Design, Machining and Installation Manual
Contents
1. FEROFORM T11 The matrix additionally incorporates evenly dispersed graphitic filler T11 can be used with water lubrication particularly where slow operational speeds are frequently used resulting in boundary lubrication conditions prevailing This grade can also operate dry unlubricated providing low frictional and high load carrying attributes up to a PV limit of 120 kg cm m min FEROFORM 112 Grade T12 incorporates molybdenum disulphide evenly dispersed throughout the matrix to give low friction at high pressure even when used dry For applications requiring low stick slip low noise and or dry start up T12 is often specified e g by military users Used where electrolytic corrosion could be a problem e g with graphited materials For dry running a PV limit of 140 kg cm m min should be adhered to NOTE All grades are fully approved by the leading Classification Societies for Propeller Shaft Applications water lubricated open system oil lubricated closed system Rudders all types water grease or oil lubricated FEROFORM F36 F36 is a grade specially developed for bearing and wearing applications at elevated temperatures up to 200 C It utilises a high temperature phenolic resin encapsulating aramid composite textile reinforcement 6 4 FEROFORM F363 As F36 but additionally incorporating graphite to provide low friction at high pressure and elevated temperature F36 and F363 a2. Design Machining and Installation Manual CONTENTS PAGE INTRODUCTION 1 APPLICATIONS 2 LUBRICATION 3 5 GRADE SELECTION 6 7 BEARING CONFIGURATION 8 10 Standard available forms SHAFT MATERIAL CHOICE 11 12 Surface finish and tolerances DIMENSIONING 13 21 Length to diameter ratio Wall thickness Groove configuration and dimensions OD ID calculation A Graphical format B Calculations from first principles C Computer Programme Information required from the user RETENTION METHODS 22 23 MACHINING 24 34 Health handling and storage conditions FITTING METHODS 35 36 APPROVALS 37 Appendices Machining Graphs 38 47 INTRODUCTION TENMAT FEROFORM MARINE BEARINGS are used in many diverse application areas across all vessel types The UNIVERSAL nature of the material means that one basic grade T14 can be used with all manner of fluids from clean water through to heavily abrasive laden conditions for greases oils through to various fuels and chemicals For dry self lubricating bearing applications or where dry start up or indeed where lubrication starvation may be encountered or where noise free running is a pre requisite then graphite T11 or molybdenum disulphide T12 containing grades are available to cater for these special needs These advanced HIGHLY TECHNOLOGICAL composites are setting new standards of wear resistance versatility and reliability for marine bearings and are thu
3. SIDE PLAN 3 79 8 8 29 Right angle Head Minimum ID approximately 250mm Supplier Centreline Machine Tool Company Leicestershire Kennametal Bristol Erikson Bristol Spiral Grooving This should be done with the following tool angle SIDE PLAN END gt 3 15 15 159 15 25 It is recommended that internal spiral grooving be done using a right angle head attachment to a vertical borer machine with a spiral straight slot drill See end milling slot drilling for speed feed depth of cut data Spiral grooving with a single point tool can be carried out on a lathe but great care must be taken to ensure a keen sharp cutting edge is used along with small depth cuts For example 12mm wide groove on a lathe in a 150mm ID Cutter Details See sketch above Spindle Speed 50 rpm Depth of Cut per pass 0 25mm Pitch 100mm Spiral grooving using Power Driven live tooling on a lathe results in a good quality groove achieved in half the time An adapted thread grinding lathe attachment is suitable 30 i HACK SAWING The FEROFORM T grades can be easily cut using a hacksaw with preferred blade range of 10 to 18 teeth per 25mm j TAPPING This can be carried out using a normal tap wrench or a radial arm drill with HAND TAP selected For example 80 rpm for 10mm Whitworth Please note with drilled or tapped hol
4. When freeze fitting staves it is important to ensure that each stave is covered with the cooling medium otherwise some may not fully shrink Freeze fitting can be used with all stave constructed bearings whether secured by interference fit utilising a longitudinal keeper strip or when fitting dovetailed staves into a dovetailed housing Adhesive Bonding The adhesive manufacturers instructions must be followed In general terms both housing bore and bearing OD should be clean and grease free The machined finish of the housing and bearing will provide adequate mechanical keying which further improves the adhesive bond Since no interference is involved there should be a clearance between the OD of the bearing and the housing bore The required clearance varies according to the adhesive used and therefore the adhesive suppliers recommendations should be sought Similarly cure times vary for example a cold cure two part epoxy may take 6 8 hours to harden and up to 48 hours to achieve full strength at normal ambient temperatures 36 APPROVALS Classification Societies approve FEROFORM T grades for the following Oil lubricated sealed system stern tube propeller shaft bearing e Water lubricated open system stern tube propeller shaft bearings Grease lubricated propeller shaft bearings e Grease water or oil lubricated rudder bearings Notes Allowable pressures and L D ratios vary slightly between Societies T
5. angle head TOOLING Spiral flute Specially extended tool bar at 660 As for drill carbide tipped mm long with carbide tip welded to shaping 90 Tip to have maximum 5 clearance on all sides Improvised workholding required Shaper Lathe DEPTH OF CUT Up to 6 4 mm gt deep per pass SPINDLE SPEED 500 rpm FEED RATE 0 25 mm rev 0 5 mm 1 mm 0 02 to 0 04 per As for stroke shaping Stroke rate 9 5 m min As for 1 IMPORTANT Wherever possible final bore after grooving to improve results stock removal of 0 5mm total 28 If cannot disengage spindle drive from feed Lathe Using steel running bearing as steady gripped in chuck with its bore machined to suit OD of bearing being grooved Use steady to lock up or clamp bearing xt Boring Bar Lathe Bed Graduations on chuck to equispace grooves if can disengage spindle if not mark each bearing Grease must be applied to the OD of the bearing running in the steel check ring to prevent over heating Engage feed traverse forward then reverse taking depth cuts as per shaping detail until desired depth is achieved Obviously if it is possible to disengage the spindle still use feed and the need for running bearing disappears Axial Grooves For tooling angles see below and for typical speeds and feeds see shaping information Sketch B
