At first basic terms and definitions to describe magnetically hard materials are specified. Subsequently, a literature study on different types of permanent magnets and the possibilities to magnetize or demagnetize them is performed. Furthermore the main applications of NdFeB magnets are determined and their characteristic magnetic values are dedicated. The experimental work includes tests to demagnetize the magnetic material as single components or embedded in compounds. A combination of preheating the magnets, followed by a complete demagnetization with an AC coil is tested particularly.