Ball screws
Medical equipment Press brakes EDM Woodworking
General Contents d Ø Load C o Rolling element Recommendations for selection Overview: ball screw nuts --------------------------------------------------------------------------------------------------- 0 Basic dynamic load rating (C a ) --------------------------------------------------------------------------------------------- 0 Static load carrying capacity (C oa ) ----------------------------------------------------------------------------------------- 06 Critical rotating speed for screw shafts ---------------------------------------------------------------------------------- 06 Permissible speed limit ------------------------------------------------------------------------------------------------------ 07 Lubrication ---------------------------------------------------------------------------------------------------------------------- 07 Effi ciency and back-driving ------------------------------------------------------------------------------------------------- 07 Axial play and preload -------------------------------------------------------------------------------------------------------- 0 Static axial stiffness of a complete assembly --------------------------------------------------------------------------- 0 Screw shaft buckling --------------------------------------------------------------------------------------------------------- 0 Manufacturing precision ----------------------------------------------------------------------------------------------------- 09 Materials and heat treatments ---------------------------------------------------------------------------------------------- 09 Recommendations for assembly Radial and moment loads ---------------------------------------------------------------------------------------------------- Alignment ----------------------------------------------------------------------------------------------------------------------- Lubrication ---------------------------------------------------------------------------------------------------------------------- Designing the screw shaft ends ------------------------------------------------------------------------------------------- Operating temperature ------------------------------------------------------------------------------------------------------ Separating the nut from the screw shaft -------------------------------------------------------------------------------- Starting-up the screw ------------------------------------------------------------------------------------------------------- Other technical data Lead precision according to ISO -------------------------------------------------------------------------------------------- Product information SD/BD miniature screws ---------------------------------------------------------------------------------------------------- SDS/BDS/SHS miniature screws in stainless steel ------------------------------------------------------------------- SH miniature screws --------------------------------------------------------------------------------------------------------- SX/BX universal screws ------------------------------------------------------------------------------------------------------ Accessories for SX/BX nuts ------------------------------------------------------------------------------------------------- SND/BND precision screws, DIN standard ------------------------------------------------------------------------------ PND preloaded screws, DIN standard ------------------------------------------------------------------------------------ 6 SN/BN precision screws ----------------------------------------------------------------------------------------------------- PN preloaded screws --------------------------------------------------------------------------------------------------------- 0 SL/BL long lead screws ------------------------------------------------------------------------------------------------------ SLT/BLT rotating nuts -------------------------------------------------------------------------------------------------------- Standard machined ends ---------------------------------------------------------------------------------------------------- 6 Screw shaft accessories ----------------------------------------------------------------------------------------------------- Calculation formulas ---------------------------------------------------------------------------------------------------------- 6 Designation --------------------------------------------------------------------------------------------------------------------- 9 Roller screws and cylinders ------------------------------------------------------------------------------------------------- 0
Nuts for ball screws Nuts for ball screws Screw assembly Type of recirculation SD/BD Internal, by inserts Right hand lead Diameter, - - - - Catalogue page Screw accessories Nut accessories Preload for optimum rigidity Backlash elimination Axial play SD SD SD SD BD BD BD BD SD BD SDS/BDS Stainless steel optional SH External, by integrated tube 6 SH SH,7,7 SH SHS Stainless steel optional SX/BX Internal, by inserts 0 6 - - - SX SX SX SX SX SX BX BX BX BX BX BX SND/BND/PND Internal, by inserts SND SND BND BND PND PND - SND BND PND - SND BND PND - SND BND PND DIN VERSION 0 6 SND SND BND BND PND PND SN/BN/PN Internal, by inserts SN SN BN BN PN PN - SN BN PN - SN BN PN - SN BN PN 0 SN BN PN 6 SN BN PN SL/BL - SLD/BLD By faces 0 - - - 0 SL SL SL SLD SL SL BL BL BL BLD BL BL SLT, BLT, Rotating nuts Accessories: FLBU, PLBU, BUF with SL/BL long lead screw
Recommendations for selection Recommendations for selection Only basic selection parameters are included. To make the very best selection of a ball screw, the designer should specify such critical parameters as the load profile, the linear or rotational speed, the rates of acceleration and deceleration, the cycle rate, the environment, the required life, the lead accuracy, the stiffness, and any other special requirement. If in doubt, please consult an SKF ball screw specialist before placing an order. Basic dynamic load rating (C a ) The dynamic rating is used to compute the fatigue life of ball screws. It is the axial load constant in magnitude and direction, and acting centrally under which the nominal life (as defi ned by ISO) reaches one million revolutions. Nominal fatigue life L The nominal life of a ball screw is the number of revolutions (or the number of operating hours at a given constant speed) which the ball screw is capable of enduring before the fi rst sign of fatigue (fl aking, spalling) occurs on one of the rolling surfaces. It is however evident from both laboratory tests and practical experience that seemingly identical ball screws operating under identical conditions have different lives, hence the notion of nominal life. It is, in accordance with ISO defi nition, the life achieved or exceeded by 90 % of a suffi ciently large group of apparently identical ball screws, working in identical conditions (alignment, axial and centrally applied load, speed, acceleration, lubrication, temperature and cleanliness). Service life The actual life achieved by a specifi c ball screw before it fails is known as service life. Failure is not only by fatigue (fl aking or spalling); but also by inadequate lubrication and wear; wear of the recirculation system, corrosion, contamination, and, more generally, by loss of the functional characteristics required by the application. Experience acquired with similar applications will help to select the proper screw to obtain the required service life. One must also take into account structural requirements such as the strength of screw ends and nut attachments, due to the loads applied on these elements in service. To attain L life performance a mean working load of up to 0 % of C a and a stroke higher than leads are permitted. Life test bench () SKF can help you to define this value in relation with the actual conditions of service.