6. in lower wear resistance particularly in abrasive conditions General commercial grades offer hardnesses of around 10 15 Rockwell C 180 200 Brinell which are acceptable Stainless steels are however available with relatively high hardness and are preferred if conditions are at all abrasive Hardness should be greater than 30 Rockwell C The 18 8 stainless steels austenitic contain approximately 1896 chromium and 8 nickel They cannot be hardened by heat treatment but harden rapidly when cold worked Molybdenum is often added to further increase corrosion resistance Another very good resistant alloy for sleeves is Inconel 625 This high nickel alloy 60 work hardens thus it is relatively easy to machine but hardens during operation SURFACE FINISH AND TOLERANCE For Shafts Experience has shown that a fine machine finish is an acceptable surface for FEROFORM bearings to operate against It is not necessary to polish the shaft liner or sleeve since this naturally occurs during the early operational period A surface finish of 0 8 micro metre 32 micro inch RMS can be specified Machining tolerances for shafts should be ISO tolerance h7 or h8 For Housings Out of round housings should be avoided Again a H7 or H8 ISO tolerance is preferred 12 DIMENSIONING LENGTH TO DIAMETER RATIO L D For industrial uses L D ratios vary typically from 1 1 to 1 5 1 An L D of 1 1 can be considered optimum since it perm
7. into the housing use Graphs 1 and 6 For semi finished and grease lubricated Rudder Bearings where the bore is finish machined after the bearing is pressed into the housing use Graphs 1 and 7 17 DIMENSIONING FROM FIRST PRINCIPLES 1 Interference Fit FEROFORM bearings are usually retained in their housings by using an interference fit Minimum recommended values are given on Graph 8 as are suggested achievable manufacturing tolerances For oil lubricated and sometimes water lubricated propeller shaft bearings some form of additional mechanical fixing such as keys or locking strips is recommended 2 Running Clearance Recommendations of bearing running clearance for a given shaft diameter are indicated on Graph 9 The amount of running clearance is critical to the performance of a bearing Where applicable such as rudder bearings society regulations should be consulted with respect to minimum running clearances 3 Swell Is a linear surface effect and not volumetric We calculate swell as 0 5 x OD ID FEROFORM grades are stable in oil and greases In water the longitudinal axial swell of T grades is 0 296 4 Bore Closure Graph 10 indicates the optimum wall thickness and bore closure allowance to be made when the wall thickness is greater than the optimum size The wall will compress by a certain percentage shown on the graph depending on how over thick it is Min wt 0 05 d The
8. open water lubricated system assuming a flow rate of 0 15 litres per minute per mm of shaft diameter is used there would be no need to consider PV since the water flow will more than adequately dissipate any heat produced As water has a very good cooling effect on the bearing PV values well in excess of 1000 kg cm m min are achievable for propeller shaft bearings In fact 2000 PV would be well within the capability of FEROFORM grades under hydrodynamic conditions For an oil lubricated system if the PV exceeds 275 MPa m min then use of oil coolers in the system may be necessary Please consult our Technical Department for advice See also table Guide to Limiting PV Value in section entitled GRADE SELECTION FRICTION Extensive friction data is available in dry wet or oil lubricated conditions Should friction levels with any of these particular media be required please consult TENMAT Limited Values down to 0 01 have been recorded where hydrodynamic lubrication conditions exist 4 GRADE SELECTION All FEROFORM Marine grades are non asbestos synthetic fibres impregnated with phenolic resins FEROFORM T14 The universal grade for fluid lubricated conditions Therefore in most marine applications T14 is acceptable since lubrication will be present as oil grease water or the chemical being handled For the rudder application the latest 10 MPa high pressure approval by leading societies gives further bonuses
9. r 0 33 g N number of grooves NB No groove at 6 o clock position for propeller shaft bearings Groove width is nominally 2 5 g however to minimise the number of grooving tools required use the averaged groove widths specified in Table 2 for each particular shaft diam eter 14 Oil Lubrication Since closed sealed oil lubricated systems offer a clean operating environment longitudinal grooves are not necessary and therefore it is recommended that lead in washway grooves only are used positioned at 9 o clock and 3 o clock or 10 o clock and 2 o clock possibly in the case of twin screw vessels C Grease Lubrication Grease lubricated systems are generally used in very slow moving or oscillatory motion applications such as rudders Here grooves are not necessary although in some installations dependent on the method of supplying grease to the bearing annular or closed end grooving may be used For grease lubricated propeller shafts grooves should always be used as indicated in water lubrication section 19 4 FEROFORM Grade ID Groove Design for WATER Lubricated Propeller Shaft Bearing Optimum Wall thickness W T 0 625 d 2 5mm Maximum groove depth g 0 33 W T w 2 5 r 0 339 number of grooves Water Lubricated Propellor Shaft Bearings No Groove FEROFORM T Grade ID Groove Design for OIL Lubricated Stern Tube Optim
