Precision Ring Forging

LYJW provides custom ring forging services using either customer-supplied materials or our own material stock, including 35CrMo, 42CrMo, 40Cr, 35SiMn, and other grades. Our subsidiary forging plant, Hengjia Heavy Industry, is equipped with 4,000-ton and 8,000-ton presses, an 8.5-meter ring rolling mill, and 5-meter CNC lathes, enabling integrated production from forging to finished components.

• Raw Materials: 40Cr, 35SiMn, 35CrMo, 42CrMo, 50Mn
• Forging Process: Large presses and ring rolling equipment are used to reshape the billet, control grain flow, and reduce internal defects.
• Final Product: Custom ring blanks or semi-finished gear rings in your required dimensions.

Precision Ring Forging Process

Billet Preparation

Sawing

Heating Furnace

Forging Press

Ring Rolling

Tempering Heat Treatment

Finished Ring Forging

Inspection and Quality Control

Turning

• Rough turning.
• After rough turning, the workpiece is detected by an ultrasonic flaw detector to examine cracks or other flaws and ensure the bearing’s stable quality and normal service life.
• Quenching and tempering can be conducted according to the requirements, to improve the strength and fatigue resistance of the material.
• Aging treatment (within 48h) is carried out to eliminate the inner stress and prevent workpiece deformation.
• Finish turning. In this process, in order to prevent the bearing parts deformation, the parts clamping tool must be loosened first and retightened again after adjustment.
• Special process for inner rings of crossed roller bearings and three-row roller slewing bearings: the inner rings of these bearings must be processed in pair and cut after heat treatment.

High-Precision Raceway Grinding: Consistent Raceway Quality

Raceway grinding is a critical process in slewing bearing manufacturing because it directly affects running accuracy, load distribution, and service life. LYJW uses dedicated grinding equipment and follows a controlled two-step grinding process:

• Rough Grinding
  A 36-grit resin-bond grinding wheel is used at a speed of ≤1500 rpm and a cutting depth of ≤1 mm. This removes excess material efficiently while protecting the raceway surface.
• Fine Grinding
  A 46- or 60-grit resin-bond grinding wheel is used for finishing, helping achieve the required surface finish and dimensional accuracy.

Heat treatment

• Perform medium frequency hardening on the surface of bearing raceway to form a hardened layer with hardness≥55HRC, depth≥4mm and the width of soft zone is≤50mm with a “S” mark on it.
• Perform dye penetrant inspection to detect whether there are cracks or other flaws on the raceway.

Gear Cutting

For slewing bearings with external or internal gears, gear cutting is performed before final grinding to achieve the required gear profile and machining accuracy.

High-Precision CNC Drilling: Core Accuracy for Slewing Bearings

Our double-spindle gantry CNC drilling machine integrates drilling, boring, and tapping for large-diameter slewing bearings with multiple mounting holes. Built with a high-rigidity structure, closed-loop CNC control, and dual-spindle synchronization, the equipment delivers accurate hole positioning, tight tolerance control, and excellent parallelism.

This process supports the demanding requirements of wind power, construction machinery, and tunnel boring machine (TBM) applications. Each bearing is machined with strict dimensional control to help ensure reliable installation and long-term operating performance.

Precision Assembly

Assembly accuracy has a direct impact on the operating stability and service life of a slewing bearing. Therefore, after precision grinding, our technical team carries out pre-assembly and calculates the appropriate internal clearance according to the bearing design and application requirements.

The bearing then undergoes starting torque inspection. If the starting torque does not meet the specified standard, the team reviews and adjusts the raceway and clearance matching, then verifies the result again. This process continues until the key parameters fall within the required design range.

Through controlled assembly and repeated verification, LYJW ensures that each delivered bearing meets the required standards for precision, rotation performance, and reliability.

Full-Process Quality Inspection: Ensuring Reliability

Multi-Dimensional Inspection Across All Processes

• Dimensional Accuracy Control: Using calipers, dial indicators, height gauges, and other professional measuring tools, we verify key dimensions such as inner diameter, outer diameter, gear profile, and mounting holes to ensure that tolerances meet design requirements.
• Mechanical Performance Testing: Portable hardness testers and hardened layer depth testers are used to inspect hardness, hardened layer depth, and other mechanical properties. This helps ensure strength and durability under heavy-load and high-impact operating conditions.
• Non-Destructive Testing (NDT): Using equipment such as CDX-III magnetic particle flaw detectors, we conduct non-destructive inspection on critical areas such as raceways, gear teeth, and welds to identify cracks, slag inclusions, and other potential defects—eliminating safety hazards.
• Final Pre-Delivery Inspection: After assembly, clearance adjustment, and starting torque verification, each product undergoes final comprehensive inspection covering dimensions, performance, and appearance before shipment.

Quality Commitment — Full Traceability

Inspection data for every bearing is recorded and traceable from material sourcing to final delivery. Through strict quality control standards, professional inspection methods, and disciplined production management, LYJW helps ensure reliable product performance for demanding industrial applications.

Protective Packaging: Safeguarding Every Precision Component

• Lifting: Multi-point balanced lifting methods are used for heavy components to help prevent deformation during handling.
• Protection: Anti-rust and moisture-resistant film, combined with cushioning materials, provides protection during sea or land transport and helps prevent rust, moisture damage, and impact.
• Crating: Custom reinforced wooden crates are secured with steel strapping and internal supports to provide the structural strength required for international shipping.
• Custom Packaging: Tailored packaging solutions are available for slewing bearings, large structural components, and irregular parts to meet different transport requirements.