Neuss, Germany, 21. August 2018

Succesful modernization of ALUNORF's Hot Rolling Mill 1

Aluminium Norf GmbH (ALUNORF) is the world’s largest integrated aluminum smelter and rolling mill at a single site. It fabricates products for high quality aluminum applications which are used for instance to make cans, lithographic sheet, automotive sheet, aluminum foils and many other specialty sheets. The facility located in Neuss near Düsseldorf includes two hot rolling lines and five cold rolling mills supplied by the German SMS group, a leading supplier for metallurgical plants.

In autumn 2012, ALUNORF launched a comprehensive modernization project for the Hot Mill 1. This rolling line was originally supplied by SMS and is in operation since 1967. ALUNORF selected SMS group as their reliable partner to modernize the hot rolling mill in three steps with the target to boost output and to further improve flexibility and the product quality:

  1. A major upgrade of the roughing stand
  2. A new edger mill
  3. An additional finishing mill stand.

Due to the capacity requirement of the plant, production should be affected as less as possible. This fundamental requirement was realized by a meticulous planning and by considerable utilization of regular maintenance downtimes. The intensive and trustful cooperation between ALUNORF and SMS group proved to be a key success factor.

The modernization were scheduled in three main steps over a total period of more than three years which was completed in 2016. The successful results reveal the potential for a significant optimization of the rolling process, making ALUNORF’s Hot Mill #1 fit for the requirements of the future.

The production facilities of ALUNORF in Neuss, Germany

With an annual rolling capacity of 1.6 million tons of aluminum flat-rolled products, Aluminum Norf GmbH, ALUNORF for short, can still call themselves the world’s largest integrated aluminum smelter and rolling mill at a single site. The basic production lines, consisting of two hot strip mills and several cold rolling stands, have essentially remained the same throughout the years. However, repeated modernizations have continuously boosted the plant’s productivity and finally increased its capacity to its current dimension. In 2014 and 2015, further modernization measures on Hot Rolling Mill 1 were carried out to increase significantly the company’s hot-rolling capacity. These measures vividly demonstrate that even an almost 50-year old plant has great potential that can be harnessed by means of a smart modernization concept.

A condition precedent to succeed an ambitious revamp project is having a qualified and experienced partner as supplier aside. ALUNORF trusted in SMS group, one in the world of metals well known supplier of plant technology and equipment. Against the background of a highly competitive global market, efficient utilization of existing equipment becomes more and more important for producers. SMS group carried out more than 190 revamps of hot and cold rolling mills alone since 2000. Among these there have been more than 20 modernizations of aluminum plants.

In 2010, in order to elaborate a concept for a medium-term significant capacity increase of Hot Rolling Line 1, ALUNORF installed a project team of internal senior experts. The team identified details for the revamp potentials of the line. On the basis of these facts, appropriate modernization steps or performance modules have been defined, which resulted in the required performance targets and modules. What made the performance modules approach special is that already every individually completed modernization step facilitated a previously defined improvement. In combination with tight scheduling of all installations and commissioning and limiting them to one regular shutdown, it is adequate to characterize the individual modernization steps as performance modules. SMS group turned out as the most qualified partner on supplier side.

Initial situation of Hot Rolling Line 1, consisting of roughing mill with separately arranged edger in the foreground, heavy and light crop shears and finishing mill in the background

In 1965 the ALUNORF plant in Neuss, nearby Düsseldorf in Germany was founded as a 50:50 joint venture between VAW Aluminium and Alcan Inc.. Due to various reorganizations undergone by their founders under business law, their shares were finally transferred to the current shareholders Novelis Deutschland GmbH and Hydro Aluminium Rolled Products, who jointly operate the plant with equal shares to supply their various downstream operations with semi-finished rolled products. These products are used for the manufacture of ends and bodies of beverage cans, aluminum foil and other types of packaging material, components for ship building, exterior wall and ceiling claddings and other components for building construction, offset printing plates and, to a growing extent, high-quality automotive sheet.

