AUTOMATICALLY PROGRAMMED TOOLS(APT)

Submitted by:Amit Kumar ChauhanMT13IND001

INTRODUCTION OF APT The APT language was the product of MIT development work on NC

programming systems. Its development began in June 1956, and it was first used in production

around 1959. Today it is the most widely used language in NC part programming. Although first intended as a contouring language , modern versions of APT

can be used for both positioning and continuous path programming.

TYPES OF STATEMENTS IN APTThe four types of statements in the APT language are:

1. Geometry Statements: which define primitive elements such as points, lines, circles, planes, cones and spheres. They are also sometimes called definition statements

2. Motion Statements: which describe the tool path in relation to the part geometry

3. Postprocessor Statements: which give specific machine tool code information as well as feeds and speeds

4. Auxiliary Statements: which give part and tool tolerances

1. GEOMETRY STATEMENTS The general form of geometry statements is:

symbol = geometry type / descriptive data

An example of such statement is:

P1 = POINT/100.0, 200.0, 300.0 The statement is made up of three sections. The first is the symbol use to identify the geometric element. Normally the

alphabet “P” is used for defining a Point, “C” for Circle, “L” for Line and “Pl” for Plane.

The second section of the geometry statement is an APT vocabulary word that identifies the type of geometry element. e.g. POINT, LINE, CIRCLE, PLANE, etc.

The third section of the geometry statement is the descriptive data

DEFINITION OF POINT-1: ( COORDINATE VALUES )

P1 = POINT/2,2,2

X

Y

P1

2

2

DEFINITION OF POINT-2: (INTERSECTION OF TWO PREVIOUSLY DEFINED LINES)

P2 = POINT / INTOF,L1,L2

P2

L2

L1

DEFINITION OF POINT-3: (INTERSECTION POINT OF A PREVIOUSLY DEFINED LINE AND CIRCLE)

P3 = POINT / XSMALL, INTOF, L1, C1

Or P3 = POINT / YSMALL, INTOF, L1, C1

P4 = POINT / XLARGE, INTOF, L1, C1

Or P4 = POINT / YLARGE, INTOF, L1, C1

P3

C1

L1

P4

Y

X

DEFINITION OF POINT-4: (INTERSECTION POINT OF TWO PREVIOUSLY DEFINED CIRCLES)

P3 = POINT / XSMALL, INTOF,C1,C2

Or P3 = POINT / YLARGE, INTOF, C1,C2

P4 = POINT / XLARGE, INTOF, C1,C2

Or P4 = POINT / YSMALL, INTOF, C1,C2

P3

P4

C1

C2

Y

X

DEFINITION OF POINT-5: (ON THE CIRCUMFERENCE OF A PREVIOUSLY DEFINED CIRCLE )

P2 = POINT / C1,ATANGL,75

P2

X

C1

75°

DEFINITION OF POINT-6: (CENTER POINT OF A PREVIOUSLY DEFINED CIRCLE )

P2 = POINT / CENTER, C1

C1

P2

DEFINITION OF LINE-1: (PASSING THROUGH TWO PREVIOUSLY DEFINED POINTS)

L1 = LINE/P1,P2

L1P2

P1

DEFINITION OF LINE-2: (PASSING THROUGH A PREVIOUSLY DEFINED POINT AND TANGENT TO A PREVIOUSLY DEFINED CIRCLE)

L3 = LINE / P1, RIGHT, TANTO, C1

L4 = LINE / P1, LEFT, TANTO, C1

The RIGHT or LEFT modifiers are applied by looking from the point to the circle and deciding whether the line will pass to the right or left of the circle.

P1

C1

L3

L4

DEFINITION OF LINE-3: (TANGENT TO TWO PREVIOUSLY DEFINED CIRCLES)

L1 = LINE / LEFT, TANTO, C1, LEFT, TANTO, C2 L1 = LINE / RIGHT, TANTO, C2, RIGHT, TANTO, C1 The RIGHT & LEFT modifiers are applied looking from the first circle

quoted to the second

L1

C2

C1

DEFINITION OF LINE-3: CONTD. (TANGENT TO TWO PREVIOUSLY DEFINED CIRCLES)

