Ultra Precision Air Bearing Slides:

A range of box section slides are available as basic linear bearing units or as fully integrated modules with direct drive motors, encoders, sealing bellows and cable management systems. The slides are designed specifically for high static stiffness and low motion errors and feature:-

  • A modular construction enabling them to be easily integrated into machine systems.
  • Thermally stable, natural granite beams with bronze carriages.
  • Micro recessed air bearings giving high stiffness and low air consumption.
  • Bearing arrangement resistant to roll, yaw and pitch.
  • Integral cogging free linear motor.
  • Integral high resolution encoder.
  • Frictionless weight compensation system for vertical slides.
  • Available in a range of standard sizes or as a bespoke design.

Basic slide units simply consist of a natural granite beam and a bronze carriage. The granite has low porosity and is precision lapped to give flatness, parallelism and squareness tolerances to within +/-1 μm over the beam’s full length. Bronze is an excellent bearing material tolerant of dry sliding contact in the event of overload. The slides may be used with either the beam or the carriage fixed in position. Standard fixing holes on the end faces of the beam enable end plates or external drives to be attached. Carriages are supplied with an array of tapped holes to customer specifications to facilitate mounting or allow the attachment of drives or work holding devices.   

Basic slide units fitted with integral linear motors and encoders are suitable for use in clean environments or in sealed systems.

The motors are of a compact design with magnets mounted in a U channel to eliminate net magnetic attraction. Motors are also designed to be cogging free to enable smooth motion and high positional accuracy to be achieved. Under low and moderate duty cycles heat generation is negligible and cooling is generally unnecessary but where high duty cycles are encountered motors with integral cooling are available.

With frictionless bearings, the slides are suitable for use with high resolution encoders and are generally supplied with encoder resolutions in the range of 1 to 10 nm.

In addition to linear motors and encoders fully furnished slide systems incorporate sealing bellows, end mounting plates and energy chain cable management.

Frictionless pneumatic cylinders provide weight compensation for vertical slides ensuring negligible heat generation from the linear motor. The cylinders are fitted with pneumatic locking mechanisms that can be activated in the event of air pressure or electricity supply failure.

Micro Recessed Bearings:

Micro recessed air bearings (patent granted) are a feature of all UPM’s motion products. They overcome a basic limitation of conventional air bearings when used in ultra precision applications. The recesses are designed to provide a near uniform air pressure distribution in the bearing film and to allow the film thickness to be reduced to a level that is impractical with conventional orifice fed air bearings. The result is higher static stiffness, lower motion errors and reduced air consumption.

Acknowledgements:

UPM gratefully acknowledges funding from the UK’s South West Regional Development Agency enabling the development of the micro recessed bearing and the collaboration of ITP Group Ltd in developing the slide systems.

OUTLINE SPECIFICATION (hover mouse over table to pause):

Slide Data:
The following data provides an example of slide performance.

Size and Travel Distance
Parameter Slide Model No. BL200
Carriage Width  - Wc (mm) 200
Carriage Length -  Lc (mm) 200
Carriage Height - Hc (mm) 115
Beam width – Wb (mm) 75
Beam height – Hb (mm) 160
Beam Length – Lb,  Min to Max (mm) 300-600
End Fixing Thread M10
Travel distance, Min to Max (mm) 50-300

 

 

Drive Performance
Parameter Slide Model No. BL200
Anorad Motor Type LEM-S-3-S
Continuous Force (N) 75
Peak Force (N) 238
Motor Constant (NW 1/2) 7.1
Thermal  Resistance (Thermal)                       0.89
Max Power Dissipation (W) 113
Max Bus Voltage (V) 325
Electrical Cycle Length (mm)       30
Electrical Time Constant (ms) 0.5
Max Coil Temp (°C) 125
Force Constant (N/Apk) 16.7
Back EMF Constant p-p (V/m/s) 19.7
Pk Current (A) 14.3
Continuous Current (A) 4.5
Resistance at 20°C (Ohm) 5.3
Inductance p-p (mH) 2.7

 

Slide Performance
Parameter Slide Model No. BL200
Load Capacity
Vertical (N) 1000
Horizontal (N) 1000
Pitch (Nm) 27
Roll (Nm) 32
Yaw (Nm) 28
Static Stiffness
Z (N/μm) 320
Y (N/μm) 320
Pitch (Nm/μrad) 1.1
Roll (Nm/μrad) 1.4
Yaw (Nm/μrad) 1.1
Motion Error per 100 mm of Travel
Z (μm) 0.2
Y (μm) 0.2
Pitch (μrad) 2
Roll (μrad) 2
Yaw (μrad) 2
   
Air Consumption (l/min) 28
Maximum Speed (m/s) 0.162 – 1.625

 

 

Encoder System
All slides are fitted with Renishaw Tonic readheads and RELM invar or stainless steel scales. The following options are available:-
Parameter Model No.
  Ti-0400 Ti-1000 Ti-2000 Ti-4000
Readhead Resolution* (μm) 50 20 10 5
Max Speed ** (m/s) 1.625 0.648 0.324 0.162

* Quoted resolution is without interpolation
** Quoted speed is for a maximum receiver clock frequency of 50 MHz.


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