10. wide with 7 teeth 25mm For improved results a diamond electroplated blade can be used free hand feed rate but again not forced as excessive heat will be quickly generated CIRCULAR SAW Due to large heat generation the best results are obtained by cutting wet with diamond blades metal bonded type but can be cut dry at 2000 RPM x 3m min feed rate using a 300mm diameter carbide tipped saw blade with 3 2mm cut tooth width and 50 teeth When cutting through material in excess of 40mm thick it is recommended that 2 or more depth cuts are taken For example 50 mm thick in 2 cuts 90 mm thick in 2 3 cuts This is in order to prevent excessive heat generation leading to loss of tension in the saw blade If cut wet the size of the blade used determines the maximum depth thickness 27 4 DRILLING Carbide tipped or masonry drills are recommended but high speed steel drills can also be used for small batch work Typical Data Drill Size Speed RPM Feed 3 mm 800 1 mm sec 6 mm 700 1 25 mm sec 12 mm 600 1 mm sec 19 mm 400 0 75 mm sec 25 mm 250 0 6 mm sec 38 mm 200 0 4 mm sec NB Drills with a standard helix spirl are to be used and these must be continually cleared pecked GROOVING For example Bush size 500mm OD x 450mm ID x 600mm long with 25mm slots through bore 12mm deep Machining of Longitudinal Grooves in Feroform Recommended Alt 2 MACHINE Vertical bored right
11. 5 8010 SHOU 114 6 H31VM S3ONVHV310 39NVMOTIV 3GISNI SNINIHOVIN LNOHLIM JHL OLNI 55 HOIHM SONIHV38 L340VH8 ANY 38 NH31S 1 qalvoldg d31VA 3ONVAOTIV LL YALAWNVIC 3GISNI L 1 HdVH9 39 BUSH INSIDE DIAMETER ALLOWANCE mm LHVHS 000 006 INWS 2 VIG LAVHS X 629070 SS3NMOIH L TIVM WAWILdO NO Q3Sv8 801 SHOE TISMS SHONVHV3T1O SONVMOTIV 3GISNI men L HdVH9 LNOHLIM 5 AHL OLNI Q3SS 38d 3811 Ndd31S Qa31VO91d8 1 AONVMOTIV YALAWVIG 3dqVd9 1 IVIAN3 L 40 BUSH INSIDE DIAMETER ALLOWANCE mm LHVHS INWS 2 VIG LAVHS X 2290 0 40 SS3NMOIH L TIVM WAWILdO NO Q3sva H0S019 3409 TI3MS S3ONVHV31O 39NVMOTIV YALSWVIG 3GISNI ONINIHOVIN H3H LHf14 LNOHLIM OLNI 9559 HOIHM 3811 15 Qa1volggsrri 3jSV3u9 H3JVM 39ONVMOTIV YALAWVIC 3GISNI 3QV89 IVIAN3 L HdVH9 41 BUSH INSIDE DIAMETER ALLOWANCE mm LHVHS TI3MS S3ONVHV3T1O SACNTONI 39NVMOTIV H3l3WVIO 3GIS
12. AILURE 1 FEROFORM IS FULLY APPROVED TO OPERATE WITH WATER LUBRICATION AND EVEN IF THE SYSTEM UTILISES NON CORROSION RESISTANT MATERIALS WATER CAN BE SAFELY USED TO REACH PORT 2 POLLUTION PROBLEMS ARE RESTRICTED SINCE THE OIL SUPPLY CAN BE SHUT OFF AND WATER INJECTED INTO THE SYSTEM INSTEAD GREASE Grease will not readily flow and hence does not offer any cooling effect Grease is therefore normally used where heat generation is not significant namely very slow rotation or oscillatory motion as in a rudder application Also where bearings are used fairly infrequently such as hatch covers grease is a good choice of lubricant since it protects metallic parts from corrosion Warning Ref Grease Please note that we can assume due to load and speed heat would be generated in a stern tube application This should be taken as a WARNING against the use of grease in this application However we do have society approvals happy with the concept and designs This is a warning only for stern tube therefore excluding the rudder application SEALS Experience has shown that all approved seals can be used in conjunction with TENMAT s FEROFORM bearings No special requirements are necessary fitting and operation should be in accordance with the seal manufacturer s recommendations PV LIMITS PV need only be considered when heat is likely to be produced and not dissipated by the lubrication medium i e For an
13. Bearing Inside Diameter i Determine from Graph 9 the minimum Running Clearance for rudder or stern tube or use Shipping Society recommendations RC min i Calculate swell allowance in water by OD ID x 0 005 SA 50 swell allowance should be added to oil lubricated bearings in case of seal failure Determine bore closure by calculating maximum interference max OD max minimum housing If wall is optimum or less than optimum thickness BCF 1 but if wall is thicker than optimum determine Percentage Factor from Graph 11 That is if wall is twice optimum then use 5096 BCF Bore Closure max x BCF BC iv Calculate Thermal Expansion for oil lubricated propeller shaft bearings or if applicable for warm water applications using Table 2 Expansion OD ID x 50 x 10 6 x 65 20 C Temperature rise NB 65 C is normal high temperature alarm setting v Therefore ID machining size is given by max shaft dia RC min SA TE ID min ID max ID min Machining tolerance Calculate Bearing Length Society rules generally state what length to shaft diameter may be used for particular vessel bearings be they water or oil lubricated propeller shafts or rudder bearings For non society classed vessels 2 1 L D oil propeller shaft bearing ratios can be considered and typically 1 5 L D oil propeller shaft bearings ratios can be considered and typically 1 25 1 L D ratio for rudder bearings Calcu
14. ENMAT Permitted running clearances also vary slightly and for this reason the TENMAT recommendations quoted are minimum allowable values Societies Having Approved FEROFORM include Lloyds Register of Shipping e American Bureau of Shipping Det Norske Veritas Bureau Veritas e Germanischer Lloyd Nippon Kaiji Kyokai e Korean Register of Shipping Biro Klasifikasi Indonesia China Classification Society e China Corporation Register of Shipping Registro Italiano Navale The information herein is presented in good faith but TENMAT does not warrant the conformity of its materials to the listed properties or the suitability of its materials for any particular purpose In the event of any uncertainty regarding suitability for any application please contact Tenmat and ask for our Technical Services Department on 44 0 161 872 2181 37 INTERFERENCE 002 000 008 H3 13INVIG SNISNOH 0011 006 00 00S 00 00L 009 007 002 0 24 0 9 0 Duipnjoul p eouaiepelu XEN BuriuiuoejA XEN 10 343441 30V89 L LVINNAL 38 BUSH INSIDE DIAMETER ALLOWANCE mm LHVHS 000 006 008 00 009 0056 007 006 000 00 0 IWINS 2 VIO 1 5 X 52900 SS3NMOIHL TIVM WAWILdO NO
15. H __ __ eee eee __ INTERFERENCE amp MACHINING mm 00 c0 0 90 90 20 80 60 01 S3QV89 L SAONVEATOL Lid 8 HdVH9 45 LIVHS SONIMv3H SEM 16 ___ RUNNING CLEARANCE mm OPERATIONAL RUNNING CLEARANCES L3 GRADE MARINE BEARINGS MINIMUM RECOMMENDED 6 HdVH9 46 BORE CLOSURE SS3NPOIH L TIVM Q3aQN3 AIWOO38 SS3N9OIHL TIVM OEL Oct OFF 00 06 08 0 09 06 Ot 06 02 01 0 YOLOVA 3915015 39089 06 1 LIVHS S3AOOHD HOS SS3aNOIHI 2 96001 506 SSANMOIHL TIVA WOWINIW 9501 L D 60 0 SI SS3NXOIHL TIVM WAWINIW 3H L q3HinO3t LON S3AOOHO 3H3HM SONIHV38 G Z p SZ90 0 SI S3A0OHO SONIHV38 SS3NMOIH L TIYM WNNILdO 0L 47
