In CNC machining, Canned Cycles are powerful G-code commands designed to simplify repetitive machining operations such as drilling, boring, and tapping. This article provides a clear and practical explanation of G81 to G89 canned cycles, helping CNC programmers improve efficiency, accuracy, and program readability.
What Are CNC Canned Cycles?
Canned cycles are predefined CNC routines that execute a series of motions using a single G-code command. Instead of writing multiple lines of code for each hole, machinists can use canned cycles to reduce programming time and minimize errors. They are widely used in CNC milling and CNC drilling operations.
G81 – Simple Drilling Cycle
G81 is the most basic drilling canned cycle. The tool moves rapidly to the reference plane, feeds to the specified depth, and then retracts. It is ideal for shallow holes where chip evacuation is not critical.
G82 – Drilling with Dwell
G82 adds a dwell time at the bottom of the hole. This canned cycle is useful when a cleaner hole bottom is required, especially in spot drilling and counterboring operations.
G83 – Peck Drilling Cycle
G83 is a peck drilling canned cycle designed for deep holes. The tool periodically retracts to clear chips, reducing heat buildup and improving tool life. This cycle is commonly used when drilling hard materials.
G84 – Tapping Cycle
G84 is used for rigid tapping operations. The spindle rotation is synchronized with the feed rate, allowing precise thread cutting. Accurate spindle control is essential when using this canned cycle.
G85 – Boring Cycle (No Dwell)
G85 performs a boring operation where the tool feeds into the hole and retracts at the same feed rate. It is suitable for finishing holes that require smooth internal surfaces.
G86 – Boring Cycle with Spindle Stop
G86 stops the spindle at the bottom of the hole before rapid retraction. This prevents tool marks and is often used in precision boring applications.
G87 – Back Boring Cycle
G87 is a specialized canned cycle for back boring operations. The tool enters the hole, expands or engages, machines the back side, and then retracts safely.
G88 – Boring with Manual Dwell
G88 allows the machine to pause at the bottom of the hole until the operator resumes the cycle. This is useful for inspection or special machining requirements.
G89 – Boring with Dwell and Feed Retract
G89 combines a dwell at the bottom of the hole with a controlled feed-out motion. It is ideal for high-precision boring where surface finish is critical.
Benefits of Using G81–G89 Canned Cycles
- Reduced CNC programming time
- Improved code readability and consistency
- Higher machining accuracy
- Lower risk of programming errors
Conclusion
Understanding G81–G89 canned cycles is essential for anyone working with CNC machines. By selecting the appropriate canned cycle for each operation, machinists can optimize productivity and achieve better machining results. Mastering these cycles is a key step toward advanced CNC programming.
CNC G-code, Canned Cycles, G81 G89, CNC Drilling, CNC Milling, CNC Programming
