Bolt Sleeves For Metal

Carbon steel or stainless steel casings can be spot welded directly to the metal structure to achieve pre-positioning, and the welding strength can reach more than 70% of the tensile strength of the base material. For example, for a casing with a thickness of 2 mm, the pull-off force after spot welding exceeds 5 kN. This feature facilitates rapid placement of sleeves on automated assembly lines, reduces additional fixture costs, and increases production efficiency by approximately 25%.

The surface hardness of heat-treated stainless steel casing can reach 250 HB, which is more than 40% higher than ordinary mild steel. In high-strength bolted connections, even if the preload force causes the contact stress to exceed 300 MPa, there will be no obvious indentation on the casing surface. This ensures the flatness of the bolt head or nut bearing surface, maintains uniform pressure on the gasket, and prevents leakage.

In a vibration environment, the fretting wear of bolts and hole walls will damage the surface of the base body. The stainless steel casing is harder than the aluminum-magnesium alloy base (250 HB vs 80 HB), which concentrates wear on the replaceable casing. Tests show that after 2 million micro-motion cycles, the weight loss of the base material is only 5% of that without the casing. This significantly extends the service life of valuable components such as engine blocks.

When connecting thin plates (thickness ≤2 mm), the bolt pretightening force can easily cause the thin plates to bend or the nuts to sink. The metal sleeve can increase the stress area and disperse the contact compressive stress from 500 MPa to less than 50 MPa. Experiments show that after using a casing with a length twice the thickness of the plate, the deformation of the thin plate is reduced by 85%, and the bolt torque can be safely applied to the target value, completely solving the "penetration" problem of thin plate connection.

►Functional coating available

Metal sleeves can be electroplated with silver, tin, cadmium and other coatings. The contact resistance of the silver-plated bushing is less than 0.5 mΩ and is suitable for large current connections; the tin-plated bushing has excellent solderability and is convenient for welding and fixing the ground wire.

► Compatible with standard fasteners

The inner diameter of the metal casing is designed according to GB/T, DIN, and ISO standards and can directly match commercially available standard bolts. Purchase costs can be saved by more than 30%.

► Can withstand high preload torques

The pretightening torque exerted by the electric torque wrench can reach more than 500 N·m. Metal sleeves will not slip or chip like plastic, ensuring precise transmission of torque to the bolt and avoiding assembly rework.

► Convenient for on-site modification

If the length needs to be adjusted during on-site installation, the metal casing can be cut with an ordinary hand saw or angle grinder. The end surface after cutting is flat and does not affect use. Cutting plastic casing is prone to burrs or cracks, and the conversion efficiency is low.