STAUFF Slotted Head Screw (Type LI – Standard Series)
STAUFF Slotted Head Screws (Type LI – Standard Series) are hydraulic fasteners in accordance with DIN 3015 Part 1. Compliant with ISO 1207 and ANSI/ASME B18.6.3, they require use with US washers and are installed without a DP cover plate. Supplied with metric or UNC threads in carbon steel and stainless steel. The available product codes are: LI-M6x20-W3, LI-1/4-20UNCx3/4-W3, LI-M6x25-W3, LI-1/4-20UNCx1-W3, LI-M6x30-W3, LI-1/4-20UNCx1-1/8-W3, LI-M6x35-W3, LI-1/4-20UNCx1-3/8-W3, LI-M6x50-W3, LI-1/4-20UNCx2-W3, LI-M6x60-W3, LI-1/4-20UNCx2-1/2-W3.
The STAUFF Slotted Head Screws (Type LI – Standard Series) are essential mechanical fastening elements for tightening and correctly securing components in hydraulic systems. This specific product belongs to the Standard Series, which is strictly classified in accordance with the international DIN 3015, Part 1 technical standard. These components are designed to ensure maximum structural reliability in industrial environments requiring precise and standardised fastening parameters.
The profile and geometry of the Slotted Head Screw are manufactured in full compliance with ISO 1207 specifications. In addition, for markets and industrial sectors requiring imperial-system specifications, the components fully comply with ANSI/ASME B18.6.3 standards. This dual dimensional compliance ensures complete versatility, allowing the product to be integrated into both hydraulic circuits designed using the metric system and those developed with American Unified threads.
Type LI screws from the Standard Series are manufactured for six main dimensional groups (STAUFF Groups 1 to 6, equivalent to DIN Groups 0 to 6). The range covers fastening requirements by offering two different thread variants. For the metric system (ISO Metric Thread), sizes range from M6x20 up to M6x60. In parallel, for Unified Coarse Thread (UNC), options range from 1/4-20 UNC x 3/4 up to 1/4-20 UNC x 2-1/2. The dimensions listed in the catalogue refer exclusively to use of the product on its own and not combined with other cover components.
To ensure the mechanical retention required by the Standard Series, installation of Type LI screws is subject to specific requirements described by the manufacturer. Firstly, the stated dimensions are applicable only when the screw is used without the upper DP Cover Plate. In addition, STAUFF technical guidelines strictly require Type LI slotted head screws to be used in conjunction with the corresponding Type US washers. Please note that US washers are not included with the product and are available separately.
To meet different requirements for mechanical strength and corrosion protection, the screws are available in three specific material classes, identified by dedicated ordering codes. The standard material, indicated by code W3, consists of carbon steel and is treated with a zinc/nickel-plated finish. For environments requiring stainless steel, two additional variants are available: code W4 identifies V2A Stainless Steel, corresponding to specifications 1.4301/1.4305 (AISI 304/303); code W5, used for extremely demanding applications, identifies V4A Stainless Steel, corresponding to standards 1.4401/1.4571 (AISI 316/316 Ti). Additional alternative materials and surface finishes may be available upon direct request to the manufacturer.
| Feature | Value / Specification |
|---|---|
| Product Family | Slotted Head Screw – Type LI |
| Series | Standard Series (according to DIN 3015, Part 1) |
| Dimensional Standards (Head) | ISO 1207 or ANSI/ASME B18.6.3 |
| Thread Types | ISO Metric Thread or Unified Coarse Thread (UNC) |
| Installation Requirements | Use without DP Cover Plate; mandatory use with US Washers |
| Material Code W3 | Zinc/Nickel-Plated Carbon Steel |
| Material Code W4 | V2A Stainless Steel – 1.4301/1.4305 (AISI 304/303) |
| Material Code W5 | V4A Stainless Steel – 1.4401/1.4571 (AISI 316/316 Ti) |
| STAUFF Group (DIN) | Thread Dimensions | Product Code (Standard W3 Options) |
|---|---|---|
| 1 (0) | M6 x 20 / 1/4-20 UNC x 3/4 | LI-M6x20-W3 / LI-1/4-20UNCx3/4-W3 |
| 1A (1) | M6 x 20 / 1/4-20 UNC x 3/4 | LI-M6x20-W3 / LI-1/4-20UNCx3/4-W3 |
| 2 (2) | M6 x 25 / 1/4-20 UNC x 1 | LI-M6x25-W3 / LI-1/4-20UNCx1-W3 |
| 3 (3) | M6 x 30 / 1/4-20 UNC x 1-1/8 | LI-M6x30-W3 / LI-1/4-20UNCx1-1/8-W3 |
| 4 (4) | M6 x 35 / 1/4-20 UNC x 1-3/8 | LI-M6x35-W3 / LI-1/4-20UNCx1-3/8-W3 |
| 5 (5) | M6 x 50 / 1/4-20 UNC x 2 | LI-M6x50-W3 / LI-1/4-20UNCx2-W3 |
| 6 (6) | M6 x 60 / 1/4-20 UNC x 2-1/2 | LI-M6x60-W3 / LI-1/4-20UNCx2-1/2-W3 |