Product Catalog

St/WM-multilayer plain bearings Hydrodynamic and hydrostatic bearings St/WMProduct LinePlain bearings GeneralToday, a great number of special designs such as multi-surface plain bearings, offset bearings, and tilting pad bearings ensure that optimum plain bearings can be built for a wide range of loads and rotational speeds in order to meet the highest demands placed upon their functioning and operati-onal safety.The operational safety of our plain bearings is granted through a comprehensive performance for our customers. Taking the operational data as the starting point, we compute and design the plain be-arings, manufacture them in a state-of-the-art qua-lity with the help of modern facilities and support our customers in the application of our products. With regard to technical advice, prototype manuf-acture and practical testing, our high-capacity Pro-duct Development Department is at your disposal at any time.The plain bearing is one of the oldest and, at the same time, one of the most advanced machine elements.»A plain bearing forms only one part of a tribolo-gical system. The required operational safety can only be achieved when both other partners of the system, i.e. the shaft and the lubricant, fully meet all the requirements placed upon them«Cylindrical journal bearings had already been de-signed and successfully used a long time before their functioning was fully understood and could be calculated.The question as to whether plain bearings or roller bearings are more favourable cannot be answered in general, but has to be dealt with in each indivi-dual case. Both bearing types have their inherent characteristics and advantages that have to be carefully considered with regard to their respective requirements before making a decision.tilting-pad bearingFor the material combination, we preferably use support shells of C10 or C15, and employ tin or lead alloys of high purity to be used as bearing materials.We manufacture hydrodynamic and hydrostatic bearings under the product designation St/WM, in particular:•• plain journal bearings•• plain journal and thrust bearings•• tilting pad journal bearings•• tilting pad journal and thrust bearings•• thrust rings•• tilting pad thrust bearing St/WM-multilayer plain bearingsHydrodynamic and hydrostatic bearings norixlager®Thrust bearing segmentsAdvantagesThe essential advantages of plain bearings are: • • simple structure and little radial space required• • split bearings for easy maintenance• • noise-free operation, also with high rotational speeds• • optimum attenuation of vibrations• • immunity to shock loads • • wear-free operation with lowest and highest rotational speeds• • long service-life without material fatigue• • increased price advantage of plain bearings against roller bearings with increasing constructional size• • cost-effi cient repair of large plain bearings in case of damageThe fi eld of application of multilayer plain bearings can be expanded considerably by hydrostatic bea-rings offering utmost guiding precision and maintai-ning the bearing capacity during standstill, too.You obtain optimized bearingsby making use of the classicaladvantages of hydrodynamic plain bearings in comparison to other bearing types.Fields of applicationEstablished fi elds of application are:•• piston and rotary pumps•• piston and turbo-compressors •• turbines•• couplings•• electric motors and generators•• machine-tools•• gears•• bearings for rolls•• cement and lime plants •• crushers and comminution installations•• gas machines•• blowers/ventilators•• mills and framed saws•• tube mills •• grinding spindles•• presses and centrifuges•• printing and paper machinesWe research and developWe are curious by nature and believe that a stand-still means nothing else but a step backwards. That is why we research in close co-operation with Universities and skilled specialists to develop new plain bearing technologies. Some of the results are really exciting.The adjacent photograph was taken at our high-speed bearing test bench stand and shows the measurement of the gap variation of the rotating shaft in a tilting pad journal bearing with 5 pads.We plan and design Make use of our experience in research, develop-ment, and product design. In the case of new ma-chine developments with bearing applications, we recommend you to contact us already during the