Types & Classification of Pins in Machinery

In machinery, pins are primarily used for assembly positioning and can also function as overload shear connections in safety devices that allow for connection and relaxation. The main types of pins include:

• Cylinder pin
• Cone pin
• Pin with hole
• Cotter pin
• Safety pin

Classification of Pins

The fundamental forms of pins are cylindrical pins and cone pins.

• Cylindrical Pins: These pins are secured in a pin hole with a slight interference fit. While effective, repeated assembly and disassembly can reduce their positioning accuracy.
• Cone Pins: Featuring a taper of 1:50, cone pins are self-locking. They are fixed in the pin hole through a conical extrusion action, offering high positioning accuracy. Their installation is convenient, and they can be repeatedly assembled and disassembled without significant loss of accuracy.

Selecting the Right Pin

The choice of pin type depends on its specific working requirements:

• For Connections: The diameter of the pin for a connection can often be determined based on the structural characteristics and experience. A strength check may be necessary if there are specific load requirements.
• For Positioning: Positioning pins can be selected directly based on the structural design.
• Length: The length of the pin within each connector typically ranges from 1 to 2 times its diameter.

Common Materials for Pins

• Standard Pins: Common materials for general pins include 35 steel or 45 steel.
• Safety Pins: Materials for safety pins include 35, 45, 50, T8A, T10A, among others. After heat treatment, these pins achieve a hardness of 30~36HRC.
• Pin Sleeves: Materials for pin sleeves can be 45, 35SiMn, 40Cr, etc. After heat treatment, their hardness reaches 40~50HRC.