Deep hole drilling automation moves parts and manages the process while the machine cuts. Cells range from a single robot loading one gundrill to fully unmanned multi-machine lines that run second and third shifts with no one on the floor. The economics hinge on recovering idle spindle time — most shops believe they run at 80% utilization when the reality is closer to 40%.
Match automation complexity to part geometry, batch size, and the hours of unattended operation you actually need. Most manufacturers start at Level 2 and expand incrementally.
| Level | Description | Loading | Best For | Investment | Spindle hrs/day | ROI Period |
|---|---|---|---|---|---|---|
| L0 Manual | Manual load, manual drill cycle — every part attended | Hand | Prototype, R&D | $0 (existing machine) | 4–6 | N/A |
| L1 Automated cycle | Manual load, automated drilling cycle | Hand | Low volume (<50 parts/yr) | $0 (existing machine) | 6–7 | N/A |
| L2 Robot + pallet | Robot loads from pallet or grid plate, single machine | Robot | Medium batch (50–500), one part family | $50k–$100k | ~12–14 | 12–18 months |
| L3 Multi-machine | Robot serves several machines with a conveyor system | Robot + conveyor | High volume (500–5000), multiple operations | $150k–$300k | 16–20 | 18–24 months |
| L4 Lights-out cell | Fully automated cell: gantry, washer, CMM, tool presetter, auto changers | Full system | High volume (>5000), lights-out production | $300k–$800k+ | 22–23 | 24–36 months |
Deep hole drilling machines are expensive, high-value assets that sit idle 16+ hours a day on a single shift. Unattended machining is the most direct way to turn that idle time into production.
| Machine situation | Typical utilization | Source basis |
|---|---|---|
| Manually attended machine | 30–40% | Datanomix utilization studies |
| Shops running pallet / robot loading | approaching 95% | Pallet-system operators |
| Bottom-quartile Top Shops | ~8 hrs/day | Modern Machine Shop Top Shops survey |
| Top-quartile Top Shops | ~14 hrs/day | Modern Machine Shop Top Shops survey |
| Approach | Median profit margin |
|---|---|
| Baseline (no improvement methodology) | ~1% |
| + Improvement methodology | ~5% |
| + Unattended machining | ~8% |
| + Machine monitoring | ~9% |
A cell is more than a robot bolted beside a machine. Every subsystem must be sized and interfaced so the machine never waits and never runs blind.
| Sub-system | Function in the cell | Typical hardware |
|---|---|---|
| Machine core | Drill the hole | Gundrill, BTA or ejector machine with through-spindle coolant, feed and spindle drives sized for unattended cycles |
| Robot / handling | Move parts between stations | 6-axis articulated robot (FANUC, ABB, KUKA), gantry robot for long shafts, collaborative robot for small parts |
| Workpiece storage | Buffer raw and finished parts | Grid plates, pallet systems, bulk feeders, walking beams, multi-level discharge magazines |
| Fixture & guide bushing | Locate the part, guide the drill at entry | Hydraulic/mechanical clamps, entry guide bushing, bushing-changer station |
| Coolant & chip handling | Supply coolant, remove chips | High-pressure pump, filtration (10–50 μm), hinged-belt or scraper chip conveyor, tramp oil separator, level/temp monitoring |
| Tool management | Change, track, and preset drills | Automatic tool changer with RFID, offline presetter, spindle-load wear monitoring |
| Inspection | Verify the hole in or near the cell | Post-process CMM or plug gage, bore scope station, coolant pressure/flow monitoring |
| Cell controller | Coordinate machine, robot, and peripherals | PLC/robot cell controller, OPC-UA or MTConnect connectivity, OEE data logging |
| Method | Best for | Typical capacity | Field example |
|---|---|---|---|
| Grid plate | Shafts, medium batch | 176 positions (20–35 mm) + 88 positions (35–50 mm) | TBT ML250 + Halter LoadAssistant (Ott-Jakob) |
| Pallet system / pallet changer | High variety, multiple part families | Multiple pallets swapped at cycle time | UNISIG flexible pallet changers |
| Bulk feeder (vibratory / step) | High volume, simple geometry | Hours of unattended operation | UNISIG R-4-2-2 barrel cell |
| Walking beam / conveyor | Inline shaft production | Continuous flow between stations | Precihole shaft gun drilling lines |
| Multi-level discharge magazine | Finished parts | Auto-stacks machined parts | UNISIG R-4-2-2 finished-barrel discharge |
An integrated sensor re-checks shaft position and re-measures length before loading — drilled parts can drag out of clamping position, and an out-of-position load is a guaranteed crash.
