mbb best practice e

8/3/2019 Mbb Best Practice e

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INFORMATION ON THE USE OF MBB`s

Subject to change without notice. Last changed on: 10/2008. STREB AG Am Molkenborn 1 DE-63303 Dreieich-Buchschlag, page 1 of 11

Contents

Delivery, storage ......................................................................................................................... 1

Opening the shipping boxes ......................................................................................................... 3

Manufacturer's documentation ......................................................................................................4

Handling (removal, avoiding kinks) ................................................................................................5

Packing foil ..................................................................................................................................7

Bending ......................................................................................................................................8

Makeready, cleaning and tips .........................................................................................................9

Service life general experience ...................................................................................................10

We would like to thank our supplier Trelleborg Engineered Systems S.p.A. for providing the photos and diagramsin this document.

Delivery, storage

Metalback blankets are delivered in sturdy, reusable wood boxes. The shipping boxes are collected by the userand picked up by the supplier free of charge at the agreed-on time. The loaded shipping boxes are alwaysdelivered in horizontal position never standing up!

Correct storage of MBBs.


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Incorrect storage/delivery. In this case, the printingblankets may be damaged irreparably and becomeunusable!

The "Tilt Watch" seal tells you whether the horizontal position of the box was changed during transport.

The seal on the left side has been triggered. You can see this by the red dot. The seal on the right side has notbeen triggered. The metalback blankets are likely in order. The seals are always provided at the sides of thetransport boxes.If a seal has been triggered, the recipient should refuse to accept the shipment. At the very least, he or sheshould pen a note on the forwarder's delivery or transport documents; this note should be acknowledged with the

forwarder's signature.


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Opening the shipping boxes

Before the spring lock can be opened, the tabs must beunbent using pliers.

Only then can the lock be opened.

Using the wrong tool to open the shipping boxes maycause irreparable damage to the metalback blankets.


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Manufacturer's documentation

The data sheet below documents the properties of the MBB, which is always manufactured to match thespecifications of the printing press manufacturer. The sheet lists the date of manufacture, batch number, andthickness, among other things. This document is important and must be kept for reference.


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Handling (removal)

Persons removing metalback blankets from the shipping boxes must always wear protective gloves to preventcuts to their hands!

Recommended procedure.

NEVER LIKE THIS!


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Handling (preventing kinks)

NEVER LIKE THIS!

Handling after bending!Handling prior to bending!


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Packing foil

Metalback blankets need fairly thin packing foils (0.14 - 0.18 mm), depending on the undercut of the blanketcylinder. This packing foil must be mounted without any kinks!

Today, it has become common practice for blanket manufacturers to apply these packing sheets directly to theback of the MBBs using a calender (see photos). Manufacturers are planning to eliminate the adhesive of thepacking foils. Instead, the packing foil is to be calendered to the back of the blanket with heat.


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Bending

The leading and trailing edges of a metalback blanket must be bent. This is done in a high-precision bendingmachine.

A bend that is located too close to a sealed seam will always shorten the service life of the metalback blanket. Ifthe seam is damaged, the exposure of the blanket to washing fluids will generally cause the cover plate of theblanket to come loose. This may lead to considerable press damage!

The leading edge of the metalback blanket is marked "VL" by the manufacturer; both the leading and the trailingedge must be positioned at right angles to the guides for bending.

The leading edge is always bent first! This edge is markedby the manufacturer. This is necessary because theprofiles of the front bend and the rear bend are different.

The metalback blanket must be positioned exactly at rightangles for bending! The silicone seam must never bedamaged!


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Makeready, cleaning and general tips

Proper mounting of the metalback blanket is essential for a long service life. However, other points must beobserved as well:

The leading and trailing edges must not be damaged (e.g. bent)!

The silicone seams must not be damaged!

The blanket must be mounted on the blanket cylinder in the correct direction (leading edge andtrailing edge).

The batch number and position of the mounted MBBs in the printing unit must be noted down! Thiswill facilitate tracking and analyses in case of technical difficulties.

The cylinder gap (mini-gap) must be kept clean at all times!

The metalback blankets must be cleaned regularly, depending on the paper quality. Due to the highproduction speeds, washup intervals may be shorter than with conventional printing blankets!

The contact pressure of the washup unit must not be too strong! Otherwise, the cover plate of themetalback blanket will be abraded too quickly.

Only washing fluids approved by the printing press manufacturer and the blanket manufacturer maybe used!

When metalback blankets are changed, the operator should note down the batch number, date,reason for the change (e.g. web break/paper jam) and the number of revolutions on the cylinder(service life).


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Service life general experience

As shown in the diagram below, there is a direct connection between the consumption of metalback blankets andthe phase of their use (introduction phase to advanced phase).

The following factors were the cause of a reduced service life of metalback blankets:

Incorrect handling (e.g. removal from the shipping box).

Incorrect bending in the bending machine.

Delamination of the cover plate due to prior incorrect handling.

Damage of the cover plate due to buildup of ink or filler material.

Plate edges cutting into the cover plate.

Abrasion of the cover plate due to mechanical damage (wrong cylinder rolling, washup unit).

Loss of the MBB due to heavily soiled cylinder gap (mini-gap).

Paper jam due to web breaks.

A B

approx. 5 Mio.revolutions

approx. 20 Mio.revolutions

MBBService life/number of revolutions

1 2 3 Time

A

B1 = Start phase (3 6 months)

fairly high consumption

2 = Lern-Phase (1 3 years)normal consumption

3 = Advanced-Phaselow consumption

due to long service life


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The washing fluids used in the unit also have a considerable impact on the service life of metalback blankets. Thefollowing factors were causes of a short service life:

Swelling (caused high wear of the cover plate, plate abrasion, register).

Penetration (caused bad print results, damage to the cover plate, bubbles).

Delamination (caused web breaks, damage to the printing unit/cylinder body).

Slipping of the packing foil (damage to the cover plate, breaking of the metal carrier).

1.Start phase

2.Learning phase

3.Advanced phase

Average service life(min. number of revol. in mio.)

5 12 20

Service life with defects(minimum Umrollungen in Mio.)

2 7 12

Natural service life(minimum Umrollungen in Mio.)

25 25 25

Start phase Advanced phase

87%

13% 28%

72% 62%

38%

Learning phase

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