Projects of Sealing Technology

Institute of Machine Components (IMA)

Overview of current projects, recently completed projects and the project archive

Current projects

Recently completed projects

Project archive

Nino Dakov, IMA

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The aim is to derive functional mechanisms of PTFE sleeve seals with dynamic recirculation structures. For this purpose, the fluid-structure interaction in the sealing gap between the PTFE sleeve shaft surface and the lubricant is investigated by means of EHD simulation (elasto-hydrodynamics).
 

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Lothar Hörl, IMA

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Analysis and optimization of sealing systems in rotary transformers, taking into account modular design, low friction and space-saving construction. Integration of modern technologies and innovative sealing elements.
 

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Frank Bauer, IMA

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Radial shaft seals (RWDR) are used in all areas of mechanical engineering to seal shaft entry points in housings. However, there are also limits to its range of application. The requirements placed on the seal ring with regard to shaft running speed, ambient temperatures and chemical compatibility are very high. The requirements placed on the seal ring in terms of shaft speed, ambient temperatures and chemical compatibility with the fluid to be sealed (e.g. so-called bio-oils) are becoming ever greater.
 

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Simon Feldmeth, IMA

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Rotary shaft seals (RWDR) with elastomer sealing lips are used for sealing between rotating and stationary machine parts. During operation, frictional heat is generated in the contact area between the RWDR and the shaft. The more frictional heat is generated and the less easily it can be dissipated, the greater the temperature rise in the contact area. High temperatures are extremely damaging to the sealing system.
 

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Jan Gölz, IMA

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In many applications, elastomer rotary shaft seals (RWDR) fail due to high temperatures and chemically aggressive fluids. Mechanical seals or other complex, expensive and large sealing systems are then often used. However, if the application limits of elastomer RWDR are exceeded, a universally applicable, easy-to-control, reliably functioning sealing solution is required.
 

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Axel Eipper, IMA

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Radial shaft seals (RWDR) have become an indispensable part of everyday industrial life. Despite their widespread use, it is not currently possible to predict their service life by calculation. The behavior of each individual sealing system can only be estimated by means of complex test runs. However, these test runs are time-consuming and cost-intensive, which is why small and medium-sized enterprises (SMEs) in particular are at a disadvantage here in competition with large corporations.
 

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Cornelius Fehrenbacher, IMA

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The new 3D characteristic values according to DIN ISO 25178 for surface description are almost unexplored with regard to their usability for sealing technology. Therefore, in this practical project, permissible limits are to be determined by correlating measured conveyance values of different shaft surfaces with 3D characteristic values.
 

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Peter Schuler, IMA

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Shaft passage points through housing walls that are splashed or flooded without pressure are sealed with rotary shaft seals (RWDR). RWDRs have a dynamic sealing mechanism that counteracts the leakage of liquid. The sealing mechanism has been previously explained by flow effects that neglect the wetting property of the lubricant and assume isothermal conditions. Difficulties in sealing biodegradable lubricants could not be explained by previous approaches.
 

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Florian Bosch, IMA

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Non-contact seals with grease-filled gaps have been used to seal dirt for many decades. In order to be able to develop grease-filled non-contact seals unerringly and also to meet future challenges, sound design advice is urgently needed.
 

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Sumbat Bekgulyan, IMA

Logo Projekt Dichtgüte IIComputational Estimation of the Sealing Quality of Rotary Shaft Seals considering System Parameter Influences II

 

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Matthias Baumann, IMA

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In the past research projects Structure Analysis I and II, a structure-based evaluation method for swirl structures was developed. The functional evaluation of seal mating surfaces is based on optically measured surface topographies. On the basis of experimental investigations and fluid simulations, the function of the method could be demonstrated by means of correlation considerations.
 

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Mario Stoll, IMA

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The aim of the research project is to describe the processes in the sealing gap, which describes the influence of the surface topography of the hydraulic rod on sealing friction and leakage. With the help of a simple 3D surface measurement, the user should be able to estimate the occurring friction and leakage and thus the suitability of the rod.
 

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Jan Totz, IMA

Logo zum ProjektImportant empirical values are available for the production process of grinding in the groove of hardened shafts due to many years of application. These empirical values cannot be transferred 1:1 to the manufacturing process for soft-ground mating surfaces. In the case of soft-ground mating surfaces, defects frequently occur which can lead to unforeseeable sealing problems and even to complete failure of the seal.

 

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André Daubner, IMA

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Wear is the main cause of failure in polytetrafluoroethylene (PTFE) boot seals. It occurs due to a relative movement between the boot seal ring and the mating surface. This loss of material changes the geometry in the contact area. At a certain degree of wear, the sleeve seal ring fails and leakage occurs.
 

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Christian Simader, IMA

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Up to now, there have been no calculation rules for the design of liquid-sealed gaskets. Particularly for the development of small series and one-off products, possibilities of numerical design are needed for a fast, cost-effective design process, which also serve as a justification basis for design decisions.
 

