Choosing TBM Disc Cutters: 17, 19 or 20 Inch and the Right Ring for Your Ground

Mixed-face conditions across Middle East metro, road and utility tunnels — desert sand overlying limestone or basalt — punish the wrong cutter size. As a rule, 17-inch cutters suit smaller-diameter machines and softer, more abrasive ground, while 19-inch and 20-inch rings carry higher thrust, take deeper penetration per revolution and resist impact in hard rock. Larger diameters also mean fewer cutter changes per cubic metre, which matters where cutterhead access is slow.

Ring material follows the rock. Standard steel rings perform well in soft to medium ground; heavy-duty steel rings add hardness and wear volume for medium-hard rock; carbide-insert rings, where tungsten carbide buttons sit in a tougher matrix, are the choice above roughly 300 MPa. Behind the ring sits the cutter body, tapered roller bearings, a metal-face or lip seal retaining grease, and the pin or shaft that locks the assembly into the saddle.

Expect 10-30 m of advance per ring in hard abrasive rock and 50-100 m in soft ground — track wear by cutter position, not just total hours. For procurement, OUSUN manufactures cutters and rings to interchange with major international brands, so saddles and hubs need no modification. Factory-direct supply from the Deyang TBM cluster in Sichuan, China, typically ships in two to four weeks, keeping mixed-face drives supplied without long overseas lead times.