A deep hole drilling machine specification sheet is the foundation of a successful machine purchase. Unlike standard CNC machines where a few key specs define the machine, deep hole drilling machines require detailed specifications across multiple systems — and missing a single critical parameter can render the machine unsuitable for its intended work.
Part Requirements Section
Workpiece Parameters
| Parameter | Specification | Notes |
|---|
| Part name/number | | |
| Material type and hardness | | Include hardness range |
| Maximum part length | | Determines machine bed length |
| Minimum part length | | Affects workholding design |
| Maximum part diameter | | Determines spindle bore and steady rest range |
| Minimum part diameter | | |
| Maximum part weight | | Determines steady rest capacity |
| Hole diameter(s) | | List all diameters |
| Hole depth(s) | | List all depths |
| Depth-to-diameter ratio | | Key parameter for machine selection |
| Tolerance requirements | Diameter, straightness, surface finish | Defines precision class |
| Production volume (annual) | | Drives single vs multi-spindle decision |
Tip: List your most demanding part first and your most common part second. Suppliers will design for the demanding part and optimize for the common one. If you only specify the most common part, the machine may not handle the demanding parts.
Machine Configuration Requirements
Mandatory Specifications
| Specification | Required Value | Notes |
|---|
| Drilling method(s) | Gun drilling, BTA, or both | Determines coolant system design |
| Number of spindles | 1, 2, 4, etc. | Based on production volume |
| Maximum drilling depth | mm | Should exceed longest hole by 20% |
| Maximum drilling diameter | mm | |
| Minimum drilling diameter | mm | |
| Spindle power | kW (continuous) | Based on material and diameter |
| Spindle speed range | RPM (min–max) | Must cover all diameters |
| Spindle taper | BT, HSK, CAT, custom | |
Guide Bushing System
| Specification | Required Value | Notes |
|---|
| Bushing type | Fixed, rotating, or retractable | Based on application |
| Bushing diameter range | Min–max in mm | |
| Bushing change method | Manual or automatic | |
| Bushing alignment adjustment | Type of adjustment provided | |
| Bushing-to-spindle concentricity tolerance | mm TIR | |
Coolant System
| Specification | Required Value | Notes |
|---|
| Coolant type | Emulsion, oil, or both | Determines material compatibility |
| Maximum coolant pressure | bar | Based on smallest diameter |
| Maximum coolant flow | L/min | Based on largest diameter |
| Coolant tank capacity | Liters | |
| Filtration level | Microns | 20–50 µm typical |
| Filtration type | Paper, cartridge, or magnetic | |
| Coolant chiller | Yes/No and capacity (kW) | Required for precision work |
| High-pressure pump type | Piston, gear, or screw | |
Optional Features
Evaluation Options
| Feature | Benefit | Cost Impact | Recommended For |
|---|
| Automatic tool changer | Faster tool changes | High | High-volume production |
| Automatic bushing changer | Reduced setup time | High | Multi-diameter production |
| In-process gauging | Real-time diameter feedback | High | Tight tolerance, critical parts |
| Parts loader/unloader | Reduced labor | High | High-volume production |
| Chip conveyor | Automated chip removal | Medium | All production machines |
| Mist collector | Improved air quality | Medium | Oil-based coolant |
| Coolant chiller | Thermal stability | Medium | Precision tolerances |
| Spindle through-coolant | Higher pressure at drill | Medium | Deep holes, small diameters |
| Sub-spindle | Drilling from both ends | Medium | Parts requiring both-end operations |
| Rotary coolant union | Through-spindle coolant | Included for through-coolant | |
Minimum Accuracy Specifications
| Parameter | General Production | Precision | High Precision |
|---|
| Spindle runout (at taper) | < 0.005 mm | < 0.003 mm | < 0.002 mm |
| Guide bushing concentricity | < 0.015 mm TIR | < 0.010 mm TIR | < 0.005 mm TIR |
| Positioning repeatability | ±0.010 mm | ±0.005 mm | ±0.002 mm |
| Axis resolution | 0.001 mm | 0.0005 mm | 0.0001 mm |
| Straightness (per 300 mm) | 0.5 mm | 0.2 mm | 0.1 mm |
| Criterion | Method | Acceptance |
|---|
| Drill test part | Actual production part | All tolerances met on first part |
| Repeatability test | 5 consecutive parts | All within specification |
| Thermal stability | Run for 2 hours, measure drift | < 50% of tolerance band |
| Coolant system test | Run at max pressure and flow | No leaks, stable pressure |
