number of cutting passes by means of an appropriate cut division will also be

necessary.

One example is shown in the following exercise. The different types of interpolation

an NC is capable of require that the full part contour is split into individual contour

elements which correspond to these interpolation capacities, as shown in Fig. 2.

Elements: Line Circle

Fig. 2: Transforming the part geometry into contour elements

Technological parameters like depth-of-cut, feed and cutting speed are selected from

standard value tables and also stored on the information medium. On older NC

machines, it is generally necessary to adapt these values from cut to cut to maintain

constant cutting conditions over changing part dimensions caused by the machining

progress. Newer machines, which are usually equipped with powerful CNCs, provide

useful aids to the programmer. Modern lathes for example have facilities for

automatically maintaining a constant cutting speed. Taking into account the current

working diameter, the speed of rotation and the feed rate are automatically adapted

accordingly. Additional technological data include tool changes, cooling lubricant

on/off or machine stop.

After defining all working steps required to manufacture the part, the programmer

enters this control information in tabular form on a coding sheet.


4

1.2.2 Structure of a NC programme

1.2.2.1 Coordinate systems and reference points

The geometrical information or path parameters specify the paths traversed by the

tool. These can be programmed in incremental or absolute dimensions (Fig. 3).

Incremental dimensions mean that the length of the section to be traversed is given.

In absolute programming, the traversed points are specified by giving the distance

from a reference point along the coordinate axes. If a machine is restricted to

incremental or to absolute dimensions, as is frequently the case with older NC

controls (this often depends on the type of measuring system they use) it will be

helpful to use incremental or absolute dimensions in the technical drawing itself.

Modern CNC controls can be programmed either in incremental or in absolute

dimensions, irrespective of the installed measuring systems. In this case, the control

computer inside the CNC converts the incremental or absolute dimensions, referred

to a reference point, into an internal traversed path representation that is suitable to

the measuring systems.

50

20

20

40

a) G90: absolute to a preset origin

20

30

b) G91: relative to the last point

z z

x x

Fig. 3: Position data in absolute and incremental dimensions

In order to be able to programme, it is necessary to establish a coordinate system.

Assuming that the part is fixed and the tool is in motion, the system shown in Fig. 4

can be used to specify the part axes.

Pratyush

Hervorheben

Pratyush

Hervorheben


5

+X +Z

+Z

+Y +X

+Y+X

+Z+Y

+X

+Z

+X+Z

+C'

+Z

+W'

+Y'+X'

+Z

+Y

+X'

+W'

+Z+Y

+Y

+X'

+W

+A+X

+Z

+Y

+A

+B

+C

+Y

+X

+Z

right handed, right-angled coordinate system

Lathe

X, Y, Z, A, ... tool movementX', Y', Z', A', ... workpiece movement

DIN 66217

Fig. 4: Coordinate systems

The z-axis of a right-handed coordinate system is invariably parallel to the axis of

rotation of the tool spindle. It is perpendicular to the part clamping surface defined by

the x- and y-axes, the x-axis being as horizontal as possible.

If the part is in motion and the tool is fixed, the corresponding axes are referred to as

machine axes, which are antiparallel to the part axes and designated by an

apostrophe.

In the initial state of the NC control, all absolute path information is referred to the

machine coordinate origin or zero point M (

Fig. 5).


6

Fig. 5: Reference points of an NC lathe

For machining, however, it is usually advisable to refer to the part zero point W. The

control system can internally perform a coordinate transformation using zero shifting

(ZMW, XMW) for this purpose.

At the beginning of the operation, the tool position relative to the part must be

defined. Using a special instruction (reference point traverse), the tool carriage is

traversed so that the carriage reference point F is identical with the reference point

R, which has an exactly defined position on the machine. Prior to the actual

machining operation, the required tools are inserted into the carriage with their

respective tool pre-positions and the clamping dimensions (ZFP, XFP, see

Fig. 5 and cf. chapter 1.2.3) are entered in the tool file. The programmer thus knows

the precise starting position of the tool tip in the working space of the machine and

can calculate the tool motion paths starting from this point. Any deviations of the tool

dimensions from the ideal values, e.g. as a result of wear, may be entered in the

AM

R

W

E

A

M

R

W

E

F, N

F

XEP, ZEP

XWR, ZWR

XMR, ZMR

ZMW

ZMW

XM

R,

XW

R

ZMRZWR

XE

P

ZEP

P

Län

ge

N

E

machine origin

clamping stop

workpiece reference point

tool reference point

slide, tool holder reference point

tool change position

reference point

tool lengths from clamping point

distances part origin to reference point

distances between machine origin and reference point

distances between machine origin and path origin

tool tip

diameter

leng

th

Spindle

tool

P


7

compensation value memory of the NC control. These compensation values are,

however, valid only for this respective tool.

