Application NotesTechnical Documentation & Guides

Overview

NB ball splines provide smooth linear motion along a splined shaft while transmitting torque, making them ideal for applications requiring simultaneous linear and rotational movement. Unlike conventional splines that rely on sliding contact, NB ball splines use recirculating ball bearings for low friction, zero backlash, and long service life. Proper selection requires matching the load capacity, stroke, and torque requirements to the correct spline model.

Load Capacity Calculations

Ball spline selection starts with determining the applied loads. Calculate the radial load (perpendicular to shaft), moment load (torque about the shaft), and any combined loading conditions:

• Basic dynamic load rating (C) for continuous motion applications
• Basic static load rating (Co) for stationary or slow-speed loads
• Calculate equivalent load: Pe = Fr + 0.5 × Mt/dp (radial + moment)
• Service life: L = (C/Pe)³ × 50 km (basic rating life)
• Apply service factor for shock, vibration, and environmental conditions

Spline Shaft and Nut Selection

NB offers ball splines in shaft diameters from 6mm to 50mm. Select the shaft diameter based on load calculations, then choose the nut type—flange mount, block mount, or cylindrical—based on mounting requirements. For high-torque applications, select models with more ball circuits (3 or 6 circuits) for increased torque capacity.

Installation Considerations

Proper alignment between the shaft and mating components is critical for ball spline performance. Misalignment causes uneven ball loading, reducing life and increasing friction. Use precision ground mounting surfaces and verify alignment with a dial indicator during installation. Lubricate with the specified grease before first operation.

Typical Applications

• Robotic tool changers
• Pick-and-place with rotation
• Screw driving systems
• Vertical transfer with rotation

Related Products

SSP Series • SBS Series • SSS Series

Overview

NB linear guide systems use recirculating ball or roller elements to provide smooth, precise linear motion with high rigidity. Available in miniature to heavy-duty sizes, NB guides offer accuracy grades from standard (±20µm) to ultra-precision (±2µm). This guide covers the selection process from load analysis through accuracy class selection and environmental considerations.

Load Analysis and Rail Sizing

Begin by calculating the loads on each carriage block including weight, cutting forces, acceleration forces, and moment loads. NB provides load ratings for radial, reverse radial, and lateral directions:

• Radial load capacity (downward, into the rail)
• Reverse radial capacity (upward, away from the rail)
• Lateral load capacity (side loads)
• Moment load capacity (pitch, yaw, and roll)
• Calculate equivalent load considering all directions

Accuracy Grade Selection

NB linear guides are available in multiple accuracy grades. Higher grades provide tighter running parallelism and height variation between carriages, which is essential for precision applications. Standard grade is suitable for general automation, while precision and ultra-precision grades are needed for measurement, optics, and semiconductor applications.

Sealing and Environment

For dusty, wet, or corrosive environments, NB offers stainless steel guides, special seals, and scrapers. End seals prevent contamination from entering the ball recirculation path, while bottom seals protect against debris on the rail surface. For cleanroom applications, special low-particle-generation seals and greases are available.

Typical Applications

• Machine tool axes
• Semiconductor handling
• Metrology and inspection
• Medical device mechanisms

Related Products

SGL Series • SER Series • SEB Series

Overview

Proper maintenance is essential for maximizing the service life of NB linear motion components. Regular lubrication prevents metal-to-metal contact between rolling elements and raceways, while periodic inspection identifies wear before it causes machine downtime. This guide provides maintenance schedules, recommended lubricants, and inspection procedures for all NB linear bearing product lines.

Lubrication Schedules

Lubrication frequency depends on operating conditions. As a baseline:

• Standard conditions: Re-lubricate every 100 km of travel or 6 months
• High-speed applications (>1 m/s): Every 50 km or 3 months
• Dusty/contaminated environments: Every 25 km or monthly
• Cleanroom applications: Use specified low-outgassing grease, 200 km intervals
• Vertical applications: More frequent due to gravity drainage

Recommended Lubricants

NB recommends lithium-based grease (NLGI Grade 2) for most applications. The grease should have good rust prevention properties and be compatible with the seal material. For high-speed applications, use lower-viscosity oil lubrication. Never mix different grease types, as incompatible greases can lose their lubricating properties.

Inspection and Replacement Criteria

Inspect linear bearings during scheduled maintenance for abnormal noise, increased friction, visible corrosion, or excessive play. Measure running parallelism periodically to detect wear. Replace bearings when noise increases significantly, when positioning accuracy degrades beyond application requirements, or when visible surface damage (pitting, flaking) is observed on raceways.

Typical Applications

• Preventive maintenance programs
• Machine tool maintenance
• Automated production equipment
• Cleanroom equipment service

Related Products

All NB linear motion products