G73 High-Speed Peck Drilling Cycle: The CNC Milling Guide

Understanding the G73 High-Speed Peck Drilling Cycle

A misaligned coordinate zero offset or an incorrect retraction clearance plane configuration during canned cycle setup drives the rotating spindle head directly into the physical workpiece vise jaws at rapid traverse speed. This sudden positioning deviation shatters the carbide drill insert, bends the axis ball screws, and triggers a high-current servo overload alarm that halts the entire production line. To prevent these catastrophic machine crashes and optimize machining times, programmers utilize the G73 high-speed peck drilling cycle. This cycle provides an automated method to drill deep holes by replacing the long, time-consuming retraction paths of standard peck drilling with tiny, rapid relief moves that break chips without pulling the tool out of the workpiece.

This intermediate-advanced programming cycle is particularly useful when machining high-volume hole patterns where cycle time optimization is paramount. During peck drilling, the tool feeds intermittently down to the final Z-axis depth, using rapid-traverse relief moves to relieve cutting torque and break chips. The programmer controls the peck depth and retraction amount, while the preprocessor automates the coordinate calculations, ensuring the tool returns to the previous cutting depth with minimal non-cutting transition time.

G73 Technical Summary

Technical Attribute	Specifications & Constraints
Command Code	G73 (Fanuc, Mitsubishi, Siemens G291 ISO), CYCLE83 (Siemens native G290)
Modal Group	Group 09 (Fanuc, Mitsubishi, Siemens G291 ISO Dialect mode)
Brands	Fanuc, Siemens, Mitsubishi
Critical Parameters	Peck depth (Q or DP/DPR), retraction clearance (escape amount ,D / VRT / #8012)
Main Constraint	Spindle must be actively rotating (M03/M04) with valid feedrate prior to cycle execution

Quick Read

• Program the master spindle direction (M03 or M04) before executing the cycle to avoid triggering Siemens Alarm 61102.
• Cancel tool radius compensation (G41 or G42) with G40 before calling G73 to prevent Program Error P155 or tool offset conflicts.
• Align the retraction plane (RTP) and safety clearance (SDIS) in front of the reference plane (RFP) to prevent Siemens Alarm 61101.
• Command a G80 cancel (or empty MCALL block for Siemens) after completing the hole pattern to prevent subsequent coordinates from executing unintended drill plunges.
• Re-program the depth Z and point R coordinates explicitly when the workpiece coordinate system changes on Mitsubishi controls.
• Disable the dry run feedrate (DRY) option on Siemens controls prior to cutting to prevent tool breakage from excessive velocity.

Basic Concepts of Chip-Breaking Cycles

The G73 high-speed peck drilling cycle (also known as the stepping cycle or chip-breaking cycle) is designed to optimize deep-hole drilling operations on CNC systems by replacing full retraction paths with small, rapid retract movements. Standard deep-hole drilling cycles retract the tool completely to the point R clearance plane to clear the hole of swarf, but this path accumulates significant non-cutting time. Under G73/chip-breaking, the axis feeds intermittently down to the final Z-depth, retracting only by a tiny relief distance (typically 0.5 to 1.4 mm) at rapid traverse after each peck. This rapid retraction breaks long, stringy chips and relieves torque without ever pulling the tool completely out of the hole, keeping the drill engaged in the cut, maximizing tool life, and drastically reducing cycle times on large-volume hole patterns.

Setup operators must maintain vigilance regarding chip evacuation when utilizing the chip-breaking cycle. Because the drill does not retract fully to the surface, chips are not cleared from the hole flutes dynamically. When drilling tough materials, chips can pack tightly within the flutes, causing extreme friction, tool wear, and tool breakage. Prior to cycle start, the raw stock must be physically positioned and secured in workholding—such as clamping it in a machine vise jaw, mounting it on table clamps, or securing it in a rotating chuck. If the coordinate zero offset is misaligned, or if the safe Point R clearance is programmed too close to the raw material, the spindle head or tool indexing turret will travel along a dangerously shifted path. Operators must dry-run G73 programs in single-block mode and utilize the chuck and tailstock barriers on the HMI setting screens to establish secure electronic protection zones.