Recommendations for selection Equivalent dynamic loads The loads acting on the screw can be calculated according to the laws of mechanics if the external forces (e.g. power transmission, work, rotary and linear inertia forces) are known or can be calculated. It is necessary to calculate the equivalent dynamic load. Radial and moment loads must be taken by linear bearing systems. It is extremely important to resolve these problems at the earliest conceptual stage. These forces are detrimental to the life and the expected performance of the screw. Fluctuating load When the load fl uctuates during the working cycle, it is necessary to calculate the equivalent dynamic load: this load is defi ned as that hypothetical load, constant in magnitude and direction, acting axially and centrally on the screw which, if applied, would have the same infl uence on the screw life as the actual loads to which the screw is subjected. Additional loads due, for example to misalignment, uneven loading, shocks, and so on, must be taken in account. Their infl uence on the nominal life of the screw is generally taken care of, consult SKF for advice. Static load carrying capacity (C oa ) d Ø Load C o Rolling element Ball screws should be selected on the basis of the basic static load rating C oa instead of on bearing life when they are submitted to continuous or intermittent shock loads, while stationary or rotating at very low speed for short duration. The permissible load is determined by the permanent deformation caused by the load acting at the contact points. It is defi ned by ISO standards as the purely axially and centrally applied static load which will create, by calculation, a total (rolling element + thread surface) permanent deformation equal to 0.000 of the diameter of the rolling element. A ball screw must be selected by its basic static load rating which must be, at least, equal to the product of the maximum axial static load applied and a safety factor s o. The safety factor is selected in relation with past experience of similar applications and requirements of running smoothness and noise level (). Critical rotating speed for screw shafts The shaft is equated to a cylinder, the diameter of which is the root diameter of the thread. The formulas use a parameter the value of which is dictated by the mounting of the screw shaft (whether it is simply supported or fi xed). As a rule the nut is not considered as a support of the screw shaft. Because of the potential inaccuracies in the mounting of the screw assembly, a safety factor of 0.0 is applied to the calculated critical speeds. Calculations which consider the nut as a support of the shaft, or reduce the safety factor, require practical tests and possibly an optimization of the design (). () SKF can help you to define this value in relation with the actual conditions of service. 6
Recommendations for selection Permissible speed limit Lubrication Efficiency and back-driving The permissible speed limit is that speed which a screw cannot reliably exceed at any time. It is generally the limiting speed of the recirculation system in the nut. It is expressed as the product of the rpm and the nominal diameter of the screw shaft (in mm). The speed limits quoted in this catalogue are the maximum speeds that may be applied through very short periods and in optimized running conditions of alignment, light external load and preload with monitored lubrication. Running a screw continuously at the permissible speed limit may lead to a reduction of the calculated life of the nut mechanism.! High speed associated with high load requires a large input torque and yields a relatively short nominal life (). In the case of high acceleration and deceleration, it is recommended to either work under a nominal external load or to apply a light preload to the nut to avoid internal sliding during reversal. The value of preload of screws submitted to high velocity must be that preload which ensures that the rolling elements do not slide (). Too high a preload will create unacceptable increases of the internal temperature. The lubrication of screws rotating at high speed must be properly considered in quantity and quality. The volume, spread and frequency of the application of the lubricant (oil or grease) must be properly selected and monitored. At high speed the lubricant spread on the surface of the screw shaft may be thrown off by centrifugal forces. It is important to monitor this phenomenon during the fi rst run at high speed and possibly adapt the frequency of relubrication or the fl ow of lubricant, or select a lubricant with a different viscosity. Monitoring the steady temperature reached by the nut permits the frequency of relubrication or the oil fl ow rate to be optimized. The performance of a screw is mainly dependant on the geometry of the contact surfaces and their fi nish as well as the helix angle of the thread. It is, also, dependant on the working conditions of the screw (load, speed, lubrication, preload, alignment, etc ). The direct effi ciency is used to defi ne the input torque required to transform the rotation of one member into the translation of the other. Conversely, the indirect effi ciency is used to defi ne the axial load required to transform the translation of one member into the rotation of the other one. It is used, also, to defi - ne the braking torque required to prevent that rotation. It is safe to consider that these screws are reversible or backdriveable under almost all circumstances. It is therefore necessary to design a brake mechanism if backdriving is to be avoided (gear reducers or brake). Friction Back driving torque T f > torque T r () SKF can help you to define this value in relation with the actual conditions of service. 7
Recommendations for selection Preload torque: Internally preloaded screws exhibit a torque due to this preload. This persists even when they are not externally loaded. Preload torque is measured when assembly is lubricated with ISO grade 6 oil. Starting torque: This is defi ned as the torque needed to overcome the following to start rotation: a) the total inertia of all moving parts accelerated by the energy source (including rotation and linear movement). b) the internal friction of the screw/nut assembly, bearing and associated guiding devices. In general, torque to overcome inertia (a) is greater than friction torque (b). The coeffi cient of friction of the high effi ciency screw when starting µ s is estimated at up to double the dynamic coeffi cient µ, under normal conditions of use. Axial play and preload Preloaded nuts are subject to much less elastic deformation than non-preloaded nuts. Therefore they should be used whenever the accuracy of positioning under load is important. Preload is that force applied to a set of two half nuts to either press them together or push them apart with the purpose of eliminating backlash or increasing the rigidity or stiffness of the assembly. The preload is defi ned by the value of the preload torque (see under that heading in the previous paragrah). The torque depends on the type of nut and on the mode of preload (elastic or rigid). Static axial stiffness of a complete assembly It is the ratio of the external axial load applied to the system and the axial displacement of the face of the nut in relation with the fi xed (anchored) end of the screw shaft. The inverse of the rigidity of the total system is equal to the sum of all the inverses of the rigidity of each of the components (screw shaft, nut as mounted on the shaft, supporting bearing, supporting housings, etc ). Because of this, the rigidity of the total system is always less than the smallest individual rigidity. Nut rigidity When a preload is applied to a nut, fi rstly, the internal play is eliminated, then, the Hertzian elastic deformation increases as the preload is applied so that the overall rigidity increases. The theoretical deformation does not take into account machining inaccuracies, actual sharing of the load between the different contact surfaces, the elasticity of the nut and of the screw shaft. The practical stiffness values given in the catalogue are lower than the theoretical values for this reason. The rigidity values given in the SKF ball screw catalogue are individual practical values for the assembled nut. They are determined by SKF based on the value of the selected basic preload and an external load equal to twice this preload. Lead Nut Lead + Shift Lead Elastic deformation of screw shaft This deformation is proportional to its length and inversely proportional to the square of the root diameter. According to the relative importance of the screw deformation (see rigidity of the total system), too large an increase in the preload of the nut and supporting bearings yields a limited increase of rigidity and notably increases the preload torque and therefore the running temperature. Consequently, the preload stated in the catalogue for each dimension is optimum and should not be increased. Screw shaft buckling The column loading of the screw shaft must be checked when it is submitted to compression loading (whether dynamically or statically). The maximum permissible compressive load is calculated using the Euler formulas. It is then multiplied by a safety factor of to, depending on the application. The type of end mounting of the shaft is critical to select the proper coeffi cients to be used in the Euler formulas. When the screw shaft comprises a single diameter, the root diameter is used for the calculation. When the screw comprises different sections with various diameters, calculations becomes more complex (). Screw () SKF can help you to define this value in relation with the actual conditions of service.
