Master wafer is a specialised component used in the construction of lock mechanisms, particularly in systems that require multiple individual keys to operate a single lock. Designed to facilitate a hierarchical keying system, the master wafer, or master disc, allows locks to open with both individual user keys and a master key. Situated within the cylinder of a pin tumbler lock, it functions by creating an additional shear line, which aligns when inserted with either the master key or a change key specific to that lock.
The use of master wafers enables efficient key management in complex settings such as office buildings, hotels, and apartment complexes, where access needs to be customised per user while still allowing overarching access through a master key. The component's design varies in thickness to correspond with different lock and key configurations, ensuring compatibility and security. The precision in the manufacture of master wafers is critical, as even minute discrepancies can compromise the lock's integrity and functionality. In security terms, while offering practical keying solutions, locks with master wafers are also more susceptible to certain types of lock picking and decoding techniques, which poses a consideration in their implementation.