Bolts

Bolts and nuts are generally made of steel. The threads (both internal and external) can be molded in.

Bolts and nuts produced from thermoplastics are also available with standard machine threads. Thermoplastic bolts and nuts are ideally suited for applications where improved chemical resistance or electrical insulation is required. Thermoplastic bolts can solve the problem that may occur if steel bolts with a relatively low thermal expansion coefficient are used to join plastic components with a high thermal expansion coefficient.

To avoid overstressing during tightening, hollow bosses can be designed to accommodate the pre-stress. This also avoids the walls from buckling due to the high bending stresses.

Hollow bosses are used to limit deflection

To avoid stress concentration below the head of the bolt and the nut, washers should be used to distribute the load over a larger area. Bolts with conical heads lead to high tensile stresses under the head and must be avoided.

Bolts with conical heads must be avoided

Click here for information on calculating tightening torque and the stresses in a bolt .