Command Structure and Syntax

Commanding the G73 cycle requires defining the target hole coordinate positions, the final drilling depth, the safe clearance level, and the peck increment. The preprocessor evaluates these addresses to calculate the motion steps. Spindle rotation and cutting feedrate must be modal in the active registers before invoking the canned cycle block.

Syntax formats differ between native ISO controls and parametric programming languages. ISO-based controllers command coordinates and peck depths directly in a single block. Conversational or native dialect formats use dedicated technology cycles that pass variables as parameters within parentheses. A dry run is required to verify the path of these formats.

; Standard ISO Format (Fanuc, Mitsubishi, Siemens G291)
G73 X__ Y__ Z__ R__ Q__ ,D__ F__ K__ ;
; Siemens Native Mode Format (G290)
MCALL CYCLE83 (RTP, RFP, SDIS, DP, DPR, FDEP, FDPR, DAM, DTB, DTS, FRF, VARI, _AXN, MDEP, VRT, DTD, DIS1) ;

A dry run test should be performed on this syntax before machining raw stock.

Address / Parameter	Description
X, Y	Coordinates of the target hole center position on the active plane.
Z	Absolute final drilling depth coordinate, or incremental distance to the hole bottom.
R	Safe clearance point R level (retraction clearance level).
Q	Incremental cutting depth (peck depth) for each individual feed pass.
,D	Escape/retraction amount (d) after each peck feed (comma-prefixed on Fanuc).
F	Cutting feedrate override active during the cycle.
K / L / LI	Number of repetitions for equally-spaced holes.
VARI (Siemens)	Machining type (0: chip breaking, 1: swarf removal).
VRT / V2 (Siemens)	Retraction distance for chip-breaking (default 1.4 mm).
DF (Siemens)	Infeed degression percentage or value.

Brand-Specific G73 Implementations

Fanuc

On Fanuc machining centers, the G73 high-speed peck drilling cycle is a Group 09 modal canned cycle. Retraction behavior is governed by Parameter No. 5114, which defines the default escape clearance distance, and Parameter No. 1681, which manages canned cycle overlap blending configurations.

G73 X100.0 Y100.0 Z-40.0 R5.0 Q8.0 ,D1.0 F120.0 ;

Operators must execute a dry run to verify the tool path before machining.

• Parameters: Parameter No. 5114 (default retract/escape amount when `,D` is omitted), Parameter No. 1681 (block overlap settings for drilling canned cycles, DPS, DRL, DRV, DQL, DZL bits).
• Alarms: Alarm PS0011 (zero or out-of-range cutting feedrate), Alarm PS0206 (changing active drilling axis before G80 cancel), Alarm PS0368 (modifying parameter 5040 bit 3 while offsets are active).
• Versions: Lathe systems compile G73 as the Pattern Repeating Cycle (roughing), while milling systems compile G73 as High-Speed Peck Drilling. In Series 15 format, G83.1 is used instead of G73, and repetitions are commanded using address L instead of K.

Warning: Editing Parameter No. 5040 Bit 3 while tool offsets are active triggers Alarm PS0368, halting the machine immediately.

Siemens

For Siemens SINUMERIK controls, the native G290 mode executes chip-breaking operations using the parametric cycle CYCLE83. When switching the bilingual interpreter to ISO Dialect Mode using G291, the compiler utilizes the channel data parameter MD 18800 to compile the standard G73 block.

MCALL CYCLE83 (50.0, 0.0, 2.0, -35.0, , 10.0, , 80.0, 0.5, 0.5, 1.0, 0, 3) ;

Running a dry run verifies the parametric coordinates before automatic cutting.

• Parameters: MD 18800 (enables external NC dialect interpreter), VARI (machining type, 0: chip breaking, 1: swarf removal), VRT/V2 (retraction distance for chip-breaking), DF (infeed degression percentage or value), V1 (minimum depth infeed increment when degression is active).
• Alarms: Alarm 61102 (spindle direction M3/M4 missing in modal registers), Alarm 61101 (RTP/SDIS defined behind RFP), Alarm 61003 (feedrate zero or missing), Alarm 14800 (path velocity less than or equal to zero).
• Versions: The SINUMERIK 840D sl supports widescreen displays and turning-specific options G51.2/G50.2, which are unsupported on the compact 802D sl. CYCLE830 adds predrilling, pilot tracking, and through-drilling, which standard CYCLE83 lacks.

