Half-Coupling-Shenzhen Nordson Bo Communication Co., LTD

Half-Coupling

Time：2025-08-22 Views：1

A half-coupling is a single, non-integrated component of a coupling system, designed to be attached to one shaft (either the driving or driven shaft) and paired with a complementary half-coupling (or a full coupling) to form a complete connection. Unlike full couplings (which are one-piece and connect two shafts directly), half-couplings are modular, allowing for easy assembly, disassembly, and replacement of individual components. They are widely used in industrial machinery, power transmission systems, and heavy equipment (e.g., pumps, motors, compressors, and generators) where shafts need to be connected or disconnected for maintenance, repair, or component replacement.

The structure of a half-coupling is tailored to its intended use, but most models share common features: a hub (to fit over the shaft), a flange or connecting face (to mate with the complementary half-coupling), and a locking mechanism to secure the hub to the shaft. The hub is a cylindrical section with a bore (inner hole) sized to match the shaft diameter, with tolerances of H7/js6 for a press fit or H9/f8 for a slip fit with set screws. The connecting face—usually a flat flange—has bolt holes or alignment pins to fasten the two half-couplings together. For example, a steel half-coupling for a 50 mm diameter shaft has a 50 mm bore, a 150 mm diameter flange, and 6 M16 bolt holes arranged in a circle, allowing it to be bolted to a matching half-coupling on the driven shaft.

Half-couplings are classified based on their connection type: rigid half-couplings and flexible half-couplings. Rigid half-couplings are made of solid metal (e.g., carbon steel 1045, stainless steel 304, or cast iron) and are used when shafts are perfectly aligned and require a rigid, zero-flexibility connection. They are often used in heavy-duty applications like industrial gearboxes or marine propeller shafts, where torque transmission is prioritized over misalignment compensation. Rigid half-couplings have high torque capacity—for example, a 1045 steel half-coupling with a 100 mm flange can transmit up to 20,000 N·m of torque, making it suitable for large motors or turbines.

Flexible half-couplings are designed to accommodate misalignment and dampen vibration, with the flexibility coming from either an elastomeric element (e.g., rubber or polyurethane) or a flexible metal component (e.g., discs or bellows). Elastomeric flexible half-couplings—such as jaw half-couplings—have a hub with protruding jaws that mate with a rubber spider (the flexible element) and a complementary jaw half-coupling on the other shaft. These half-couplings can handle angular misalignment up to 1°, radial misalignment up to 0.3 mm, and are used in light to medium-duty applications like electric motors or conveyor systems. Metal flexible half-couplings—such as disc half-couplings—use thin stainless steel discs bolted between the flanges of two half-couplings, offering higher torque capacity (up to 50,000 N·m) and better misalignment tolerance (up to 2° angular) than elastomeric variants. They are used in high-speed, high-precision applications like gas turbines or centrifugal pumps.

Material selection for half-couplings depends on the application’s torque requirements, environmental conditions, and cost constraints. Carbon steel (1045) is the most common material for rigid half-couplings, offering a balance of strength (tensile strength of 600 MPa) and cost-effectiveness. Stainless steel (304 or 316L) is used for half-couplings in corrosive environments (e.g., marine or chemical processing), as it resists rust and chemical attack. For high-temperature applications (e.g., boiler feed pumps), nickel-based alloys (e.g., Inconel 600) are used, with a maximum operating temperature of 1093°C. Elastomeric elements in flexible half-couplings are made of nitrile rubber (for oil resistance) or polyurethane (for higher abrasion resistance), with a Shore A hardness of 70-90 to balance flexibility and load-bearing capacity.

Installation of half-couplings requires precision to ensure proper alignment and torque transmission. First, the half-coupling is mounted on the shaft: for press-fit installations, the hub is heated (using induction heating) to expand the bore, then slid onto the shaft and allowed to cool, creating a tight fit. For slip-fit installations, set screws (usually M8-M16) are tightened into the hub’s side, pressing against the shaft to secure the half-coupling. Next, the complementary half-coupling is mounted on the second shaft, and the two flanges are aligned using a straightedge or laser alignment tool to ensure angular and radial misalignment are within the coupling’s limits (e.g., ≤0.1 mm radial misalignment for rigid half-couplings). the flanges are bolted together using high-tensile bolts (e.g., grade 8.8 or 10.9) tightened to the manufacturer’s torque specifications (e.g., 50-80 N·m for M16 bolts) to prevent loosening under vibration.

Maintenance of half-couplings involves regular inspection and lubrication (for certain types). Rigid half-couplings are inspected for cracks in the flange or hub, which can occur due to over-torque or misalignment. Flexible half-couplings with elastomeric elements are checked for worn or cracked spiders, which are replaced every 6-12 months to prevent failure. Metal disc half-couplings are inspected for fatigue cracks in the discs, with replacements needed every 2-3 years depending on usage. For gear half-couplings (a type of rigid half-coupling with gear teeth), lubrication is critical—gear teeth are greased every 3-6 months using lithium-based grease to reduce wear and noise.

half-couplings are modular, versatile components that enable reliable shaft connections in machinery. Rigid and flexible variants, along with a range of materials, ensure compatibility with diverse applications, from small electric motors to large industrial turbines. Their modular design simplifies maintenance and repair, reducing downtime and operational costs for industries worldwide.