The crankshaft undergoes high loading due to the fact it transforms the linear loading of the pistons into a usable rotational motion. In time it will wear. Rather than replace this relatively expensive forged item the surfaces can be reground.
This regrinding is a specialized process as the grinding wheel needs to travel horizontally while the crank rotates. As in animation.
AMAC Engineering has the facilities for repairing stripped threads, such as spark plug threads.
The Repair of Damaged Threads
Damage to spark plug threads normally occurs in aluminium cylinder heads when they are still warm. If the spark plug is removed whilst the engine is still warm this will result in the spark plugs ‘picking up’ the warm soft aluminium and therefore stripping the thread form the aluminium.