Warning: Activating the G73 cycle under bilingual interpreter mode while machine data MD 18800 is disabled triggers Alarm 61800.

Mitsubishi

On Mitsubishi systems, the G73 stepping cycle executes intermittent feed drilling modally under Group 09. The default return amount for chip breaking is defined by Parameter #8012, while the deep-hole retract distance is controlled by Parameter #8013.

G73 X100.0 Y100.0 Z-35.0 Q8.0 R2.0 F150.0 P500 K2 ;

Perform a dry run simulation to verify coordinate shifts and dwells.

• Parameters: Parameter #8012 (G73 return amount in 0.5 micron units), Parameter #8013 (G83 return distance), Parameter #8123 (toggles high-speed retract loss motion compensation), Parameter #1265 (toggles special format turning compiler).
• Alarms: Program Error (P801) (cycle executed with active G43.7 tool position offset), Program Error (P951) (G73 executed while simple inclined surface control G176 is active), Program Error (P186) (spindle speed override during synchronous tapping).
• Versions: Standard milling systems use G73 for stepping. If Parameter #1265 Bit 2 is enabled, the stepping cycle compiles as G83.1 instead. Prohibiting manual reverse run with G127 locks the stepping cycle out of reverse-run execution.

Warning: Executing G73 while simple inclined surface control G176 is active triggers Program Error P951, aborting execution.

Cross-Brand Comparison

Feature	Fanuc	Siemens	Mitsubishi
Programming Concept	Standard G-codes (G73/G83) distinguish cycle types	Unified parametric cycle (CYCLE83) distinguishes type via VARI	Standard G-codes (G73/G83) are used, with compiler swaps to G83.1 in Special Format
Retraction Clearance Control	Dynamic override using comma-prefixed ,D address inside the block, or system Parameter No. 5114	Pre-allocated variables or cycle parameter VRT (default 1.4 mm)	Hardcoded Parameter #8012 for G73 and Parameter #8013 for G83 retract
Infeed Control / Degression	Uniform, constant peck depth Q	Dynamic degression (DF and V1 minimum limits) supported	Uniform, constant peck depth Q
Modal Activation / Cancel	Group 09 G-codes inline with coordinates. Cancelled via G80 or Group 01 motion codes (G00-G03).	Explicit modal call using MCALL. Cancelled strictly by an empty MCALL block.	Group 09 G-codes inline with coordinates. Cancelled via G80.
In-Position Width Control	Configured globally via system parameters	Configured globally via system parameters	Dynamic overrides inside the G-code block using ,I and ,J addresses

Technical Analysis of High-Speed Peck Drilling

Analyzing the coordination of drilling cycles across major controls reveals distinct differences in compiling and coordinate tracking. While Fanuc and Mitsubishi rely on internal sequence search mechanisms and modal register groups to compile G73 cycles, Siemens native environment decouples coordinate patterns from the technology cycle entirely. In Siemens native mode, CYCLE83 is modally loaded using the MCALL command. Once loaded, any subsequent coordinate line triggers the cycle automatically. The cycle is only deselected when an empty MCALL block is executed, preventing accidental cancellations from manual traverse movements.

Parameter handling also highlights the bilingual interpreter differences. Siemens utilizes user-accessible global variables in the GUD7 module to pre-assign default depth of cut and retract amounts. Fanuc and Mitsubishi lock these default values inside system parameter lists, which require specialized access settings to modify. Additionally, Mitsubishi integrates parameter-locked single-block mapping via Parameter #1265. When enabled, this parameter collapses G73 into a single-block command that remapps the depth of cut to address D, while drawing retract amounts from Parameter #8052, a feature completely absent from Fanuc's compiler.

Infeed control presents another analytical difference. Fanuc and Mitsubishi require a constant, uniform depth per peck. This uniform rate can cause extreme tool wear and tool breakage as the drill goes deeper. Siemens CYCLE83 allows the infeed depth to be reduced continuously by a degression amount DF down to a set minimum depth limit V1. When pecking in G73, programmers must verify safe clearances and coordinate offsets to prevent the spindle head from bypassing soft boundaries and driving the tool directly into physical workpiece vise jaws.