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Max Sommer, IMA

Logo zum ProjektReliable, contact sealing of lubricating greases still poses major problems. However, leakage-free sealing as well as reliable shielding from external contamination are required to achieve high product qualities. The performance limits of grease sealing systems are known from research work carried out at the research center on the sealing of greases. Furthermore, comprehensive knowledge about the influence of the sealing environment and the system components on the operating behavior of these systems is available from this work. However, the lack of knowledge about the mechanisms relevant in sealing greases in the sealing gap prevents the design of low-loss and operationally reliable grease-sealing systems.

 

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Matthias Baumann, IMA

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Radial shaft seals are required to seal shaft entry points. A sealing element frequently used for this purpose is the rotary shaft seal (RWDR). This is part of a tribological system consisting of the RWDR, the fluid to be sealed and the seal mating surface. The components of this system interact with each other in complex ways.
 

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Marco Remppis, IMA

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The dynamic sealing function of a radial shaft seal is based on a pumping action of the sealing ring. During operation, fluid from the space to be sealed enters the contact zone between the sealing edge and the shaft surface, so that this area is sufficiently lubricated. Nevertheless, no leakage occurs on the air side as a result of an opposite recirculation effect. The system is tight and exhibits a certain sealing reliability. The level of the conveying effect depends on the individual system parameters and their interaction.
 

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N.N.

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The metal dusts generated during dry machining, for example, must be kept away from tribological systems such as spindle bearings. The aim is to create experimentally validated design guidelines for the retention of dusts of all kinds and to transfer these effectively into operational practice.
 

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N.N.

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Dynamic shaft sealing systems used in practice almost always have a sealing edge molded onto the "soft" polymer seal. The shaft is usually smooth in the contact area. With the systematically developed modular inverse test sealing system, it has been possible to demonstrate the function of an inverted sealing arrangement between relatively moving machine parts.
 

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N.N.

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The problem is to develop functional sealing elements and sealing systems for linear guides in machine tools. These sealing systems must prevent the loss of lubricant from the guide as far as possible with low friction and without stick-slip and prevent the ingress of foreign substances (cooling lubricant and dirt).
 

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Steffen Buhl, IMA

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Modern production processes produce different surfaces that influence the function of the sealing ring. Systematic investigations of the surface topography in the sealing zone are used to determine roughness parameters that establish a correlation between the friction, wear, and sealing behavior.
 

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N.N.

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For the special conditions in general mechanical, plant and vehicle engineering, there are no concrete design guidelines at the present state of the art for non-contact shaft seals at "pressureless" sprayed, completely, partially or surge-flooded shaft passage points. The problems are correspondingly varied and the measures to somehow make the BFWD leak-free are correspondingly complex and expensive.
 

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N.N.

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Influence of modern manufacturing processes and the macro- and microstructures of the shaft surface thus created on the function of radial seals. Description of the shaft surface with 3D surface parameters suitable for sealing function. Characterization of shaft surfaces that are favorable in terms of manufacturing and sealing technology.
 

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N.N.

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Surface seals are essential components in all areas of mechanical engineering. In sealing technology, surface seals belong to the field of static contact seals. Liquid sealants are increasingly being used here. Particularly in large-scale production and lightweight construction, the universal applicability for any geometries and the automatable application of the sealant are of great advantage.
 

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Stefan Schmuker, IMA

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Radial shaft seals are very frequently used sealing systems that can be found in a wide variety of applications. The boundary conditions and influencing parameters that affect the function of the sealing system are as varied as the areas of application. The main components of the system are the rotary shaft seal made of elastomer material, the shaft surface and the fluid to be sealed. Due to the complexity, no reliable predictions about the system behavior are possible at present. For known combinations, it is possible to fall back on empirical values available from seal manufacturers and some users. However, if new combinations of sealing ring, shaft surface and lubricant are to be used, comprehensive test rig investigations are essential.
 

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Ulrich Nissler, IMA

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The long-term tests on hydraulic rod seals carried out as part of this research project have shown that changes to the sealing edge in the range of hundredths of a millimeter influence the sealing behavior. The investigations carried out on the test rig and by means of FEM led to design proposals that can be expected to provide high sealing reliability with low wear.
 

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Dirk Weber, IMA

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Coupling of the wear behavior with the structural mechanics of PTFE radial seals in the FEM. Optimization of the seal geometry with regard to wear and contact pressure to increase service life.
 

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Stefan Reinhardt, IMA

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The aim of the project is to produce design guidelines specifically for liquid sealing points. First and foremost, the designer should learn how the sealing environment must be designed to achieve a long service life in terms of tightness and mechanical load on the housing interface.
 

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Gerald Pflüger, IMA

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Radial fluid feed into rotating systems is necessary in many areas of technology. In particular, when there is no possibility to provide transition points on the front side of shafts. Examples include the feeding of steam into cylinders on paper machines, tempering fluid into the extruder screws of plastic injection molding machines, cooling lubricant under high pressure into driven tools of machine tools, and pressure oil into actuators of automatic passenger car transmissions. 
Different variants are available for sealing.
 