1.2.2.2 Presentation of information

The structure of control programmes for NC machines, often also referred to as part

or NC programmes, is laid down in DIN 66025. The NC programme is composed of a

series of blocks, each block representing one working step of the machine. The

individual data in a block are termed words or NC functions. Selected words are

given in the programming key in Appendix 1. The words themselves may be sub-

divided into address characters and a code. Table 1 reviews the most common

address characters.

Address

character

Meaning

N block number (number)

G path parameter

X, Y, Z path dimensions (absolute or incremental)

F Feed

S Speed

T Tool

M miscellaneous functions

Table 1: Address characters

Table 2 lists some words formed by combining the address character G with various

codes:

Word Meaning

G00 rapid traverse

G01 linear interpolation

G02 clockwise circular interpolation (cw = clockwise)

G03 anti-clockwise circular interpolation (ccw = counter-clockwise)

G04 dwell time

G33 thread cutting

G90 absolute dimension input

G91 incremental dimension input

Table 2: Selected G words


8

In order to traverse an arc, one needs to know not only the path end point (X,Z) but

also the centre point of the arc. The position of the centre point is given in the

functions I and K (Fig. 6).

G02

G03

G02

G02

G03

G03

x

y

z

z

x

E G03

A

Z K

I

X

M

Example:

Programming of a circlular movement within the x-z-plane for turning

A: starting pointE: end of the circular arcM: center

N047 G03 X1800 Z-1800 I-1000 K-2800

Encoding (G-functions) of circulararcs in the three planes determinedby an orthogonal, right handedcoordinate system.G02: circular arc, clockwise (cw)G03: circular arc, counter clockwise (ccw)

Fig. 6: Programming circles

1.2.3 Tool offset compensation

Programming the traversed paths, one refers directly to the part contour. The control

must transform these traversing instructions in such a way that the contour-forming

cutting edges of the tool are guided along this contour. Depending on the machining

process, various corrective calculations must be performed to compensate for the

real tool dimensions (Fig. 7) ). These dimensions are determined when the tool is set

up and are stored in the compensation value memory of the control. During the

machining operation, they are retrieved from this memory and included in the

computation.

The tool-clamping position of the tools has to be compensated both for turning and

for milling. It is taken into account as an offset value in calculating the path. Other

factors considered are the cross-path distance for turning and the cutter radius for

milling.


9

tool setting point

length L

cutter radius R

length L

Q

Fig. 7: Tool dimensions for compensation calculations

1.2.3.1 Cutting-edge radius compensation

cutting edge radius rs

idealized tip of the tool(no compensation)

monitored part of the cutting edge

programmed contourproduced contour

A

detail A

Fig. 8: Cutting-edge radius compensation for turning

Lathe tools have a radius at the tip of the cutting edge in order to reduce scoring

during the turning operation and to increase cutting-edge stability. Customary radii

range from 0.4 to 0.8 mm for finishing and up to 1 mm for roughing tools. It is

necessary to compensate the cutting-edge radius when computing the traverse

paths to avoid violating the contour (Fig. 8).


10

1.2.3.2 Milling cutter radius compensation

When compensating the cutter radius computing an equidistant path from the

programmed contour so that the programmed contour can be generated. Because

additional collision checks on inside contours are needed in this calculation (Fig. 9a)

and because intermediate blocks have to be inserted on the outside contours (Fig.

9b), the cutter radius compensation entails a much greater computing effort than the

cutting-edge radius compensation for turning.

R

R

avoidedcollision

programmedendpoints

virtual endpoint

remainingmaterial

cutter locationpath

R

cutter locationpath

automaticallygenerated circular arc

Fig. 9: Milling cutter radius compensation a) inside contour b) outside contour

In order to place the offset path on the correct side of the programmed contour, it is

also important to specify whether the cutter is to the left (G41) or to the right (G42) of

the programmed contour (in the direction of travel) when activating the

compensation.

1.2.4 Additional commands for programme input

Programming complex parts solely with the standardised instructions listed in DIN

66025 is extremely time-consuming. Virtually all modern control systems therefore

provide extended instruction sets for user-friendly programming. The disadvantage of

these extended sets is that they are not standardised. As a result, programmes

containing instructions of this kind cannot be transferred to other control systems, or

can be transferred only with considerable conversion effort.


