The tubing used in the hydraulic system of the machine tool includes steel pipe, copper pipe, nylon pipe, rubber hose and plastic pipe, etc. They should be selected according to the relative position of the connecting elements, the operating environment and the working pressure.

Copper, steel, and nylon tubes are rigid tubes used to connect fixed elements that do not change in relative position. Steel tube can withstand high pressure, cheap price, oil resistance, corrosion resistance and rigidity are better. But the assembly can not bend arbitrarily, often used to assemble convenient pressure pipe. Purple steel tube bending is more convenient, because the stiffness is small in the assembly can also have a small amount of deformation, it is easy to assemble but the pressure capacity is low, the price is also expensive, the ability to resist development is weak and easy to make oil oxidation, should be used as little as possible. Brass tube has higher bearing capacity, but it is difficult to bend. Nylon tube has good pressure resistance, which can be bent at will when heated to 160-170℃ in oil. It is often used as return tubing in actual production.

Rubber and plastic hoses are often used to connect two relatively moving components. Rubber tubes are divided into high pressure and low pressure. High pressure rubber hose is in the middle of the rubber hose with a layer or several layers of woven steel wire, its pressure capacity is high. Low pressure rubber hose is woven cotton, hemp wire instead of woven steel wire, more used for low pressure oil pipeline. The bending radius of the hose should be greater than 9 times the outside diameter and should be bent at least 6 times the diameter away from the joint so that the hose takes up a large space. Do not connect the hose between the hydraulic cylinder and the speed regulating valve, otherwise the moving parts are easy to crawl.