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Markus Henzler, IMA

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Sealing rings snapped into closed grooves in the housing are used to seal rotary transmissions for high hydraulic pressure (e.g. in the rotary indexing table or in excavators). These seals are being investigated in great breadth for the first time in this project, taking into account the entire installation environment of the machine.
 

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Wolfgang Dürnegger, IMA

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Rotary shaft seals are successfully used in a wide range of technical applications for sealing liquid-loaded, rotating or stationary shafts. The lubricant supply here is large, which ensures good heat dissipation and constant renewal of the lubricant in the contact zone between the rotary shaft seal (RWDR) and the seal running surface.
 

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Johannes Kümmel, IMA

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Grease-filled non-contact shaft seals (FBFWD) are frequently used for shaft passage points with heavy contamination. These are gap seals of all possible geometries that are filled with grease. Common names in the literature or by seal manufacturers for this type of seal are also grease-filled protective or labyrinth seals. The grease is intended to prevent dirt from penetrating the seal gaps. Initially, this seal design is nothing fundamentally new, but the requirements have changed radically.
 

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Alexander Buck, IMA

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In contrast to hydraulic rod sealing, very little is known about the optimum design of the rod surface in hydraulic sealing systems. The existing surface specifications largely refer to the hard-chrome plated ground "standard rod" and have been determined empirically over the past decades. The use of alternative rod surfaces therefore always results in high leakage and excessive wear. There is no generally valid specification of what the optimum rod surface should be. The aim of this research project was therefore to determine the influence of the rod surface on friction, wear and leakage on hydraulic seals.
 

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Gert Baitinger, IMA

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Radial shaft seals are used to seal shaft passages. Together with the fluid to be sealed and the seal counterface, they form a complex tribological system. If there are active conveying structures (swirl) on the seal counterface, this can have a massive effect on the sealing system. 
The possibilities for measuring and evaluating swirl, especially micro-twist, are still completely inadequate. Therefore, the aim was to develop an evaluation method for the quantitative evaluation of microtwist on seal mating surfaces.
 

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Steffen Jung, IMA

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The standard manufacturing process for mating surfaces of rotary shaft seals to date has been "grinding by grooving". In practice, however, there is a trend towards alternative manufacturing methods, such as hard turning, soft turning, roller burnishing or deep drawing. 
Different manufacturing methods also produce different roughnesses and topographies, i.e. three-dimensional elevations and valleys.
 

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Michael Narten, IMA

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Fluid greases are frequently used in gear units lubricated for life. However, only a few imprecise empirical values are currently available with regard to the functionally correct design of the sealing of fluid grease-lubricated systems. As a result, failures often occur with partially inexplicable leakages, which cause damage with high consequential costs. The aim of the research project is to draw up a catalog of measures for the functionally reliable design of fluid-grease seals and a model that explains how fluid-grease-sealed radial shaft seals work.
 

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Max Sommer, IMA

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Lubricating greases are often sealed with radial shaft seals which were developed to seal off 
oils. This leads to a considerable limitation of the performance limits. 
Promising potential with regard to performance limits or friction reduction is not exploited as a result. The reason for this is a lack of knowledge about the influence of the system components on the operating behavior. 
In the project, the influence of the system components of the radial shaft seal system on its operating behavior was systematically investigated.
 

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Mathias Klaiber, IMA

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The use of a more efficient lubricant often improves the properties of an overall product. Synthetic lubricants are preferred here because they are more efficient than mineral lubricants. A further targeted increase in performance can be achieved by suitable additivation of the fluids. 
There have been an increasing number of failures of sealing systems in which a highly additivated synthetic fluid is used. It has not yet been possible to say which additives dissolved in synthetic base oils are incompatible with rotary shaft seals made of different materials in dynamic operation.
 

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Stefan Schmuker, IMA

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The operation of rotary shaft seals (RWDR) with hardened steel shafts, usually ground to be twist-free in the recess, has been continuously researched over the past decades. This combination has proven itself a million times over in a wide variety of applications. In addition to steel, innovative materials and coatings are increasingly being used for a variety of reasons.
 

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Jan Gölz, IMA  / Witalij Goujavin, IMA

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The elastomer rotary shaft seal (RWDR) is successfully used to seal many shaft passage points. However, there are limits to its use. For this reason, sealing rings made of polytetrafluoroethylene (PTFE) have been developed. PTFE is temperature-resistant, dry-running and universally chemically resistant. Since PTFE sealing rings do not develop a return mechanism on their own like RWDR, spiral grooves are inserted mechanically. However, these only act in one direction of rotation and are leaky in the event of (partial) flooding.
 

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Contact Head of Sealing Technology

This image shows Frank Bauer

Frank Bauer

apl. Prof. Dr.-Ing.

Head of Sealing Technology &
Head of CAD

 

Institute of Machine Components (IMA)

Pfaffenwaldring 9, 70569 Stuttgart

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