Controls and Automation
Control System Requirements
| Requirement | Specification | Notes |
|---|
| CNC control brand | Fanuc, Siemens, Heidenhain, etc. | Match existing machines if possible |
| Number of axes | X, Y, Z, spindle, plus options | |
| Feed rate range | mm/min (min–max) | |
| Rapid traverse rate | m/min | |
| Programmable coolant pressure | Yes/No | Recommended for automated operation |
| Interface for automation | Ethernet/IP, Profibus, etc. | |
| Remote monitoring capability | Yes/No | MTConnect or OPC-UA |
Supplier Evaluation
Supplier Comparison Criteria
| Criteria | Weight | Supplier A | Supplier B | Supplier C |
|---|
| Machine price | 25% | | | |
| Lead time | 10% | | | |
| Spindle/bushing concentricity spec | 10% | | | |
| Coolant system design | 15% | | | |
| Service and support in region | 15% | | | |
| References in similar applications | 15% | | | |
| Training and documentation | 5% | | | |
| Warranty terms | 5% | | | |
| Total | 100% | | | |
Questions to Ask Suppliers
| Question | Why It Matters |
|---|
| What is the concentricity between spindle and bushing on your machines? | The single most important precision parameter |
| Show me test results from a similar application | Verifies machine capability for your work |
| What is your coolant system filtration specification? | Inadequate filtration causes tool wear and finish problems |
| Where is your service technician located? | Response time for breakdowns |
| What training do you provide for setup and maintenance? | Deep hole drilling requires specialized training |
| How is the coolant return system designed? | Poor return flow causes cavitation and chip problems |
| What is the thermal growth compensation? | Critical for precision work |
Common Specification Mistakes
| Mistake | Consequence | Prevention |
|---|
| Only specifying maximum drilling depth | Machine may not handle minimum depth parts | Specify both min and max |
| Forgetting coolant temperature control | Thermal drift in hole position | Specify chiller requirement |
| Not specifying filtration level | Coolant contamination, tool wear | Specify micron level and filter type |
| Underestimating coolant flow requirement | Chip evacuation failure at max diameter | Calculate flow for largest hole |
| Not considering chip handling | Conveyor undersized for chip volume | Specify chip volume capacity |
| Overlooking operator interface | Operator difficulty, errors | Specify ergonomic requirements |
| Ignoring future needs | Machine cannot be upgraded | Specify expandability options |
FAQ
What is the most important specification on a deep hole drilling machine?
The concentricity between the spindle centerline and the guide bushing bore is the single most important specification. It determines hole straightness, diameter accuracy, and tool life. Specify maximum 0.01 mm TIR for production and 0.005 mm for precision work.
How do I specify coolant system requirements in an RFQ?
Specify the maximum pressure and flow required for your smallest and largest hole diameters. Include the coolant type (emulsion or oil), filtration level (typically 20–50 µm), tank capacity (minimum 5× the pump flow per minute), and whether a chiller is needed. Ask the supplier to confirm their system meets these requirements.
Should I specify the control system brand?
Yes. Match the control system to your existing machines if possible. Identical controls reduce operator training time, simplify programming, and allow shared spare parts inventory. Fanuc and Siemens are the most common controls on deep hole drilling machines.
How detailed does a machine specification need to be?
Detailed enough that three different suppliers could quote against it and you could compare the quotes directly. A vague specification results in apples-to-oranges comparisons. Include all mandatory requirements, the part parameters, tolerance requirements, production volume, and desired optional features.
Do I need to specify the guide bushing system in the RFQ?
Yes — in detail. The guide bushing system determines the machine's precision capability. Specify bushing type (fixed, rotating, or retractable), diameter range, change method, and alignment adjustment. A machine without a properly specified bushing system cannot produce straight holes.
A complete machine specification prevents costly gaps between expectations and delivered capability. Invest the time to specify every system in detail before sending the RFQ. This article reflects industry practice as of 2026.
