Plastic Expansion Wall Plug (Rawlplug / Fischer)
Direct Answer
The Plastic Expansion Wall Plug (Rawlplug / Fischer S-Plug / Dowel) is a split cylindrical nylon or polyethylene sleeve inserted into a pre-drilled masonry hole. When a wood or sheet metal screw is driven inside, the tapered internal profile wedges the split halves outward, generating strong radial expansion friction against solid concrete, brick, or stone.
Source: DIN EN 14592 / Artur Fischer Patent (1958) / John Joseph Rawlings (1911)
Specs
| Standard Sizing Convention | Outer Diameter × Length (e.g. 6×30 mm, 8×40 mm, 10×50 mm) |
| Standard Drill Bit Sizing | Drill bit diameter matches plug outer diameter exactly (e.g. 6 mm plug = 6.0 mm masonry bit) |
| Standard Substrates | Solid concrete, solid clay brick, natural stone, aerated block |
| Expansion Mechanism | Screw core forces 2 or 4 split ribbed plastic wings radially against hole walls |
| Anti-Rotation Features | Molded longitudinal external ribs / anti-spin fins that bite into the masonry borehole |
| Common Safe Shear Load (Concrete) | 6mm plug: ~30–50 kg (65–110 lbs) / 8mm plug: ~70–100 kg (150–220 lbs) |
| Primary Applications | Wall shelves, curtain rods, electrical panels, bathroom mirrors, light fixtures |
Historical Evolution: Jute Fiber to Nylon
In 1911, John Joseph Rawlings patented the original Rawlplug using compressed jute fiber tubes to hold screws in Victorian brickwork. In 1958, German inventor Artur Fischer revolutionized construction by patenting the split-tongue polyamide nylon S-Plug. Nylon's cold-flow elasticity allows the plastic to mold into microscopic masonry pores without cracking under heavy freeze-thaw cycles.
Screw Selection Rules
For optimal holding force, the screw diameter must match the plug's internal bore specification (e.g. an 8 mm plug requires a 4.5 mm to 6.0 mm wood screw), and the screw length must equal the plug length plus fixture thickness plus one screw diameter to ensure the screw tip fully penetrates through the tapered nose of the plug.