It is recommended that all machine tools be kept clean and free of objects that can cause damage, and this rule is even more important on 5-axis equipment. Realigning routines should be done at regular time intervals, and most certainly after heavy work, overloads, or a crash. A log should be kept of the machine s vital statistics and operators should be instructed to listen for any new sounds coming from the spindle(s) or rotary mechanisms.

Some common problems include:

• Sometimes the rotary brakes will fail and they won t disengage. The rotary mechanism will then work extra hard to rotate from position to position, and if simultaneous work is in hand, the unit will eventually fail.

• Some dual rotary table center lines do not intersect. Some of these apparent discrepancies are by design, as shown in Figure 2-39, and some are not. If the apparent error is by design, it is usually a large number that can be seen by eye. If it is not by design, it won t be noticeable. It must not be assumed that the centerlines are in line, and they must be checked. Misalignment can be compensated for by inputting the relevant value into the post processor.

  
  Figure 2-39: Example of rotary mechanisms placed in offset positions by design.

  
  Figure 2-40: These rotary mechanisms appear to be intersecting.

• Some Head/Head types of machines will not run true. To check this aspect, arrange the machine with the...