4.9 Rail Installation

4.9.1 Methods of Attachment

MONORAIL guide rails can be fastened in two ways. Standard rails (N) and rails for cover strips (C) have continuous fixing holes with countersunk holes for fastening from above. Additionally, rails with threaded fixing holes at the bottom (U) are available, which can be bolted from below the machine table. The following overview shows the advantages and disadvantages of both fastening methods.

Fastening from Above (N, ND, C, CD)

Advantages

• Easy accessibility

Disadvantages

• Rail fixing holes must be closed with plugs or cover strips to protect wipers
• Protruding edges due to closures: wiper wear, contamination

Fastening from Below (NU, NUD)

Advantages

• No closures required for rail fixing holes
• No protruding edges on rail surface

Disadvantages

• Limited accessibility
• Lower clamping force due to longer screws

4.9.2 Rail Options

Special Fixing Hole Spacing L4

Fixing hole spacing diagram

Double or Half Fixing Hole Spacing L4

On request, MONORAIL MR rails can be supplied with double fixing hole spacing L4. This is not a standard product (order code NX). Availability needs to be confirmed. It should be noted that rigidity and running accuracy will be reduced in this case.

For MONORAIL BM rails, rails with half fixing hole spacing (corresponding to MR standard L4) are also available to increase rigidity and improve running accuracy. This is not a standard product (order code NX). Availability needs to be confirmed.

Other Special Fixing Hole Spacings

Customer-specific fixing hole spacings or varying fixing hole spacings along the rail length, for example at joints of multi-segment rails, can be provided on request.

Additional Locating Fixing Holes and Threads

Rails with additional fixing holes, for example for locating pins, or rails with additional threaded holes are optionally available. Availability needs to be confirmed.

Additional Fixing Holes on Rail Top Surface

Additional fixing holes can be machined on the rail top surface according to customer-specific specifications, for example for locating pins or through holes (e.g., for mounting carriages). Availability needs to be confirmed.

Rail End Machining

Rail ends are machined after separating the rails.

Standard

4.9.3 Closures for Fixing Holes

The following closures are available for rail fixing holes:

A comparison of the advantages and disadvantages of various element types can be found in Section 4.3 - Rail Types.

For available sizes, types, and ordering details, please refer to the SCHNEEBERGER MONORAIL and AMS product catalog; for installation information, please refer to the SCHNEEBERGER steel plug and brass plug installation instructions.

Plastic Plugs

Features:

• Inexpensive
• Easy to install and remove
• Suitable for protected axes and clean working environments, e.g., handling applications
• Roller product order code: MRK
• Ball product order code: BRK
• Cannot be reused

Brass Plugs

Features:

• Inexpensive
• Smooth and gap-free surface
• Excellent scraping function
• Suitable for higher thermal loads and mechanical stresses
• Liquid-tight
• Requires hydraulic installation tool for assembly
• Cannot be reused
• Roller product order code: MRS
• Ball product order code: BRS

Steel Plugs

Features:

• Smooth rail surface
• Good scraping function
• Suitable for high mechanical and thermal stresses, e.g., outdoor environments, chip zones
• Simple assembly using hydraulic installation tool
• Expensive
• Cannot be reused
• Roller product order code: MRZ

Cover Strips

Features:

• Smooth rail surface with only one protruding edge in the longitudinal direction
• Good scraping function
• Minimal installation effort using installation tool
• Only one closure required for entire rail
• Can be reused multiple times and easily removed
• Free space required behind rail during installation
• Cover strip ends secured with end pieces (EST) or fixing bands (BSC)
• Roller product order code: MAC
• Ball product order code: BAC

4.9.4 Rail Length Tolerances

Rail Length Tolerances and Rail Fixing Hole Tolerances for N, ND, NU, NUD, C and CD Type Rails

Longitudinal tolerances for single and multi-segment rails are: L3 = -/-2 mm

Position tolerances for fixing holes of single and multi-segment rails are as follows:

Fixing hole spacing diagram L4:
L4 = Fixing hole spacing
L3 = Rail length

4.9.5 Permissible Screw Tightening Torques

The following table lists the maximum tightening torques for DIN 912 / ISO 4762 fixing screws. These values are based on the friction coefficient μ = 0.125 in the as-delivered condition.

Tightening Torques for Fixing Screws ISO 4762:

4.9.6 Permissible Lateral Force Without Locating Surface

For cases where no locating surface is provided, guidance values for maximum permissible lateral forces can be obtained from the following table.

F_{Side_max} values depend on dynamic load capacity C, carriage fastening type, and screw strength class.

MONORAIL MR Maximum Lateral Force F_{Lateral_max} (N)

MONORAIL BM Maximum Lateral Force F_{Lateral_max} (N)

Maximum Lateral Force F_{Side_max} (N) Acting on Single Carriage

The listed maximum lateral forces apply only to ideally rigid connection surfaces in the connecting structure and steel or cast steel screw fasteners. In cases of unstable connection surfaces, screw loads increase significantly and may cause screw connection loosening. For aluminum screw fasteners, maximum permissible lateral forces should be reduced according to VDI 2230 standard.

4.9.7 Permissible Tensile Forces and Lateral Torques

The maximum load of profiled rail systems is determined not only by the static load capacity C₀ and static moment M₀ of the rolling contact, but also by the screw connections of carriages and rails. In this case, the screw connection of the rail determines the maximum load limit.

Maximum Tensile Force F_{Tension_max} and Lateral Torque M_{Q_max} for Profiled Rail Systems

MONORAIL MR Maximum Tensile Forces and Lateral Torques

MONORAIL BM Maximum Tensile Forces and Lateral Torques

Precautions

When exceeding these values, always check screw connections. For this purpose, you may need to loosen the screw connections.

The listed maximum tensile forces and torques apply only to ideally rigid connection surfaces in the connecting structure and steel or cast steel screw fasteners. In cases of unstable connection surfaces, screw loads increase significantly and may cause screw connection loosening. For aluminum screw fasteners, maximum tensile forces and lateral torques should be reduced according to VDI 2230 standard.

4.9.8 Factors Affecting Accuracy

The accuracy of rail fastening is affected by a series of factors:

Detailed Information

For detailed information on each point, please refer to:

• SCHNEEBERGER MONORAIL and AMS product catalog and installation instructions
• Section 1.6 - Accuracy
• Section 1.7 - Straightness and Rail Curvature
• Section 4.7 - Straightness