16. NI S HdVH9 5 OLNI 4 9554 SI 9NIHV38 d31d4V G3HSINI4 SI 3H3HM SONIHV38 L3349V8H8 3811 NYALS 1 0 H3 VM 3ONVMOTIV YALANVIG 3GISNI L IVINN3 L 42 BUSH INSIDE DIAMETER ALLOWANCE mm LHVHS 0001 006 004 009 006 007 008 000 001 0 TI3MS S3ONVdV319 ONINNAY SACNTONI 3ONVMOTIV YALAWVIC 3GISNI E 1 Z LT LT T T T LINI1u3ddn 5 AHL OLNI Q3SSd8d SI JHL d314V Q3NIHOVIN Q3HSINIA SI SHOE AHL 3H3HM 15 Q31VOIH8 TI 10 AONVMOTIV YALAWVIC 3GISNI 3QV89 L IVIAN3 L 9 HdVH9 43 LHVHS 000 006 008 004 009 00S 0 006 000 00 0 p TI3MS 110 SSONVHW310 NINNNY p E 3DNVMOTIV 3QISNI il _ ONISNOH AHL OLNI 55 SI AHL dH3l4v Q3NIHOVIN Q3HSINIA SI 3HO8 AHL JH3HM SONIHV38 1 01 1 3SV3d9 9 YALVM 3ONVMOTIV YALAWNVIG 3GISNI L IVINN3 L BUSH INSIDE DIAMETER ALLOWANCE mm Z HdVH9 44 H313AWVIO 002 0011 000 006 008 002 009 009 007 00 00c 001 0 I CHON3WINOO3
17. closure amount This reduction of bore closure would normally increase the ID but is approximately balanced by the thermal contraction effect Thus the running clearance remains roughly constant i e it will not significantly change with temperature decrease Mechanical Traditionally used mechanical methods of retention can be used The methods should ensure that no rotational or axial movement is possible For example To prevent rotation Anti rotation key for full bearings Longitudinal keeper strip for stave bearings To prevent axial movement End keeper ring and forward stop Flange locked by screws Stepped housing and end keeper ring 22 4 Bonding 1 Adhesive Bonding FEROFORM bearings may alternatively be bonded into a housing Bonding is not the preferred method of retention since removal is made more difficult but may be necessary if i The wall thickness is insufficient to allow retention by interference fit compensate for a corroded or out of round housing Our Technical Department can offer advice on adhesive selection A two part cold cure epoxy adhesive is normally acceptable see also no 3 amp 4 below Using Chocking Compound Epoxy chocking compounds such as Chockfast Orange Epocast or Belzona can fill large gaps and can be readily poured between housing and bearing hence alignment can be easily achieved by positioning the bearing and then pouring chocking compound
18. d radius Typical speeds and feeds are 400 rpm 500mm per min with 1 5mm stock removal Cutting blades are high speed steel for small batches or solid carbide carbide tipped for larger batches Clearance from cutting edge is 15 20 Convex Profiles Same cutter body to be used but all blades must be ground to the correct radius 32 3 4 5 Sanding grades can be sanded wet ground to thickness wet grinding results in improved finish Typical Data Sanding Belt Grit Stock Approx Size Removal Feed Rate Surface Finish P36 0 25mm per pass 3 metre min 12 um P80 0 12mm per pass 5 metre min 6 um Wet Grinding Stone Stock Approx Grit Size Removal Feed Rate Surface Finish 36 0 25mm per pass 3 metre min 1 um Machines used were Grindmaster sander with 900mm wide belt Machine built by Ellesco s and Rowlands wet duplex grinder HAND FINISHING Filing FEROFORM grades can easily be filed using a medium grade file which is in good condition Emery Cloth The use of emery paper can improve the surface finish particularly if and dry up to 400 grit is used Surforming This has been shown to be an extremely good method of bulk material removal for roughing of FEROFORM 33 5 REMOVAL OF DUST AND SWARF It is essential that good housekeeping is maintained on all machines and local legislation is adhered to Swarf ge
19. done with the following tool angles PLAN END WM C FACING This can be done with the following tool angles d MILLING Again carbon tipped tooling should be used When using side and face cutters the climb milling method should be employed see below Side and Face Cutter Direction of cut Direction of feed Typical Data using 200mm Diameter Cutters with 12 Tips Width of Cut Max Depth of Cut Speed RPM Feed 0 12 25 600 0 6 mm rev 12 25 20 450 0 5 mm rev 25 40 mm 12 350 0 25 mm rev 40 50mm 6 mm 300 0 15 mm rev 26 Slab Millin For machining slots rebates or shapes FEROFORM T14 a spiral teeth design is recommended OD of Cutter Width of Cut Speed RPM Feed 75 mm 75 mm 300 0 4 mm rev 100 mm 75 mm End Milling Slot Drilling 250 0 25 mm rev Either solid carbide or tipped cutters are recommended with a straight or spiral design The climb milling method should again be employed Typical Data OD of Cutter Max Depth of Cut Speed RPM Feed 6 mm 10 mm 600 0 4 mm rev 12 mm 20 mm 500 0 25 mm rev 20 mm 40 mm 400 0 25 mm rev 25 mm 60 mm 300 0 25 mm rev BAND SAWING Rough cutting may be done with a Band Saw carbide steel blade 25mm
20. es clearance should be allowed for at the bottom of the hole or thread to prevent excessive delaminating forces caused by inserts bolts etc k PLANING FEROFORM T grades can be hand or power planed with results dependent upon operator skill Surform type hand planes may give better results When manually planing a standard wood plane with a very sharp should be used For power planing spindle speeds should be 20 000 rpm stock removal no more than 0 8mm per pass and solid carbide blades used Power planing is obviously the recommended method SHAPING Shaping operations can be carried out on FEROFORM grades but wherever possible an intermittent cutting alternative is recommended Tooling clearances should be as for turning of axial grooves on Page 29 Typical Data Depth of Cut per stroke Width of Tool Stroke Rate 3 mm 1 mm 96 st min 10 mm 0 5 mm 46 st min 16 mm 0 25 mm 33 st min 25 mm 0 25 mm 17 st min 31 Conversion Table Metric mm Imperial inches 0 05 0 002 0 10 0 004 0 15 0 006 0 20 0 008 0 25 0 010 0 40 0 015 0 50 0 020 2 STAVES Cutter Design for Concave Profile Cutting Blade m d Main body butter can be Mild Steel Bore to suit Milling Arbour Diameter When opposing flat blades are placed at diametrically opposite angles from 180 they result in a machine
21. eze Fitting FEROFORM bearings can be shrink fitted by freezing in either dry ice solid CO2 or liquid nitrogen In both cases extreme care should be taken since 1 The extremely low temperature of these products can cause severe burns or frostbite 2 Gassing off of these products displaces air leading to possible asphyxiation unless adequate ventilation is supplied If this method of freeze fitting is used manufacturer s guidance notes must be followed The temperature of dry ice is 79 C and liquid nitrogen is 196 C The freeze down time for FEROFORM bearings is shown in Table on page 36 35 Once frozen they can be slid into the housing without any difficulty i e the amount of shrinkage will be greater than the amount of interference Liquid Nitrogen Orien Freezing 1 1 Down Time 2 hour 11 2 hour Warming Up Time 21 2 hour 11 2 hour These are typical times for guidance only and will vary due to ambient conditions wall thickness bearing diameter etc On warming back to room temperature the interference fit will be sufficient to hold the bearing in place but normally for added safety a forward stop and an end keeper ring is suggested For large bearings supplied in more than one piece care should be taken to align the grooves This is quite easy when freeze fitting but it is recommended that each piece be allowed to warm and secure before installing subsequent pieces
