Carbon and Graphitefor Plain Bearings Applications This information is based on our present state of knowledge and is intended to provide general notes on our products and their uses. It should not therefore be construed as guaranteeing specific properties of the products described or their suitability for a particular application. Any existing industrial property rights must be observed. The quality of our products is guaranteed under our General Conditions of Sale. 02 02/3E Printed in Germany Graphite Specialties Business Unit SGL CARBON GmbH Werk Ringsdorff Drachenburgstraße 1 D-53170 Bonn Phone: +49 (228) 841-394 Fax: +49 (228) 841-456 Internet: www.sglcarbon.com 01 … 0. 0. if shrunk into a metal housing 0.3 . pressed-to-size.5 l ≤ 20d1 ®RIDURID V 1640 Resin bonded material for wet running bearings.15 … 0.3 % of shaft diameter at fitting temperature (cold clearance).3 F Projected bearing area I · d1 ≥ — 1. if shrunk into a metal housing High volume production Coefficient of friction EK 23 Carbon graphite grade. with very good dry running properties. also used with special impregnations (antimony or resin) depending on the application.3 µm … 3. 0. Small batch and unit production EK 20 Carbon graphite grade with good dry running properties.3 . HV > 250 Rt = 0. Suitable for plain bearings running wet and dry.1 … 0. 0.2 µm Ra = 3. mixed and dry running. graphite and resin bonded graphite. EK 40 Graphite grade for dry running plain bearings... 0. Suitable for wet running plain bearings..5 l ≤ 2d1 0.2 µm … 0.. d1 d2 d3 s l f p b v = bearing bore (mm) = bearing outside diameter (mm) = flange diameter (mm) = bearing wall thickness (mm) = bearing length (mm) = radial or axial load (N) = specific radial or axial load (N/mm2) = flange thickness = rubbing speed (m/s) f x 45° d1 d2 f x 45° d1 f l d2 d3 f r b Dry running and mixed running ≤1 Bearing size v (m/s) ≤ 0.8 µm 3 . flanged bearings (DIN 1850. EK 24 Carbon graphite grade with very good dry running properties.8 µm Do not subject bearing to tension.25 for dry running Wet running Bearing size 1) Bearing clearance1) v (m/s) ≤ 20 F Projected bearing area I · d1 ≥ — 1.. The range of use includes wet running.1 .Specialty Graphites from SGL CARBON Material Grade Recommendations for Plain Bearings Design Guideline / Calculations Cylindrical bearings. 0. Particularly suited for dry running use and for use in media with poor lubricating properties.1 Bearing clearance F Projected bearing area I · d1 ≥ — 0.5 % of shaft diameter at operating temperature (warm clearance) 0....5 … 0.05 Coefficient of friction 1) Observe the laws of hydrodynamics Information for wet and dry running Tolerances Surface finish Bearing design Fitting Outside diameter Bore Outside diameter Bore IT 6 / IT 7 IT 7 / IT 8 Ra = 6. 0.15 for mixed running 0. shear or bending stress Cold press fitting Shrink fitting Bonding Cylindrical bearing for pumps in the chemical industry 2 Counter surface material (Surface finish) Generally hard materials.5 % of shaft diameter at fitting temperature (cold clearance). Sheet 4) 15° Type M IT 8 Type N A IT 8 A 15° Base materials are carbon graphite.1 .3 % of shaft diameter at operating temperature (warm clearance) 0. shrinkfitting. Sheet 4 apply.0 about 150 1) Counter surface materials (surface finish) Cold pressing s6 H7 Example: Axial bearing calculation.1 … 0.05 Bearing surface lapped Solid or split. Press fitting is effected with a stepped fitting pin with a tolerance of h5.5 % of shaft-Ø d Shaft diameter d = 23 h6 d3 d1 b Dry running/Mixed running Bearing area A (mm2) Coefficient of friction Surface finish Bearing design Fitting v (m/s) ≤ 1 0. operating temperature F °C 1.1 d3 (see design) chosen as b = 5 mm d3 = √ 500 x 4 + 20 2 π d3 = 32 Shrink fit x8 … z8 H7 about 300 3) Bonding In principle this is possible. For housing materials having a thermal expansion > 12 · 10-6/K the maximum operating temperature is correspondingly reduced.3 0.) 