Standard Definitions and Scope of Application
DIN 471 is the German standard for external retaining rings for shafts. Here, "471" is the exclusive standard number for external retaining rings for shafts, formulated by the German Institute for Standardization. External retaining rings for shafts are mainly installed in the external grooves of shafts, used to prevent the axial movement of components on the shaft, such as bearings and gears, and play a role in positioning and fixing in various mechanical transmission systems.
DIN 472, on the other hand, is the German standard for internal retaining rings for holes. The number "472" corresponds to the category of internal retaining rings for holes. Internal retaining rings for holes are installed inside round holes, and their function is also to limit the axial movement of components, preventing the displacement of parts installed in the holes. They are commonly found in the hole systems of various mechanical assemblies.
Differences in Application Scenarios
Due to different installation positions and functions, the two have distinct application scenarios. In motor manufacturing, DIN 471 external retaining rings for shafts can be used to fix the bearings on the rotor shaft of the motor, ensuring that the bearings remain stable during the high-speed rotation of the rotor and avoiding the impact on the motor's performance caused by axial movement. In automotive transmissions, components such as synchronizers and gears on the shaft often rely on DIN 471 retaining rings for axial positioning.
DIN 472 internal retaining rings for holes are more commonly used in the connection between the piston and the cylinder barrel of hydraulic cylinders. They are installed in the annular grooves on the inner wall of the cylinder barrel to fix the piston, preventing the piston from shifting axially during reciprocating motion and ensuring the sealing performance and stable operation of the hydraulic system. In the transmission cases of mechanical equipment, DIN 472 internal retaining rings for holes are also used in the holes for installing bearings to fix the bearings in the correct position.
Characteristics of Dimension Specifications
In terms of dimensions, the dimension specifications of DIN 471 external retaining rings for shafts are centered around the shaft diameter. Their inner diameter needs to precisely match the diameter of the installation shaft, while the outer diameter, thickness, and other dimensions are designed according to different load-bearing capacities and application requirements. For external retaining rings of the same shaft diameter, there are also differences in size parameters between the standard type and the heavy-duty type. The heavy-duty retaining rings usually have a greater thickness, and the outer diameter size will be adjusted accordingly to adapt to higher axial loads.
The dimensions of DIN 472 internal retaining rings for holes are based on the diameter of the installed hole. The outer diameter of the retaining ring is slightly larger than the diameter of the assembly round hole. During installation, a circlip plier is required to compress it and then place it into the pre-machined inner groove of the round hole. Similar to DIN 471, internal retaining rings for holes are also divided into standard and heavy-duty types. The heavy-duty retaining rings increase key parameters such as thickness in terms of dimensions for application scenarios with large hole diameters and high loads, providing stronger fixing capabilities.
Material and Performance Requirements
In terms of material selection, both often use spring steel, such as C60, which complies with the DIN EN 10132 - 4 standard, to ensure that the retaining rings have good elasticity and strength and can undergo elastic deformation without failure when subjected to axial forces. For special environments with corrosion resistance requirements, stainless steel materials, such as 1.4122 stainless steel, are also used.
Regarding performance requirements, DIN 471 external retaining rings for shafts need to have sufficient fatigue resistance. During the operation of the shaft, the retaining rings will continuously bear alternating axial forces, so it is necessary to ensure that they do not experience fatigue fracture during long-term use. DIN 472 internal retaining rings for holes place more emphasis on the deformation recovery ability during the installation process. Since they need to be compressed into the round hole during installation, they should be able to quickly restore their shape and closely fit the hole wall after installation, providing stable axial fixing force and maintaining good stability when bearing the axial forces of the components inside the hole.
Installation Methods and Operation Key Points
When installing DIN 471 external retaining rings for shafts, a suitable annular groove needs to be machined on the shaft first. The dimensional accuracy of the groove has a significant impact on the performance of the retaining ring after installation. Then, use special tools, such as retaining ring pliers, to open the retaining ring and fit it into the annular groove on the shaft. During the installation process, ensure that the retaining ring is fully embedded in the groove and that all parts are evenly stressed. Otherwise, the retaining ring may come off during the operation of the shaft.
The installation of DIN 472 internal retaining rings for holes also relies on circlip pliers. Insert the pliers' jaws into the pliers holes of the retaining ring, clamp the retaining ring to reduce its outer diameter, and then place it into the pre-machined inner groove of the round hole. Pay attention to the direction of the retaining ring during installation to ensure that it can effectively block the axial movement of the components inside the hole. Also, check the installation status of the retaining ring in the groove to avoid situations such as tilting or incomplete seating, which may affect the fixing effect.
Although both DIN 471 and DIN 472 are standards for retaining rings, there are significant differences between them in terms of definition, application, dimensions, materials, and installation. In the actual processes of mechanical design, manufacturing, and maintenance, only by accurately grasping these differences can the appropriate retaining rings be correctly selected to ensure the stable operation and reliable performance of mechanical equipment.