L3 = LINE / LEFT, TANTO, C1, RIGHT, TANTO, C2

L4 = LINE / RIGHT, TANTO, C1, LEFT, TANTO, C2

C1

L4

L3C2

DEFINITION OF LINE-4: (PASSING THROUGH A PREVIOUSLY DEFINED POINT AT A SPECIFIED ANGLE TO THE X-AXIS)

L2 = LINE / P1, ATANGL, 30

L2 = LINE / P1, ATANGL, -150

L2

30°P1

150°

Y

X

DEFINITION OF LINE-5: (PASSING THROUGH A PREVIOUSLY DEFINED POINT, PARALLEL TO A PREVIOUSLY DEFINED LINE)

L3 = LINE/P3,PARLEL,L2

L3

P3

L2

DEFINITION OF LINE-6: (PASSING THROUGH A PREVIOUSLY DEFINED POINT, PERPENDICULAT TO A PREVIOUSLY DEFINED LINE)

L3 = LINE/P1,PERPTO,L2

L3L2

P1

DEFINITION OF CIRCLE-1: (COORDINATES OF CENTER OF CIRCLE, WITH A GIVEN RADIUS)

C1 = CIRCLE/X,Y,R

(X,Y)

C1

R

DEFINITION OF CIRCLE-2: (PREVIOUSLY DEFINED CENTER POINT AND TANGENT TO A PREVIOUSLY DEFINED LINE)

C2 = CIRCLE/CENTER,P1,TANTO,L2

P1C2

L2

DEFINITION OF CIRCLE-3: (PREVIOUSLY DEFINED CENTER POINT AND PASSING THROUGH ANOTHER PREVIOUSLY DEFINED POINT)

C2 = CIRCLE/CENTER,P1,P2

P1C2

P2

DEFINITION OF CIRCLE-4: (PASSING THROUGH THREE PREVIOUSLY DEFINED POINTS)

C3 = CIRCLE/P1,P2,P3

C3

P2

P3

P1

DEFINITION OF PLANE: (BY THREE PREVIOUSLY DEFINED POINTS)

PL4 = PLANE/P1,P2,P3

2. MOTION STATEMENTS APT motion statements have a general format: motion command / descriptive data e.g. GOTO / P1 At the beginning of the motion statements tool must be given a starting

point FROM / P0 Or FROM / -2, -2, 0 The FROM is an APT vocabulary word which indicates that this is the

initial point from which others will be referenced. The FROM statement occurs only once at the start of the motion sequence.

In APT there are two basic types of motion statements:

a) Point to Point motionb) Contouring motion

A) POINT TO POINT MOTION There are only two basic point to point motion commands

GOTO:

The GOTO statement instructs the tool to go to a particular point location specified in the descriptive data.

e.g. GOTO / P2

GOTO / 2, 7, 0

GODLTA:

The GODLTA command specifies an incremental move for the tool.

e,g, GODLTA / 2, 7, 0 instructs the tool to move from its present position to 2 units in x-direction, 7 units in y-direction and 0 units in z-direction

B) CONTOURING MOTION In contouring motion commands the tool position must be continuously

controlled throughout the move. For contouring movements, the tool is directed along intersecting surfaces. These surfaces have specific names in APT.

Drive Surface (DS): the surface against which the edge of tool rides. Part Surface (PS) : the surface on which the bottom end of the tool rides. Check Surface (CS) : the surface at which the tool motion is stop.

HOW TO APPROACH THE CHECK SURFACE Modifier words, such as TO, ON, PAST or TANTO, are used to govern the

position of the tool in relation to the check surface.

HOW TO USE THE DRIVE SURFACE Motion statements, GOLFT (go to the left), GOFWD (go forward) and

GORGT(go to the right), are also used to control the cutter motion.

3. POST PROCESSOR STATEMENTPost processor command for a particular tool are :MACHIN/ : use to specify the machine tool and call the post processor for the tool. e.g.- MACHIN/DRILL,3COOLNT/ : allow the coolant fluid to be turned on or off. e.g.- COOLNT/OFF COOLNT /ON COOLNT/FLOOD COOLNT/MISTFEDRAT/: specifies the feed rate for moving the tool along the part surface in inches per minutes: e.g.- FEDRAT/4.5SPINDL/: gives the spindle rotation speed in revolution per minute. e.g.- SPINDL/ 850FINI: end of program

4. AUXILIARY STATEMENTS

• It give part and tool tolerances.• The statement used for this are INTOL/0.0015 OUTTOL/0.001

Thank you