Recommendations for selection Manufacturing precision Generally speaking, the precision indication given in the designation defi nes the lead precisions see page - lead precision according to ISO - (ex. G - G7 ). Parameters other than lead precision correspond to our internal standards (generally based on ISO class 7 ). If you require special tolerances (for example class ) please specify when requesting a quotation or ordering. Materials and heat treatments Standard screw shafts are machined from steel which is surface hardened by induction (CrMo-NF EN0- for diameters > mm and CE for diameters mm). Standard nuts are machined in steel which is through hardened (0 Cr6 - NFA.6 or equivalent for diameters mm and carbon steel for diameters < mm). Hardness of the contact surfaces is 6-60 HRc, depending on diameter, for standard screws. Most assemblies made of stainless material have a surface hardness in the range 0 to HRc, depending on the type. The load rating of the catalogue are given only for standard screws. Number of circuits of balls A nut is defi ned by the number of ball turns which support the load. The number is changing, according to the product and the combination diameter/lead. It is defi ned by the number of circuits and their type. Recirculation inserts The standard products have been fi tted with composite ball recirculation inserts. System performance is improved because of the smoother ball recirculation. This results from the improved precision of the moulded insert when compared to the former steel insert. If the product is used in severe applications, or the insert is used to prevent collapse (especially in vertical applications), a steel version is available. In such cases, the specifi er should consult SKF Linear Motion to obtain the optimum solution. Working environment Our products have not been developed for use in an explosive atmosphere, consequently we cannot take any responsability for the use in this fi eld. NOTE: CrMo, an AFNOR reference is similar to AISI ; 0Cr6 is similar to AISI. () SKF can help you to define this value in relation with the actual conditions of service. 9
Recommendations for assembly Recommended assembly procedure Ball screws are precision components and should be handled with care to avoid shocks. When stored out of the shipping crate they must lie on wooden or plastic vee blocks and should not be allowed to sag. Screw assemblies are shipped, wrapped in a heavy gauge plastic tube which protects them from foreign material and possible pollution. They should stay wrapped until they are used. Radial and moment loads Any radial or moment load on the nut will overload some of the contact surfaces, thus signifi cantly reducing life (fi g. ). Alignment SKF linear guidance components should be used to ensure correct alignment and avoid non-axial loading. The parallelism of the screw shaft with the guiding devices must be checked. If external linear guidance proves impractical, we suggest mounting the nut on trunnions or gimbals and the screw shaft in self-aligning bearings. Mounting the screw in tension helps align it properly and eliminates buckling. Designing the screw shaft ends Generally speaking, when the ends of the screw shaft are specifi ed by the customer s engineering personnel, it is their responsability to check the strength of these ends. However, we offer in pages 6 to 9 of this catalogue, a choice of standard machined ends. As far as possible, we recommend their use. Whatever your choice may be, please keep in mind that no dimension on the shaft ends can exceed d o (otherwise traces of the root of thread will appear or the shaft must be made by joining pieces). A minimum shoulder should be suffi cient to maintain the internal bearing. Operating at high temperature will lower the hardness of the steel, alter the accuracy of the thread and may increase the oxidability of the materials or change lubricant properties. Lubrication Good lubrication is essential for the proper functioning of the screw and for its long term reliability (). Before shipping, the screw is coated with a protective fl uid that dries to a fi lm. This protective fi lm is not a lubricant. Depending on the selected lubricant, it may be necessary to remove this fi lm before applying the lubricant (there may be a risk of non-compatibility). If this operation is performed in a potentially polluted atmosphere it is highly recommended to proceed with a thorough cleaning of the assembly. Operating temperature Screws made from standard steel (see page 9) and operating under normal loads can sustain temperatures in the range - C to + C. Between + C and +0 C, SKF must be notifi ed so that it adapts the annealing procedure and checks that the application can be successful with a hardness below the standard minimum value (see page 9). Above +0 C, steels adapted to the temperature of the application should be selected (0Cr6, special steel, etc ). Consult SKF for advice. fig. YES! Axial loads fig. NO! Radial loads () SKF can help you to define this value in relation with the actual conditions of service.
