First: When the key can not be fully inserted into the lock hole when the door is opened, if it is in winter, first check whether the key hole is frozen; If other seasons, check the keyhole for foreign matter.
Second: hear the opening and closing of the door with metal friction sound, you can put a little lubricant on the closure of the door to try, if invalid, you can find a professional repairman.
Third, when the door is closed, the resistance is too large, and a little lubricant can also be applied to the moving lock.
Fourth, when installing anti-theft doors, we must carefully fill the cement so that the door frame and the wall are effectively closely combined, so that the door frame and the door frame can maintain reasonable cooperation, long-term use without fear of deformation.
Fifth: If it is difficult to insert the lock core when opening the door, you can apply a little graphite. Or insert the lock with a pencil.
Sixth, the problem of "winterization" is also very important in cold areas because the temperature difference between indoor and outdoor areas is very large. In the cold and hot water flow, it is very easy to damp the lock core of the door and then freeze it. This must be avoided. Before winter comes, Put two drops of antifreeze oil in the lock and wash with gasoline or diesel after winter. Vegetable oil can not be used as a lubricant for the lock core.