Ball screw with a dustproof member

A ball screw with a dustproof member, comprising:

• a screw including an axis, a circumferential surface surrounding the axis, and an outer helical groove helically formed in the circumferential surface to surround the axis;
• a nut sleeved along the axis onto the screw, and including:
• an inner helical groove helically defined in an inner surface of the nut to surround the axis, and an annular receiving groove formed at one end of the nut and concaved along the axis, wherein the inner helical groove and the outer helical groove form a load path for receiving a plurality of rolling balls;
• the dustproof member being inserted along the axis into the annular receiving groove and sleeved onto the screw, and including an annular first dustproof portion and an arc-shaped second dustproof portion, wherein the annular first dustproof portion includes a dustproof hole for insertion of the screw, the dustproof hole has a dustproof inner surface defining an clearance relative to the circumferential surface of the screw, the arc-shaped second dustproof portion protrudes from the dustproof inner surface, and includes an arc-shaped dustproof section contacting the outer helical groove;
• wherein the clearance between the dustproof inner surface of the dustproof member and the circumferential surface of the screw is 0.05 mm to 0.3 mm, the arc-shaped dustproof section of the second dustproof portion has a radian smaller than 180 degrees, the second dustproof portion includes an arc-shaped first side surface and an opposite arc-shaped second side surface, and a distance between the arc-shaped first side surface and the arc-shaped second side surface along the axis is 2 to 3 mm.