Recommendations for assembly Separating the nut from the screw shaft Never screw the nut off the shaft without a mandrel to prevent the balls coming out (fi g. ).. Remove the retaining strap. Hold the sleeve against the ball track (a). If the sleeve does not go over the diameter next to the ball track, adhesive tape can be used (b) or the sleeve held against the unmachined end (c). (fi g. ). Without forcing, engage the nut in the screw thread. a fig. fig. Starting-up the screw After the assembly has been cleaned, mounted and lubricated, it is recommended that the nut is allowed to make several full strokes at low speed; to check the proper positioning of the limit switches or reversing mechanism before applying the full load and the full speed. NOTE: Intructions for most operations like mounting a nut on a screw shaft, a wiper on a nut, etc are available in separate sheets delivered with the product: please refer to them. b c
Standard technical data Lead precision according to ISO Lead precision is measured at C on the useful stroke l u, which is the threaded length decreased, at each end, by the length l e equal to the screw shaft diameter. G G7 G9 V 00p µm 7 l u e p v up e p v up e p v up mm µm 0-0 7 () - 0 7 0 (0) - 00 7 6 6 6 (00) - 60 9 70 7 0 (60) - 00 6 0 7 0 (00) - 00 90 6 0 (00) - 0 7 9 70 60 7 (0) - 00 0 0 (00) - 00 6 0 90 70 0 (00) - 00 7 9 7 60 (00) - 0 96 69 0 (0) - 00 60 0 6 70 (00) - 000 99 7 790 (000) - 6000 70 9 90 960 0 Lead accuracy control on a complete assembly
Standard technical data l u l e l o l s = useful travel = excess travel (no lead precision required) = nominal travel = specifi ed travel c = travel compensation (difference between l s and l o to be defi ned by the customer, for instance to compensate an expansion) e p = tolerance over the specifi ed travel V = travel variation (or permissible band width) V 00p = maximum permitted travel variation over 00 mm = maximum permitted travel variation over the useful V up travel l u V 00a = measured travel variation over 00 mm = measured travel variation over the useful travel V ua fig. l e Mean travel : the line which fits the curve best by method of least squares. v00a Threaded length l u v 00p µm + l e mm v up + - l 0 v ua l m 00 mm Case with value of c specified by the customer. fig. Case with c = 0 = standard version in case of no value given by the customer. fig. le Threaded length l u m + l e mm l 0 l e Threaded length l u m + l e v up e p e p c l m v up e p l 0 mm e p - l s -
SD/BD miniature screws Standard Recirculation Customised Smooth running and excellent backdriving with the new SD/BD internal recirculation nut. Nominal diameter to mm Lead: to mm Cylindrical nut with threaded end: easy mounting Excellent repeatibility: high positioning quality Internal recirculation with inserts: smooth running and good backdriving Backlash elimination by oversize balls on request (BD designation) Optional safety device (*): xr - xr - xr Optional wipers (*): For all sizes Corrosion resistant screw (see page ) (*) It is not possible to supply safety device and wipers in the same nut. Nominal Right Maximum Basic load ratings Number Maximum Reduced Mass Mass Inertia Designation diameter hand length of circuits axial maximum of nut of screw of one lead dynamic static of balls play axial play shaft metre of (on request) screw shaft P h C a C oa mm mm mm kn kn mm kg kg/m kgmm, 00,,6 0,07 0,0 0,0 0,, SD/BD x, R 00 00,,,, 0,07 0,07 0,0 0,0 0,00 0,0 0, 0,,, SD/BD x R SD/BD x R 00 00 00,9,0,,6 6,, 0,07 0,07 0,07 0,0 0,0 0,0 0,0 0,066 0,0 0,67 0,7 0,7,0,, SD/BD x R SD/BD x R SD/BD x R 00 6,0 9,0 0,07 0,0 0,0,0,0 SD/BD x R 00 00 00, 7,6,7 6,, 7,0, 0,07 0,07 0,07 0,0 0,0 0,0 0,0 0, 0,0,,0, 9,7,9 0,7 SD/BD x R SD/BD x R SD/BD x R
SD BD A A N A D d d D M D Designation Screw shaft Nut Without With Tightening Without wiper wipers spanner wiper mm d d D M A +/-0, A (FACOM) N A D D h 6g ± 0, SD/BD x, R 6, 7,6 7, Mx,, 7, 6-A,,, SD/BD x R SD/BD x R, 7, 9,,9 9,,0 M7x Mx,0,0,0-7,,0 6-A 6-A,,,,0, - SD/BD x R SD/BD x R SD/BD x R 9,9 9, 9,,,,,0,,0 Mx Mx Mx,0,0 6,0,,0,0,0,0,0 6-A 6-A 6-A,,,,, - -, - SD/BD x R,9,7 7,0 Mx, 0,0,0,0 6-A, - - SD/BD x R SD/BD x R SD/BD x R,,7,6,6,, 9,,,0 Mx, M6x, M6x, 7,0,0 6,0 7,0,0 6,0,0,0,0 6-A 6-A 6-A,,,, - 9,,, 9, Designation: see page 9
