Metric Inch Needle Bearing Cage Assemblies

Product Overview

Metric Inch Needle Bearing Cage Assemblies are versatile components that combine needle rollers with a precision cage to support radial loads in both metric and inch-sized mechanical systems. Unlike standalone needle bearings, the cage assembly keeps the needle rollers evenly spaced, preventing roller contact (which reduces friction and wear) and simplifying installation— especially in systems where alignment is critical. The “Metric Inch” designation means the assemblies are available in both metric (e.g., 10mm × 15mm × 12mm) and inch (e.g., 0.5in × 0.75in × 0.6in) dimensions, making them ideal for retrofitting old inch-sized equipment (e.g., vintage machinery) or integrating with new metric systems (e.g., modern factory automation). The cages are made of durable materials (nylon, brass, or steel) to suit different environmental needs, while the needle rollers use high-carbon steel for high load capacity. These assemblies are widely used in general machinery, automotive, and aerospace industries due to their flexibility, compact design, and cost-effectiveness— they eliminate the need to stock separate metric and inch bearings, reducing inventory costs by up to 40%.

Product Features

Dual-Dimension Compatibility

Available in a full range of metric and inch sizes, the assemblies cover common dimensions: metric inner diameters from 5mm to 50mm, outer diameters from 8mm to 60mm, and widths from 6mm to 40mm; inch inner diameters from 0.25in to 2in, outer diameters from 0.375in to 2.5in, and widths from 0.25in to 1.5in. Each assembly is clearly labeled with both metric and inch dimensions (e.g., “12mm × 18mm × 15mm / 0.5in × 0.75in × 0.6in”) for easy identification. The dimensional precision (ABEC-3 grade) ensures compatibility with both metric and inch shafts/housings— no need to modify the equipment to fit a single dimension system.

Cage Material Options

Nylon Cages (PA66)

Lightweight (30% lighter than steel cages) and cost-effective, nylon cages are suitable for low to medium speeds (≤ 4,000 rpm) and dry or clean environments (e.g., office equipment like printers). They have good chemical resistance (resist oils and mild solvents) and operate in temperatures from -30°C to +120°C. Nylon cages are non-magnetic, making them ideal for electronic equipment (e.g., small motors) where magnetic interference is a concern.

Brass Cages (H62 Brass)

Durable and high-temperature resistant (up to 180°C), brass cages are used in high-speed (≤ 6,000 rpm) or high-load applications (e.g., automotive gearboxes). They resist deformation under heavy loads (up to 30 kN radial load) and are compatible with high-temperature lubricants (e.g., polyurea grease). Brass cages are also corrosion-resistant, making them suitable for damp environments (e.g., marine auxiliaries).

Steel Cages (SPCC Steel)

Heavy-duty and impact-resistant, steel cages handle extreme loads (static radial load up to 50 kN) and harsh environments (e.g., construction machinery). They operate in temperatures from -40°C to +200°C and are compatible with all types of lubricants. Steel cages are magnetic but offer the longest service life (up to 20,000 operating hours) in high-cycle applications.

Needle Roller Performance

The needle rollers are made of high-carbon chromium steel (SUJ2), heat-treated to HRC 60-64 for wear resistance. The rollers have a precision-ground surface (Ra ≤ 0.02μm) that reduces friction between the roller and cage, lowering operating temperature (≤ 75°C at 3,000 rpm). The roller length-to-diameter ratio (typically 3:1) maximizes the contact area with the shaft, delivering a dynamic radial load capacity of 15 kN to 45 kN (depending on size: 15 kN for 10mm metric / 0.5in inch, 45 kN for 50mm metric / 2in inch) and static radial load capacity of 25 kN to 70 kN.

Usage

Industry Applications

General Machinery Retrofitting

Vintage lathes and milling machines (often inch-sized) can be retrofitted with these assemblies to replace worn bearings, as the dual-dimension design fits both the old inch-sized shafts and new metric replacement parts. For example, a 1950s inch-sized drill press with a 0.75in shaft can use an assembly labeled “19mm × 28mm × 20mm / 0.75in × 1.1in × 0.8in,” eliminating the need to machine a new metric shaft. This retrofitting saves time and cost compared to replacing the entire machine.

Automotive Auxiliary Systems

In car power steering pumps and water pumps, the assemblies support the radial load of the pump shaft. Nylon cages are used for low-noise operation (≤ 55dB), while brass cages are used in high-temperature areas (e.g., near the engine block). The dual-dimension compatibility allows manufacturers to use the same assembly in both metric (European cars) and inch-sized (American cars) models, streamlining production.

Aerospace Components

In small aircraft landing gear auxiliaries (e.g., wheel bearings), steel cage assemblies handle the high radial loads (up to 40 kN) from the aircraft’s weight. The wide temperature range (-40°C to 200°C) accommodates the extreme temperatures of high-altitude flight (cold) and ground operations (hot). The precision ABEC-3 grade ensures smooth rotation, reducing vibration during landing— critical for passenger comfort and equipment safety.

Operational Recommendations

Choose the cage material based on the application: nylon for low speed/clean environments, brass for high speed/temperature, steel for heavy load/harsh environments. Lubricate with lithium-based grease (NLGI 2) every 3-6 months— more frequently (every 2 months) for high-speed or high-load applications. Avoid axial loads exceeding 5 kN— these assemblies are designed for radial loads, and excessive axial load can cause the needle rollers to misalign and wear prematurely.

FAQ

Installation & Maintenance

How to distinguish between metric and inch dimensions on the assembly?

The assembly’s outer ring has a laser-etched label with metric dimensions first (e.g., “15mm × 22mm × 18mm”) followed by inch dimensions in parentheses (e.g., “(0.6in × 0.875in × 0.7in)”). For unlabeled assemblies, measure the inner diameter with a caliper: metric dimensions are in whole numbers or tenths of a millimeter (e.g., 12mm, 18.5mm), while inch dimensions are in quarters, eighths, or sixteenths of an inch (e.g., 0.5in, 0.375in).

Can the cage be replaced separately from the needle rollers?

No— the cage and needle rollers are assembled as a single unit at the factory, with the rollers press-fitted into the cage pockets. Replacing only the cage can cause the rollers to be misaligned, leading to increased friction and premature failure. If the cage is damaged (e.g., cracked nylon), replace the entire assembly to ensure performance.

Performance & Compatibility

What is the maximum speed for these assemblies?

Speed depends on the cage material: nylon cages up to 4,000 rpm, brass cages up to 6,000 rpm, steel cages up to 5,000 rpm. Speed is also limited by the lubricant— use low-viscosity oil (ISO VG 32) for high-speed applications to reduce friction and temperature.

Are they compatible with both solid and hollow shafts?

Yes, as long as the shaft’s outer diameter matches the assembly’s inner diameter (metric or inch) and the shaft’s surface finish is Ra ≤ 0.8μm. For hollow shafts, ensure the shaft’s wall thickness is at least 2mm (metric) or 0.1in (inch) to prevent deformation under load. For example, a 20mm metric hollow shaft with a 2mm wall thickness can safely use a 20mm inner diameter assembly with a static radial load of up to 30 kN.