A welding mould (often used in electrical and earthing work) is a reusable block — usually made from high-temperature graphite — used to form a connection between metal conductors during exothermic welding.
Here’s a simple description you can use:
Welding mould is a precision-shaped graphite tool designed to hold conductors (such as copper cable, tape, or earth rods) in position while an exothermic welding reaction permanently bonds them together. It ensures the molten metal flows correctly to create a strong, low-resistance electrical connection.