When it comes to cutterhead tooling, there are a multitude of options available today. Disc cutters are no exception. From different disc diameters to different cutting rings and mounting configurations, there are a variety of disc cutters to choose from. So how is a final cutter configuration selected for a project? Let’s look at some of the factors used to determine the disc cutter configuration.
The expected ground conditions along the tunnel alignment play a key role in determining disc configuration. Different ground conditions demand cutter configurations for optimal performance of the cutterhead. For example, in mixed ground a double disc assembly with tungsten carbide inserts or buttons may be selected. With two cutting paths per disc, fewer cutters are needed to fill out the disc profile, providing room on the cutterhead for soft ground tooling and openings needed to help process material. The tungsten carbide inserts or buttons increase durability when excavating boulders and cobbles often seen in mixed ground and allow the cutter to engage soft ground and promote disc rotation, minimizing localized wear and flat spotting.
If competent rock is expected along the tunnel alignment, single disc cutters may be selected due to their increased capacity per cutter path, offering higher penetration rates vs double disc cutters of the same diameter. Hardened steel rings, tungsten carbide insert rings, or button rings may still be selected based on the specific geology.
TBM size and type are also important factors in disc cutter selection. Smaller diameter machines may require smaller diameter cutters to ensure an optimal disc cutter profile. Machines with face access will often utilize backloading cutter assemblies to facilitate underground tooling changes.
About the Author:
Tim Fay – Chief Engineer, Akkerman Inc.
Tim Fay is Chief Engineer of Mechanical Design at Akkerman Inc, where he has worked for 17 years after first starting as a summer intern. Tim has design experience across all Akkerman’s product lines, with a number of years focused on the Microtunnel Boring Machine product line. Outside of work, you can find him spending time with is wife and three children, playing golf in the summer, or coaching 7th & 8th Grade Boys Basketball in his hometown during the winter.
