Swedish companies play a leading role in the production of lignite
Prince Herrmann Ludwig Heinrich von Pückler-Muskau, a
landscape gardening genius, built the Muskau Park in the Lusatia
region in 1817 — it is part of a UNESCO world heritage site
today. In the same era, 1850, the first lignite was mined in the
region and still today, Swedish company Vattenfall extracts lignite
without subsidies. It does so in Jänschwalde among other places,
one out of the five open-cast mines currently in operation. As
one of the largest employers and apprenticing companies in East
Germany, Vattenfall currently employs almost 8,000 employees
and about 800 apprentices. Sandvik Mining and Construction
also plays a leading role — in the literal sense. At the
Jänschwalde location there are 320 sets of 5–roller garlands of
HM150 formed rollers in action on the overburden conveyor
bridge AFB 60m. On belt five, the main belt conveyor (belt type
3000 ST3000-18:8, idler spacing approximately 800mm) and on
belt eight, the stockpile belt conveyor (belt type 2750
ST2500-18:8, idler spacing approximately 800mm).
This all began in the spring of 2004. Bernhard Hofmayer,
production manager at Sandvik in Schöppenstedt, introduced the
HM150 formed roller to Vattenfall. The engineers were
impressed by the completely new design and the innovative
assembly technique. The discussion about the advantages and
disadvantages of the component optimized formed roller were
ready to begin.
Quickly and unbureaucratically they were able to agree upon
a test phase in the open-cast mine in Welzow-Süd. Due to the
extreme operating conditions the highest requirements are
demanded for rollers and conveyor systems. The belt speeds at
the location are between 10–11m/s and the tonnages add up to
52,000 tonnes of waste hourly. Sandvik accepted this challenge
and developed the innovative formed roller.
During the period August 2004 to April 2005 the first 250
rollers all passed the test phase. Vibrations in the entire steel
construction of the conveyor bridge were minimized and noise
emissions were reduced by about 20dB(A). The weight savings
were beneficial for the statics. The result: operational release by
the TÜV [Technischer Überwachungs-Verein — technical
inspection association in Germany]. In conclusion all formed
rollers in use on the conveyor bridge were exchanged for the
Sandvik HM150.
With the positive experiences from the Vattenfall open-cast
mine Welzow-Süd the rollers were also installed in Jänschwalde
50km away. Vattenfall’s intention for the planned operation of
the formed rollers on the overburden conveyor bridge AFB 60m
was to improve conditions for employees, residents and the
environment by investing in modern technology. Furthermore, it
was about fulfilling TÜV requirements.
Even here the focus was on the sophisticated statics of a
conveyor bridge weighing 30,000 tonnes. Through the weight
saving of 10–15%, which was obtained compared to conventional
manufactured rollers, the extensive and cost-producing
modification of the steel colossal was prevented.
The weight optimization is also an advantage in case of a
replacement of a single roller or garland which is required less
frequently due to the extremely long operation period of the
rollers. “I do not remember that I ever had to exchange one of
the 1,600 formed rollers in the last six months,” stated mechanic
Christian Ramm. “In-house we call the HM150 fire extinguishers
because of their orange-red colour and form,” he added. In the
first three years the failure rate was at 2.9%, well below the
statistical average for conventional rollers.
Operations engineer Peter Hobracht sums it up: “The lifetime
of the rollers, which is prolonged by the low failure rate and the
low-noise surrounding area due to the running smoothness,
strongly convinced us to use the innovative formed roller.”
 Currently, more than 19,000 Sandvik formed rollers have
been delivered to Vattenfall in the Lusatia region. The technicians
as well as the purchasing managers are very satisfied with the
relationship, which includes both the delivered formed rollers
and the services provided by Sandvik. Vattenfall’s order of
another 1,700 sets of three-roller garlands of HM150 for a cross
country conveyor system shows the positive overall impression
of the company, brand and product.
In the 19th century, Prince Pückler planted fully grown trees
in his 750-hectare landscape park for the first time. Since 2007
Vattenfall has followed in his footsteps and afforested three
million deciduous and coniferous trees as part of its recultivation
programme of its used surfaces in a region which was
characterized by only pine forests. Furthermore, by 2030 a
1,900-hectare large ‘Eastern Lake’ shall be created which will be
the largest artificial inland water in the Lusatia region — it may
not be an UNESCO World heritage site, but it will certainly be
an attractive area for sports and relaxation for generations to
From this point of view Sandvik with the HM150 currently
plays a leading role in the present era in production and the
transportation of lignite.
The term ‘formed roller’ refers to both the specific and
optimized production procedure of Sandvik and also to the final
product. By using high-precision production procedures and
facilities, the HM150 formed rollers feature improved
characteristics which are described in the following list:
  • optimized load distribution in the ball bearings;
  • tilt angle reduction for the ball bearings;
  • HM150 rollers garland & single HM150 roller.
  • reduced noise emissions;
  • higher permissible rotational speeds;
  • smoothed bearing seats Rz ~ 0.5µm (reduces fretting corrosion);
  • weight reduction of the formed roller by 10–30%;
  • inherent balance G smaller 14 according to DIN ISO 1940;
  • and maximum concentricity deviation ~ 0.3 mm.
The component-optimized, patent-protected HM150 formed
roller mainly consists of the load-resistant and deformation reduced
flow formed shell, bearing seats manufactured by means
of deformation (end formed), the forged hollow shaft as well as
the newly developed highly effective labyrinth seals.
Sandvik HM150 formed rollers are available in lengths from
380 to 1,450 mm, diameters from 159 to 219 mm, and with
multiple shaft dimensions, bearing seats, and bearing sizes.
Sandvik is a global industrial group with advanced products and
an enviable position in selected areas — tools for metal cutting,
equipment and tools for the mining and construction industries,
stainless materials, special alloys, metallic and ceramic resistance
materials as well as process systems. In 2009 the group had
about 44,000 employees and representation in 130 countries,
with annual sales of nearly SEK72,000 million.
Sandvik Mining and Construction is a business area within the
Sandvik Group and a major global supplier of equipment,
cemented-carbide tools, service and technical solutions for the
excavation and sizing of rock and minerals in the mining and
construction industries. Annual sales 2009 amounted to about
SEK32,600 million, with approximately 14,400 employees.