DIN 7346 Light Duty Threaded Spring Pins (Roll Pins)

Threaded spring pins, or roller pins, are headless hollow tubes with a longitudinal groove along the pin. Their ends are usually beveled to facilitate installation, and they are self-locking as their outer diameter is typically slightly larger than the diameter of the hole they will be inserted into.

The “DIN 7346 Light-duty grooved spring pins (roll pins)” standard, published by the German Institute for Standardization (DIN), is a comprehensive guide containing the requirements for grooved spring pins or roll pins.

The DIN 7346 standard includes light-duty grooved spring pins, also known as roll pins or compression sleeves. These fasteners are self-holding cylindrical pins formed by rolling a sheet of spring steel into a grooved tube. When driven into a slightly smaller hole, the pin compresses and grips the hole walls with radial force for secure positioning and alignment without permanent deformation of the base material. This standard was later revised and aligned with the “ISO 13337 Spring type straight pins - Grooved, light duty” standard.

Light-duty splined spring pins, also known as roll pins, are self-locking cylindrical pins formed by rolling a spring steel into a splined tube shape. These fasteners, when inserted into a slightly smaller hole, compress, gripping the hole walls with spring tension and providing a secure and vibration-resistant connection.

Parts conforming to the DIN 7346 standard are widely available and used due to their proven reliability, interchangeability, and minor dimensional differences (e.g., wall thickness and slot width) compared to their ISO equivalents.

Their basic features and designs are as follows:

• Grooved design: A longitudinal groove allows for radial compression (typically 0,2-0,5 mm). A bevel is present at one or both ends for easy insertion.
• Light-duty version: Thinner walls and a narrower slot compared to the heavy-duty DIN 1481 (ISO 8752) standard make them ideal for lower shear loads while saving space.
• Materials:
• Spring steel: Hardness 420-560 HV. Finish options: palin, zinc (yellow/white), phosphate.
• Stainless steel: Hardness 1.4310. Finish options: polished, passivated.
• Insertion: The drilled hole is 0,05-0,15 mm smaller than the nominal size. Chamfer guides direct the entry, and the pin expands to fill the hole.
• Self-adhering: No adhesive or holding compound required. Can be removed with pliers, resistant to loosening in dynamic applications.

Applications generally include the following:

• Automotive: Transmission shafts, linkages, hinges - Environments with high vibration.
• Machinery: Pivots, stops, axes in tools and devices.
• Electronics/home appliances: Lightweight installations where space is limited.
• Furniture/installation: Removable pins for adjustable parts.

Not suitable for high fatigue or ultra-high load applications; for these purposes, DIN 1481 / ISO 8752 standards are used.

In short, the DIN 7346 standard is an industry standard that specifies the dimensions, materials, and tolerances for lightweight versions of spring-type flat pins. These lightweight, slotted cylindrical pins, made from spring steel, compress and expand to provide a secure, friction-based fit. Diameters typically range from 1,5 mm to 6 mm. Lengths can reach up to 120 mm depending on the diameter. Hardened steel with a hardness of 420-520 HV is generally used as the material for durability and flexibility. They feature beveled ends for easy insertion, a central recess for compression, and a slight taper for self-locking.

The DIN 7346 standard plays a critical role in mechanical engineering and manufacturing for the following reasons:

• It ensures precision and interchangeability: By defining precise dimensions and tolerances (e.g., wall thickness and inner diameter), it guarantees a consistent fit of pins from different manufacturers. This is important for global supply chains, reducing assembly errors and enabling modular designs in machines.
• Provides cost-effective, vibration-resistant connections: These light-duty pins are ideal for non-permanent connections (e.g., hinges, connectors, or retaining pins) that require disassembly. They absorb spring-like movements, shocks, and vibrations better than rigid anchors and prevent loosening in dynamic environments such as automotive or machine components without the need for adhesives or welding.
• Supporting safety and reliability in applications: In industries such as automotive, aerospace, electronics, and furniture, these pins secure moving parts (e.g., gears, levers, or cabinet doors). Compliance with this standard minimizes the risk of failures that could lead to equipment malfunctions or safety hazards, such as pin jamming or severing.
• It facilitates standardization and the transition to global norms: As a precursor to the ISO 13337 standard, it helps harmonize fastener standards, thereby increasing efficiency in international trade.

In conclusion, the DIN 7346 standard offers a reliable and economical solution for semi-permanent fasteners in low to medium difficulty applications. Although it has been superseded by the ISO 13337 standard, its influence remains in global manufacturing. It is unrivaled for high-vibration or reusable connections, being lightweight, strong, and simple. Nevertheless, to be future-proof and for new designs, the ISO 13337 standard should always be referenced.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "DIN 7346 Light-duty grooved spring pins (roll pins)" standard.