What are the manifestations of oil leakage in CNC milling machines

The oil leakage of CNC milling machine is divided into three states, namely, leakage, dripping and oil flow. In general, a drop of oil every 0.5h at the static joint surface and a drop of oil every 6min at the dynamic joint surface are leakage. No matter whether it is the dynamic joint surface or the static joint surface, when one drop of oil is dropped every 2-3min, it is a drop of oil; More than 5 drops per minute is flowing oil. The general requirements for the equipment to achieve leakage control are that there shall be no leakage at the static joint surface outside the equipment, and slight leakage is allowed at the dynamic joint surface, but it is not allowed to flow to the ground. Some leakage is allowed inside the equipment, but it is not allowed to penetrate into the electrical box and the drive belt, and can be led back to the lubrication box.

(1) The oil return of CNC milling machine is not smooth or there is no oil return channel

Generally, the oil return at the bearing is not smooth, which is easy to accumulate oil, forming a certain pressure and causing oil leakage. Some oil return holes are not designed properly and are easily blocked by dirt. The capacity of some oil return tanks is too small, causing oil to overflow from the oil return tank. Some have not designed recovery devices. After using for a period of time, it was found that the oil leakage of the sliding seat was serious, and the oil was on the ground on both sides of the guide rail of the machine tool. After the oil is used for a period of time, the oil becomes dirty and some iron particles will fall on the guide rail surface when the machine tool processes parts, which is not easy to be scraped off by the chipper.

(2) Defects such as sand hole, air hole, crack and loose structure appear in the casting, but no measures are taken. These defects are often the source of oil leakage during the use of equipment.

(3) When plastic or oil resistant rubber products are used for oil pipes and pipe joints, the materials will age, become hard and brittle, resulting in rupture of oil pipes and pipe joints and oil leakage.

(4) After long-term use of the sealing ring, especially those at the moving parts, the sealing performance will be lost due to friction and wear. In addition, if the clearance between the shaft and the shaft hole (shaft sleeve) increases, oil leakage will also be caused.

(5) Machining accuracy error of parts and other reasons. For example, the flatness of the joint surface of the box and the box cover is out of tolerance, the surface roughness is too large, and the residual stress of the workpiece is too large, which causes the deformation of the workpiece, and the joint surface is not tight. Or loose fasteners will cause oil leakage.

(6) Oil leakage caused by improper selection or assembly of relevant parts is common.

(7) There are three main problems in oil change of CNC milling machine. First, for the parts and components that use high viscosity lubricating oil, when changing the oil, the low viscosity lubricating oil will have a certain impact on the sealing performance of the corresponding box and shaft hole, and sometimes the sealing performance of these parts will be greatly reduced. Second, if the oil tank is not cleaned during oil change, the dirt in the oil tank may enter the lubrication system, block the oil path, wear the seals and cause oil leakage. Third, when changing the oil, there is too much oil, especially in the parts with rotating parts. Due to the agitation of rotating parts, oil spillage is more likely to occur.

(8) Oil leakage is caused by improper selection and adjustment of lubrication system parts of CNC milling machine. For example, when the oil pump with high pressure or large oil output is selected for maintenance, or when the system pressure is adjusted, the pressure of overflow valve, safety valve, pressure reducing valve, etc. is adjusted too high, and the flow of the lubricating system of the machine tool is too large, which does not match the oil return system and the sealing system, resulting in oil leakage.