Chapter 2CANNED CYCLES AND SUBROUTINES

"Canned" ?

The word "canned" has probably been borrowed from canned goods, which one usually stores away for later use.

CANNED CYCLES

"Cycle" ?

Because the instructions represented a set of routine like repetitive patterns.

CANNED CYCLES

Canned cycles & G-code address

These canned cycles are filed away under a standardized G-code address

G84

G81

G82

G83

G76

G84

G85

G86

Types of canned cycles

1-Milling and Drilling Canned cycles

2- Turning Canned cycles

Usually, in one tape block, the canned cycle will control all or most of the following motions:

• Positioning the tool in the X-Y plane • Rapid motion to the "R" level, Rapid Down To• Controlled feed motion to the "Z" level,• Commanded motions at "Z" level, such as dwell, spindle stop, spindle reverse, spindle orientation, spindle lateral shift, etc.,• Rapid or feed return to "R" level, as applicable, and• Rapid return to INITIAL level.

Tapping canned cycles

Consist of the following steps:•Clockwise rotating of the tap at the correct rpm• Rapid advancing of the tap to (R-level)- Rapid Down To• Feeding the rotating tap to a set depth at a rate of one thread pitch per revolution (or mm/rev, or in in. /rev.)• Reversing both feed and spindle rotation •Feeding the rotating tap until the tap reaches the R-Level• Returning spindle rotation to its original clockwise direction

The spindle is now ready to rapidly return "home" for a tool change, relocate to another position or carry out any other instruction of the program.

Similar motion patterns are available for drilling, boring, turning, threading, etc.

N G G X Y Z R Q P F L

N is the sequence number of the block

G is the respective canned cycle (e.g., G81, G84, G73, G76, etc.)

The second G may be G98 or G99.

G98 will return the tool point to the initial level. ( Save Rapid Level)

G99 will return the tool point to R level;

X and Y are the coordinates of the location to be machined

General format of the fixed Milling canned cycle is the following:

Z is the level attained by the tool in feed modeR is the level reached by the tool at the end of its rapid motionQ is the depth of cut in feed in peck drilling P is the dwell in spot facing or boring operationsF is the feed L is the number of repeats, if applicable

The following observations apply to canned cycles for machining centers in general:• The tool motion starts in canned cycle from an Initial Level.• The tool will move in Rapid mode to the programmed X-Y location• The quill will move in Rapid mode to the R (for Rapid) Level. •The tool will feed to the Z-Level,

Z-Level is measured from Initial in absolute mode (G90) Z-Level is measured from R in incremental mode (G91).

Three levels of tool position in any canned cycle:• The Initial level, which is the specific position of the tool at the moment the canned cycle becomes effective,• The "R" for Rapid level, which is the end of the rapid quill motion, usually 0.020 to 0.100 inches (0.5 to 2.5 mm) from the part surface, and• The "Z" level which is the end of the feed (metal cutting) motion.

•If the tool is already on location, there is no need to program

X andY.

• A canned cycle is in effect until canceled (or replaced by

another canned cycle). Accordingly, subsequent locations can

be machined by simply programming X and Y in subsequent

blocks.

•If you do not intend to perform the canned cycle at the next

location, you must cancel it first (G80).

Z-Level is measured from Initial- Level in absolute mode (G90) Z-Level is measured from R- Level in incremental mode (G91).

AbsoluteIncremental

• Cutter Compensation ..................No.

Since X-Y motions are strictly for positioning and the programmed machining patterns take place in the Z-axis, no canned cycles are to be used in cutter diameter compensation mode.

•Canned Cycles for all systems are standard................No.Most systems provide numerous canned cycles as standard equipment, but not all systems use the same codes to designate the same cycles. Always use the codes provided by your system manual.

Drilling Canned Cycle G81:G81 Is a canned cycle for drilling holes in a single drill stroke. Its motion is rapid motion to R plane, feed down (into the hole) and rapid up (out of the hole) to the R level or to the initial Z level (Zinitial)

G81 Xn Yn Zn Rn Fn

Counter boring or countersinking holes cycle G82:G82 Xn Yn Zn Rn Fn Pn

Its action is similar to G81, except that it has a timed dwell at the bottom of the Z-stroke. Will spot face, bore, or counter bore. The canned cycle will perform as follows: Rapid to "R" , Feed to "Z," Dwell at "Z" for a duration given by "P" Rapid return to "R" or Initial depending on whether G99 or G98 was called in the program. One second is P100 and 3 seconds are P300,

Counter boring or countersinking holes cycle G82:G82 Xn Yn Zn Rn Fn Pn

Rapid to "R" , Feed to "Z," Dwell at "Z" for a duration given by "P" Rapid return to "R" or Initial depending on whether G99 or G98 was called in the program. One second is P100 and 3 seconds are P300,

Deep drilling canned cycle G83 :

•Hole depth > 3 times the drill's diameter.

