Information on the new rubber mixture from the RESATEC AG
There are various suppliers of rubber suspension units worldwide who follow the H. Neidhart
principle. They have all adapted their products to the particular sales potential and offer an
appropriately extensive standard program according to the requests of particular customers.
From these suppliers there are two manufacturers who are capable of, developing their
products and their diverse rubber mixtures separately from one another in collaboration with
their partners and to continuously improve them through innovation.
The ROSTA produces up to 80% of its rubber suspension units with the standard quality
“Rubmix 1O”, a large proportion of which is based on natural rubber (NR).
Reference publication: ROSTA “Die blauen von ROSTA” {“The blue ones by ROSTA”}
pageT.7 paragraph 10
The RESATEC AG produces up to 95% of its rubber suspension units with its standard
quality rubber, a large proportion of which is based on styrene-butadiene rubber (SBR).
Both qualities are suitable for use in rubber suspension units in basic quality. Both mixtures
are reinforced using fillers. This reinforcement adapts the mechanical properties, the
resistance and the performance data of the particular type of unit.
Knowledge of the performance data of the mixtures, the ability to develop required product
performance values with the right compression, replication that ensures quality by using
trademarked installation methods, and years of experience bringing products to the market
gives both manufacturers a unique position on the market.
By adding fillers the mechanical properties in both mixtures can be reinforced so they are the
same in operational terms, with the exception of a few parameters. However, certain
properties still remain, which are carried forward from the basis material and promote the
performance parameters in the rubber suspension unit more or sometimes even less. These
properties subsequently define both mixtures and the products of both manufacturers. The
table below serves to form an overview of these differences. Neither of the mixtures can be
used to indicate the properties of the basis material with regard to the properties that are
reinforced by fillers in both mixtures, as these properties have a completely different
performance level to basic quality without fillers. These properties are similar in both
mixtures, which were reinforced for the same application. The differences are rarely
important in application and, in real terms, are normally covered by the tolerance zone.
Decisive market guidelines:
- Constant performance data over the entire period, meaning high resistance to wear and
minimum
- A balanced relationship between damping and rebound resilience in order to, for example,
guarantee the best, permanent and consistent friction in a transmission engine. To
illustrate this aspect a comparison can be made with the suspension in cars, a familiar
concept to most people. Every car suspension is subjected to high levels of acceleration
due to uneven roads. The steel spring is able to absorb the load forces; however, it does
not ever enable a smooth drive due to the very high rebound resilience. A damper is
therefore activated in combination with it to compensate for this rebound resilience and
RESATEC AG
Information to our customer
HK, 30.05.2013
not only ensure a comfortable drive but also the necessary contact with the driving
surface, guaranteeing friction when braking.
- Both rubber mixtures show a more or less distinct compression set. This compression set
differs according to the mixture, the duration, the temperature and the level of
deformation. By using the full range of performance limits, or rather by entering high
loads, for example for filter supports in combination with the increased temperature in the
rubber core, set values can be defined.
Natural rubber (NR) is a natural product and is therefore prone to large variation due to
climatic conditions, the age of plantations and soil properties, etc. These variations need to
be compensated for by individual dosing of fillers. Since these fillers directly influence the
behavior of the rubber suspension units, the final products are usually supplied with an
extended tolerance zone for different performance data. It is rarely possible to control the
parameters with precise accuracy, making additional redistribution of the production batch
necessary and sometimes leading to new sources of error. A great deal of work is necessary
in the measurement of data in order to maintain the required parameters and tolerances
.These measuring systems are frequently displayed as proof of extended knowledge. In
reality they are normally necessary investments for quality assurance. Excipients are needed
in order to process natural rubber. The natural rubber mix sticks to the contact surfaces of
the operating equipment if no excipient is used. These excipients behave like lubricants that
are mixed in and, over time, they also wear away on the final product more quickly due to
stresses caused by movement on the outer surface of the rubber body, and can therefore
have a negative impact on friction. So that the performance data published in the catalogues
can be maintained after reducing the power density with the first movements (parts of the
Mullins effect), a very high level of crosslinking is needed in natural rubber. This level of
crosslinking is achieved through vulcanisation in steam, which does not enable continuous
production. Transfers into different vessels therefore result in the loss of the round material
cross-section. Due to the large deviations in cross-section (sticky rubber mix) that already
occurred during extrusion, variance of the performance parameters in the rubber suspension
units cannot be ruled out.
The RESATEC AG was founded in 1989 and used such natural rubber in its products up to
about 2009, which was obtained from various rubber manufacturers. Aware of all of the
above-mentioned aspects and of the fact that they were becoming dependent on technology
that was out-dated and almost extinct the RESATEC AG decided as early as 2003 to
develop a rubber mixture with another basis in parallel. By approximately 2005 the results of
the first trials meant that the manufacture of the new mixture and the following changeover
had been decided on. In the meantime the constructive and coating aspects were adapted
and from the year 2010 the rubber suspension units produced by the RESATEC AG were
manufactured with a new rubber mixture (code A) with a SBR basis. As of 2012 the first
further development of this mixture was commissioned to implement the feedback received
from the market. Without compromising the good properties, the rebound resilience was
adjusted to an optimal ratio and the compression set, in particular in the rubber core
temperature range that is present during use, was improved considerably. The constructive
aspects also needed to be adapted for the pre-compressed dimension types manufactured
on a large scale. At the performance show in Hanover the RESATEC AG presented the new
products with the new mixture (code C) and their performance data.
RESATEC AG
Information to our customer
HK, 30.05.2013
The integration of this mixture into all types of units is now being promoted .All products can
however already be ordered with the new mixture on request.
Benchmarking test:
Parameter
Base
Reference
Rating
Value
DVR
NR
DIN ISO 815[24h,70°C,50%]
9.6[%]
DVR
SBR (Code A)
DIN ISO 815[24h,70°C,50%]
9.4[%]
DVR
SBR (Code C)
DIN ISO 815[24h,70°C,50%]
5.7[%]
DVR
NR
DIN ISO 815[24h,23°C,50%]
4.4[%]
DVR
SBR (Code A)
DIN ISO 815[24h,23°C,50%]
5.7[%]
DVR
SBR (Code C)
DIN ISO 815[24h,23°C,50%]
4.9[%]
Abrasion
NR
DIN ISO 4649
+
Abrasion
SBR (Code A)
DIN ISO 4649
++
Abrasion
SBR (Code C)
DIN ISO 4649
++
Aging
NR
DIN ISO 53508
+
Aging
SBR (Code A)
DIN ISO 53508
++
Aging
SBR (Code C)
DIN ISO 53508
++
Resilience
NR
DIN ISO 53512
~60[%]
Resilience
SBR (Code A)
DIN ISO 53512
>44[%]
Depending on the
section
Resilience
SBR (Code C)
DIN ISO 53512
>49[%]
Depending on the
section
RESATEC AG
Information to our customer
HK, 30.05.2013
Base
Range of application
NR
from -40°C until +80°C
SBR (Code A)
from -42°C until +85°C (short time 100°C possible)
SBR (Code C)
from -55°C until +85°C (short time 100°C possible)
Managing Director
H. Kerschberger
RESATEC AG
Information to our customer
HK, 30.05.2013