1. Consider Dynamic Applications: For applications involving a high number of deflection cycles or critical forces and deflections, choose disc springs that conform to the DIN 2093 (DIN EN 16983) specification. This ensures durability and reliability under dynamic conditions.
2. Select the Largest Compatible Spring: From the available range, opt for the largest possible disc spring that meets your desired characteristics. Larger disc springs help maintain lower stress levels, thereby enhancing fatigue life. Additionally, in stacked columns, the greater deflection capacity of larger springs reduces the overall stack length, improving efficiency and performance.
3. For static, or dynamic applications, select a disc spring that at 75% of its total available deflection offers the maximum force and/or deflection required. Between 75% deflected and the 'flattened' position, the actual force/stress characteristics become considerably greater than those calculated.
4. During manufacturing, residual tensile stresses can develop at the upper inside diameter edge (denoted as d). When the disc spring is deflected up to approximately 15% of its total deflection, these tensile stresses convert to normal compressive stresses. However, in applications with a high number of cyclic deflections, these stress reversals can significantly reduce the fatigue life of the disc spring. To mitigate this issue, it is crucial to pre-load disc springs in dynamic applications to a minimum of 15% of their total available deflection. This pre-loading helps maintain consistent compressive stresses, enhancing the spring's durability and performance.
Proper guidance and location of disc springs are crucial to their performance, ensuring desired characteristics and repeatability. Recommended guide clearances are provided in the tolerance tables, and attention should also be given to the nature of the guidance and seating surfaces.
The severity of duty in the application plays a significant role in determining the appropriate guidance and seating. For static clamping force applications on mild steel or cast/forged steel surfaces, the existing setup is likely satisfactory. However, if the seating faces are made of softer materials like aluminum, copper, or brass, it is preferable to use a hardened thrust washer to prevent face damage or indentation.
In dynamic applications with a large number of deflection cycles, it is essential to have hardened seating faces and sufficiently hard guidance surfaces to prevent excessive wear or "stepping." For both support washers and guide elements, a polished surface with a hardness of 58 HRC and a minimum case depth of 0.60 mm is recommended. Nitride hardening is permissible, provided the hardened surface layer is adequately supported.
Lubrication is vital for the efficient and extended life of disc springs. For low-duty applications with small numbers of deflection cycles, a liberal application of a suitable solid lubricant (e.g., molybdenum-disulfide grease) to the contact points and locating surfaces of the spring is adequate. In more severe dynamic or highly corrosive applications, maintained lubrication is beneficial. In such cases, disc springs are often housed in an oil or grease-filled chamber to ensure continuous lubrication.
