The main material of Ptfe sheet is a white crystalline polymer with good chemical and thermal stability. It can work for a long time at high temperatures below 250 ℃, and has low friction coefficient and excellent lubrication performance. Its dynamic friction coefficient is only 0.04, so the sheet has a wide application prospect in lathe repair.
In order to bond polytetrafluoroethylene sheets to metal, the main method currently used is the use of nano naphthalene activation method. By removing some fluorine atoms from the surface of the sheet, the material surface is activated, thereby increasing the surface tension to 3 × 10-1N/m, with good adhesion. Surfactant plates have good lubrication and wear resistance, high bonding strength, easy maintenance, and are widely used in the repair of lathe guide rails, with objective economic benefits. The bonding process is also relatively simple, mainly by bonding the activation plate onto the lathe guide plate. According to the general bonding method, the contact surface is cleaned first after bonding, and it can be processed and assembled by pressurizing and curing at room temperature for 48 hours. The bonding strength can reach over 10MPa.
How to solve many difficulties encountered during the processing of polytetrafluoroethylene sheets?
1. Drilling
The substrate is soft, and the number of drilled plates should not be too large. Usually, a thickness of 0.8mm plates should be stacked in two pieces; The speed cannot be achieved with most drill bits, it should be slower; For drill bits with severe substrate wear, new or back mounted drill bits should be used; There are special requirements for the top angle and thread angle of the drill bit.
2. Hot air leveling
According to the inherent property of fluororesin, rapid heating of the board should be avoided as much as possible. Preheat the hot air for 30 minutes before leveling, and then immediately perform the hot air leveling. The temperature of the impregnation drum should not exceed 245 ℃, otherwise it will affect the adhesion of the isolation pad and may fall off or warp.
3. Process transportation
It cannot be placed vertically and can only be separated by film or paper in the cargo frame. During the entire production process, it is not allowed to touch with fingers, but only to use hands to clamp the edges of the board and handle it gently. During the entire process, it is necessary to prevent wiping, and attention should be paid to preventing scratches, pinholes, indentations, gaps, and other factors from affecting the performance of this type of board.
