Table stability can cause problems for customers with high “Center of Gravity” systems. This occurs in applications with thick tables and/or narrow table widths. Use of high CG equipment such as table enclosures and SEMs can also cause instability. Below is a description of stability problems and an applications checklist.
There are two types of rocking or hunting motions to which pneumatic isolator supported tables systems are susceptible. The first type is simple static instability caused by a high CG payload combined with a narrow isolator spacing; the table lurches, tilting from one side to the other, pauses, and then lurches back and forth again repeatedly in a jerking sort of motion. The second type is a dynamic or leveling control-oscillation. In this case, the table rocks quickly from side to side at about 2 Hz and the valves hiss significantly. The causes and cures for these two problems are different, but the symptoms are similar enough to cause misdiagnosises.

Table stability can cause problems for customers with high “Center of Gravity” systems. This occurs in applications with thick tables and/or narrow table widths. Use of high CG equipment such as table enclosures and SEMs can also cause instability. Below is a description of stability problems and an applications checklist.
There are two types of rocking or hunting motions to which pneumatic isolator supported tables systems are susceptible. The first type is simple static instability caused by a high CG payload combined with a narrow isolator spacing; the table lurches, tilting from one side to the other, pauses, and then lurches back and forth again repeatedly in a jerking sort of motion. The second type is a dynamic or leveling control-oscillation. In this case, the table rocks quickly from side to side at about 2 Hz and the valves hiss significantly. The causes and cures for these two problems are different, but the symptoms are similar enough to cause misdiagnosises.