As with most things in life, having the right tools for a job makes the job much easier. With cutter dredgers this is not different. So today we discuss the best cutterhead and cutter teeth for the different soil types.
1. Cutting the soil with the right tool
When dredging it is important that you use the right tool for the job. Different types of cutterheads have been developed, depending on the soil characteristics. Roughly there are three types, although types somewhere in between and special purposes cutterheads also exist.
This material is the hardest to break. The cutterheads are very sturdy. The arms are very thick, and they are helix shaped. This means the arms are “twisted”.
Although we typically associate sand with a loose material it can also be quite compact and difficult to dredge although not as difficult as rock. For sand often so called multi-purpose cutterheads are used. The arms of these are a bit thinner, but they are still in a helix shape.
Clay is one of the most difficult materials to dredge as it can be very sticky and at the same time hard to cut.
In the last decade or so a new type of cutterhead has been developed to dredge this difficult material. The cutterhead has more arms, sometimes as much as eight. They are straight, and the teeth form an almost closed knife. On the right is a design from Royal IHC, although other designs are around as well.
2. Equip the tool with the right parts
Once you selected the right cutterhead you need to choose the right teeth to use. This again depends on the soil type
Use a pickpoint. These are very sharp and will break the rock the easiest. Depending on your cutterhead type there may be several sizes to chooses from. Trial and error is the best way to find out the best match for the material that you are dredging.
For soft sand use wide chisels. If the sand is too compacted for those, change to narrow chisels. And if the sand is even more compact, pickpoints can also be used.
You might think, since pickpoints can also be used, that you might as well always use pickpoints. When you do that for sand you will lose production and the cutterhead wears more, as it is less protected by the teeth.
When dredging clay you want to try to create more of a knife. You can do that by using the flared teeth. When aligned correctly the edges of the teeth will almost touch.
The idea of tis and the use of more arms in the cutterhead is that you cut very small layers of clay, which then get sucked into the suction mouth more easily.
So there you have it, a quick overview of the cutterhead and teeth types. Discussions with the equipment providers will provide more details for the exact choice, but at least you have a few pointers, so you understand the importance of the cutterhead selection.
To your success,