Cylindrical Roller Bearing NU414M/C3 SKF

The SKF NU414M/C3 is a single-row cylindrical roller bearing with a removable outer ring, engineered for heavy radial loads and moderate-speed operation. It complies fully with ISO 355 and DIN 628 standards, featuring optimized internal geometry, high rigidity, and reliable performance in industrial environments. The suffixes denote key configurations: M for a brass cage and C3 for increased radial internal clearance, making it ideal for applications with thermal expansion and heavy-duty requirements.

1. Detailed Dimensional Parameters

Conforming to ISO 355 standards, the bearing has an inner diameter (d) of 70mm, outer diameter (D) of 180mm, and width (B) of 42mm. The minimum chamfer size (rₘᵢₙ) is 2.5mm, with a tolerance grade of P0 (ISO 492). Its basic dynamic load rating (C) is 224kN, basic static load rating (C₀) is 224kN, reference speed (grease lubrication) is 4500r/min, and limiting speed (oil lubrication) is 6300r/min. The C3 radial internal clearance (0.030–0.048mm) accommodates thermal expansion in high-temperature operations, while the NU design allows free axial displacement of the inner ring relative to the outer ring.

2. Specific Material Description

The inner ring, outer ring, and cylindrical rollers are manufactured from high-carbon chromium bearing steel (AISI 52100/SUJ2), refined via vacuum degassing to minimize non-metallic inclusions. After precision heat treatment, it achieves a hardness of 60–64 HRC, delivering exceptional wear resistance, fatigue strength, and dimensional stability under cyclic loading. The cage (suffix M) is a solid brass cage, offering excellent thermal conductivity, impact resistance, and wear resistance to ensure stable roller guidance and reduced friction at high speeds. For corrosive environments, optional stainless steel (SUS440C) components are available.

3. Core Processing Technology

Key manufacturing processes follow SKF’s stringent quality standards:

• Closed-die forging: Produces a dense internal structure with continuous metal fibers, enhancing load-bearing capacity and fatigue life.

• CNC turning: Achieves a surface roughness of Ra ≤ 0.4μm, ensuring precise dimensional control for tight fits.

• Controlled atmosphere heat treatment: Uses a nitrogen-hydrogen protective atmosphere to prevent oxidation and decarburization, resulting in uniform hardness distribution.

• Precision grinding and superfinishing: Employs CBN grinding wheels to reduce raceway roughness to Ra ≤ 0.05μm, minimizing friction, noise, and wear.

4. Service Life

Under standard operating conditions (3000r/min, radial load of 70kN, proper lubrication, and a clean environment), the L₁₀ basic rated life (90% reliability) is 21,000 operating hours, calculated in accordance with ISO 281:2007 and SKF’s proprietary life prediction model. Key factors affecting service life include lubrication quality, contamination levels, installation accuracy, and load magnitude; insufficient lubrication or excessive contamination can reduce service life by 30–50%.

5. Application Scenarios and Industries

The NU414M/C3 is widely used in heavy industrial sectors, including mechanical manufacturing, mining, power generation, and construction machinery. Typical applications include large electric motors, gearboxes, rolling mills, crushers, and conveyor systems. It is well-suited for these scenarios due to its high radial load capacity, C3 clearance for thermal adaptability, and brass cage for stable high-speed operation, making it ideal for heavy-duty, moderate-speed applications.

6. Basic Maintenance Requirements

• Maintenance cycle: 2000 operating hours.

• Lubrication: Use lithium-based grease (NLGI 2) or extreme pressure gear oil (ISO VG 68), with a filling amount of 15–30% of the bearing’s free space. Re-lubricate every 1500–2000 hours.

• Cleaning: Remove dust and old grease with clean kerosene; avoid corrosive cleaners and ensure thorough drying after cleaning.

• Inspection: Regularly check for abnormal noise, temperature rise, and grease leakage. Replace lubricant immediately if it darkens or deteriorates, and inspect for roller or raceway wear if vibration increases.

7. Installation Precautions

• Pre-installation: Keep the installation area clean; remove burrs from the shaft and housing, and verify dimensional accuracy. Do not open the bearing package until installation to prevent contamination.

• Installation: Apply a thin oil film to fitting surfaces; use a press to apply force evenly to the inner ring (avoid hammering to prevent damage). Ensure coaxiality tolerance ≤ 0.02mm.

• Fastening torque: Tighten housing bolts to 130–160N·m in a diagonal sequence.

• Post-installation: Rotate the bearing manually to check for jamming; measure operating temperature after 30 minutes (normal ≤ 70℃).

• Safety: Wear protective gloves and goggles; use specialized lifting tools for handling, and avoid direct contact with raceways to prevent surface damage.