SDS/BDS/SHS miniature screws in stainless steel Standard SDS Standard SHS Customised SDS Nominal diameter 6 to mm Lead: to mm Cylindrical nut with threaded end: easy mounting Excellent repeatibility: high positioning quality Backlash elimination by oversize balls on request (BDS designation) Optional wipers: For all sizes Material for both shaft and nut: X0Cr (AISI equivalent) Balls are in XCrMo7 (AISI C equivalent) except for size xr (SDS/BDS): balls are in 0 Cr6 (AISI equivalent) Nominal Right Maximum Basic load ratings Number Maximum Reduced Mass Mass Inertia Designation diameter hand length of circuits axial maximum of nut of screw of one lead dynamic static of balls play axial play shaft metre of (on request) screw shaft P h C a C oa mm mm mm kn kn mm kg kg/m kgmm 6 00,0, x, 0,0 0,0 0,0 0, 0,7 SHS 6x R, 00,, 0,07 0,0 0,0 0,, SDS/BDS x, R 00,6,7 0,07 0,0 0,06 0,, SDS/BDS x R 00 00 00,,0,,,,6 0,07 0,07 0,07 0,0 0,0 0,0 0,0 0,06 0,06 0,67 0,7 0,7,0,, SDS/BDS x R SDS/BDS x R SDS/BDS x R 00,7, 0,07 0,0 0,07,0,0 SDS/BDS x R 00 00,0,7,0, 0,07 0,07 0,0 0,0 0,066 0,,,0 9,7,9 SDS/BDS x R SDS/BDS x R
SDS BDS A A N A D d d D M D Designation Screw shaft Nut Without With Tightening Without wiper wipers spanner wiper mm d d D M A +/-0, A (FACOM) N A D D h 6g ± 0, SHS 6x R,7 6,0, Mx,0-7, 6-A,, - SDS/BDS x, R 6, 7,6 7, Mx,0,, 7, 6-A,,, SDS/BDS x R, 9, 9, M7x,0,0,0 7, 6-A,,, SDS/BDS x R SDS/BDS x R SDS/BDS x R 9,9 9, 9,,,,,0,,0 Mx,0 Mx,0 Mx,0,,0,0,,0,0,0,0,0 6-A 6-A 6-A,,,,,,,,, SDS/BDS x R,9,7 7,0 Mx,,0,0,0 6-A, 7, 7, SDS/BDS x R SDS/BDS x R,,7,, 9,, Mx, M6x, 7,0,0 7,0,0,0,0 6-A 6-A,,,,,, Designation: see page 9 7
SH miniature screws Standard Recirculation Customised Rolled thread ball screw with ball recirculation by integrated tube. Nominal diameter 6 to,7 mm Lead: to,7 mm Nut with threaded end for easy mounting High positioning accuracy Increased security: optional reinforced safety device available on request in size SH,7x,7R Wipers available on request for size SH,7x,7R It is not possible to supply safety device and wipers in the same nut. Nominal Right Maximum Basic load ratings Number Maximum Reduced Mass Mass Inertia Designation diameter hand length of circuits axial maximum of nut of screw of one lead dynamic static of balls play axial play shaft metre of (on request) screw shaft P h C a C oa mm mm mm kn kn mm mm kg kg/m kgmm 6 00,, x, 0,0 0,0 0,0 0, 0,7 SH 6 x R 00,, x, 0,07 0,0 0,00 0,0, SH x R,7,7 00, 9,0 x, 0,07 0,0 0,0 0,7, SH,7 x,7 R
A A N A D d d D M D Designation Screw shaft Nut Tightening Without spanner wiper d d D M A A (FACOM) N A D D h 6g ± 0, ± 0, mm mm SH 6 x R,7 6,0, M x 7, 6.A,, - SH x R 7,9 9,9,0 M x 9 9,0 6.A,,, SH,7 x,7 R,,0 9, M x, 0,0 6.A,, - Designation: see page 9 9
SX/BX universal screws Standard Recirculation Customised Rolled thread ball screw internal recirculation nut with threaded end. Standard version: composite inserts Special version: steel inserts which can act as a safety device for severe requirements or vertical applications Contact us. Nominal diameter to 6 mm Lead: to mm Cylindrical body of minimum diameter to simplify assembly Lubrication hole for nipple or automatic SKF system, positioned relative to the ISO thread Handling screw: nut with axial play Screw shaft can be phosphated on request Wipers available Backlash elimination by oversize balls on request (BX designation) Nut mounting fl anges available Screw shaft accessories: FLBU - PLBU & BUF off the shelves. (see pages to ) Nominal Right Maximum Basic load ratings Number Maximum Reduced Preload Mass Mass Inertia Designation diameter hand length of circuits axial maximum torque of nut of screw of one lead dynamic static of balls play axial play BX shaft metre of (on request) average screw shaft P h C a C oa T pr mm mm mm kn kn mm mm Nm kg kg/m kgmm 700,, 0, 0,0 0, 0,7,0 SX/BX x R 700 700 9,, 7,,7 0, 0, 0,0 0,0 0,7 0, 0,9 0,6,, SX/BX x R SX/BX x R 700 700,,9 0,,7 0, 0, 0,0 0,0 0, 0, 0, 0,79,6,6 6 69 SX/BX x R SX/BX x R 700 700, 6,6 6, 7, 0, 0, 0,0 0,0 0, 0,6 0,66, 9,0, 9 7 SX/BX x R SX/BX x R 0 700,9 9, 6 0, 0,0,0,,6 76 SX/BX 0 x R 6 700 9,7, 6 0, 0,0,,90,0 99 SX/BX 6 x R
SX BX A Wiper N Wiper 90 D d d M x x Lubrication: Q A A A Designation Screw shaft Nut Lubrication hole Tightening spanner d d D M A A Q A N A js 6g mm mm SX/BX x R,7 9, M x, M6 x HN SX/BX x R SX/BX x R,7,,6,6 M x, M x, 69 7 9 9 M6 x M6 x HN6 HN6 SX/BX x R SX/BX x R,7 7,,6,0 M x, M x, 6 9 9 9 M6 x M6 x HN7 HN7 SX/BX x R SX/BX x R 6,7,0 9,6 9, 60 6 M6 x, M60 x,0 6 9 M6 x M x HN9 HN9 SX/BX 0 x R,0 9,7 7 M7 x,0 9 M x HN SX/BX 6 x R 7,0 6, 9 M x,0 9 M x HN Designation: see page 9
FHRF round flanges for SX/BX nuts SX nut SX nut with fl ange Flange A A J G H Nominal Dimensions Designation diameter P h A A G H J h h h js mm M FHRF 70 M6 M6 60 60 0 0 FHRF FHRF 70 96 M6 M6 69 69 9 9 FHRF FHRF 70 M M 9 69 76 FHRF x FHRF x 0 0 M 9 FHRF 0 6 0 M 6 FHRF 6
FHSF square flanges for SX/BX nuts SX nut SX nut with fl ange Flange A A N L J J Nominal Dimensions Designation diameter P h A A L J J N h h h js mm 60 6,6 6,6 FHSF 70 70 70 7, 7, 9,0 9,0 FHSF FHSF 70 96 0 0 60 60,, 9,0 9,0 FHSF FHSF 70 90 0 70 7 99,0,,0,0 FHSF x FHSF x 0 0 9,0,0 FHSF 0 6 0 0 7,0,0 FHSF 6 On special request, trunnion flanges are available.