•Prevent chips from packing in the drill's flutes, resulting in drill

breakage.

G83 Xn Yn Zn Qn Rn Fn

Deep drilling canned cycle G83 : •Drill in at feed rate a small distance (called the peck نقر increment) and then retract at rapid travel. •Then the drill advances at rapid travel back down to its previous depth, feeds in another peck increment, and rapids back out again.•Then it rapids back in, feeds in another peck increment, etc., until the final Z-depth is achieved. G83 Xn Yn Zn Qn Rn Fn

Deep drilling canned cycle G83 :

G83 will:G83 Xn Yn Zn Qn Rn Fn

1. Rapid to X-Y location and to "R" level,

2. Feed by the amount "Q"

3. Rapid return to "R"

4. Rapid in by "Q-d,"

5. Feed "Q" from there,

6. Rapid return to "R" thus removing the swarf from the part,

7. Rapid in by "2Q-2d"

8. Feed "Q" from there,

9. Rapid return to "R" etc.

The G84 The programmed feed must be fully synchronized with the spindle speed Before starting the tapping portion of the program, we have to set tapping speeds and calculate tapping feeds.

G84 Is a canned cycle for tapping. It coordinates the spindle's rotary motion to the Z-axis motion for feeding the tap into and out of the hole without breaking off the tap. G84 Xn Yn Zn Rn FnG81 Xn Yn Zn Rn Fn

G84 Xn Yn Zn Rn Fn

The G84 canned cycle will perform the tapping of one or more holes as follows: Rapid to "R" level, Feed to "Z-" level, Reverse direction of rotation at "Z-" level, Feed up to "R" level, Reverse direction of rotation to original direction.

Suppose the tapping speed has been selected to be 100 rpm (S100), What is the tapping feed (ipm) for 3/8 "-16 ?

1. Calculate the pitch in inch: Sixteen tpi represent a pitch of 1/16 or 0.0625 inch.

2-Find the feed per rev: Feed / rev = Pitch in inches =0.0625 inch/ rev.

3- Calculate the feed per minute Feed per minute = feed per rev * Speed (rpm) 100 x 0.0625 = 6.25 ipm, ( F6.25 )

Short Formula:

Divide the selected speed by the number of tpi.

Therefore, 100/16 = 6.25 and we program F6.25.

Using an "inch" tap in a metric program

Multiplying 6.25 ipm by the factor 25.4 = F158.75 mm/min.

Metric threads in a metric program

M 6 x l , Using 125 rpm F..... mm/min.?

We just multiply the pitch by the selected rpm

Feed will be 1 X 125 = 125

F125.

Metric threads in an inch program

F125 mm/min = .......inc/min.

We simply divide the feed obtained by 25.4.

Hence, 125 (mm/min) / 25.4 will be programmed as F4.9213 ipm

Fine boring canned cycle G76

G 76 Xn Yn Zn Rn Q n Fn

1- Rapid to "R" (point A).

2- Feed to "Z" (point B),

3- Spindle stop

4- Orient, shift the tool point by the programmed amount Q away from the hole wall, 5- Rapid return to "R" or Initial as programmed6-Restart of spindle.

Example:Write the program to bore the hole in the following part in absolute

Example:Write the program to bore the hole in the following part in absolute

N0010 G20 G40 G80 G90 G00-

G20: (Inch programming, shown above as G20, is programmed on many controls as G70. Check your programming manual.)G40: Cancel Radius CompensationG80: Cancel previous canned cycleN0020 T01 M06N0030 G92 X0 Y0 Z0This command will zero the registers with no motion taking placeN0040 S600 M03 - Spindle OnN0050 M08 - Coolant OnN0060 G98 G76 X9.0 Y7.5 Z-5.9 R-4.75 Q 0.1 F 0.75

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سؤال:How many ridges will be remains on the hole after executing the above CNC program (600 rpm, F 0.75 inch/min) ?

الجابة:اAt 600 rpm, F 0.75 inch/min will ensure 800 tool marks or ridges in 1 inch of bored surface. How?Feed per rev = 0.75 ÷ 600 = 0.00125 inch per rev = Ridge Thickness

Number of Ridges in 1 inch = 1 ÷ 0.00125 = 800

سؤال:How to produce finer surface ( Increase Number of Ridges)

االجابة:

Feed per rev = Feed per min ÷ Speed= ........ inch per rev = Ridge Thickness

Number of Ridges in 1 inch = 1 ÷ Ridge Thickness = ......

Should a finer surface be required, we can increase S, reduce F, or both. In a production situation, a carbide-tipped boring tool could run at speeds to 3,000 rpm and feeds to 3.5 ipm.

Canned cycle cancellation G80G80 deactivates (cancels) any of the G80-series canned Z-axis cycles.

Each of these canned cycles is modal. Once put in effect, a hole will be drilled, bored, or tapped, each time the spindle is moved to a new location.

