PURPOSE: To maintain the content of a dense machining liquid tank to a low solid density capable of being used for cleaning the dense machining liquid without causing clogging of a membrane filter by combining the membrane filter and partial treatment of dense machining liquid achieved by a fleece filter.
CONSTITUTION: The filter to which a dense machining liquid is supplied from a dense machining liquid tank 1 and from which a permeation liquid is discharged is made to be a membrane filter 3, and a treatment container 8 equipped with a fleece filter 9 is provided. At least partial dense machining liquid is supplied to the treatment container 8, and a partial flow prepared by the fleece filter 9 is returned to the dense machining liquid tank 1 from the treatment container 8.
GIDEON REBUI
FUUGOO KUTEIRU