11

1.2.4.1 Combined contours

G11 X... Z... B... R... K... L... X1=... Z1=... B1=... R1=... K1=... L1=... F.. S.. T.. M..

aiming point

angle(lieu X,Z)

radius

width ofchamfer

length(lieu X, Z)

aiming point

angle(lieu X1=,Z1=)

radius

width ofchamfer

length(lieu X1=, Z1=)

technologicaldata

1. Line

2. Line

Fig. 10: Combined contour programming using the G11 instruction (Source: TRAUB)

Combined contours can be used to programme a number of contour elements in a

single NC block. Fig. 10 shows an example. Using the instruction in Fig. 10, two or

three traversing instructions can be combined into one while the control unit can

compute unknown coordinate values automatically.


12

LR

L1

K1B

B1

1.aiming point1. line

starting point1. line

aiming point2. line

aiming point ofnext scentence

Fig. 11a: Polar coordinates

X

X1

Z Z1

K

R1

1.aiming point1. line

aiming point2. linestarting point

1. line

aiming point ofnext scentence

Fig. 11b: Cartesian coordinates

Fig. 10 and Fig. 11a/b explain how exactly the G11 instruction is to be used.

Basically this specific instruction can be programmed with polar as well as Cartesian

coordinates. The following example programmes the contour of the part shown in

Fig. 12. Beginning at P1, the first section of the contour is programmed in polar

coordinates and the second section, from P2 onwards, with Cartesian coordinates.

The entire contour is then re-entered using the G01/G02 instructions for comparison.

1. Contour from P1 to P2 in polar coordinates: G11 B90 R7 L60 B1=0 K1=20 L1=88

2. Contour from P2 to P1 in Cartesian coordinates; G11 X100 Y7 R20 X1=12 Y1=7 K1=20

3. Contour using G01/G02: G01 X12 Y80 G02 X19 Y87 I7 J0 G01 X80 G01 X100 Y67 G01 Y27 G02 X80 Y7 I-20 J0 G01 X32 G01 X12 Y27


13

10

5W

Z

X

W

87 1

00

80

100

120

64

67

32

120

27

12

7

P1

P2

X

Y

R7

R20

Fig. 12: workpiece drawing

1.2.4.2 Sub-routines

Sub-routines are used if a particular series of instructions is repeated frequently in a

programme, for example when programming drilling patterns. In such cases, it is

useful to store the relevant series of instructions in a sub-routine which can be

invoked repeatedly from the main programme. This technique reduces the total size

of the programme and makes it easier to understand by saving the relevant

information for the instruction series centrally. Optional transfer of parameters from


14

the main programme to the sub-routine also enables the programmer to use the sub-

routine for different applications.

1.2.4.3 Cycles

Cycles are sub-routines permanently implemented in the control system. Most

control systems provide cycles for standard tasks in the corresponding machining

operations. For turning these are, for example, roughing or chamfer-turning cycles;

for milling, cycles for milling slots and pocket holes are frequently provided. Drilling

cycles are relevant to both machining technologies. Fig. 13 shows a cycle for slot

milling.

cutter location path

cutter location path

Fig. 13: Slot milling cycle

1.3 References

1. Weck, M.; Brecher, C. Werkzeugmaschinen / Fertigungssysteme, Band 4: Automatisierung von Maschinen und Anlagen Springer-Verlag, Berlin, 2006

2. N.N. DIN 66025, Teil 1 und Teil 2: Programmaufbau für numerisch gesteuerte Arbeitsmaschinen Beuth-Verlag, Berlin, 1983

3. Kief H.B. NC/CNC Handbuch, Carl Hanser Verlag, München Wien, 1999


15

2 Exercise

2.1 Programming exercise

In order to manufacture a part (Fig. 14) on an NC lathe, a NC programme must be

written. The lathe, tools, self-centring chuck and clamping position are given.

15 25 15 15 10

Ø 4

0

Ø 5

0

Ø 1

00

60

60

190

Futter Spannbacken

M

R

W

Fig. 14: Technical drawing of the part

Two tools stored in position 1 and position 2 of a tool-changer shall be used for the

operation. Compensation value memories 6 and 7 are chosen for any tool length

compensations. Tool 1 is to be used for roughing and tool 2 for finishing. The tools

have no cutting-edge radius and are placed pre-adjusted in the tool carrier.

chuck yaw


16

Owing to the work material/tool material combination and the installed machine

power, a constant cutting speed of 100 m/min is to be used. In order to ensure good

chip formation, the decisive parameters for the chip cross-section have been chosen

as follows:

Depth-of-cut: a = 10 mm

Feed (roughing): s1 = 0.5 mm/rev.

