The cutter head, with a half dozen ‘toothed blades’, is one of the most crucial parts of this unique type of equipment. These teeth come in a variety of types, like wide or narrow chisels which are used for cutting sand, peat and soft clay or teeth with pick points which are used for cutting rock. The wear and tear on these teeth is a significant factor in the cost-efficiency of a cutter head, because they influence the frequency with which operations must stop to change the teeth of the cutter head.
In addition, the dimensions and speed of the cutter head as well as the diameter of the cutter head influence production rates. The cutter head speed will influence the amount of spillage – material that is cut but not sucked up by the suction pipe. Spillage reduces the productivity of the cutter suction dredger and therefore needs to be minimized. To work efficiently, a balance has to be found between the cutter speed and the pump capacity to optimize the particle size of the rock dredged and reduce spillage.
WHICH CUTTER HEAD IS SUITABLE FOR WHICH TYPE OF SOIL?
Different cutter heads are designed for different types of soil, for instance, hard soil, non-cohesive or cohesive soils have different requirements:
- For hard soil, a cutter head should be used that can withstand impact forces on its teeth. It should be heavy but have a small contour with replaceable teeth so that it can withstand extreme wear on both the cutter head itself and on the teeth. Often more teeth (or chisels) are used for hard soil and good, accurate tooth positions are necessary.
- For non-cohesive soil it should be possible to achieve high production rates. A good mixture formation with replaceable chisels or cutting edges will be able to withstand wear. Here as well, good, accurate tooth positions are needed.
- And, for cohesive soil, a primary concern is that the cutter head does not become blocked. For this reason, the cutter head should be round in contour and large enough. It may require fewer blades with different types of edges (e.g., plain, adapter, toothed or serrated) on multiple smaller teeth.