Question:
I clean the ballscrew on my machine regularly but the seals on the nut allow small particles to enter. The seals seem to be made of some sort of plastic. Can I replace them to keep the chips out?

Answer:
The seals you mention are in fact wipers because it would be almost impossible to perfectly seal a ball nut. Manufacturers use varying materials to accomplish the task but the results are rarely 100% efficient. Plastic, neoprene, felt and brush wipers are used, some ball screw designs are supplied without wipers. All have their advantages and disadvantages depending on conditions of use. In your case, continue to clean and lubricate the ball screw but do not use an air gun to blow away chips. The use of compressed air to remove chips from a ball screw should be avoided.