This code is normally used in three situations:

1-When different programs are run consecutively on the same machine, it issued before the first motion statement, in conjunction with other codes as a safety feature, to cancel potential leftover canned cycles from a previous program. On some controls, a previously used canned cycle may remain active even if the control is reset or the power is turned off.N0010 G20 G40 G80 G49 G91 G00

2-When a canned cycle is canceled, as it should be, as soon as it is no longer needed in the program.N0040 G80

3-When it is required to reposition the spindle without any machining taking place at that location (such as an intermediary position in a change of direction).N0090 G80 X3.0 Y4.5

Zn , Rn

صفحة األمثلة و 160و 159تصحيح161

Write a CNC program to perform the drilling operation in the following figure, use the data in the table

Operation Tool Speed Feed

Deep drill 4 thru holes Twist drill, D=0.125 1600 5

0.0376 +0.1000 +0.7500 = 0.8876

Turning Canned cycles

Longitudinal turning cycle G84

A G0 command is used to bring the tip of the tool to starting position S.

The G84 command will make the tool move in a series of rectangular paths cutting material axially until the tool tip reaches target point K where the cycle ends.

Cutting movements will be at the cutting feed rate. All other movements will be at rapid traverse rate.

N Block NumberG84 Longitudinal Turning CycleX,Z Absolute, Incremental Coordinates of the contour joint point KPo Taper dimension in X DirectionP2 Taper dimension in Z DirectionDo Allowance in XD2 Allowance in ZD3 Cut divisionF Feed

N Block NumberG85 Threading CycleX,Z Absolute, Incremental Coordinates of the thread end point K or NP2 Thread run outD3 Depth or Number ( From Table)D4 Number of no load cuts to cleanD5 Angle of threadD6 Total thread depthD7 Identification number (from table)F Feed

D3 D7

( Decrement or Constant ) Depth or Number K or N

0 Decrement Depth 1 Constant Depth

K

2 Decrement Depth 3 Constant Depth

N

4 Decrement Number 5 Constant Number

K

6 Decrement Number 7 Constant Number

N

Plunge – cut cycle G86

A G0 command brings the right-hand corner of the tool to starting position P. The G86 command will make the tool move forward, back and left repeatedly to cut the groove. The movements continue until the left-hand corner of the tool tip reaches target point K where the cycle ends.

N Block NumberG86 Plung Cut CycleX,Z Absolute, Incremental Coordinates of the contour joint point KD3 Feed per Cut ( feed /rev)D4 Dwell timeD5 Tool widthF Feed

G25 Subroutine CallCanned cycles could be made even more efficient by the use of the Subroutine feature, when sevral operations (center drill, drill, booring, tap, etc. ) are performed at the same location. The location pattern is placed in a Subprogram known as Subroutine and called as needed by the main program

O10 Main program Name

N010 ……………… N020 ……………… N030 G25 L 81 04 Call Subroutine 81 Four times

N040 ………………

Main Program

N050 M30 O81 Name of the Subroutine

N500 ………………… N510………………….. N520 ……………………

Subroutine

N530 M17 Return to Line N040 in the main Program after four execution

Write a program for milling the shown 4 rectangular pockets in the shown part, use G25 subroutine call to facilitate your programming.

X

Y

20 45 45 45

2525 50

N10 G90 S800 M03N20 G00 X20 Y12.5N30 G01 Z0.1 F55M08N40 G25 L200 01N50 G00 X65N40 G25 L200 01N50 G00 X110N40 G25 L200 01N50 G00 X155N40 G25 L200 01N50…………………N60…………………N70…………………N80…………………N90…………………N100 M30

O200N500 G92 X0 Y0N510 G42 G90N520 G01 Z-5 F2.5N530 G01 Y25 F5N540 X25N550 Y0N560 X0N570 G00 Z0.1N580 M17

15

R5M 24x1.5

34

151015595

%

021102

N000 G71

N010 G00 X35 Z141 T0101 S700 M04

N020 G84 X24 Z95 P0=0.0 P2=0.0 D3=500 F100

N030 G01 X24 Z140 F50

N040 G84 X15 Z115 D3=500 F100

N050 G00 X15 Z141

N060 G84 X0.0 Z140 P2= -15 D3=500 F100

N070 G00 X40 Z150

N080 G00 X25 Z100 T0202

N090 G86 X15 Z95 D3=100 D4=1 D5=4000 F50

N100 G00 X40 Z150

N110 G00 X25 Z98 T0404 S300

N120 G85 X24 Z115 P2=2 D3=6 D4=2 D5=80 D6=1200D7=7 F1500

N130 G00 X40 Z150

N140 G00 X24 Z95 T0101

N150 G02 X34 Z90 I5 K0 F50 S500

N160 G00 X40 Z156

N170 M30

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Select a point a little amount far from the begining to avoid error message

Select a point a little amount far from the end to avoid error message

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