Hinged belt filters are used in the cleaning of contaminated cooling lubricants in the field of metal processing, and in the treatment of various sludge in the field of rough processing, especially aluminum, or for processing. Matte grinding sludge. If the cooling lubricant and grinding residue are cleaned, they can be reused in the process for a longer period of time. This greatly helps to protect the environment. Other advantages are heat dissipation at the processing point and surface quality optimization of the workpiece.