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This article is a buyers' guide to the Y-Parts used on Tunnel Boring Machines (TBM). Y-Parts are the spare parts used on the TBM's Cutter Head. These are the parts which are worn most and need replacement most often during the boring operation.

The purpose of this article is to give an overall information about the TBM Y-Parts to help buyer with their buying process.

Y-Parts, Cutters, Collectors & Supports

The parts which do the actual cutting on a TBM Cutter Head are called TBM Cutters. Or simply Cutters. A typical Cutter Head also contains the support parts which we here call 'Supports'.

Here are the categories which together make up the Y-Parts:

TBM Y-Parts

• Disc Cutters (also called: Roller Cutters)
• Bica Cutters
• Collectors
• Supports

General Buying Advice

When you buy a TBM for a tunnelling project, you are right in expecting that the TBM manufacturer provides you with some sort of warranty (spare parts etc) during the whole project run for your TBM that you paid millions of Euros.

In addition to this, often a good contract stipulates that the TBM manufacturer takes the supervisory responsibility for the first X-meters (500 meters or so) of the boring operation. During this 'first X-meters' (often with a time constraint as well), your TBM team is still in charge. But the TBM manufacturer will be there to direct and help your TBM team to counter the early assembly & operation problems and attain a certain performance level.

These "first X-meter" clauses often require that the TBM uses the Y-Parts supplied/sold by the TBM manufacturer during this suprevisory period of operation. There are two reasons for this requirement. The first one is that, the TBM manufacturer wants to operate in a relatively controlled environment in this supervisory period by fixing some of the variables, ie in this case by working with Y-Parts that they are familiar with, rather than some Y-Parts you throw in from of them. Basically if you are telling them "500 meters of boring within 30 days", they have the right to set some counter constraints. Often the Y-Parts that the TBM manufacturers like to call "Original parts" is one of them. Secondly, the TBM manufacturer bets on your inertia (your lack of action). They hope that, rather than taking the (supposedly) "risky" decision of changing the sourcing of Y-Parts, you will simply be inclined to continue buying their Y-Parts.

Now comes this question:

Do Y-Parts of TBM Manufacturers Perform Better than that of Independent Producers? Please read this page to be able to better answer this question: Should you buy your TBM Cutters from TBM Manufacturer or from Independent Manufacturers?

The short answer is, you often get much better price/performance from independent manufacturers. But you need to do your homework in searching for a good manufacturer.

• Disc Cutters (also called: Roller Cutters)

Also called 'Roller Cutters', becase they turn when they are cutting the "wall" that the TBM is boring.

Disc Cutters are used for boring the hard surfaces like rocks. Their working method is causing cracks on the "wall" by applying pressure on it.

• Bica Cutters
• Collectors
• Supports