ZA Milling Cutter: The Silent Pioneer of Hard Rock Tunnel Excavation
Classification： Blog
Release time：2025-10-29
ZA Milling Cutter: The Silent Pioneer of Hard Rock Tunnel Excavation
Deep beneath the city's surface, within the tunnels of underground engineering, as the shield machine roars through solid rock strata, a precision tool is quietly executing the core task of ‘underground excavation’ – the ZA cutterhead. These disc-shaped cutters, measuring 400-500 millimetres in diameter, resemble diamond-tipped fangs embedded in the head of a steel serpent. Exerting immense pressure of 50-200 kilonewtons, they carve concentric circular tracks into the rock surface, providing the vital driving force for humanity's expansion into subterranean realms.
Unlike conventional rock-cutting tools, the ZA cutter employs a philosophy of ‘yielding to overcome hardness’ in rock breaking. As the cutter head presses the rollers against the rock face, the high-strength alloy steel ring with a 60° cutting angle first forms a crushing zone on the rock surface, much like a precision geological scalpel making an initial incision in the rock mass. As the cutter head rotates, the rollers simultaneously perform both orbital and rotational movements, carving grooves of varying depths across the working face. When cracks from adjacent rollers interconnect, rock fragments naturally flake away like petals, achieving highly efficient rock fragmentation. This process, progressing from point to plane, enhances the rock-breaking efficiency of a single roller by 3-5 times compared to conventional tools.
The structural design of the ZA cutter head embodies engineering ingenuity: its single-edge cutter ring employs a standard 20-millimetre cutting width, paired with an optimal 60-millimetre cutter spacing, achieving peak rock-cutting performance at a penetration rate of 10 millimetres. The internal metal floating seal ring and precision bearing system ensure stable operation even at a linear speed of 2 metres per second. Practical application in the Fuzhou Coastal Expressway project demonstrates that synchronous rock breaking with dual milling cutters enhances efficiency by 40% compared to sequential breaking. This technological breakthrough has elevated the tunnel's daily advance record to 28 metres.
In the mining and tunnelling sectors, ZA cutterheads have become the standard equipment for hard rock excavation. From underground rail tunnels to hydraulic engineering projects, dozens of cutter bits are arranged in concentric circles on the cutterhead. By increasing the number of peripheral cutting tools, the load is distributed, forming a collaborative ‘rock-breaking matrix’. Crafted from high-strength, wear-resistant alloy steel and utilising carbide-tipped tooth embedding technology, each individual cutter bit can achieve a service life of 300 to 500 metres of excavation distance, significantly reducing project maintenance costs.
With the advancement of finite element simulation technology, engineers are continually optimising the operating parameters of ZA rock cutters. By simulating the rock fragmentation process, a mathematical model linking rock strength to cutter spacing has been established—when encountering granite with a uniaxial compressive strength of 120 MPa, a 60-millimetre cutter spacing paired with 150 kilonewtons of normal pressure achieves an optimal balance between energy consumption and efficiency. This precision calculation enables this silent subterranean pioneer to continue its legendary feat of breaking through rock and stone within the grand blueprint of urban development.
keyword： ZA Milling Cutter