22. hing 3mm on diameter finishing TOOLING Tungsten carbide is most often utilised with polycrystalline diamond tipped tooling used for large batch orders For small quantities and one off s High Speed Steel tooling is perfectly adequate In all machining applications a sharp cutting edge is of paramount importance and the grade of carbide recommended is K10 K68 ISO designation When turning large diameter or thin wall tubes a dummy centre should be used in the bore at the chuck jaw end to prevent the tube distorting a tight fit bung or revolving centre is to be used at the tailstock end of the tube Large diameter tubes can be supported with a suitable steady however as steadies 24 may leave marks it may be desirable to have an allowance on OD to clean afterwards Before finish cuts are applied the material should be left to cool to ambient temperatures to allow for frictional heat generated in roughing out to be dissipated Note the finish cut should be a minimum of 1mm to ensure that cutting rather than rubbing takes place Turning operations can be speeded up by approximately 5096 if a coolant is used i e water but little improvement to the surface finish will result only extended tool life Tooling Geometry for Turning and Boring Turning work piece SIDE 3 5 MAN WOMAN Boring SIDE 0 030 TIP RAD b PART OFF This can be
23. is used the choice being dependent on whether the system is open or closed and the speed of operation Under certain circumstances FEROFORM T11 or T12 grades can be used without lubrication e g where speed is so low as to not generate any significant heat It is strongly recommended that wherever an unlubricated application is considered our Technical Department is consulted in order that combined pressure and velocity effects PV limits can be evaluated WATER Water is commonly used with FEROFORM T14 grade propeller shaft impeller pump stabiliser and lower rudder bearings For high speed full rotation applications e g propeller shaft it is generally preferred to have a positive water flow Rotational speed generates heat and being such a good cooling medium water is an ideal lubricant in these conditions The flow rate should be high enough to fully dissipate any heat produced by the rotational speed A minimum flow rate of 0 15 litres per minute per mm of shaft diameter is recommended This flow rate is good for all speeds and does not have to be increased for high rotational speeds This is because at high speed hydrodynamic lubrication films are formed significantly decreasing friction and therefore reducing heat generation Water lubrication systems are normally of the open type i e no aft seal Water should be supplied at the innermost point of the bearing line Since FEROFORM has high temperature resistance and does
24. its adequate cross sectional area to provide acceptable bearing pressure ease of alignment alignment becomes progressively more difficult the longer the bearing adequate outside surface area to permit retention by an interference fit good pressure distribution throughout bearing length allows a hydrodynamic film of lubrication to be readily established and retained Historically however for marine applications larger L D ratios are used In oil lubricated propeller shaft systems typical permitted ratios are from 1 5 1 to 2 1 In water lubricated propeller shaft systems typical permitted ratios are from 2 1 to 4 1 For rudder bearings typical permitted ratios are from 1 8 1 to 2 1 The historical reason for this is to keep the bearing pressure low Our experience indicates that the shortest possible L D ratio should be used however Rules and Regulations of the Classification Societies must be adhered to Since TENMAT FEROFORM T grades are capable of operating at very high pressures more than 60 MPa we are currently evaluating in conjunction with leading Classification Societies use of reduced L D ratios particularly in propeller shaft applications WALL THICKNESS W T With a material such as FEROFORM exhibiting fairly high stiffness values wall thickness is not normally a critical design criterion Therefore FEROFORM bearings can be used to replace bearings of virtually any design size envelope Nonetheless given f
25. late Grooving Configuration Grooving configurations can be calculated using Table 2 and the Groove design drawings on Page 14 20 BEARING CALCULATIONS BY COMPUTER PROGRAMME TENMAT offer the facility of T grade Marine Bearing calculations by Computer written in MS DOS GWBASIC for IBM compatible PC s for rudder bearings and oil water or grease lubricated propeller shaft bearings Please consult TENMAT on 44 0 161 872 2181 or Approved Distributors throughout the world for details INFORMATION REQUIRED FROM THE USER In order that we may offer advice on optimum FEROFORM grade design configuration and dimensional fits etc it would greatly assist us to have the following information Type of Equipment Specific Application Speed rpm or surface velocity if fully rotating cyclic speed if oscillating Operational Temperature Range Lubrication If not sealed recirculating system condition of lubricant e g abrasive content temperature Operational Pressure or load Housing Diameter min max Shaft Diameter min max Length of Bearing Preferred method of retention if any Interference Mechanical Adhesive Bonding Preferred Method of fitting if any e g Hydraulic Press Freeze Fitting Any additional related information or comment If replacing another material details of any problems associated with that material or details of required improvements in performance etc would be
