Peck drilling cycle

Peck drilling cycle is a critical technique in CNC machining, especially for creating deep, precise holes while managing chip evacuation and tool longevity. Unlike standard drilling, which involves continuous cutting, peck drilling breaks the process into incremental steps, ensuring efficient material removal and reducing heat buildup. Let’s dive into the details of this essential cycle.

What is Peck Drilling ?

Peck drilling is a method where the drill bit advances in controlled increments (pecks) rather than a single pass. After each peck, the tool retracts partially or fully to clear chips, improve cooling, and prevent tool wear. This approach is particularly useful for deep holes, as it avoids chip clogging and maintains hole accuracy .

Key Components of the Peck Drilling Cycle

1. Incremental Drilling: The tool drills a predefined depth (peck amount), then retracts to allow chips to evacuate.
2. Chip Breaking: Retracting the drill breaks chips into manageable pieces, reducing the risk of tool damage.
3. Coolant Application: Retraction phases provide opportunities for coolant to reach the cutting edge, enhancing lubrication and heat dissipation.

G-Codes for Peck Drilling

• G81 (Simple Drilling Cycle): Rapidly moves to the hole position and drills in a single pass, best for shallow holes.
• G73 (High-Speed Peck Drilling): Uses rapid, short pecks with minimal retraction, ideal for softer materials.
• G83 (Deep Hole Peck Drilling): Retracts completely after each peck, ensuring maximum chip clearance for deep holes .

Optimizing Parameters

• Peck Depth: Adjust based on hole depth and drill type. Deeper holes may require progressively smaller peck increments.
• Speeds and Feeds: Match spindle speed and feed rate to material hardness and drill diameter to balance efficiency and tool life.
• Retraction Height: Full retraction (G83) is preferred for stubborn chips, while partial retraction (G73) speeds up cycles for easier materials.

Applications

Peck drilling is widely used in aerospace, automotive, and mold-making industries for tasks like:

• Drilling engine components with high depth-to-diameter ratios.
• Creating precise coolant channels in tooling.
• Machining materials prone to work-hardening, such as stainless steel.

Peck drilling cycle programs examples

Here are sample programs demonstrating Peck Drilling cycles (G73, G83, and G74) for CNC milling and turning operations, based on industry-standard G-codes and references:

1. G83 Deep Hole Peck Drilling Cycle (Milling)

Use for deep holes requiring full retraction to clear chips

O1000 (G83 Example Program);
G54 G90 G17 G40 G49 (Safe startup);
T1 M06 (Select drill tool);
G00 X10. Y10. S2000 M03 (Rapid to position, spindle on);
G43 H1 Z5. M08 (Tool length compensation, coolant on);
G99 G83 Z-20. R2. Q3. F100 (G83 cycle: Z-depth=-20mm, R-plane=2mm, Peck=3mm);
X20. Y20. (Next hole position);
G80 G00 Z5. M09 (Cancel cycle, retract, coolant off);
M30 (End program);

• Key Parameters:
• Q3. = Peck increment of 3mm.
• R2. = Retract to 2mm above the workpiece (G99).
• Full retraction after each peck prevents chip clogging.

2. G73 High-Speed Peck Drilling Cycle (Milling)

For softer materials with minimal retraction

O2000 (G73 Example Program);
G54 G90 G17 G40 G49;
T2 M06 (Select drill);
G00 X30. Y30. S1500 M03;
G43 H2 Z5. M08;
G98 G73 Z-15. R1. Q2. F80 (G73 cycle: Z-depth=-15mm, Peck=2mm);
X40. Y40.;
G80 G00 Z5. M09;
M30;

• Key Parameters:
• Q2. = Peck increment of 2mm.
• G98 = Retract to initial Z height (5mm) after each peck.
• Short retraction improves cycle time for non-ductile materials.

3. G74 Peck Drilling Cycle (Turning)

For lathe operations (e.g., drilling axial holes)

O3000 (G74 Lathe Peck Drilling);
G50 S2000 (Set spindle speed clamp);
G97 S1000 M03 (Spindle on, 1000 RPM);
G00 X0 Z5 T0101 (Rapid to start position, select tool);
G74 R1.0 (Peck retraction amount = 1mm);
G74 Z-30. Q3000 F0.1 (Drill to Z-30mm, Peck=3mm per cut);
G00 X100 Z100 M05 (Retract, spindle off);
M30;

• Key Parameters:
• Q3000 = Peck increment of 3mm (value in microns: 3000 = 3mm).
• R1.0 = Retract 1mm after each peck to break chips.

4. G81 Drilling Cycle with G98/G99 (Milling)

Shallow holes with controlled retract levels

O4000 (G81 with G98/G99);
G54 G90 G17 G40 G49;
T3 M06 (Select drill);
G00 X50. Y50. S1800 M03;
G43 H3 Z5. M08;
G99 G81 Z-10. R2. F60 (G81 cycle, retract to R-plane=2mm);
X60. Y60.;
G98 G81 Z-10. R2. F60 (Retract to initial Z=5mm);
G80 G00 Z5. M09;
M30;

• Key Parameters:
• G99 = Retract to R-plane (2mm above part).
• G98 = Retract to initial Z height (5mm) .

Programming Tips

1. Peck Depth: Start with 3-5mm pecks for deep holes, reducing increment size as depth increases .
2. Coolant: Use M08 (coolant on) and M09 (off) to manage heat.
3. Tool Wear: Replace drills if chip evacuation becomes inconsistent.

By adapting these examples to your machine’s specifications, you can optimize hole quality and tool life. Always simulate programs in CAM software (e.g., Fusion 360) before machining.

Final Thoughts

Peck drilling is indispensable for achieving precision and efficiency in deep-hole machining. By understanding G-code cycles, optimizing parameters, and leveraging modern CAM tools, manufacturers can enhance productivity while extending tool life. Whether you’re working on a CNC mill or lathe, mastering this cycle ensures superior results in even the most challenging projects.

Note: While this guide focuses on drilling cycles, turning operations (e.g., intermittent cuts on lathes) may involve similar “pecking” principles but are distinct processes governed by different parameters and G-codes.