Choosing TBM Disc Cutters: 17-Inch, 19-Inch or 20-Inch Rings for Your Ground

Disc cutter selection starts with ground, not catalogue. Standard steel rings suit soft to medium ground — alluvial sands, clays and weathered rock — where abrasion is low and cutter cost dominates. Move to heavy-duty steel rings for medium-hard rock with higher impact loads, and carbide-insert rings once intact rock strength climbs past roughly 300 MPa, where conventional rings spall or wear out within metres.

Diameter follows the same logic. A 17-inch cutter is the classic workhorse for smaller-diameter EPB and pipe-jacking machines, 19-inch cutters are now standard on most metro TBMs, and 20-inch cutters raise penetration and reduce the number of cuts per revolution on large hard-rock drives. In hard rock expect ring changes around every 10-30 m; in soft ground 50-100 m is typical.

Whatever the size, the assembly is the same: cutter ring, hub/body, bearing set, seals and pin/shaft. Seal and bearing quality, not just the ring, decides how long a cutter survives a high-water-table drive. For buyers in South Asia's expanding metro markets, OUSUN in Deyang, Sichuan supplies interchangeable 17", 19" and 20" cutters and spares with roughly 2-4 week lead times. Contact [email protected].