Feed (finishing): s2 = 0.1 mm/rev.

The pre-processed blank has the following dimensions:

Diameter: D = 100 mm

Length: L = 80 mm

The finishing allowance is to be 1 mm.

The feed rate can be programmed only in mm/min. With absolute dimension

programming, the x-axis must be programmed in diameter values; with incremental

dimensions, simple traverse displacements are entered in the x-axis.

Create the NC programme and fill out the coding sheets (see chapter 2.4).

Pratyush

Hervorheben


17

2.2 Solution

Step 1

The allowance is removed in a series of longitudinal cuts (Fig. 15). Points 1—18

mark the end points of the NC blocks representing tool movements.

15 25 15 15 10

20

5

starting point of theroughing operation(tool 1)

starting point of the finishing operation(tool 2)

12

3 4

56

7 8

910

1112

13

1415

1617

18

2 safety distance

z

x

Fig. 15: Cut division

Considering the maximum depth-of-cut of 10 mm and the finishing allowance of 1

mm, three cuts are needed for roughing and one cut for finishing.

The coordinate values for the first cut (1-2) are calculated as an example. Xs, and Zs

are the coordinates of the corresponding end-of-block point.


18

zs

40

r

b

h

26

50

xs

According to the drawing: mmr 24=

hmmxs

−= 50

bmmzs

−= 40

It may be stated that: 222bhr +=

22hrb −=

For the first step, taking mmah 10== , the result is:

mmmmb ==

mmx =2,1

mmz =2

For the second step, taking mmh == :

mmx =6,5

mmz =6


19

Point x[mm] z[mm]

1

2

3

4

5

6

7

.

.

Step 2

The technology values for the speed and feed rate are determined.

According to the task:

v = 100 m/min = const.

s1 = 0,5 mm/Umdr. (roughing)

s2 = 0,1 mm/Umdr. (finishing)

The following relationship between the cutting speed, the turned part diameter and

the speed is:

ndv π=

Using

d

vn

π=

it follows, that for Step 1:

=1n

and for the feed rate: nsu =

=1u


20

For the remaining steps, it follows that:

Cut Feed d [mm] n [min-1

] u [mm/min]

1 - 2 s1

5 - 6 s1

9 - 10 s1

10 - 11 s1

12 - 13 s1

14 - 15 s2

15 - 16 s2

17 - 18 s2

Step 3

A zero shift is used to move the machine zero point M to the part zero point W. This

simplifies defining the movement instructions, since the dimension data from the

part drawing can largely be transferred to the NC programme.

Generally speaking, there are two different methods of zero shifting.

The first uses instructions G53 to G59 and shifts the zero point starting from a

reference point known to the control. A reference point in this sense could, for

example, be the machine zero point M or a previously defined part reference point

W.

Example: G54 X0 Z60

Instruction G54, refers the part coordinate system to the machine zero point. The

machine coordinate system is shifted by a value of 0 mm in the x-axis and by a value

of 60 mm in the z-axis.


21

The second method of zero shifting is to set the actual value memory using

instruction G92. The values for the current position are set in the memory and can

therefore be used to specify the part zero point indirectly.

If, for example, the carriage reference point F is at the reference point and if the

distance of the reference point R from the part zero point W in the different axes

(XWR, ZWR) is known (60 mm in the X- and 130 mm in the Z-axis, Y=0), these

values can be set in the actual value memory and establish the position of the

reference point in relation to the part zero point.

Example: G92 X60 Z130

(Note: There is no need for zero shifting if the position of the tool at the beginning of

the machining operation is known and if all dimensions are programmed

incrementally.)1

Step 4

The NC programme is drafted and is encoded with the aid of the programming key

(see chap. 2.3).

1 It should be noted here that the use of these instructions often varies on different control systems. It

is, for example, possible that, when instruction G54 is invoked, the magnitude of the shift need not be

specified explicitly in the NC programme, but has already been communicated to the control before the

beginning of the operation. Instruction G54 will then only retrieve the saved values.


