Bernardo URS 800 N Universal Cylindrical Grinding Machine
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Description
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Product safety
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Reviews
Description
The Bernardo URS 800 N universal cylindrical grinding machine grinds externally from Ø 8 to 8–200 mm and internally from Ø 13 mm, on workpieces up to 800 mm between centers and a maximum weight of 60 kg, with a hydrodynamic spindle, inclinable table, external grinding wheel Ø 400 × 50 × 203, and an internal grinding speed of 20,000 rpm. Manufactured in Austria, distributed in Italy by Krollit as an official Bernardo distributor since 2007.
- Distance between centers: 800 mm
- External grinding diameter: 8–200 mm
- Internal grinding diameter: 13–100 mm
- Maximum workpiece weight: 60 kg
- Workpiece spindle speed: 25–380 rpm
- External grinding wheel: Ø 400 × 50 × 203 mm
- Internal grinding speed: 20,000 rpm
Who uses the URS 800 N and for what
The Bernardo URS 800 N is a professional universal cylindrical grinding machine for the precision external and internal grinding of shafts, pins, bushings, and seats: the machine that brings surface roughness below Ra 0.4 µm and dimensional tolerance to the order of hundredths on workpieces up to 800 mm in length. The hydrodynamic workpiece spindle—the main differentiator compared to grinding machines with rolling bearings—ensures constant precision even over prolonged cycles, because it eliminates vibrations transmitted by the bearings. The grinding head, which can be tilted by ±30°, allows the grinding of tapers, spherical seats, and shoulders. In Krollit customers' workshops, it is used by precision mechanical workshops, equipment manufacturers, and industrial maintenance centers that process high-precision components.
Who the Bernardo URS 800 N is for
| Profile | Compatibility | Reason |
|---|---|---|
| Hobbyist | Not suitable | Industrial precision grinding machine. Not suitable for hobby use. |
| Precision mechanical workshop | Ideal | External and internal grinding on workpieces up to 800 mm with hydrodynamic spindle: the choice for tolerances in the order of hundredths on shafts and bushings. |
| Industrial production | Ideal | For maintenance and production of precision components in continuous cycle. |
Not suitable for: workpieces over 800 mm in length (consider a larger model); workshops without knowledge of cylindrical grinding; occasional use where a bench grinder is sufficient.
Working capacity
| Specification | Value |
|---|---|
| Distance between centers | 800 mm |
| Center height | 180 mm |
| External grinding diameter | 8–200 mm |
| Maximum workpiece weight | 60 kg |
| Internal grinding diameter | 13–100 mm |
| Max. internal grinding depth | 125 mm |
Table and feeds
| Specification | Value |
|---|---|
| Table inclination | +3° to −7° |
| Table longitudinal travel | 850 mm |
| Table feed | 0.1–4 m/min |
| Manual table feed | 6 mm/rev |
Workpiece spindle and grinding wheel
| Specification | Value |
|---|---|
| Workpiece spindle speed | 25–380 rpm |
| Workpiece spindle taper | MT 4 |
| Spindle inclination | +90° |
| External grinding wheel (Ø × H × bore) | Ø 400 × 50 × 203 mm |
| External grinding wheel speed | 1670 rpm |
| Internal grinding speed | 20,000 rpm |
| Grinding head inclination | ±30° |
| Grinding head travel | 200 mm |
Compliance and safety
| Specification | Value |
|---|---|
| Marking | CE |
| Directive | Machinery Directive 2006/42/EC |
Logistics
Bernardo shipping: 5–9 working days (7 days to the South). Heavy precision machine: coordinate unloading equipment with Krollit before delivery. Original spare parts available with 3–5 working days shipping. Customer assistance in Italian available.
Frequently Asked Questions
What does "hydrodynamic spindle" mean and why is it important?
The hydrodynamic spindle supports the shaft on an oil film instead of rolling bearings. This eliminates the micro-vibrations typical of bearings—which transfer to the ground surface as undulations—and guarantees superior dimensional repeatability. It is the standard for industrial precision grinding machines. Grinding machines with rolling bearings cost less but do not achieve the same tolerances.
What is the achievable dimensional precision with the URS 800 N?
Under optimal conditions (well-balanced workpiece, correct grinding wheel, adequate cooling fluid), the URS 800 N achieves dimensional tolerances of IT5–IT6 (order of hundredths of a mm) and surface roughness Ra 0.2–0.4 µm. The actual precision depends on the operator, the type of material, and operating conditions.
What type of grinding wheel is used for internal grinding?
For internal grinding, the head reaches 20,000 rpm—necessary to maintain optimal peripheral speed with small diameter grinding wheels. Cylindrical grinding wheels mounted on a mandrel with a diameter compatible with the hole to be ground are used. For different materials (steel, cast iron, aluminum, carbides), grinding wheels of different compositions (corundum, silicon carbide, CBN) are used.
Is 45° grinding and taper grinding possible on the URS 800 N?
Yes. The grinding head can be tilted by ±30° relative to the workpiece axis, allowing the grinding of tapers, angled shoulders, and complex shapes. The table can be tilted from +3° to −7° for taper grinding on long workpieces. The combination of the two inclinations covers almost all geometries required in a precision workshop.
What cooling fluid is used?
For cylindrical grinding, a 3–5% water+oil emulsion or neat grinding oil is typically used, depending on the material and grinding wheel. The cooling system of the URS 800 N is integrated. Contact Krollit for details on the coolant delivery system.