Program Examples and Dry Run Walkthroughs

Fanuc G73 Example

G90 G99 G73 X120.0 Y85.0 Z-45.0 R3.0 Q8.0 ,D1.0 F150.0 ;
G80 ;

dry run:

• Phase 1: The spindle moves in rapid traverse to the starting coordinates (X120.0, Y85.0) and starts positioning at Point R level (R3.0).
• Phase 2: The preprocessor scans parameters, identifying absolute coordinates and a peck increment of 8.0 mm (Q8.0).
• Phase 3: The axis feeds 8.0 mm deep and rapid-retracts 1.0 mm (,D1.0) to break stringy chips.
• Phase 4: Feed steps continue down to the final target Z-depth of -45.0 mm (Z-45.0).
• Phase 5: Upon reaching Z-depth, the tool rapid-returns to the Point R clearance plane.
• Phase 6: G80 cancels Group 09 modal canned cycles.

Siemens CYCLE83 Example

N10 T="DRILL_10" D1 M6 ;
N20 G290 G17 G94 F150.0 S1800 M3 M8 ;
N30 MCALL CYCLE83 (50.0, 0.0, 2.0, -35.0, , 10.0, , 80.0, 0.5, 0.5, 1.0, 0, 3) ;
N40 X100.0 Y150.0 ;
N50 MCALL ;

dry run:

• Phase 1: The tool change load command selects DRILL_10 and applies the length compensation offset.
• Phase 2: Mode switch G290 activates native Siemens compiling, enabling plane selection and spindle start.
• Phase 3: MCALL loads the modal CYCLE83 technology cycle configured for chip-breaking (VARI=0).
• Phase 4: Axis move to X100.0 Y150.0 automatically triggers the cycle, cutting in 10.0 mm increments.
• Phase 5: Peck steps are dynamically reduced by an 80% degression rate down to a minimum 0.5 mm infeed.
• Phase 6: Empty MCALL command cancels the modal call, securing safety during travel.

Mitsubishi G73 Example

G90 G99 G73 X100.0 Y100.0 Z-35.0 Q8.0 R2.0 F150.0 P500 K2 ;
G80 ;

dry run:

• Phase 1: Tool positions to center coordinates (X100.0, Y100.0) and rapid-traverse positions to Point R level (R2.0).
• Phase 2: Intermittent feeds cut 8.0 mm increments (Q8.0) with rapid retracts governed by Parameter #8012 return amount.
• Phase 3: At the final Z-depth of -35.0 mm, the axis dwells for 500 milliseconds (P500) to clear the bottom.
• Phase 4: The tool retracts to Point R clearance plane.
• Phase 5: The cycle executes a second repeat (K2) at the subsequent coordinate block if programmed.
• Phase 6: G80 cancels Group 09 modal canned cycles.

Error and Alarm Diagnostics

Brand	Alarm Code	Trigger Condition	Operator Symptom	Root Cause & Resolution
Fanuc	Alarm PS0011	Feedrate programmed as zero or omitted in a cutting block.	Spindle stop and HMI displays "FEED ZERO (COMMAND)" error.	Configure a valid cutting feedrate using F-code before or in the G73 command.
Fanuc	Alarm PS0206	Drilling axis or plane modified while canned cycle is active.	Machine stops mid-program and shows "ILLEGAL AXIS OPERATION" alarm.	Drilling axis modifications require a G80 cancel command before switching coordinate planes.
Siemens	Alarm 61102	Master spindle direction command missing in modal registers.	Program execution halts, displaying "No spindle direction programmed".	Program spindle direction command M03 or M04 before invoking CYCLE83.
Siemens	Alarm 61101	Retraction plane or safety clearance positioned behind RFP.	HMI displays "Reference plane defined incorrectly" error and stops motion.	Adjust retraction plane and safety clearance so they lie in front of RFP.
Mitsubishi	Program Error (P801)	Drilling fixed cycle executed while G43.7 offset is active.	CNC screen halts execution and shows P801 program error.	Cancel tool position offset G43.7 prior to executing the canned cycle.
Mitsubishi	Program Error (P951)	G73 executed while simple inclined surface control G176 is active.	Axis positioning halts and throws P951 block compiler error.	Deactivate inclined surface control G176 with G69.1 prior to cycle call.