22

2.3 Programming key

Code Function and meaning

% Start of programme

: 1 to 9999 Main block N Block number /: Maskable main block

/N Maskable block

G 00 Rapid traverse 01 Linear interpolation 02 Clockwise circular interpolation 03 Counter-clockwise circular interpolation 33 Thread cutting

G � 04 Dwell time defined in ms at address X

G 17 Plane selection X-Y 15 Plane selection X-Z 19 Plane selection Y-Z

G 39 Corner correction for cutter radius path compensation

G 40 Cancel tool compensation 41 Tool path compensation left, tool left of part 42 Tool path compensation right, tool right of part

G 53 No zero shifting

G 54 Zero shifting 1 55 Zero shifting 2

G 70 Input system inches 71 Input system metrical

G 80 Cancel work cycle 81 to 89 Work cycles

G 90 Absolute dimension inputs 91 Incremental dimension inputs

G � 92 Set actual value memory

G 94 Feed in mm/min at address F 95 Feed in mm/U at address F

D 1 to 99 Tool compensation number

X 0 to ± 99999,999 Displacement information in mm 1 to 99999,999 Dwell time in ms

Y 0 to ± 99999.999 Displacement information in mm

Z 0 to ± 99999,999 Displacement information in mm

4th axis 0 to ± 99999,999 Displacement information in mm or degrees Possible addresses A, B, C, U, V, W

R 0 to n Parameters (e.g. for sub-routines)

I 0 to ± 99999,999 Interpolation parameters for X-axis for circular interpolation or 1 to 2000,000 Thread lead in mm

J 0 to ± 99999,999 Interpolation parameters for Y-axis for circular interpolation or 1 to 2000.000 Thread lead in mm

K 0 to ± 99999,999 Interpolation parameters for Z-axis for circular interpolation or 1 to 2000,000 Thread lead in mm

F 0 to Fmax Feed in mm/min or mm/U

S 0 to Smax Spindle speed in min-1

T 1 to 9999 Tool number

H 1 to 999 Auxiliary function

L 01 to 99 Number of sub-routine to be invoked

M � 00 Programmed stop, unconditional 01 Programmed stop, conditional 02 End of programme without rewind, in final block of programme 30 End of programme with rewind to start of programme, in last block of

programme

M 03 Spindle rotation clockwise 04 Spindle rotation counter-clockwise 05 Spindle stop

M 00 to 99 Extra functions, some freely programmable

( Start of comment ) End of comment

LF End of block

� only valid for one NC-block (current line of program), all others are modal


23

2.4 Coding sheet

Comment Spindle speed Feed

x[mm] z[mm] n[min-1

] u[mm/U]

Beginning of program

1 Zero shift

2 Spindle on, Tool 1

3 Absolute dimensioning

4 Infeed R->1

5 1st cut 1->2

6 Retract 2->3

7 Move back 3->4

8 Infeed 4->5

9 2nd cut 5->6

10 Retract 6->7

11 Move back 7->8

12 Infeed 8->9

13 Incremental dimensioning

14 3rd cut 9->10

15 Dwell time

16 4th cut 10->11

17 5th cut 11->12

18 Dwell time

19 6th cut 12->13


21 Return to R R

22 Tool change

23 Infeed R->14

24 Incremental dimensioning

25 7th cut 14->15

26 Dwell time

27 8th cut 15->16

28 9th cut 16->17

29 Dwell time

30 10th cut 17->18


32 Return to R, Sp. off

33 End of program

Movement


24

N G X Z I K F S T M

%

N10

N20

N30

N40

N50

N60

N70

N80

N90

N100

N110

N120

N130

N140

N150

N160

N170

N180

N190

N200

N210

N220

N230

N240

N250

N260

N270

N280

N290

N300

N310

N320

N330


25

3 Bonus task

3.1 Introduction

The machining operation for a flute shall be demonstrated on a TRAUB TNS 65 D

lathe (Fig. 16). The technical drawing of the flute is shown in Fig. 17. The raw

material is an aluminium shaft section measuring ∅30x130. All machining steps,

including drilling and milling, can be performed on this machine. Powered tools are

available for milling and drilling. The part can be transferred to a counter-spindle for

rear-side machining.

Fig. 16: Lathe TRAUB TNS 65 D

The lathe has two tool carriages which can work simultaneously. For example, one

carriage can carry out a roughing operation while the second, slightly offset, performs

the finishing step. This greatly reduces manufacturing times. The NC programme

runs on two separate channels, one for each cut. Each channel behaves like an

autonomous NC programme, but both channels are run simultaneously.

In order to avoid collisions between the two carriages, however, it is essential to

synchronise the channels. Synchronising labels (exclamation marks “!” are used as

synchronising labels on the TRAUB TX 8D) are integrated in the programme code.