The largest extension of the plant took place between 1990 and 1994 and mainly comprised the investment in a second hot strip mill, making ALUNORF the world’s largest aluminum smelter and rolling mill. Today, 1,000,000 tons of rolling ingots are produced in the smelter at ALUNORF. These ingots are rolled down to hot-rolled strip on the two hot strip mills both supplied from SMS group. A minor percentage of these strips leave the plant as hot strip, while the major part is processed further to produce cold strip on five downstream cold rolling mills also supplied by SMS group.

The modernization referred to in this paper focused on the Hot Rolling Mill 1, supplied in 1967 by Siemag, which today forms part of the SMS group. The hot rolling line consists of a roughing stand, an edger and a three-stand tandem finishing mill. ALUNORF’s most important goal for the entire modernization was to increase capacity with meeting higher quality standards of the future. Furthermore, the future possibility of more flexible planning of the entire hot rolling operations was considered a major advantage by ALUNORF, because before the revamp certain products could only be rolled on the newer Hot Rolling Line 2, which was installed and commissioned in the 1990s. One result of the modernization is that ALUNORF now has the option of processing these products also on Hot Rolling Mill 1.

MODERNIZATION STRATEGY
Conceptual design of the new roughing stand

Previous to the order, internal investigations of the line have been carried out by a team of senior ALUNORF`s specialists. These investigations resulted in a modernization strategy that was discussed with several suppliers. Finally ALUNORF trusted SMS group with the order.

One precondition of the project schedule was that the production at ALUNORF should be affected as less as possible and production downtimes had to be kept to at a minimum. That means that assembly of the new equipment and all installations had to be performed in accordance with a sophisticated process schedule, because only a few days were available to carry out the required work. Under consideration of the operating processes it was decided to implement the modernization in several self-contained stages. These mainly comprised the roughing stand, the edger as well as the supply of a fourth finishing stand.

A MAJOR UPGRADE OF THE ROUGHING STAND
Roughing stand before modernization

After being put into operation in 1967, the roughing stand went through decades of continuous operation and was revamped in 2000/2001. The 4-high stand with work roll width of 3300 Millimeter and a maximum roll force of 30 Mega Newton, referred to the original design value, is capable to process ingots with a maximum width of 3200 and a maximum entry thickness of 630 Millimeter. The maximum pass reduction is 50 Millimeter. The ingots are rolled down to a minimum transfer bar thickness of <15 Millimeter. What turned out as the most important limitations of the roughing stand was the speed of the mechanical roll gap adjustment. SMS group received the order for the comprehensive modernization of the roughing stand in November 2012. Main target of revamp was an increase of the speed of the roll gap adjustment.

SMS group provided the roughing stand with a new mechanical and hydraulic work roll adjustment system for fast roll gap adjustment with high positioning accuracy. Part of the mechanical revamp was also the new back-up roll balancing system with new back-up roll chocks.

Also the mill stand service platform and the fume exhaust hood were replaced. As clearly visible in figure 4, the new mill stand platform, containing the hydraulic valve stands, makes a very tidy and clearly arranged impression. The accessibility of the installations is excellent and therefore beneficial for maintenance works. The new entry and exit side fume exhaust hoods the roughing mill area regarding the emission of fume and dust.

In addition to the mechanical scope of supply and the required modification of the fluid systems, SMS group also had the task of carrying out the assembly/installation.

The most important basic condition for ALUNORF was to gain full deliver capacity in the first quarter of the upcoming year. So all installations were finalized during the short regular “Christmas shutdown”, starting on December 25th 2013 and completed on January 2nd 2014. The pictures below give an impression of the dismantling and assembly works on site.

