Differential Pressure
Differential pressure measures the pressure difference between two points in a system. In CNC and millwork, it indicates system performance across components—such as pressure drop across a filter, vacuum differential across a spoilboard, or air supply differential across a manifold. It is critical for assessing workholding force, filter loading, and pneumatic balance, ensuring reliable machining operations.
On a CNC router vacuum table, differential pressure creates workholding force: air is evacuated under the part while atmospheric pressure pushes the panel down. This pressure differential determines hold-down force; a failing seal or porous spoilboard reduces differential and risks part movement. In coolant systems, differential pressure is monitored across filters to detect clogging. As contamination builds, pressure drop rises, forcing pumps to work harder and starving the spindle of coolant, which can overheat tools. For pneumatic systems, verifying differential pressure ensures the machine receives adequate supply—typically 110 PSI minimum. Excessive loss across undersized lines or wet air leads to inconsistent cylinder actuation and intermittent faults. In powder handling equipment, maximum differential pressure limits define safe operating envelopes to prevent leakage. The practical shop metric is not just absolute vacuum but the difference between chamber and atmosphere, because that directly translates to clamping force and process stability.
Is differential pressure the same as pressure?
No. Pressure is an absolute or gauge value at one point; differential pressure is the difference between two points in the same system or across two sides of a component.
Why is differential pressure important on a vacuum table?
Because the clamping force depends on the pressure difference between the evacuated underside and atmospheric pressure above the part; more differential generally means more hold-down force, assuming leakage is controlled.
What does rising differential pressure across a filter mean?
It usually indicates increasing restriction from contamination, which can reduce flow and require maintenance before the system reaches an unacceptable pressure loss.