When the programme for a carriage reaches one of these labels, it waits until the


26

programme for the other carriage has also reached it. Both programmes are then

continued.

A separate NC programme is written for each tool carriage. These run in the two

channels, designated $1 for carriage 1 and $2 for carriage 2. The table below lists

the two programmes alongside one another. The synchronising labels (“!”) are easily

recognized. The second programme begins with an exclamation mark. It continues

only when the first programme also reaches an exclamation mark. In this case, two

exclamation marks are in fact placed one after the other to ensure that the two

programmes never run simultaneously. At each exclamation mark, machining is

effectively switched to the other carriage.

In the machining operation, both tool carriages are used, but for the sake of simplicity

they never contact the part simultaneously. The turret of the first carriage contains

the powered tools (milling cutters and drills) and the counterspindle. The second

carriage holds the lathe tools for roughing and finishing.


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Fig. 17: Workpiece: Flute


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For easier understanding of the rather more complex NC programme (8 pages), the

actual machining steps have been stored in sub-routines (SR). The main programme

reproduced below lays down only the general sequence of machining steps,

indicating which tool carriage is used for each step. The individual sub-routines are

invoked by instruction G22, the number of the sub-routine being specified at address

A (in this case 8017 – 8030).

Carriage 1 Carriage 2 Comment $1 $2 Select carriage

G59 X0 Z294.7 Part additive zero shifting

G22 A8018 SR prepare

! ! Synchronising label

G59 X0Z294.7 Part additive zero shifting

G22 A8017 SR prepare

! !

G22 A8019 SR press down part

! !

G22 A8020 SR rough mouthpiece

! !

G22 A8022 SR drill holes in mouthpiece

G22 A8023 SP mill mouthpiece

G22 A8024 SR mill air gap

! !

G22 A8021 SR finish mouthpiece contour

! !

G22 A8025 SR transfer to counterspindle

G59 Z364.7 Part additive zero shifting

G22 A8026 SR position counterspindle

! !

G59 Z364.7 Part additive zero shifting

G22 A8027 SR rough second side

G22 A8028 SR finish second side contour

G59 X0 Z0 Part zero shifting OFF

! !

G22 A8029 SR drill and bore

G22 A8030 SP flush flute

G59 X0 Z0 Part zero shifting OFF

! !

M30 M30 End of programme

Table 3: Main programme for machining the flute

The complete NC programme is listed in the appendix. Some of the machining steps,

especially the milling operations, are highly complex and too specific to be dealt with

in detail as part of this exercise. However, those who are interested should not feel

deterred from taking a closer look at the NC programme.


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3.2 NC programme for test part

Main programme 20 (flute)

% O20 (00-00 -0000 00:00) $1 NC channel for carriage 1 (FL0ETE HAUPTPR0GRAMM) G59 X0 Z294.7 Additive zero shifting G22 A8018 Sub-routine prepare

! ! G22 A8019 Sub-routine press down part

! ! G22 A8022 Sub-routine drill holes in mouthpiece

G22 A8023 Sub-routine mill mouthpiece

G22 A8024 Sub-routine mill air gap

! ! G22 A8025 Sub-routine transfer to counterspindle

G59 Z364.7 G22 A8026 Sub-routine position counterspindle

! ! G22 A8029 Sub-routine drill and bore

G22 A8030 Sub-routine flush flute

G59 X0 Z0 ! M30 End of programme $2 NC channel for carriage 2 ! G59 X0 Z294.7 G22 A8017 Sub-routine prepare

! ! G22 A8020 Sub-routine rough mouthpiece

M10 ! ! G22 A8021 Sub-routine finish mouthpiece contour

! ! G59 Z364.7 G22 A8027 Sub-routine rough second side

G22 A8028 Sub-routine finish second side

G59 X0Z0 ! ! M30 End of programme %

Sub-routine 8017 (prepare carriage 2)

% O8017 (00-00 -0000 00:00) $1 (FL V0RBEREITEN) G26 Rapid traverse to tool change position T101 Select roughing tool M99 End of sub-routine %


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Sub-routine 8018 (prepare carriage 1)

% O8018 (00-00 -0000 00:00) Sub-routine 8018 $1 (FL V0RBEREITEN) M71 Release tailstock G28 R869 Reference point traverse M72 Fix tailstock M29 Tailstock quill back G27 Rapid traverse to tool change position

bottom T505 Select tool pressure pin M99 End of sub-routine %

Sub-routine 8019 (press down part)