26. lso exhibit higher working pressure capability 85 MPa 12320 Ibf in2 and 75 MPa 10900 Ibf in respectively Used in marine equipment requiring combination of high pressure high temperature and low friction GUIDE TO LIMITING PV VALUE Table 1 Regular Grease Re lubrication Grade 2 Lithium Oil Impregnated Material Type Dry Rubbing SAE 30 Oil T14 390 18 213 780 72 852 300 14 000 11 410 18500 240 11 200 360 16 800 112 420 19 590 260 12 130 380 17 730 6 800 1 200 16 000 6 1 000 1 500 2 000 PV values quoted in kg cm m min Ibf in ft min and derived from work done on mild steel shafts EN3B with 0 8 surface finish BEARING CONFIGURATION All traditionally used configurations can be utilised either in a fully machined ready to fit form or semi finished for final machining by the shipyard Where dimensions of the shaft and housing are pre known e g new ship build bearings can be supplied fully finished but where shafts or housings may be re worked to re sleeve or clean off corrosion for example then semi finished bearings should be ordered and final dimensioning machining carried out by the shipyard once shaft and housing diameters are confirmed Full Cylindrical Bearings This is generally the recommended configuration to use since machining fitting and retention are all made easier by dealing with only one piece F
27. nerated from cutting of staves is much finer chip broken and therefore easier to extract as it is being generated Swarf from continuous contact cutting operations i e shaping and turning needs to be bagged off at the machine with care taken not to allow the turnings to clog up any extraction equipment used Safety Handling and Storage See FEROFORM Product Data Sheet 34 FITTING METHODS Press Fitting It is recommended that bearings to be fitted by pressing have an entry chamfer to facilitate starting Once started pressing should be a continuous operation until fully installed since if stopped re starting may require extra pressing force The housing should be round with a truly parallel bore clean and grease free The graph indicates the nominal fitting force for T14 It is based on optimum wall thickness and 2 1 R d ratio For L d ratios over 2 1 higher forces than those indicated can be expected NOTE Bearings may be supplied in more than one piece Since water lubricated bearings have longitudinal grooves in the base it is important to ensure that grooves line up To assist a keeper bar placed in a groove will help It is suggested that an annular groove is machined into one end of each length of a multi piece bearing to facilitate flow of water through the bearing even if the grooves are not fully aligned The annular groove should be to the same depth as the longitudinal grooves Fre
28. not suffer from hydrolysis engine cooling water may be used to lubricate the stern tube bearings L D ratios and groove configurations are described fully in section entitled Dimensions OIL Commonly used as lubricant in stern tubes Oil is normally considered to be a better lubricant than water but not such a good coolant Also oil must be used in a closed system fully sealed Systems traditionally used with white metal bearings are perfectly satisfactory for use with FEROFORM bearings Such systems include a Gravity flow from header tank through stern tube to drain tank The oil is then normally pumped back to the header tank perhaps via a cooler b Thermally induced flow where the stern tube is often kept cool by flooding the after peak Full circulation by pump Generally any SAE30 marine quality stern tube oil is acceptable However in a closed oil lubricated system it is not normal practice to use corrosion resistant stainless materials Therefore it is recommended that an emulsifiable oil is used so that in the event of water ingress no free water will exist in the system thereby preventing potential corrosion Vickers Hydrox 550 oil is an acceptable example of such an emulsifiable oil Flow rates in the order of 0 01 litres per minute per mm of shaft diameter have been recorded NOTE THERE ARE TWO VERY SIGNIFICANT SAFETY FACTORS ASSOCIATED WITH USING FEROFORM IN THE EVENT OF CATASTROPHIC SEAL F
29. nzes should not be used where operating continuously in abrasive conditions here a harder shaft liner should be used Steels When carbon is alloyed with iron the hardness and strength of the metal first increases e g steel containing 0 496 carbon may be twice the strength of pure iron and with 196 carbon nearly three times as strong However as carbon content increases ductility reduces From 1 to 1 596 carbon hardness increases but strength begins to decrease When it contains more than 2 carbon the metal is classed as cast iron having good castability moderate strength and hardness but usually low ductility Steel Type Approximate 96 Carbon Mild Steel Up to 0 25 Medium Carbon Steel 0 25 0 45 High Carbon Steel 0 45 1 5 Cast Iron 2 5 4 5 4 Mild steel and medium carbon steel be used in closed oil lubricated systems where corrosion is unlikely For water lubricated systems corrosion resistant steels should be used In very abrasive operating conditions hard corrosion resistant steel sleeves should be used Hard sleeves generally use a carbide coating e g tungsten or boron carbide and exhibit a hardness around 50 60 Rockwell C Stainless steels whilst offering corrosion resistance are not highly wear resistant Like aluminium stainless steels containing chromium achieve their corrosion resistance by the formation of a protective oxide film It is this oxide film that primarily results
30. or example Machining is basically just two operations OD and ID Retention can be by a simple interference fit Fitting can be carried out by freeze fitting This is the most commonly used configuration for rudder and propeller shaft bearings Whilst FEROFORM grade tubes are manufactured in 1200mm lengths for ease of handling and machining it may be preferred to use 600mm length pieces Split Bearings Sometimes used where a need exists to be able to change a bearing without removing the shaft In such cases either mechanical methods of retention are used or if an interference fit is used a method has to be used whereby the interference can be broken mechanically This can be accomplished by use of for example tapered keys If a bush is split by milling shims are normally used to fill the gap left by the cut It is however possible to produce a split bush with no gap by splitting a semi finished tube having say 3 5mm oversize and undersize on OD and ID respectively lightly bonding the two halves back together using say an anaerobic adhesive and mechanical strapping machining OD and ID in the normal way and then breaking the bond Such split bushes can if required be retained by normal interference fit Flanged Bearings Split or Full Cylindrical May be used where either the flange is utilised as a method of location mechanical retention or where a light axial load has to be accommodated NB High a
