The CNC control is the interface between the operator and the machine. For deep hole drilling, the control needs specific features that general machining centers don’t always have.
I’ve worked with FANUC, Siemens, and Heidenhain controls on deep hole drilling machines. Each has its strengths.
What Deep Hole Drilling Needs
A CNC control for deep hole drilling needs:
- Pecking cycles. The control should support programmable peck depth, retract distance, and feed rate for each peck.
- Variable feed. The ability to reduce feed at entry and exit, where the cutting forces change.
- Spindle load monitoring. The control should monitor the load on the spindle and trigger an alarm or stop if the load exceeds a threshold.
- Coolant pressure monitoring. The control should monitor coolant pressure and stop the machine if pressure drops below a set point.
- Tool life management. The control should track the number of holes drilled per tool and remind the operator to change tools at the right interval.
These features are available on most modern CNC controls, but they need to be set up correctly for deep hole drilling applications.
FANUC
FANUC is the most common control I’ve seen on deep hole drilling machines, especially on machines built in Asia. FANUC controls are reliable, easy to program, and widely supported.
For deep hole drilling, FANUC offers:
- G73 and G83 peck drilling cycles (standard)
- Custom macro programming for specialized cycles
- Spindle load monitoring (optional)
- Tool life management (standard)
The G83 peck drilling cycle is adequate for most gun drilling work. For more specialized cycles, I use custom macros that I’ve developed over the years.
Siemens
Siemens controls are more common on European-built machines. Siemens offers:
- ShopTurn or ShopMill programming (conversational)
- G-code programming (standard)
- Cycle800 for angled drilling (on multi-axis machines)
- Spindle load monitoring (standard)
The conversational programming on Siemens controls can be easier for operators who aren’t comfortable with G-code. I’ve seen shops train operators on Siemens controls in a few hours.
Heidenhain
Heidenhain controls are common on high-precision machines from Europe. Heidenhain offers:
- TNC conversational programming
- Cycle programming for deep hole drilling
- High-precision contouring
- Spindle load monitoring (standard)
Heidenhain controls are the most intuitive for conversational programming. The TNC language is close to English and easy to learn.
Control Features Comparison
| Feature | FANUC | Siemens | Heidenhain |
|---|---|---|---|
| Programming | G-code | G-code + conversational | Conversational + G-code |
| Peck cycles | Standard | Standard | Standard |
| Custom cycles | Macro B | Cycle800 | Q-parameter |
| Load monitoring | Optional | Standard | Standard |
| Tool management | Standard | Standard | Standard |
| Ease of learning | Moderate | Moderate | Easy |
| Global support | Excellent | Good | Moderate |
What I Program
For deep hole drilling, I program the following into the control:
- Peck cycle parameters. Peck depth (typically 5-10x drill diameter), retract distance (full retract for chip clearance), and feed rate.
- Feed reduction zones. Reduced feed at entry (first 2-3mm) and at exit (last 5mm). The reduced feed prevents tool damage at the critical entry and exit points.
- Spindle load limits. An alarm threshold at 120% of normal load and a stop threshold at 150% of normal load. This catches tool breakage and chip packing before they cause damage.
- Tool life counter. A counter that tracks the number of holes per tool and alerts the operator when it’s time to change.
Common Control Problems
The most common CNC control problems I’ve seen on deep hole drilling machines:
- Incorrect peck cycle settings. The peck depth is too deep or the retract is too short, causing chip packing.
- No feed reduction at entry. The drill hits the part at full feed and chips the cutting edge.
- Load monitoring not enabled. The machine breaks a tool and keeps running, damaging the bore.
- Tool life counter not used. The operator runs a dull tool and produces out-of-spec holes.
Most of these problems are solved by proper setup and operator training. A well-programmed control runs the machine consistently regardless of the operator.
Key Takeaways
The CNC control is a tool, not a solution. A good control with a poor program produces poor holes. A basic control with a well-written program produces good holes.
I spend time developing good programs for each job. The programs account for the material, diameter, depth, and machine characteristics. A well-written program runs the machine consistently and produces predictable results. For more on how controls integrate with production automation, see Automation Options and ROI.
Key Takeaways
- Deep hole drilling controls need pecking cycles, variable feed, and load monitoring as standard features.
- FANUC is the most common control on deep hole machines; Siemens and Heidenhain offer advantages in conversational programming.
- Program feed reduction zones at entry and exit to protect the cutting edge.
- Enable spindle load monitoring on every job – it catches tool breakage before damage occurs.
- Use tool life counters to replace tools at the right interval.
- A well-written program on a basic control outperforms a poor program on an expensive control.