% O8019 (00-00 -0000 00:00) $1 (FL ANDRUECKEN) G00 Z10 X0 Z-5 M11 Release part M10 Clamp part G04 X1 Wait 1 second G27 Rapid traverse to tool change position M07 Cooling lubricant ON – high pressure M99 End of sub-routine %

Sub-routine 8020 (rough mouthpiece)

% O8020 (00-00 -0000 00:00) $2 ( FL MUNDSTK.SCHRUPP) G27 Rapid traverse to tool change position T505 G00 Z0 X35 M07 Cooling lubricant ON – high pressure G96 S250 M04 G01 X-1 F0.1 X25.5 Z-87 F0.2 X30 G00 Z1 X22 G01 Z-8 X25.5 Z-16.5 G97 M05 Speed constant G26 Rapid traverse to tool change position M09 Cooling lubricant OFF M99 End of sub-routine %

Sub-routine 8021 (finish mouthpiece contour)

% O8021 (00-00 -0000 00:00) $2 (FL MUNDSTK.K0NTUR)


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G27 Rapid traverse to tool change position

T303 G00 Z1 X15 M07 G96 S250 M04 G46 Cutting-edge radius compensation ON G01 X19 Z0 F0.1 G03 P19 Q-1.5 G02 X19 Z-4.1 R1.5 G01 Z-8 X25.5 Z-16.5 Z-55 G03 I-18 K0 G02 X22.577 Z-77.895 R20 G03 X25.5 Z-85 I-16.539 K-7.105 G01 X32 G00 Z-8 X25 G01 Z-55 F0.05 G03 I-18 K0 F0.1 G02 X22.077 Z-77.895 R20 G03 X25 Z-85 I-16.539 K-7.105 G40 G01 X32 G97 M05 Spindle rotation constant G26 Rapid traverse to tool change position

M07 Cooling lubricant ON – high pressure M99 End of sub-routine %

Sub-routine 8022 (drill holes in mouthpiece)

% O8022 (00-00 -0000 00:00) $1 (FL L-L0ECHER) G27 Rapid traverse to tool change position T101 B 063200 M22 M23 G97 M05 Speed constant G94 Feed in mm/min M17 C-axis operation ON G28 C0 Reference point traverse M73 C-axis damping brake closed G01 X50 Z2 F5000 G01 X15 Z1 F5000 G01 Z-2 F64 M07 G00 Z1 G83 Z-25D4H15 F140 G00 Z1 M74 C-axis damping brake open G00 C-54 M73 C-axis damping brake closed G01 Z-2 F64 G00 Z1 G83 Z-23 D4 H15 F140 G00 Z1 M74 C-axis damping brake open G00 C-27 M73 C-axis damping brake closed G01 Z-2 F64 G00 Z1 G83 Z-25 D4 H15 F140 G00 Z1 M74 C-axis damping brake open


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G00 C27 M73 C-axis damping brake closed G01 Z-2 F64 G00 Z1 G83 Z-25 D4 H15 F140 G00 Z1 M74 C-axis damping brake open G00 C54 M73 C-axis damping brake closed G01 Z-2 F64 G00 Z1 G83 Z-23 D4 H15 F140 G00 Z1 M18 C-axis operation OFF M22 M25 G27 Rapid traverse to tool change position M09 Cooling lubricant OFF M99 End of sub-routine %

Sub-routine 8023 (mill mouthpiece)

% O8023 (00-00 -0000 00:00) $1 (FL MUNDSTK.FRAESEN) G97 M05 Speed constant G94 Feed in mm/min G27 Rapid traverse to tool change position T1111 Tool ball-end mill cutter M07 Cooling lubricant ON – high pressure M17 C-axis operation ON G28 C0 Reference point traverse B061600 M22 M23 Auxiliary spindle ON G00 X42 Z-16.5 G11 Milling function ON G17 Milling plane face G02 X-12.5 Y-16.875 P0 A0 F1000 G01 X-12.5 Y21 A0 F80 X-12.4 X-12.4 Y-21 F40 G00 Z1 G10 M18 C-axis operation OFF M22 M25 G27 Rapid traverse to tool change position M09 Cooling lubricant OFF M99 End of sub-routine %

Unterprogramm 8024 (Luftspalt fräsen)

% O8024 (00-00 -0000 00:00) $1 (FL L-FRAESEN) G26 Rapid traverse to tool change position T909 M17 C-axis operation ON G28 C0 Reference point traverse G00 Z-22 X90 M07 B 060300 M22 M24 G94 Feed in mm/min G11 Milling function ON


