From control panels for industrial productions to fuse boxes in private homes: Terminal blocks ensure safe currents as well as safe wiring of installations. Plastics used to manufacture terminal blocks have to meet high requirements for fire protection and mechanical and thermal properties.
In electrical engineering, terminals are used to connect wires and cables. Continuous safe contact has to be ensured for the connection – mechanical fixing ensures this. Terminal blocks can be arranged in any order on a mounting rail and installed with a simple snap.
This defines the mechanical properties required for this material: plastics used in this application must exhibit high elasticity and good toughness – or run the risk of breakage when snapping. Connections require sufficient stiffness and strength.
When handling electrical power, sparking and fires may occur – thus the highest requirements for fire behavior are industry standard (UL94 V-0, GWEPT 960). Other requirements include high temperature resistance and heat aging resistance.
Plastics have electrical insulating properties, which generally recommends them for electronic applications; in addition, high tracking resistance (CTI 600) is required for terminal blocks.
Terminals are produced in extremely large quantities by injection molding. Economic production requires short cycle times and low maintenance cost for injection molding tools and machinery. It is also necessary to be able to produce very low (0.4 mm) wall thicknesses with the plastic.
In addition, good colorability of the material plays an important role: Different colors of the terminal blocks serve to differentiate between different functions (e.g. neutral conductor, protective conductor, etc.) and ensure safe installation.
Due to the high requirements, unreinforced polyamides are considered as materials. PA66/6 copolyamid (Ultramid® C3U) and PA66 (Ultramid® A3U32) in BASF's comprehensive portfolio of engineering plastics are especially suitable for the application in terminal blocks.