SND/BND precision screws, DIN standard 690 Standard Recirculation With fl anged housing Rolled thread ball screw with internal recirculation nut. Standard version: composite inserts Special version: steel inserts which can act as a safety device for severe requirements or vertical applications Contact us. Nominal diameter to 6 mm Lead: to mm Lubrication hole for nipple or automatic SKF system Compact nut with integral fl ange for simple mounting and axial play Ground fl anged nut: precise mounting Wipers available Backlash elimination by oversize balls on request (BND designation) Screw shaft can be phosphated on request Screw shaft accessories: FLBU - PLBU & BUF off the shelves (see pages to ) Nominal Right Maximum Basic load ratings Number Maximum Reduced Preload Mass Mass Inertia Designation diameter hand length of circuits axial maximum torque of nut of screw of one lead dynamic static of balls play axial play BND shaft metre of (on request) average screw shaft P h C a C oa T pr mm mm mm kn kn mm mm Nm kg kg/m kgmm 00 00,,7, 7,0 x, 0,0 0,07 0,0 0,0 0,0 0, 0, 0,,0,,0 0,7 SND/BND x R SND/BND x R 700,7, 0, 0,0 0,0 0,,00,0 SND/BND x R 700 700,0,,7,7 0, 0, 0,0 0,0 0, 0, 0,9 0,6,0,0,0,0 SND/BND x R SND/BND x R 700 700 9,,6,, 0, 0, 0,0 0,0 0, 0, 0, 0,,60,60 6,0 69,0 SND/BND x R SND/BND x R 700 700, 6,6 6, 7, 0, 0, 0,0 0,0 0,6 0,6 0,6, 9,00, 9,0 7,0 SND/BND x R SND/BND x R 0 700 70,6 7,6 0, 0,0 0,,7,60 76,0 SND/BND 0 x R 6 700 7,,9 0, 0,0,,,00 99,0 SND/BND 6 x R
SND BND L L Lubrification hole M6x L 0' D (6x) D ØIT D6 D d d D -0, -0, DESIGN 90 Lubrification hole Mx 0 L L 7 L (x) D ØIT L tn DESIGN 0 90 Designation Screw shaft Nut Design d d D D D D 6 L tn L L 7 L L L g6 H h h mm SND/BND x R SND/BND x R,7,6,,,,, 7,0 7 SND/BND x R,7 9, 6 7 6,6, SND/BND x R SND/BND x R,7,,6,6 6,6 6,6 6 6, 7,0 SND/BND x R SND/BND x R,7 7,,6,0 0 0 6 6 9,0 9,0 0 0, 69,0 6 6 6 6 SND/BND x R SND/BND x R 6,7,0 9,6 9, 6 6 7 7 9,0 9,0 9 9, 9,0 70 70 7 7 SND/BND 0 x R,0 9,7 7 9,0 9,0 SND/BND 6 x R 7,0 6, 90,0 9,0 9 9 Designation: see page 9
PND preloaded screws, DIN standard 690 Standard Recirculation With plummer housing Rolled thread ball screw with internal recirculation nut. Standard version: composite inserts Special version: steel inserts which can act as a safety device for severe requirements or vertical applications Contact us. Nominal diameter to 6 mm Lead: to mm Lubrication hole for nipple or automatic SKF system One-piece nut with integral fl ange offering an internal preload for optimum rigidity Wipers available Screw shaft can be phosphated on request Screw shaft accessories: FLBU - PLBU & BUF off the shelves (see pages to ) Nominal Right Maximum Basic load ratings Number Preload Mass Mass Inertia Designation diameter hand length of circuits torque of nut of screw of one Preload for lead dynamic static of balls average shaft metre of optimum screw shaft rigidity P h C a C oa T pr mm mm mm kn kn Nm kg kg/m kgmm 00 00,7,7, 7,0 x x x, 0,0 0, 0, 0,,0,,0 0,7 PND x R PND x R 700,, x 0, 0,,00,0 PND x R 700 700,0,,7, x x 0, 0,0 0, 0,9,0,0,0,0 PND x R PND x R 700 700 9,,6,, x x 0, 0,6 0, 0,9,60,60 6,0 69,0 PND x R PND x R 700 700,, 6,,7 x x 0,7,7,,0 9,00, 9,0 7,0 PND x R PND x R 0 700 70,6 7,6 x,7,,60 76,0 PND 0 x R 6 700 7,,9 x,6,,00 99,0 PND 6 x R 6
S S+ S S Preload A displacement s is ground into the nut ball track between the two series of recirculation inserts: this displacement is made in an unused part of the track. The balls thus have two points of contact even under small external loads. L L Lubrification hole M6x L 0' D (6x) D ØIT D6 D d d D -0, -0, DESIGN 90 Lubrification hole Mx 0 L L 7 L (x) D ØIT L tn DESIGN 0 90 Designation Screw shaft Nut Design d d D D D D 6 L tn L L 7 L L L g6 H h h mm PND x R PND x R,7,6,,,, 7 77 PND x R,7 9, 6 7 6,6 0 PND x R PND x R,7,,6,6 6,6 6,6 6 6 6 7 PND x R PND x R,7 7,,6,0 0 0 6 6 9,0 9,0 0 0 7 6 6 6 6 PND x R PND x R 6,7,0 9,6 9, 6 6 7 7 9,0 9,0 9 9 0 70 70 7 7 PND 0 x R,0 9,7 7 9,0 PND 6 x R 7,0 6, 90,0 7 9 9 Designation: see page 9 7
