Machine Accessories: Using Standard Parts Efficiently
Standard machine parts – often called "commodity parts" – form the backbone of every mechanical design. Featherkeys, retaining rings, machine feet, clamping collars, and rubber-metal buffers appear in virtually every machine, yet their selection and correct use are often underestimated.
This guide shows which standard parts are most important in mechanical engineering, how to read DIN designations correctly, and how to procure them efficiently.
Typical Standard Parts
Featherkeys DIN 6885
Featherkeys (parallel keys) transmit torque between shaft and hub. They are standardized according to DIN 6885 and available in forms A (square ends), B (radius ends), and C (one radius end). Selection is based on shaft diameter and transmitted torque. The key sits in grooves in both shaft and hub and forms a positive (form-fit) connection.
Retaining Rings DIN 471 / DIN 472
Retaining rings (snap rings) axially secure components on shafts (DIN 471) or in bores (DIN 472). They snap into a groove and provide a defined axial retention force. They are inexpensive, easy to install with snap ring pliers, and available in a wide range of sizes. For safety-critical applications, always check the allowable axial force.
Machine Feet DIN 95
Machine feet level machines on uneven floors and isolate vibrations. They consist of a steel plate with mounting thread and a rubber element. The rubber Shore hardness determines the vibration isolation properties. For heavy machines, machine feet with large load capacity and low natural frequency are required.
Clamping Collars and Set Collars
Clamping collars axially secure shafts, spacer sleeves, or bearings. Unlike set screws, split clamping collars distribute the clamping force evenly and do not damage the shaft surface. They are available in single-split and double-split versions.
Rubber-Metal Buffers
Rubber-metal buffers dampen vibrations and shocks between machine components. They consist of a rubber element vulcanized between two steel plates or threaded studs. The stiffness (spring rate) and damping are defined by the rubber compound and geometry. They are used under motors, compressors, and machine bases.
Spline Shafts DIN 5480
Spline shafts have multiple teeth evenly distributed around the circumference and transmit higher torques than featherkey connections. Standardized according to DIN 5480 or ISO 4156, they also allow axial movement between shaft and hub, making them ideal for sliding hubs, telescoping shafts, and power take-off shafts.
Standard Designations Explained
Standard designations are structured as follows:
Featherkey DIN 6885-A 8x7x50
DIN 6885 = Standard number | A = Form A (square ends) | 8 = Width [mm] | 7 = Height [mm] | 50 = Length [mm]
Retaining ring DIN 471 – 25 × 1.2
DIN 471 = Retaining ring for shafts | 25 = Shaft diameter [mm] | 1.2 = Ring thickness [mm]
Machine foot M10 × 30 Shore 45
M10 = Thread size | 30 = Adjustment range [mm] | Shore 45 = Rubber hardness
Advantages of Standard Parts
- Interchangeability: DIN/ISO parts can be sourced from multiple manufacturers – no supplier dependency.
- Cost efficiency: Mass production reduces unit costs significantly compared to custom parts.
- Fast availability: Standard parts are typically available from stock – short delivery times.
- Proven quality: Standardized manufacturing ensures defined tolerances and material properties.
- Documentation: DIN standard tables provide all technical data for calculations and design verification.
Selection Guide
Select standard parts based on your application:
| Use Case | Recommended Part | Standard |
|---|---|---|
| Torque transmission shaft-hub | Featherkey | DIN 6885 |
| Axial retention on shaft | Retaining ring for shaft | DIN 471 |
| Axial retention in bore | Retaining ring for bore | DIN 472 |
| Machine leveling and vibration isolation | Machine foot | DIN 95 / DIN EN ISO |
| High torque transmission, axial movement | Spline shaft | DIN 5480 |
5 Procurement Tips
- Use complete designations: Always specify the full DIN designation including all dimensions for error-free ordering.
- Consider materials: Standard parts are available in various materials (steel, stainless steel, plastic). For corrosion-sensitive environments, choose stainless steel variants.
- Stock planning: For maintenance-relevant standard parts, maintain a small safety stock. Their low cost makes this worthwhile.
- Supplier consolidation: Sourcing multiple standard parts from a single supplier reduces logistics costs and simplifies procurement.
- Check current standards: DIN standards are regularly updated. Always check whether you are working with the current edition, especially for safety-relevant applications.
TEA Recommendation
TEA offers a wide range of machine accessories including featherkeys, retaining rings, machine feet, clamping collars, and rubber-metal buffers. We supply both individual parts and complete kits for specific applications.
Through our supplier consolidation service, we can bundle your standard parts procurement and reduce your administrative overhead. Contact us for more information.
Request InformationFrequently Asked Questions about Standard Machine Parts
Standard parts are manufactured according to DIN, ISO, or EN standards and are interchangeable from different manufacturers. Custom parts are made to individual drawings and usually more expensive. Standard parts offer faster availability, lower cost, and easier replacement – which is why they should be preferred whenever technically feasible.
The standard designation consists of the DIN number (6885 = Featherkeys), the form (A = square cross-section), followed by width × height × length in mm. This designation uniquely identifies the part and allows ordering from any compliant manufacturer.
For machine feet, the key parameters are the maximum load per foot, the required adjustment range (height), the vibration isolation properties (Shore hardness of the rubber element), and the floor covering material. For wet areas or food environments, stainless steel feet with FDA-approved elastomers should be used.
In principle yes, but it is not recommended for safety-critical applications. Retaining rings (DIN 471/472) are slightly deformed when installed and removed, which reduces the clamping force. For critical applications such as bearing retention, always use new retaining rings after disassembly.
Rubber-metal buffers combine the vibration-damping properties of rubber with the mechanical strength of metal. The bonded steel plates prevent overloading of the rubber and allow force transmission through the metal inserts (e.g., threaded studs). They offer defined stiffness values and a long service life.
Über den Autor
Thomas Albrecht
Head of Procurement · Procurement
Over 15 years of experience in technical purchasing and supplier management for mechanical engineering components.