Stage parts in a buffer station in front of the machine so the robot can load four at a time while the drill runs. The TBT/Ott-Jakob cell loads four shafts per cycle to cut machine idle time to near zero.
Robot payload must include the weight of coolant clinging to a freshly drilled part. A part that reads dry and leaves dripping can stall the gripper at full extension.
In gundrill cells the entry bushing defines hole position. When diameter changes, the cell must swap bushings or re-machine the seating — a bushing-changer station keeps the cell running between part families.
Overspecify the cell controller and coolant system capacity from day one. Adding machines, inspection stations, and cleaning stations later is cheap only if the backbone was built for them.
The drilling method shapes the cell as much as the robot does — coolant pressure, chip volume, and tool-change frequency drive the automation design.
| Design factor | Gundrill cells | BTA (STS) cells | Ejector (DTS) cells |
|---|---|---|---|
| Diameter range | 0.5–50 mm | 6–2000 mm | 18–250 mm |
| Coolant pressure | 50–150+ bar | 15–100 bar | 10–50 bar |
| Filtration target | 10–20 μm | 30–50 μm | ≤30 μm (protect Venturi) |
| Tool change frequency | High — regrind after short depth | Lower — indexable inserts | Moderate |
| Fixturing | Entry guide bushing mandatory | Pressure head seal at workpiece face | No face seal — irregular faces OK |
| Chip load | Fine, continuous chips | Large-volume C-chips | C-chips; Venturi needs clean coolant |
| Robot / loading notes | Light parts, frequent changeover, bushing handling | Heavy bar loaders, swivel units | Lowest entry cost; retrofits onto existing machines |
| Automation complexity | Highest (tooling + coolant + bushing) | Medium | Lowest entry cost |
Unattended operation is impossible without sensors watching the process. Coolant and spindle signals are the eyes of a deep hole cell.
| Monitored signal | How it is measured | What it catches |
|---|---|---|
| Coolant pressure | Pressure transducer on the supply line | Sudden drop = chip blockage or pump failure; ejector Venturi loses chip evacuation below ~8 bar |
| Coolant flow | Flow meter (e.g. Guhring PQ 3000) with tool clamped in spindle | Clogged filters, pump/seal wear, narrowed coolant ducts, drill breakage |
| Spindle load / thrust power | Drive feedback or load cell | Tool wear, tool breakage, chip jamming |
| Vibration | Accelerometer on spindle housing | Abnormal gundrill vibration before breakage — critical for small-diameter gundrills (≤4 mm) |
| Axial force | Load cell in the feed axis | Chip evacuation failures during the cut |
Calculate ROI on actual utilization, not theoretical maximum throughput. Include programming time, maintenance, and the learning curve for setup personnel.
Spindle-on time versus clock time over a real production week. Most shops overestimate — the perceived 80% is usually closer to 40%.
How many unattended hours per night or shift, and at what planned utilization. Proven processes justify higher targets.
Hardware + integration + programming + training + ongoing maintenance and consumables, not just the robot price.
Contribution per machine hour × added productive hours × operating nights per year.
Scrap events, alarm-response time, commissioning duration, and the setup learning curve all eat into the model.
Second-shift operator cost versus robot total cost of ownership. A fully loaded CNC operator runs $55k–$75k/year.
Run these conditions before you trust the machine to work alone. Each one is a failure mode that scrapes an entire night of production if it breaks.
The drill must survive the full unattended window. Monitor spindle load and program automatic retract on threshold before breakage.
Chip-conveyor capacity and coolant filtration must handle peak chip flow. A jam four hours into a lights-out run is a full scrap event.
Automatic level make-up, temperature control, tramp-oil separation, and pressure/flow alarms with remote notification.
Probe hole position and depth on the first part of every shift; plug-gage or bore-scope critical features before letting the cell continue.
Remote alarming to a phone, written recovery procedures, and clear instructions for the morning shift about what to inspect first.
High-pressure oil mist is a fire risk. CO₂/inert-gas suppression, mist extraction, spark detection, and an overpressure-rated enclosure.