Lantier Solutions Inside: ExtraFlex Blade Holder – giving benefit of the papermaker

The usage of removable blade holders is becoming more and more a standard solution in new paper machines, rebuilds or equipment upgrades. However, identifying the requirements of customers and installing this type of blade holders where they really need them is a challenge and requires full understanding of the customer, its machine, the paper producing process and other input. If all these are not evaluated, frustration, non proper operation and lack of benefits may arise.

It can be said that as well as the classical K35 type and DST type doctors are quite similar from one manufacturer to the other, the removable blade holders have a wide range of variety, each one of them having its own strong points. Hence, this is something that the customer must be aware of, and also we the sellers, because offering the wrong blade holder could result in more problems than benefits, even though theoretically the proposed solution is good.

This article tries to overview where these blade holders can be used and which differences are between different blade holders on the market.

Why to install a removable blade holder?

• Do you have positions on your machine where it is mandatory to erect scaffolding in order to service a doctor?
• Are there positions where doctoring must be always at its best due to heavy requirements?
• Does dirt accumulation in a certain position causes problems?
• Are some doctors in such a narrow space that it is almost impossible to service them?

These are very typical situations where a removable blade holder is absolutely required. In some of these situations, the ROI can be as fast as a single maintenance operation. Of course, from a theoretical point of view, removable blade holders should be installed in every single position on the machine, except those positions where the blade holder is trapped between the machine frame or other elements, hence making it impossible to extract any blade holder.

Using a removable blade holder with an additional spare blade holder turns the blade holder service/maintenance an external operation to the machine, which can be done while the machine is producing. Furthermore, having full access to the blade holder outside the machine allows extremely easy blade holder inspection, cleaning and servicing. However, it is necessary to find a balance between the benefit one gets and the added investment in this kind of systems. A typical question from the customers is where to start with when installing removable blade holders

Where to put a removable blade holder?

As stated before, due to budgetary limitations, removable blade holders cannot be installed everywhere in the machine at the same time. So, if we have to decide where to start, which must be the criteria? The position where more savings will come. That is the quickest, simplest and correct answer. These savings can come from productivity reasons, maintenance cost reasons, health and safety issues… It depends, and changes from one mill to another.

For example, putting a removable blade holder on the double doctor of a central press looks very logical even the customer doesn’t have any paper passing problems on the central press, as maybe the papermaker needs to scaffold every 2 or 3 shuts to service the doctor. There is no need from productivity point of view but the upgrade will be really good from the point of view of efficiency in the shut-downs and safety.

Maybe, there are other positions that are more critical in the machine than the Central Press. That is why a wide, holistic approach is required when taking this decision, which is absolutely customized for every mill. Of course, there is a general guideway that can be followed as a first approach and that is what we develop here. These are the typical theoretical positions to install removable blade holders. Generally speaking, any position where doctoring must always be perfect requires a removable blade holder. Besides that, positions where maintenance is very slow -bad access- or expensive -scaffolding- are also potentially ideal for removable blade holders.

WET SECTION
First Return Roll: This doctor can be responsible for taking the paper off and throwing it down to the pulper. If a knock off shower is used normally, this doctor would normally clean only, but if the shower fails, the doctor will have to take out the paper.

PRESS SECTION
Central Press Tandem Doctor: This is the most critical position on the machine. Hence, it is the first position to check when thinking about a removable blade holder. Due to the constant take off duties of this doctor, the blade holder must be working perfectly at any time.

DRYER SECTION
First Dryers: These are the positions that have to cope with the biggest amount of dirt on the dryer section. They need much maintenance and cleaning, that is why a removable blade holder saves a lot of time to the operators.
Take Off Positions: Every take off position on battery changes has to doctor perfectly the dryer, moreover if there is a pulper underneath. On those positions, the doctor can’t fail and the blade holder must be perfect also.
Dryers After Size-Press/Coaters: Normally the first dryers after a size press or a coating station are very dirty or full of starch/coating. These doctors have to be comprehensively serviced in order to be in perfect cleaning conditions to avoid rings on the dryers.

Types of removable blade holders

Three main groups can be identified when talking about removable blade holders:

TYPE A: “detachable full-featured DST”
The idea behind these blade holders is to remove the complete blade holder from the doctor body (doctor back), so proper maintenance is easy to achieve, as all the elements are accessible for maintenance personnel. This concept follows the idea of making a good DST blade holder detachable. Lantier’s Extraflex® fits in this group.

TYPE B: “light and easy to detach, but not DST”
The main thinking when developing these blade holders is the compact design and low weight, in order to have easy and quick extraction. Hence, composite materials are a must in this group of blade holders.

TYPE C: “mixed design”
This type is a mixture of the two above, so the customer gets a bit of both… but not full advantage of any. Basically the base plate remains always fixed to the doctor body and it’s the top plate what is extracted from the machine.

Lantier ExtraFlex® Blade Holder

Lantier’s Extraflex® blade holder sits on the ‘Type A’ group. We have chosen to use stainless steel as raw material and also a heavy duty design has been searched.

Although designing a fully detachable heavy duty blade holder, we have been able to have a blade holder with reasonable weight. Lantier recommends to always have a number of spare blade holders in order to make quick changes during shut down. The spare blade holder is inserted in the machine, the old one removed and serviced while the machine is producing paper. On a later shut, the blade holder can again be inserted in the machine.

Health and Safety

So far Lantier has installed a big number of removable blade holders. During these installations and thanks to the collaboration of the paper makers we have developed an Extraflex® extraction tool that makes the blade holder change a very simple and non demanding task. Right now, a 12m wide machine’s blade holders are being extracted and inserted by two people using this tool in 15 minutes.

As company policy, Lantier is offering since its foundation a wide range of Solutions to the papermakers in order to improve safety, quality, efficiency, productivity, cost saving. ExtraFlex Blade Holders is one of the best examples nowadays where every machine is finding for producing faster, better quality, safer and in a lower cost.