SN/BN precision screws Standard Recirculation Customised Rolled thread ball screw with internal recirculation nut. Standard version: composite inserts Special version: steel inserts which can act as a safety device for severe requirements or vertical applications Contact us. Nominal diameter to 6 mm Lead: to mm Lubrication hole for nipple or automatic SKF system Compact nut with integral fl ange for simple mounting and axial play Ground fl anged nut: precise mounting Wipers available Backlash elimination by oversize balls on request (BN designation) Screw shaft can be phosphated on request Screw shaft accessories: FLBU - PLBU & BUF off the shelves (see pages to ) Nominal Right Maximum Basic load ratings Number Maximum Reduced Preload Mass Mass Inertia Designation diameter hand length of circuits axial maximum torque of nut of screw of one lead dynamic static of balls play axial play BN shaft metre of (on request) average screw shaft P h C a C oa T pr mm mm mm kn kn mm mm Nm kg kg/m kgmm 00,, 0,0 0,0 0,0 0,, SN/BN x R 700,7, 0, 0,0 0,0 0,,0 SN/BN x R 700 700,0,,7,7 0, 0, 0,0 0,0 0, 0, 0, 0,6,, SN/BN x R SN/BN x R 700 700 9,,6,, 0, 0, 0,0 0,0 0, 0, 0,,,6,6 6 69 SN/BN x R SN/BN x R 700 700, 6,6 6, 7, 0, 0, 0,0 0,0 0,6 0,6 0,6,6 9,0, 9 7 SN/BN x R SN/BN x R 0 700 70,6 7,6 0, 0,0 0,,9,6 76 SN/BN 0 x R 6 700 7,,9 0, 0,0,,70,0 99 SN/BN 6 x R
SN BN A A A A = = Q D D +0, -0, d d D -0, -0, D J D Designation Screw shaft Nut Lubrication hole d d D D A A A A J D Q g9 js mm SN/BN x R,7,, 0 6 x. M6 SN/BN x R,7 9, 7 6, 0 6 x 6.6 M6 SN/BN x R SN/BN x R,7,,6,6 6 67 6, 7,0 0 0 0 6 x 6.6 6 x 6.6 M6 M6 SN/BN x R SN/BN x R,7 7,,6,0 70 7, 79,0 0 6 70 6 x 6.6 6 x 9.0 M6 M x SN/BN x R SN/BN x R 6,7,0 9,6 9, 6 0 9, 9,0 0 0 6 7 6 x 6.6 6 x 9.0 M6 M x SN/BN 0 x R,0 9,7 7 99,0 6 90 6 x M x SN/BN 6 x R 7,0 6,,0 6 6 x M x Designation: see page 9 9
PN preloaded screws Standard Recirculation Customised Rolled thread ball screw with internal recirculation nut. Standard version: composite inserts Special version: steel inserts which can act as a safety device for severe requirements or vertical applications Contact us. Nominal diameter to 6 mm Lead: to mm Lubrication hole for nipple or automatic SKF system One-piece nut with integral fl ange offering an internal preload for optimum rigidity Wipers available Screw shaft can be phosphated on request Screw shaft accessories: FLBU - PLBU & BUF off the shelves (see pages to ) Nominal Right Maximum Basic load ratings Number Preload Mass Mass Inertia Designation diameter hand length of circuits torque of nut of screw of one Preload lead dynamic static of balls PN shaft metre of for optimum average screw shaft rigidity P h C a C oa T pr mm mm mm kn kn Nm kg kg/m kgmm 00,7, x 0,0 0,, PN x R 700,, x 0, 0,7,0 PN x R 700 700,0,,7, x x 0, 0,0 0, 0,6,, PN x R PN x R 700 700 9,,6,, x x 0, 0,6 0,6,7,6,6 6 69 PN x R PN x R 700 700,, 6,,7 x x 0,7,7 0,,0 9,0, 9 7 PN x R PN x R 0 700 70,6 7,6 x,7,,6 76 PN 0 x R 6 700 7,,9 x,6,0,0 99 PN 6 x R 0
S S+ S S Preload A displacement s is ground into the nut ball track between the two series of recirculation inserts: this displacement is made in an unused part of the track. The balls thus have two points of contact even under small external loads. A A A A = = Q D D +0, -0, d d D -0, -0, D J D Designation Screw shaft Nut Lubrication hole d d D D A A A A J D Q g9 js mm PN x R,7, 0 6 x. M6 PN x R,7 9, 7 0 6 x 6.6 M6 PN x R PN x R,7,,6,6 6 67 6 7 0 0 0 6 x 6.6 6 x 6.6 M6 M6 PN x R PN x R,7 7,,6,0 70 7 7 0 6 70 6 x 6.6 6 x 9.0 M6 M x PN x R PN x R 6,7,0 9,6 9, 6 0 9 0 0 6 7 6 x 6.6 6 x 9.0 M6 M x PN 0 x R,0 9,7 7 7 6 90 6 x M x PN 6 x R 7,0 6, 6 6 x M x Designation: see page 9
SL/BL long lead screws Standard Recirculation Customised A new ball circulation system allowing high linear speed and low noise level. Nominal diameter to 0 mm Lead: to 0 mm Lubrication hole for nipple or automatic SKF system Two versions: - nut with axial play SL - nut with backlash elimination by oversize balls BL Double protection with polyamide wipers and brush wipers (WPR = with brush wipers NOWPR = without brush wipers) Screw shaft can be phosphated on request Screw shaft accessories: FLBU - PLBU & BUF off the shelves (see pages to ) Nominal Right Maximum Number SL BL Mass Mass Inertia Designation diameter hand length of circuits Basic load Maximum Preload of nut of screw of one lead of balls ratings axial play torque BL shaft metre of average screw shaft P h C a C oa S ap T pr mm mm mm kn kn mm Nm kg kg/m kgmm /m 700 700 x,7 x,7,0,6,6,0 0,0 0,0 0, 0, 0,6 0,7,, SL/BL x R SL/BL x R 700 700 700 700 x,7 x, x, x 0,,7 6,0 6,0,7 6, 6, 6,,6 0,0 0,0 0,0 0,0 0,9 0,9 0,9 0, 0,,0 0,9 0,7,,,,9 0 600 600 90 SL/BL x R SL/BL x R SLD/BLD x R SL/BL x R 700 700 x,7 x,7,, 9,, 0,0 0, 0, 0,,,,, 0 0 SL/BL x R SL/BL x R 0 0 700 x,7 9,, 0,,9,, 60 SL/BL 0 x 0 R
SL BL A = = Q A A A D D J L D -0, -0, d d D -0, -0, D Lubrification hole M6x 0 (6x) D ØIT J D See table below DESIGN 90 Designation Screw shaft Nut Lubrication hole mm d d D D A A A A J L D Q g9 js SL/BL x R SL/BL x R,7,,, 7 7 7,,6 66, 77,9 7 60 60 6 x 6.6 6 x 6.6 M6 M6 SL/BL x R SL/BL x R SLD/BLD x R SL/BL x R 7,,, 6,9 0,0,, 9,6 6 6 0 g6 g6 0 0 0 0 7,,0,0,0 66, 0, 0,,0 7 6 6 6 6 6 6 x 6.6 6 x 6.6 6 x 9.0 6 x 6.6 M6 M6 M6 (Design ) M6 SL/BL x R SL/BL x R,, 7,7, 6 7 9 7,, 6,, 7 90 6 x 9.0 6 x M6 M x SL/BL 0 x 0 R, 9,,,0 60 6 x M x Designation: see page 9
