What is D28 hole system on a 3D welding table?

The D28 hole system is a universal international standard modular positioning system widely adopted on 3D flexible welding tables. The term D28 refers to precision holes with a nominal diameter of 28 mm, arranged in a regular 100 mm × 100 mm grid on the tabletop and vertical side faces. Every hole is machined with tight geometric tolerances to ensure accurate fitting for matched positioning pins, clamps, support blocks and angular fixtures.

Distinguished from simple flat workbenches, the D28 system creates a three-dimensional reference network. Holes are processed on the top surface as well as four side panels, enabling flexible clamping horizontally, vertically and obliquely. Operators can build customized fixture layouts to fix planar sheets, tubular frames and complex spatial components without making dedicated one-off jigs.

Classified as a heavy-duty standard, D28 outperforms the D16 system in load capacity and clamping force. It is preferred for medium and large metal structures, automotive frames, engineering machinery parts and heavy steel fabrication. All D28 accessories feature full interchangeability, allowing rapid reconfiguration for different workpieces and drastically shortening setup time between production batches.

Most high-quality 3D welding tables with the D28 hole system undergo stress relief treatment and surface hardening. The reinforced hole edges resist abrasion, impact and welding spatter. Thanks to consistent positioning accuracy, the D28 hole system effectively reduces dimensional errors and welding deformation, improving repeatability and product consistency for small-batch custom work and mass production alike.