Zero-point clamping systems

In the rigid-fixture example, seating regions are 200 mm apart and one sits 0.010 mm higher. The ideal tilt is 0.000050 rad, causing 7.5 µm vertical displacement 150 mm from the lower region. A repeatable interface can reproduce that offset. The model illustrates geometry, with no tolerance or limit on permissible contamination implied.

Use Choosing workholding to compare location, support and restraint across fixture types.

What the interface does

Jergens ZPS receivers locate and clamp fixtures or pallets through mating studs. A suitable workpiece can mount directly through attached studs. Jergens ZPS overview flyer, copyright 2016

The machine pallet changer, repeatable exchange interface and workpiece locators each establish separate relationships.

Location and constraint

Jergens distinguishes zero-point, timing and clearance pull-studs to accommodate spacing tolerances between studs and modules. The zero-point stud establishes the reference; the timing stud constrains the remaining free direction, while clearance studs avoid requiring every connection to locate identically. Its FAQ also defines repeatability as the position range after removing and reclamping the same workpiece. These functions are distinct from merely counting clamping modules. Jergens ZPS FAQ

A concrete configuration appears in Jergens's February 10, 2021 product announcement: a two-stud plate uses one zero-point and one timing stud; a four-stud plate adds two clearance studs. The announcement specifies less than 0.005 mm system repeatability for the described pneumatic subplates. That configuration and performance claim do not establish compatibility with another manufacturer's pins, receivers or spacing. Jergens pneumatic subplate announcement

Force is different from pressure

Pull-in or pull-down force draws the exchanged component into its seat. Holding force describes resistance to pullout after engagement. Jergens's FAQ defines these separately, identifying holding force as the maximum permissible pull force of the engagement screw. A holding-force value is therefore not automatically available as seating preload, lateral capacity or allowable cutting force. Jergens force definitions

Actuation pressure is another quantity. SCHUNK's standard NSE3 138, ID 1313721, is spring-loaded and pneumatically opened. It lists 8 kN pull-down, 28 kN with turbo, 6 bar unlocking pressure and less than 0.005 mm repeat accuracy. The 6 bar figure concerns unlocking; it is not a workpiece contact-pressure specification or a direct conversion into either force rating. Clamping pins are excluded from the stated module delivery scope. SCHUNK NSE3 138

Actuation also varies by product. Jergens's SP installation modules use spring-force mechanical locking and pneumatic opening at 6–12 bar, with repeatability below 0.02 mm. Its manual K10 module 559775 instead uses a single hex drive, specifying 30 N·m tightening torque, 6 kN pull-in/locking force, 25 kN holding force and repeatability below 0.01 mm. These examples rule out treating pneumatic release or a single accuracy figure as defining every zero-point system. Jergens SP modules, Jergens manual ZPS

Repeatability and finished-part accuracy

Mounting repeatability concerns a recurring interface position. Finished-part accuracy additionally includes the machine, workpiece location in its fixture, tool behavior, thermal effects and deformation under load. A system can repeatedly reproduce an offset from the intended machine coordinate; a repeatability specification alone does not bound that offset.

Original geometric example: assume a rigid fixture has two seating regions 200 mm apart, with one sitting 0.010 mm higher because of an assumed seating error. The resulting small tilt is approximately 0.010/200 = 0.000050 rad. At a point 150 mm from the lower seating region, that tilt contributes about 0.0075 mm (7.5 µm) vertical displacement. This simplified example illustrates geometry, not a permitted contamination size or a manufacturer's tolerance stack.

Original load example: assume a horizontal cutting force of 1,000 N acts 0.15 m above an interface. Its overturning moment is 150 N·m. An idealized pair of reaction lines 0.20 m apart would need a 750 N force couple to resist that moment, before other forces are considered. Real module reactions depend on preload, supports, fixture stiffness and load direction; multiplying one module's holding force by module count does not establish an assembly's moment capacity.

Seating and status information

A locked mechanism and a correctly seated fixture are separate physical conditions. Jergens's sensor-equipped ZPS modules provide two inductive sensors for opened/locked status. SCHUNK's cited NSE3 module describes dynamic-pressure monitoring of slide positions. Those descriptions identify monitored mechanism states; they do not alone prove workpiece location or collision clearance. Jergens modules with sensors, SCHUNK module monitoring

Coverage limits

The product pages and FAQ establish no verified issue dates here; the flyer prints a 2016 copyright, not a confirmed revision date. Ratings apply to the named interfaces and configurations. Stud attachment, receiver mounting, seating surfaces, permissible lateral loads, moments, operating environment and workpiece restraint remain application-specific. No generic force rating, pressure, repeatability or finished-part tolerance follows from the term “zero-point.”