Application Note on Workholding and Safety Barriers

Incorrect zero offsets or miscalculated tool height compensations cause the indexing turret or spindle head to travel along a shifted trajectory during automatic G73 execution. Under these conditions, the tool nose bypasses software limits and drives the cutting tool directly into rotating spindle chuck jaws, table-mounted clamps, or workpiece vise jaws. This results in a catastrophic hard collision that shatters the carbide insert, damages axis ball screws, and converts the raw stock into a completely ruined scrap part. To prevent turret damage, setup operators must dry-run G73 programs in single-block mode and utilize the native chuck barrier and tailstock barrier screens on the HMI to establish electronic protection limits around the spindle chuck jaws.

A critical hazard is the Dry Run Feedrate (DRY) option on Siemens controls. Programmers use this function during testing to replace programmed cutting velocities with a fast, pre-defined dry run speed. If an operator fails to deactivate DRY before machining a workpiece, the control will ignore the programmed feedrates and drive the tool at this high dry run speed. This altered velocity easily exceeds the maximum cutting rates of the tooling, leading to immediate tool breakage, a destroyed workpiece (yielding a scrap part), and a catastrophic hard collision into clamping fixtures such as a machine vise jaw, workpiece chuck, or table clamps. To safely establish and verify G73/CYCLE83 toolpaths, operators must dry-run programs in single-block mode and utilize the Reduced Rapid Traverse (RG0) switch to scale down positioning speeds, dry-run programs with the spindle off, and check active G-group modal displays to confirm that the proper scaling and clearances are active.

Related Commands in the CNC Network

• G83 (Peck Drilling Cycle): Performs deep-hole drilling with full retraction to Point R level to clear chips completely. Read the full G70 finishing cycle guide for details on related finishing steps.
• G80 (Canned Cycle Cancel): Cancels the modally active G73 cycle to prevent subsequent coordinate coordinates from triggering accidental drill plunges. Learn more in the G71 metric dimensioning guide.
• MCALL (Modal Cycle Call): Activates technology cycles modally on Siemens native controls, requiring an empty MCALL block to cancel.
• G290 / G291 (Mode Switch): Switches Siemens Sinumerik controls between native Siemens programming (G290) and ISO Dialect interpreter mode (G291).
• G127 (Manual Reverse Run Prohibit): Locked out of coordinate recovery during Mitsubishi's stepping cycle to prevent arbitrary manual reverse movements. Refer to the G69 balance cut cancel article for coordinate cancellation context.

Conclusion

Properly configuring the G73 high-speed peck drilling cycle reduces program complexity and machining cycle times on large diameter workpieces. By utilizing parameter-driven depth of cut and retraction values, programmers can automate bulk stock removal while keeping finishing allowances secure. Always verify coordinate zero offsets and safety boundaries before running automatic cycles.

Frequently Asked Questions

How do I adjust the G73 retraction distance on Fanuc controls?

Use the comma-prefixed ,D address directly in the G73 block (e.g., ,D1.0 for a 1.0 mm retract) to override the default system value. If you omit ,D, the controller automatically references Parameter No. 5114. Adjust Parameter No. 5114 on the settings screen to change the default retraction distance for all subsequent cycles.

Why does Siemens CYCLE83 prevent tool breakage better than standard G73?

Siemens CYCLE83 supports infeed degression through the DF parameter, which dynamically reduces the peck depth as the drill moves deeper. Standard G73 cycles on Fanuc and Mitsubishi use a constant peck depth (Q), which increases torque and friction near the bottom of deep holes. Program a percentage value for DF and a minimum increment V1 to safeguard the tool.

What causes Mitsubishi's Program Error P801 during G73 execution?

This error is triggered when the G73 cycle is commanded while tool position offset G43.7 is modally active. Mitsubishi controls prohibit mixing these compensation commands. Fix this by programming a G49 offset cancel before invoking the stepping cycle.

Can I switch coordinate planes while the G73 cycle is active?

No. Attempting to modify the active drilling plane (e.g., switching from G17 to G18) before canceling the canned cycle will trigger Fanuc Alarm PS0206 or Mitsubishi coordinate alarms. Always program a G80 cancel command before switching coordinate planes or drilling axes.