Machine Accessories: Using Standard Parts Efficiently
Standard parts are standardised machine components whose dimensions, materials, and designations are defined by DIN/ISO standards. Typical examples such as featherkeys, retaining rings, machine feet, and clamping elements are cost-effective, globally interchangeable, and available from stock.
Yet the variety is vast. Which standard applies when buying a featherkey? What distinguishes a retaining ring DIN 471 from DIN 472? How do I specify machine accessories correctly? This guide answers these questions and shows how to procure and use standard parts efficiently.
Key takeaway: DIN/ISO standard parts are cost-effective and interchangeable. Featherkeys (DIN 6885) are ideal for straightforward applications; spline shafts (DIN 5480) handle high loads. Standardised machine feet (DIN 95) and retaining rings (DIN 471/472) save design time. Always keep stock levels and lead times in view.
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. Standardised 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. For non-standard dimensions we manufacture spline shafts to drawing.
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. For high-precision applications (robotics, medical), combine spline shafts with tight ISO fits H7/k6 or j5:
| 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 InformationFrom design to enquiry: procurement notes
- Cost drivers: Special variants (non-standard materials, special threads, 3.1 certificates per DIN EN 10204) cost a multiple of catalogue items - prefer standard-grade parts wherever possible.
- Standard vs. custom: Catalogue standard parts suffice for most drive applications. Only order specials (e.g. stainless steel, non-standard lengths) when the operating environment strictly requires it — costs rise sharply and early enquiry is essential.
- What an enquiry should include: Full standard designation (e.g. DIN 6885-1 featherkey 8x7x40), material requirement, desired batch size, certificate requirement (3.1 per DIN EN 10204 yes/no), and required delivery window.
- Total cost of ownership: Inexpensive C-parts generate disproportionate procurement costs when each order is processed individually - framework agreements or consignment stock for frequently needed standard parts reduce the workload considerably.
- Advice & supply: Our procurement team assists with standard selection and supplier consolidation - get in touch.
Frequently Asked Questions about Standard Machine Parts
DIN 6885 featherkeys (one flank, simple and inexpensive) suit standard drives; DIN 5480 spline shafts (4-10 flanks) transmit higher torques, allow axial movement, and are ideal for frequent assembly/disassembly. Rule of thumb: featherkey up to about 500 Nm, spline shaft above that.
DIN 6885 Part 1 defines key dimensions by shaft diameter. Rule of thumb: key width is approximately one quarter of the shaft diameter. For a 20 mm shaft, 6x6 mm is typical; for 25-32 mm, 8x7 mm is standard. Exact dimensions are in the DIN 6885-1 tables. An undersized key is overloaded; an oversized key unnecessarily weakens the shaft.
M10 indicates a metric thread with 10 mm nominal diameter; 1.5 is the pitch (mm advance per revolution). M10 x 1.5 is the coarse pitch per DIN 13 and therefore the standard choice. Use fine pitch (e.g. M10 x 1.25) only when finer clamping force control or vibration resistance is required.
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.
About the Author
Thomas Albrecht
Head of Procurement · Procurement
Over 15 years of experience in technical purchasing and supplier management for mechanical engineering components.