31. pproval society shipyard ship owner architect APPLICATIONS FEROFORM Marine Bearings exhibit a versatility of applicational use unsurpassed by any other materials This is made possible by the very wide range of physical chemical and mechanical properties inherent in FEROFORM FEROFORM s major attributes Resistance to abrasive conditions High mechanical strength Wide operational temperature range Low friction No stick slip Resistance to shock loads Very low water swell No oil swell High PV limit dry Can be lubricated by any compatible fluid oil water grease etc Excellent chemical resistance As a consequence of this unique versatility FEROFORM Marine Bearings have been successfully used in a very wide range of applications including Hull structure Propeller shaft stern tubes and brackets Rudders all types Stabilisers Bow thrusters CP Propeller e g pitch adjustment slides Deck equipment Hatch covers bearings and slide pads Winches and Windlasses Fairleads Davits Stern rollers Ro Ro ramps and doors Other ship borne equipment Pumps Cargo handling e g expansion pads container handing amp Cable laying equipment Other Naval applications Submarines hydroplane mast bearings e g periscope communications mast 2 4 LUBRICATION Any compatible fluid can be used to lubricate FEROFORM bearings Generally water oil or grease
32. reedom of design the optimum wall thickness recommended is 0 0625 d 2 5mm where d is shaft diameter in mm This gives sufficient thickness for incorporation of grooves if required adequate wall thickness to permit interference fits to be used for retention cost effective use of material volume i e optimum costs optimum stiffness for ease of machine and fitting Should a thinner wall be required the minimum recommended wall thickness is 0 05 d but TENMAT should be consulted if grooves are necessary in such a bearing GROOVE CONFIGURATION AND DIMENSIONS A Water Lubrication Longitudinal lubrication grooves are recommended in accordance with Table 2 TABLE 2 Approx Angle Between Shaft Number Diameter of Grooves Grooves Width Depth mm Grooves Grooves mm 20 79 80 159 160 239 240 319 320 399 400 479 480 559 560 639 640 719 720 799 800 879 880 959 960 1000 They are primarily important to permit abrasive particles to pass easily and quickly through the bearing They do not assist in the promotion and retention of a hydrodynamic film of lubrication and therefore to enhance this aspect it is recommended that the bottom 6 o clock groove in the loaded area is omitted viz For propeller shaft bearings only T14 ID Groove Design for Water Lubricated Propeller Shaft Bearing Optimum Wall thickness W T 0 0625 d 2 5mm Maximum groove depth g 0 33 W T w 2 5 g
33. rmal Expansion TABLE 3 Normal to Parallel to Material Grade Laminae Laminae x 108 C x 109 C F21 24 60 20 F363 45 15 F36 41 13 F61 16 8 F21 100 T11 T12 T14 50 45 The above data is typical for the materials up to their normal maximum operating temperatures T11 T12 T14 have a thermal contraction of 20 x 10 on diameter normal to laminae from 20 to 70 C Lubrication Grooves a Water Lubrication Multi grooved configuration is generally adopted in plain bearings or alternatively stave construction for larger diameters See Groove Configuration on Page 14 for dimensions b Oil Lubrication Feed in washway grooves are usually incorporated into oil lubricated propeller shaft bearing design to promote an hydro dynamic fluid film See Groove Configuration on Page 16 for dimensions note this is for the design of grooves only suitable arrangements must be made for the free flow of heated oil out of the bearing area system For those wishing to undertake T grade rudder or propeller shaft bearing calculations a brief calculation procedure is shown below A more detailed method for Industrial Bearings is shown in TENMAT s Wearing and Bearing brochure Note dimensions are in millimetres Calculate Bearing Outside Diameter i Add minimum interference fit from Graph 8 to maximum housing diameter OD min machining tolerance to OD min OD max 19 Calculate
34. s able to offer the Ship Owner Operator Shipyard and Naval Architect a number of substantial cost savings This manual gives details of the Design Criteria Machining Data and Fitting Instructions for FEROFORM Marine Bearings and bushes in all application areas including propeller shafts rudders stabilisers pumps general deck equipment such as winches windlasses davits fair leads cargo handling equipment and hatch covers and also for off shore dockside applications Our experienced Technical Services Department are available to discuss and advise on all aspects of Marine Bearing use Please Telephone 44 0 161 872 2181 Alternatively Fax 44 0 161 872 7596 for assistance IMPORTANT NOTICE Tenmat welcomes the use of this manual or the associated C D ROM However any copies of the document must be transposed in its entirety including this notice No partial copy amendments are authorised without the express written permission of Tenmat Ltd The information offered in this document is only relevant to Tenmat Ltd products or materials and is only offered to assist engineers in the overall deisgn of marine stern tube and rudder bearings The information herein is presented in good faith but Tenmat does not warrant the conformity of its materials to the listed properties or the suitability of its materials for any particular purpose Therefore the final design of the bearing system must be the responsibility of the appropriate a