planning or design stage. We will provide you with detailed installation proposals and the best soluti-ons to your problems.From product development to manufacturing All advantages from one single partnerGap (unloaded) Gap (loaded)We compute, help and advise After making the decision on the optimum bearing type and lubricant, we employ our proven compu-ting methods to determine the bearing capacity, the friction, lubricant requirements and wear resis-tance. We can provide you with all important data for a secure bearing operation.After installation and during operation of the bea-rings, we are at your disposal to provide you with further service at any time.We test In order to test the design and the computer simula-tions, we build your prototypes to test them on our test rigs, e.g. on the high-speed plain bearing test bench stand shown in the adjacent photograph.We manufactureThe experience of our qualifi ed employees together with the latest manufacturing methods combined with a modern quality management certifi ed to DIN ISO 9001:2000 guarantee you a high quality stan-dard as well as delivery in due time.Our delivery programmeIndividual items or in series production - ready for installationHydrodynamically lubricated radial bearings (journal bearing) • • Circular cylindrical radial bearing, e.g. as per DIN 7473• • Split bearings, e.g. as per DIN 7474• • Bearings as per DIN 31690, Part 2, with cylindrical, concentric, or spherical seats• • Multi-surface plain bearings, e.g. bearings with oval clearance, offset bearings, lobed bearings with 3 or 4 lobes • • Tilting pad bearings for radial or combined radial/axial load • • With thrust collar on one or both sides • • With hydrostatic discharge to serve as starting and run-down assistance • • With electrical insulation against voltage puncturesHydrodynamically lubricated axial bearings (thrust bearing) • Circular or split design• Operational on one or both sides, with reduced thrust surface• For one or two directions of rotation• With rigid slide surfaces or tilting pads• For single or changing directions of rotation • With circular tilting padsAs per customer’s specifi cation or as per own design•• Eccentric bushes•• Oil ring bearing•• Thrust washers•• Bearing rings with and without fl ange•• Floating plain bearings•• Slide plates•• Guide shoes•• Crossheads•• Hydrostatically lubricated journal and thrust bearingsRepair and overhaulApart from the manufacturing of new multilayer plain bearings, we also repair used bearings by app-lying a new lining of bearing metal with the following pre-machining or fi nish.Chemical composition% (mass) MW 10 MW 80 MW 81 MW 88 MW 81 SPb Rest 2 max. 0,06 max. 0,06 max. 0,06Sn 9 – 11 80 81 88 81,3Cd - - 1,2 0,8 -Cu 0,7 6 5,0 3,5 6Sb 14 – 16 12 12 7,5 12Ni - - 0,3 0,2 -As 0,6 - 0,5 < 0,1 Ag 0,1Zn 0,6*The indicated values are average values.Bearing metals and support shellsTechnological data *Hardness and elevated temperature hardnessHB 10/250/18020 °C 21 27 35 28 2450 °C 16 23 28 23 20 100 °C 15 13 17 16 12150 °C 10 7 10 9 10Tensile stress0,2% Proof stress Rp0,2 MPa 43 62 84 66 76Tensile strength Rm MPa 89 102 100 78Extension A5 % 3,0 1,5 8,4 1Elastic modulus E MPa 55700 52500 49500 57000Bonding strength(steel C 10; bearing metal thickness = 6mm) (DIN ISO 4386, Part 2) RCH MPa 70 39 98 86 71Dynamic stressFatigue strength under reversed bending stresses sbW MPa ± 25 ± 28 ± 39 ± 33 ± 35Impact fatigue limitAverage number of impacts before breaking 490 910 2689 2856Average work resulting from impacts before breaking J 134 250 739 785Physical data*MW 10 MW 80 MW 81 MW 88 MW 81 SDensity kg/dm3 9,9 7,39 7,34 7,35 7,35Linear extension coeffi cientbei 20 – 100 °C mm (mm · K)-1 · 10-6 24,0 21,6 20,2 23,8 21,0Thermal analysisLower melting point 240 183 235 233 235Upper melting point 270 400 390 360 360Casting temperature°C 480 – 520 520 520 440 540*The indicated values are average values.QualityMain-Metall is certifi ed in accordance with DIN EN ISO 9001:2000. In manufacturing our bearings, the materials and the manufactu-ring process in the mechanical workshop are subject to continu-ous quality tests with permanent documentation after each of the working steps. The tests are performed by employees indepen-dent from Manufacturing and in accordance with internal quality guidelines or the regulations DIN ISO 12301 »Test techniques and testing of the quality characteristics of geometry and material of plain bearings «.We inspect:• chemical analysis of the bearing metal and of the support shell material.