WARNING UNDER CONSTRUCTION. NOT GOOD QUALITY YET

Bicak Cutters ("knives" or "scrapers") are cutters used for boring in soft to medium ground. Basically they have metal blocks often with tungsten-carbide bits on the edges which do the digging.

Different TBM manufacturers use different names like "Knives" or "Scrapers" for Bicak Cutters. They come in different designs. Design differs depending on the TBM model and/or the placement position of the bicak cutter on the cutter head.

In addition to the tungsten-carbide bits which do the active digging, bicak cutters also have hardfacing welding on the surfaces which are most likely to have contact with the excavated material. Such hard-facing not only protects the bicak part from secondary impact, but also protects the canals in which the tungsten-carbide bits are fitted (otherwise the bits will fall off).

Your check-list before ordering Bicak cutters

You can eliminate a lot of the potential problems for later by getting extra information during the selection process before actually ordering the product.

BC-1 What is the Steel type?

BC-2 What is the Steel hardness?

BC-3 What is the composition of the Tungsten-Carbide bits?

BC-4 What is the hardness of the Tungsten-Carbide bits?

BC-5 Which method are they using to fit the Tungsten-Carbide bits to the steel body?

Important to note that, you cannot weld the bits to the steel body (please read Differences between welding and soldering). Instead soldering is used for fitting the bits to the canals in the steel body. There are different sorts of soldering. Which one are they using?

BC-6 What is the hardness of the Hardfacing welding?

BC-7 Covering

Often producers oil or paint their products before the delivery. This makes the product look nice and also prevents it from rusting. Both of these are actually not very important because nobody cares how it looks as long as it functions and very often the product will be used within a few months of the delivery, hence if will only have a surface rust which will go away in the first centimeters of the operation - provided that it is a newly produced part.

Insist that the product is not painted to cover the visibility of the metal. This is very important. If it is painted with a thick layer of paint, this will prevent you from visually inspecting the quality of the products. You will not be able to see if the tungsten-carbide bits are properly soldered into the body, of if there are any cracks on the body because of the heat treatment or if there are cracks on the hardfacing welding.

Good producers often do not paint their products and instead they only cover them with a thick layer of oil. In the worst case, at least insist on a transparent and thin layer of paint.  Your quality control people will really appreciate it during visual checks.

BC-8 Quality Control Procedures

Ask the producers for some information about their quality control processes. Like, how do they check the bicak cutter body against gaps in the metal or cracks? How do they check the quality of their soldering and welding?