Coolant supply system

A coolant supply system that supplies a coolant to be discharged in an inside of a machine tool, the coolant supply system comprising:

• a coolant tank that stores the coolant discharged from the inside;
• a first passage connecting a first outlet of the coolant tank with a first discharge part provided in the inside, the first passage leading the coolant discharged through the first outlet to the first discharge part;
• and
• a second passage connecting a second outlet of the coolant tank with a second discharge part provided in the inside, the second passage leading the coolant discharged through the second outlet to the second discharge part,
• wherein the coolant tank includes:
• a vertical tank body;
• and
• a swirling flow generating structure that causes the coolant discharged from the inside to swirl along an inner face of the tank body,
• wherein, in the tank body, the first outlet is located at a gathering position toward which sludge contained in the coolant is caused to gather by a swirling flow of the coolant, and the second outlet is located at a position away from the gathering position,
• wherein the first discharge part is a spindle unit that holds a tool having an internal passage through which the coolant is to be discharged, and has a communication passage through which the inner passage and the first passage communicate with each other,
• wherein the second discharge part is a discharging device having a discharge outlet larger than a discharge outlet of the tool, and
• wherein a centrifugal filter having a function of separating the sludge by a centrifugal force is provided on the first passage, and no centrifugal filter is provided on the second passage.