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G17 Milling plane face G00 X45 Y0 Z-35.670 G02 X41.25 Y-17.984 P0 A0 F5000 M73 C-axis damping brake closed G01 Y17.984 F400 G02 X39.75 Y-21.094 P0 A0 F5000 G00 Z-33.072 G01 Y21.094 F400 G02 X38.25 Y-23.705 P0 A0 F5000 G00 Z-30.474 G01 Y23.705 F400 G02 X36.75 Y-25.970 P0 A0 F5000 G00 Z-27.876 G01 Y25.970 F400 G02 X35.25 Y-27.972 P0 A0 F5000 G00 Z-25.278 G01 Y27.972 F400 G02 X33.45 Y-30.101 P0 A0 F5000 G00 Z-22.160 G01 Y30.101 F400 G02 X33.36 Y-30.201 P0 A0 F5000 G00 Z-22 G01 Y30.201 F400 Y-30.201 F200 G00 Z20 G10 M18 C-axis operation OFF M22 M25 G27 Rapid traverse to tool change position M09 Cooling lubricant OFF M99 End of sub-routine %

Sub-routine 8025 (transfer to counterspindle)

% O8025 (00-00 -0000 00:00) $1 (FL UEBERNEHMEN GEGENSPINDEL) G27 Rapid traverse to tool change position T707 Select counterspindle G00 Z5 X0 G97 M05 Speed constant M22 M25 M67 G94 Feed in mm/min G01 Z-41 F1000 M66 G04 X1 M11 G04 X1 G01 Z29 M99 End of sub-routine %

Sub-routine 8026 (position counterspindle and turn)

% O8026 (00-00 -0000 00:00) $1 (FL GEGENSP.P0SITI0N+DREHEN) G27 Rapid traverse to tool change position T707 Select counterspindle


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G00 Z-41 X0 B062500 M22 M23 M99 End of sub-routine %

Sub-routine 8027 (rough second side)

% O8027 (00-00 -0000 00:00) $2 (FL 2.SEITE SCHRUPPEN) G26 Rapid traverse to tool change position T404 G00 Z-120 X32 G94 Feed in mm/min G01 X-1 F500 G46 Cutting-edge radius compensation ON G01 X24 X25.2 Z-119.5 Z-78 G40 G26 Rapid traverse to tool change position M99 End of sub-routine %

Sub-routine 8028 (finish contour second side)

% O8028 (00-00 -0000 00:00) $2 (FL 2.SEITE K0NTUR) G26 Rapid traverse to tool change position T303 G00 Z-78 X25 G94 M07 Feed in mm/min G01 Z-102.056 F250 G03 P22 Q-102.056 G02 X24 Z-105.41 R1.5 G03 P22 Q-106.528 G02 X24 Z-109.882 R1.5 G03 X25 Z-111 P22 Q-111 G01 Z-122 G40 G26 Rapid traverse to tool change position M09 Cooling lubricant OFF M99 End of sub-routine %

Sub-routine 8029 (drill and bore)

% O8029 (00-00 -0000 00:00) $1 (FL B0HREN + AUSDREHEN) G27 Rapid traverse to tool change position G94 Feed in mm/min B060800 M22 M23 M32 G59 X-330.65 Z378.3 T1313 G00 X0 Z1 M53 G83 Z-98D20H15 F120


35

G00 Z1 G27 Rapid traverse to tool change position T1414 G00 X0 Z1 G01 Z-92 F1000 Z-98.1 F100 G04 X1 G00 Z1 G27 Rapid traverse to tool change position T1515 G00 X0 Z1 G01 Z-34 F120 G00 Z1 G27 Rapid traverse to tool change position T1616 G00 X23.5 Z1 B062000 M22 M24 G01 Z0 F200 X22.5 Z-0.5 Z-9.5 X21.6 Z-28 X21 G00 Z1 G27 Rapid traverse to tool change position M22 M25 M09 M33 T1700 M99 End of sub-routine %

Sub-routine 8030 (flush flute)

% O8030 (00-00 -0000 00:00) $1 (FL SPUELEN) G27 Rapid traverse to tool change position T505 M07 Cooling lubricant ON – high pressure G04 X5 M17 C-axis operation ON G28 C0 Reference point traverse G04 X2 G00 C60 G04 X2 G00 C120 G04 X2 G00 C180 G04 X2 G00 C240 G04 X2 G00 C360 G04 X2 G00 M18 C-axis operation OFF T707 B063000 M22 M23 M53 G04 X4 M55 M09 M22 M25 M99 End of sub-routine %

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