• geometrical measurement, test on deviation of shape and positional deviations.• surface roughness.• absence of cracks and lack of fusion with the help of the dye penetration test ISO 4386-3.• non-destructive ultrasonic testing for lack of bonding. This is realized with several ultrasonic test units equipped with special sound heads. The test itself is made in accordance with the ISO guidelines 4386-1, testing class 1, 2, or 3 depending on the requirement.• hardness test of the bearing metal according to DIN ISO 4384-1.• in addition, there are destructive test methods for the mechanical workshop area available to be applied for random testing. This includes particularly the hammer-and-chisel test as a reli- able checking method within the foundry industry, moreover the Chalmers test following the guidelines of the Tin-Research Insti- tutes London or the destructive fusion test as per ISO 4386-2.• the inspection of the metallic structural constitution is done microscopically.• upon request, a micrograph can be produced. The results of the fi nal inspection are recorded in works protocols to serve as documents for the certifi cation of material specifi cation tests as per DIN EN 10204. Upon request, these documents are provided in the form of works certifi cates, test certifi cates and acceptance test certifi cates, and are enclosed with the delivery documents. Additionally, acceptance tests can be agreed upon and performed in our works by representatives of the customer.Bearing metalsMetallic sliding materials used for multilayer plain bearings are mainly leaded bronze materials and lead, as well as tin cast alloys. Apart from the main components tin, lead and copper, these bea-ring metals contain antimony as a hardening alloy element. The bearing metals based on lead and tin have a characteristic structural constitution. Primarily or secondarily separated hard and brittle inter-metallic compounds are embedded in a soft eu-tectic basic mass. This is called a heterogeneous structure and is of great importance for the technological characteristics and the operational behaviour of the bearing.The two most important alloy groups are:• alloys rich in tin and lead-restricted, lead-free and cadmium- free alloys containing 80 % or more tin,• alloys rich in lead with approx. 75 to 80 % lead and 1 to 12 % tin.In our foundry, only original primary metals as per DIN ISO 4381 or high-quality lead and tin cast alloys of leading metallurgical works are being used. Upon request of the customer, it is also possible to cast any other standard or commercially available bearing metal on a lead and tin basisSupport shellsFor the manufacture of support shells, we use the following techniques: • cast • forged• rolled metals under the consideration of DIN ISO 6280, predominantly made of• steel C 10 or C 15 as per DIN 17210 (with a content of C of up to a maximum of 0.25 %)• cast copper alloys as per DIN EN 1982, e.g. CuSn12-C or CuSn7Zn4Pb7-C• cast steel as per DIN 1681 • cast iron as per DIN EN 1561• cast iron with nodular cast iron as per DIN EN 1563The premise for operationally safe multilayer plain bearings are support shells materials establishing an optimum bond with the bearing metal, e.g. the above mentioned low-carbon steels or cast copper alloys. All bonding surfaces have a surface roughness of Ra = 4 to 8 µm as per DIN ISO 6280.The hydrogen content with steel support shells having a thickness of more than 40 mm must not exceed 1.7 mg/kg.Compression stress20°C 100°C 20°C 100°C 20°C 100°C 20°C 100°C2% Offset yield strength sd2 MPa 87 69 122 80 103 60 107 64Compression strength sdB MPa 189 121 195 126 235 136 190 91Strain at failure edB % 46 53 34 34 39 44 36 4403/09 406591Main-Metall Tribologie GmbHIndustriestr. 1D-66885 AltenglanFon: + 49 6381 913-0Fax: + 49 6381 913-110Main-Metall International AGBusiness CubeBirkenstr. 47CH-6343 RotkreuzFon: +41 41 740-6400Fax: +41 41 740-6402 www.main-metall.comMain-Metall do BrasilIndústria e Comércio Ltda.Rua Dois, 368Distrito Industrial João NarezziBR-13347-404 Indaiatuba (SP)Fon: +55 19 3936-6565Fax: +55 19 3936-6566Main-Metall Española, S.L.Apartado 73E-39300 TorrelavegaFon: + 34 942 8259-00Fax: + 34 942 8259-06