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Dismantling of old equipment
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Assembly of the new media platform
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Assembly almost completed

Already on January 3rd 2014 the first ingot was rolled after completion of the revamp. Only a little later, the planned higher production performance was reached, confirming that the modernization measure was a success. One of the key factors in achieving this goal was a significant increase of the roll gap adjustment system’s traversing speed from 32 to 56 millimeters per second. In this way, the rolling sequences could be shortened, thus increasing production by up to 4.5% per year. The roll force of the roughing stand was increased from 30 up to 45 Mega Newton.

RENEWAL OF EDGER

In April 2013 SMS group was awarded the contract for the second stage of the modernization. This second stage comprised the supply and the erection of a new edging stand in the roughing mill, in order to replace the old edger. An edger serves to control the rolling stock width between the individual passes and to improve strip edge quality. It is particularly the higher strip edge quality that boosts the output of the entire rolling line as hot strip coils need less side trimming.

The edger renewal was intended to improve two essential issues: on the one hand, the distance between the old edger and the roughing stand used to be approx. 11 meters. Due to the long reversing distances between the roughing mill and the edger, this arrangement was unfavorable with regard to the desired increase in production performance. A potential increase of the production output by a further 7 % was identified.

On the other hand, the existing edger with a maximum roll force of 10 Mega Newton had reached its limits as regards the roll forces required. That was why the decision in favor of a stronger and optimally positioned new edging stand was the only sensible solution here.

In fact, what was being installed, was one of the world`s strongest edging stands with a roll force of 12 Mega Newton. The new edger was attached directly to the roughing stand with a distance of only four meters. In this way, transport distances and operating cycles can be significantly reduced. Together with the new edger, SMS group also supplied an entry-side roller table and side guides. Furthermore, SMS group expanded the existing fluid system and was responsible for the assembly, installation and commissioning of the new equipment.

Pre-assembling of the new edger in SMS group’s workshops in Hilchenbach

In this context, extensive work of the foundation was required. As like the roughing mill revamp, assembly and installation of the new equipment was planned meticulously in advance. Because the only time frame available for the work performed on site was the slightly extended “Christmas” shutdown in 2014. To ensure compliance with the tight planning, the new edger was manufactured and pre-assembled in the workshop of SMS group in Hilchenbach. By intensive workshop preassembly and testing of the mechanical functions, site assembly and commissioning was made more predictable and therefore safer

On site, the new edger was set up in parallel to the rolling mill during ongoing production. The old edger was demounted within just four days, from December 18 to 22, 2014. Parallel to these activities, SMS group adapted the foundations to receive the new edger. On December 25, 2014, the extensive work was completed and the new pre-assembled edger could immediately be positioned in its new location at the roughing stand by means of a heavy duty lifting device. The new edger started production on the dot on January 8, 2015.

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Prior to assembly, comprehensive work on the foundations was necessary
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The new edger had to be pre-assembled and completed as far as possible in parallel to the existing one
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Via a special shifting device it was moved to its final position

The new edger is directly flanged to the roughing stand and hence much closer than its predecessor. This substantially shortens the reversing distances and significantly boosts capacity.

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The new edger was successfully and on time put into operation on January 8, 2015
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Hot rolling line 1 after the modernization with the strong new edger attached to the roughing stand in the foreground
AN ADDITIONAL FINISHING STAND
Three stand finishing mill of ALUNORF, operating since 1967

To make the modernization project complete, the capacity of the existing finishing mill had to be increased and to be adapted to the capacity for the roughing mill as the third stage of the revamp. That was why in February 2014 ALUNORF awarded SMS group the order for addition of a fourth mill stand to the entry section of the three-stand finishing mill. By means of the example finishing mill is shown, how a well elaborated plant concept containing options for adjustment to future requirements can be used efficiently even after decades.

SMS group had already considered the option of later extension of the three-stand finishing mill already in the planning and designing phase of the hot rolling line 50 years ago. The conceptual drawing in figure 16 gives an overview about the basic line concept, including the options for later growth. The main equipment installed is colored orange and comprises – from the left to the right side – the roughing mill, heavy and light crop shears, the finishing mill with three stands installed as well as further strip handling equipment, like trimming shear, coiler and coil cars. As can be learnt from the scheme, there is a designated space on the entry side of the finishing mill for the later installation of up to two further mill stands.

