Spindle Selection Guide
Choosing a spindle comes down to three questions: what are you grinding, what is it made of, and how tight is the tolerance. This guide walks each one to a specific model.
Select by Application
The fastest route — find the job, get the model.
| Application | Recommended | Why |
|---|---|---|
| PCB micro drilling (0.1–0.5 mm holes) | 80KG150Q1 | 150,000 RPM — the only range where drills that small stay true |
| Dental implant thread milling | 80KG150Q1 / 100KG120Q1.5 | High speed for fine features in stainless and titanium |
| Aluminium small parts (drone, electronics) | 120KG60Q5 | 60,000 RPM and 5 kW — the best speed-to-power balance |
| Carbon fibre composite cutting | 120KG60Q5 | High speed with low vibration prevents delamination |
| Engine block roughing (cast iron / aluminium) | 170KG18Q29 | 34 kW for heavy-duty material removal |
| Bearing inner ring grinding | 170KG09Z15 | 9,000 RPM with high torque; roundness below 2 μm with CBN |
| Die and mould finishing | 100KG120Q1.5 / 120KG60Q5 | High speed for fine surface finish |
| Motor shafts, transmission shafts (50–120 mm) | 150KG03Z11 | 3,000 RPM, 11 kW — our most popular OD grinder |
| Rolls and large hydraulic cylinder rods | 210KG015Z28 | NN3024 heavy bearings, 28 kW for multi-tonne parts |
| P2 grade bearing races, optical moulds | 200KG024Y20 | Hydrostatic film, roundness below 0.3 μm |
Select by Workpiece Diameter
For cylindrical grinding, diameter sets the frame size — and the workhead has to match.
| Workpiece Diameter | OD Grinding Spindle | Matching Workhead |
|---|---|---|
| Under 50 mm | 120KG04Z6.3 | 90KG02Z1 |
| 50 – 120 mm | 150KG03Z11 | 170KG01Z4.5 |
| 100 – 200 mm | 170KG03Z18 | 170KG01Z4.5 |
| 200 – 300 mm | 190KG025Z22 | 240KG003Z9.5 |
| Over 300 mm | 210KG015Z28 | 240KG003Z9.5 |
Material matters too: soft materials such as aluminium and copper allow higher speeds, while hardened steel, bearing steel and carbide call for the higher-power, lower-speed models.
Built-in vs External Motor
Where the motor sits decides how the spindle behaves thermally.
Angular Contact vs Hydrostatic
Rolling elements or an oil film — a decision about accuracy class, not preference.
| Angular Contact | Hydrostatic | |
|---|---|---|
| Bearing type | Angular contact ball bearing (mechanical contact) | Hydrostatic (oil film, no contact) |
| Accuracy | Micron level (1–5 μm) | Sub-micron (below 0.5 μm) |
| Vibration | Slight vibration from rolling elements | Near zero — the oil film absorbs it |
| Service life | Bearings wear and need replacement | No contact wear |
| Speed | Very high (60,000 – 150,000 RPM) | Moderate (around 2,400 RPM) |
| Best for | General machining, high-speed cutting | Ultra-precision grinding, mirror finishing |
Sizing a Dressing Spindle
Match the dresser to the wheel diameter — and to the abrasive.
Common Questions
What information do you need to recommend a spindle? +
Three things get you a specific answer: what workpiece you are grinding and its diameter, what material it is, and what tolerance you need. Diameter narrows the frame size, material decides whether you need speed or torque, and tolerance determines the bearing grade and assembly class.
How do I read the model numbers? +
Take 170KG09Z15: 170 is the housing diameter in mm, 09 indicates 9,000 RPM maximum speed, and 15 is the power in kW. As the frame number rises from 120 to 210, speed falls and power and torque rise — bigger, heavier workpieces.
Built-in motor or external motor? +
Built-in for high speed, compact space and frequent tool changes. External motor for long continuous runs, heavy cuts and retrofits, because the motor heat never reaches the spindle and accuracy stays stable across a full shift.
When is a hydrostatic spindle worth the cost? +
When you need sub-micron roundness — P2 grade bearing races, optical moulds, hydraulic valve spools. Below that requirement, angular contact bearings are faster and considerably more economical.
Can you match a spindle to an existing machine? +
Yes. Send the mounting dimensions, the interface and the drive arrangement. The external motor series in particular is designed with flexible interfaces for retrofit work.
Tell Us Your Application
Send us the workpiece, the material and the tolerance. Our engineers will come back with a specific model, not a catalogue.
- Engineering-led support
- Drawings welcome
- Reply within one business day