0.3 Bearing bore l d1 ≥ — . bonded or screwed Usually hard materials.5 m/s load P = 150 N temperature 60 °C Determining bearing size Projected bearing area P 150 l x d1≥ — = = 500 mm2 0. bonded or screwed Usually hard materials. Cold press fitting and shrink fitting are treated separately.d12) 4 d3 = √ F x 4 + d12 π Bearing outside diameter chosen as d3 = 35 mm Bearing length b ≥ 0. The recommendations of DIN 1850.45 mm 23 + 2 x 3.069 mm (is added to nominal bore) Bearing tolerances (see below) Bearing outside diameter chosen s6 (cold press fitting) Bearing bore chosen F7 Bearing lenght DIN 7168 medium Resulting in: Ø 23. rounded up l = 22 mm Bearing outside diameter d2 = d1 + 2s smin = 0.15 x d1 = 3.7 mm Bearing clearance (min. HV > 250 Rt = 0. lubricating grooves Cold press fitting.01 … 0. shrink fitting. 1) Determining bearing size Bearing bore d1 = 20 mm (given) 4 5 .0 Fitting Recommended ISO-Tolerances Method of fitting d1 before after before after F7 H7 … H8 D8 E8 … E92) d2 Housing diameter Max.8 µm F A≥ — 0. HV > 250 Rt = 0. 3) For higher temperatures and for housing materials having a thermal expansion > 12 · 10-6/K the special tolerances and/or a locking arrangement may be employed – please enquire about this.3 .45 = 29.2 Axial Bearings The following information applies also when calculating the face surfaces of cylindrical and flanged bearings when loaded axially. wet running Given values shaft-Ø rubbing speed load medium temperature Bearing outside diameter d3 20 mm v = 3 m/s P = 500 N Water 30 °C By going back and calculating from the required area P 500 F= — = = 500 mm2. We can recommend suitable bonding agents.36 mm rounded up d1 = 23 mm Bearing length l= 500 23 = 21.Specialty Graphites from SGL CARBON Example: Cylindrical bearing calculation.069 F7/30 s6 x 22 ± 0.3 Wet running v (m/s) ≤ 20 0.5 … 0.0 1.3 % x 23 = 0. we choose d1 = l 2 d1 = √ 500 = 22. 1. 2) We recommend that the bearing bore be finished to size after shrink fitting..9 rounded up d2 = 30 mm Bearing dimensions Ø 30/23 x 22 mm Bearing clearance Dry running 0.8 µm F A≥ — 1.5 … 0.. dry running Given values rubbing speed v = 0.25 Bearing surfaces fine ground to lapped Solid or split Cold press fitting.0 π it results in: F = — x (d32 . 0. 5 1 1. EK 3245 EK 2200 0. Break sharp edges Counterface Materials.1 N/mm2 ≈1 v < 1 m/s p < 0. even hydrodynamically poor media such as water or petrol will achieve some compensating effect and reduce friction between the micro-irregularities of the mating surfaces. Sheet 2. In addition we recommend following the design recommendations given below: • bearings for dry running should have a smooth bore • when bearings are running wet. 0. 10 EK 20 1 EK 24 EK 2240 Any arrangement to prevent rotation such as a check plate or plain pin. Dimension l ≥ 0. non-alloy and nitrided (hard) • hard metal • aluminium oxide • silicon carbide • glass Of limited use • steel.1 EK 3205 0. if possible not below 3 mm D l Surface finish of metallic counter parts Load l<2d s = 0. alloy and non-alloy (soft) • light metal alloys • chromium plated materials • non-ferrous metals • carbon materials In dry running conditions the surface finish should generally be of a higher standard than when a liquid film is present.5 2 2.2 x d smin = 3 mm Rt µm v < 0.. Groove design is shown in DIN 1850. HV > 250 • grey cast iron • steel. Wear Rates Recommended are hard materials. Sheet 4.01 0 1 2 3 4 5 6 6 Specific load (N/mm2) Bearing Ø 30/20 x 20 mm 7 .5 m/s p < 0.5 4 S Load (N/mm2) Bearing Ø 30/20 x 20 mm Wear rates of machined bearings of different carbon grades at a steady rubbing speed of 1 m/s and with increasing specific load when running wet. should be in an unloaded area not in the bore.8 v < 3 m/s p < 0. b≥s b 0.15 .2 N/mm2 0. Avoid sharp steps in the bore and on the outside.1 D.Specialty Graphites from SGL CARBON Bearing Design In principle design should follow the requirements of DIN 1850.5 P S l Wear [µm/h] EK 200 EK 24 Wear rates of machined bearings of different carbon grades at a steady rubbing speed of 1 m/s and with increasing specific load when running dry. “Carbon Bearings”.01 0 0.3 N/mm2 < 0. Cylindrical bearings should be fully supported by the housing or by a special metal bush 10 EK 40 EK 305 EK 2240 EK 3245 1 Wear [µm/h] Flange thickness should be at least equal to wall thickness.5 … 0. Housing thrust face for flange to be machined. Any keyway should be axial and milled out carefully to avoid breakage. bores should have spiral grooves or axial grooves according to the application. alloy.. In the latter case. Surface Finish. A transitional angle should be radiused.5 3 3.