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The original basic line arrangement of Hot Rolling Mill 1 contains options for later extension.

For the extension of the finishing mill, SMS group supplied the mechanical equipment for the new mill stand in 4-high design, including hydraulic adjustment, positive and negative work roll bending, pertaining drive technology as well as the main drive components needed to upgrade the existing mill stand in order to realize higher rolling speeds and rolling torques. The new mill stand takes the first position in the finishing line and performs a significant part of the deformation energy as it rolls the incoming material.

Schematic presentation of the new finishing stand concept including drive train (drive side view)

Therefore the new drive train has been equipped with high-performance components as the Sieflex® HT gear-type drive spindles, in order to transmit safely the high rolling torque in the first mill stand to the work rolls. The Sieflex® HT gear type drive spindle is developed by SMS group as a solution for rolling od advanced material grades requiring higher roll torques. In general, it allows to design new mills in a more compact design and to increase the capability of existing equipment.

The design of the new stand can be seen in the figure above. It is equipped with a powerful drive train, fume hood, cladding and a media platform on top. Prior to shipment, as like the edger, the new mill stand was pre-assembled and functionally tested in SMS group’s Hilchenbach workshops. 

The second and third mill stands were each equipped with new gear wheel sets due to the required speed setups in the finishing mill. The extension of the available media systems and the emulsion filter equipment was also supplied by SMS group.

The completed finishing mill with the new entry side mill stand (operator side view)

In order to ensure the flatness requirements, the set up range of the bending system had to be significantly extended from a range between minus 700 Kilo Newton and plus 800 Kilo Newton per neck to between minus 1200 Kilo Newton and plus 1200 Kilo Newton per neck. An important modernization target of ALUNORF was the transition to a flexible production on both hot rolling lines. Because of the excellent preparation and good cooperation of the entire interdisciplinary modernization team, the startup proceeded perfectly smooth.

After several preparatory works, which usually utilized the weekly maintenance downtimes, the major part of the installation work was carried out during a regular shutdown that started on-December 18th, 2015. On January 6th, 2016 the first strip was rolled on the finishing mill. The regular production process could be started again on January 8th, 2016.

Already on January 20th approximately 300 coils have been produced on the new finishing mill. Within this time a fifteen fold productivity increase was already measurable and has been confirmed since then.

MODERNIZATION RESULTS

The three-stage revamp of Hot Rolling Mill 1 resulted in a remarkable annual capacity increase of the total production and thereby solidifies ALUNORF’s worldwide top position among the producers of Aluminum flat products. With its two hot rolling mills, the aluminum melt and rolling facility of ALUNORF in Neuss, Germany belongs to the world`s largest. The completed extension offers a better utilization of the existing infrastructure solves the capacity bottleneck of the site, enables more flexibility in production planning and most important enables ALUNORF to meet in future toughest quality requirements with a very tight process window.

CONCLUSION
After the first coil being rolled on ALUNORF’s Hot Rolling Line 1, only a few days were needed to achieve the rated production.

The successfully finished modernization of ALUNORF’s Hot Rolling Mill 1 may serve as a model case. The measures have clearly revealed the potential for a productivity increase that lies hidden in a plant, which was built almost 50 years ago in a solid manner in accordance with the state of the art at that time. In three individual steps that have been taken for operational reasons, SMS group together with ALUNORF has updated the aluminum Hot Rolling Mill 1 to the latest state technology and thus made it ready to face future challenges.

Speaking of a revamp model case does not only include the latest generation technology installed, but also comprises the project planning and execution. The synchronization of the modernization time schedule with the production requirements and especially with projected maintenance shutdowns has turned out as a key factor in ensuring productivity in any stage of the revamp.