35. to fill the gap between bearing and housing Alternatively a dummy bearing the OD of which has been coated with mould release agent can be used during the pouring and curing operation When the chocking compound has fully cured the dummy bearing can be removed and a finished FEROFORM bearing fitted by interference via freeze shrinking FEROFORM materials can be bonded together For example where two or more bearing sections need to be joined then the ends of each section can be machined with spigot recess to a transition fit condition and a cold cure two part epoxy adhesive used For additional security radial holes can be drilled through the spigot join overlap and FEROFORM dowels be bonded and knocked into position Typical adhesives which can be employed are BOSTIK M890 and ARALDITE 2004 NOTE Tenmat are NOT manufacturers of any adhesives Therefore users are recommended to follow the manufacturers recommendations 23 MACHINING 1 Bearings a TURNING OD AND ID Finished Diameter mm inches NB If turning ring diameters from sheet use RPM x 2 with the same feed rates FEED RATES SURFACE FINISH Operation Rough Standard Fine OD ID 0 4 mm rev 0 2 mm rev 0 1 mm rev Facing 0 25 mm rev 0 1 mm rev 0 08 mm rev Partinf off 0 1 mm rev 0 08 mm rev 0 05 mm rev NB For machining of washways use OD ID operation Stock Removal Rate 10mm on diameter roug
36. um Wall Thickness W T 0625 d 2 5mm R 0 4 d g 0 025 d Wash Ways for Oil Lubricated Stern Tube Bearings Load Area No Groove Load Area No Groove OD ID CALCULATIONS The following pages detail the method of designing FEROFORM Bearings Two methods are described A A Graphical format where machining sizes can be taken directly from the graphs for finished or semi finished bearings but in ONLY for bearings with optimum wall thickness See graphs 1 7 Calculations from first principles See pages 18 20 Computer Programme See page 21 GRAPHICAL FORMAT FOR FEROFORM T GRADE BUSH OD AND ID DIMENSIONING FOR MARINE STERN TUBE AND RUDDER BEARINGS Only with Optimal Wall Thickness For fully machined water lubricated Stern Tube and Bracket Bearings which are pressed into the housing without further machining use Graphs 1 and 2 For fully machined oil lubricated Stern Tube Bearings which are pressed into the housing without further machining use Graphs 1 and 3 For fully machined water and grease lubricated Rudder Bearings which are pressed into the housing without further machining use Graphs 1 and 4 For semi finished lubricated Stern Tube and Bracket Bearings where the bore is finish machined after the bearing is pressed into the housing use Graphs 1 and 5 For semi finished lubricated Stern Tube Bearings where the bore is finish machined after the bearing is pressed
37. upplied semi finished for final machining by the shipyard or repairer FEROFORM tubes are available to suit shaft diameters of 20mm to 1200mm or larger on request Tubes are of 1200mm standard maximum length but can be supplied as 900mm lengths to be more cost effective particulaly in urgent ship repair A standard size list is available Sheet Standard sheet size is 1220mm x 1220mm a range of thicknesses from 1 6mm to 75mm Thicker by request Staves Available as required Some distributors keep a stock of some sizes 10 SHAFT MATERIAL CHOICE All traditionally used bearing shaft materials can be used with FEROFORM bearings It is generally accepted that the harder the shaft or liner sleeve material the better its wear resistance will be against almost any bearing material This is particularly true for abrasive conditions in water lubricated systems Bronze Strictly speaking bronze is an alloy of copper with tin but the word has become synonymous with a superior material compared to brass Hence materials such as silicon bronze and aluminium bronze contain no tin The bronzes commonly used in marine applications are 1 Phosphor bronze 2 Admiralty gunmetal 3 Nickel aluminium bronze 4 Copper Nickel Generally bronze shaft liners give good performance against FEROFORM bearings but although offering resistance to sea water and corrosion easy machining and being non magnetic bro
38. useful For quotation purposes we would additionally need to know the quantity and whether the material is to be supplied fully finished ready to fit or semi finished with allowances for on site finish machining e g by shipyard 21 4 RETENTION METHODS Any conventional method of retention can be adopted with FEROFORM bearings such as Interference Fit The level of interference required is given in Graph 8 This is the preferred method of retention of a full configuration bearing since not only is installation quick and easy but additional benefits are gained Is The recommended amount of interference fit should prevent either bearing rotation or axial movement It is normal practice to additionally use an end keeper ring shoulder as an additional safety precaution 2 An interference fit provides intimate contact between the housing and bearing OD alleviating the possibilities of water ingress and thus preventing corrosion of the housing bore Also bearing ovality that can occur in machined bushes is removed following 3 Experience has shown that a light film of flushing oil is condusive on the OD for ease of fitting 4 When a bearing is fitted with an interference there will be an associated amount of bore closure In the event of temperature decrease the resultant contraction will mean a loss of some of the interference accounted for in the dimensioning calculation which also means a reduction of bore
39. xial loads should be accommodated by a separate thrust ring and this would generally be a less expensive method to employ unless the flange were needed for location retention removal consideration Stave Construction Stave construction of a bearing was originally developed when hard maple lignum vitae was a popular choice for bearing material In order to utilise as much of the tree as possible bearings were made up of a series of pieces i e staves The side angles are such as to enable the staves to be laid up alongside each other to form a complete bearing Often longitudinal keeper strips are additionally used say at 9 o clock and 3 o clock positions to facilitate fitting and retention A variation of this is to use a dovetailed housing i e slotted housing After installation of the staves they should be line bored to the correct inside diameter Some owners and shipyards retain a preference for this configuration and FEROFORM T grades can be supplied ready to use or in sheet form from which staves can be cut and machined PLAIN HOUSING with keeper bars Housing FEROFORM SIAVES stave 1 4 DOVETAILED HOUSING Each Segment is normally supplied with flat internal face for machining in the housing Radii Chamfer after turning bore STANDARD AVAILABLE FORMS Tubes Except for new build and OEM use where bearings can be supplied machined to drawing bearings are normally s
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