Rotating nut Concept The nut rotates inside bearings and moves along the fi xed long lead screw shaft. The drive motor moves with the nut, so inertia & critical speed problems, associated with a long rotating shaft, are minimised. Design details 7 series angular contact bearings are directly mounted on the nut. They are preloaded in 0 confi guration in order to fully support the torque due to the belt tension. Nilos seals protect these bearings against pollution and permit lubrication for life. Two versions available: * Ball screw with axial play: SLT * Ball screw with backlash elimination: BLT Two brush wipers are mounted in the standard confi guration for better protection. Ball screw lubrication: through the nipple placed on the housing external diameter in the standard version, or as an option through the screw shaft. Ball nut greased with SKF LGMT. Other lubricants possible on request. Benefits Easy and simple to incorporate. Compact solution, ready to use. Fixed screw shaft: simplifi ed mounting. Inertia considerably reduced: 00 kgmm instead of 6000 kgmm for a screw shaft, x -. m stroke. Smaller, lighter, lower power motors. Higher linear speeds: up to m/min. Ball screw capacities Bearing axial capacities Size Dynamic capacity Static capacity Dynamic capacity Static capacity C a C oa C a C oa kn kn kn kn x x 9,, 96,6 0, 6, 6, 6,0 6,0 x x x 9,, 0,0, 7,,7 7,0 7,0 7,0 76, 76, 76, x x,7, 76,7, 9,6,0 9,,0 0x0 9,,,0 6,0
Rotating nut inertia Size Inertia Mass of Pulley support rotating nut kgmm kg x x,,6 Rotating nut capacities Size Max. transmissible Max. transmissible torque axial load Nm kn x x 0 0 6, 6, x x x 9 99 99 7, 7, 7, x x x 9 9 9 7,0 7,,7 x x 09 7 7,, x x 6,0 9, 0x0, 0x0 0,0 L L7 L9 Z x H Z x H L L L6 Ø Ø Ø Ø6 Ø R L Ø7 Ø H R J J L L L Ø Ø Ø Ø Ø Ø6 Ø7 L L L L L L L6 L7 L L9 R R J J ZxH ZxHx H useful depth Designation h g6 max max mm SLT/BLT x SLT/BLT x 7, 7, 0,0 0,0 0 0 6 6,0 6,,, 9,9 9,9 7 7,9,9,,9,, 0, 0, 0, 0, 6xØ9 6xØ9 6xM6x 6xM6x M6x M6x SLT/BLT x SLT/BLT x SLT/BLT x 0 0 0,0,0,0 9, 9, 9, 0 0 0 76 76 76 6 0, 6,,7,,, 7, 7, 7, 9 9 9,,, 7,,,7,0,0,0 0, 0, 0, 0, 0, 0, 6 6 6 6xØ9 6xØ9 6xØ9 6xM6x 6xM6x 6xM6x M6x M6x M6x SLT/BLT x SLT/BLT x 60 9,0 9,0,0 7,0 9 7 0 6 7, 9, 7 9,,, 9,0,7 0 7,,,0, 0,,6 0,,6 7 0 xø9 xø9 6xM6x 6xM6x Mx Mx SLT/BLT 0x0 70,0 70,0 70,,, 0,,,7,6,6 90 6 xø 6xMx0 Mx All tolerances js if not specified.
Shaft end combinations In the order code, shaft end machining is defi ned by: - one letter for Ø < mm - two letters for Ø mm resulting from the combination of two machined ends (see designation page 9). Machined ends are represented in details in page 7 for Ø < mm and page for Ø mm. Ø < mm Ø mm Order code Two machined ends Order code Two machined ends A (without length indication) cut only AA (without length indication) cut only A (+ length) cut + annealed B + BA A + A F * + FA * A + A G * + GA * A + A H + HA A + A J M + + JA MA A + A A + A UA end machining S (+ length) Ends to root diameter, any possible lengths SA (+ length) UA n (+ length) Ends to root diameter d, any possible lengths. End machined to diameter d under induction hardening, any possible lengths. Dimensions Ød Ød mm mm K Keyway K Keyway x,7 9 Z To customer s drawing Z To customer s drawing x,7 * Attention! This mounting requires the greatest precautions. Please contact us. x x x x,7,,7, 9 9 n UA: end machined to diameter d under induction hardening, any possible lengths. x x DIN x x x x,7 7, 6,0 7,, 6,9 6 6 x x x x 6,7,0,, d d 0 x 0 x 0,0, 6 x 7,0 6
Standard end machining for nominal diameter < mm Special ends are machined to customers drawing on request. For SD - SH Type Type Type Type Type Keyway d d B B B B B B 6 G G m d 6 c b a d 7 r a a b e j S Keyway h7 js7 js js js H js 6g + 0, h/h h maxi N9 +0, DIN 6 0 0 6 7, 7 M x 0,7 7,0 0,, 0,,,9 7 6,6 9 M x 0, 7, 0,7, 0,,,7 0, 6 6 9 6,7 M6 x 7, 0,,7 0,,, 0, /,7 6 0 7, M x, 0,9 7,6 0,, 6, 0,, 0, A x x 6 9,0 M x,,, 9,6 0,, 7, 0, 6, 0, A x x 7
Standard end machining for nominal diameter mm Standard shaft ends for ball screws, nominal diameter mm, have been developed to suit the SKF thrust bearings FLBU, PLBU and BUF. These standard ends are the same for all screw types. However, for the SL/BL long lead screw, an additional shoulder, part of the threaded length, will be machined to protect the wiper and nut thread during assembly (both sides). Apart from this, the end itself is the same for all screw types. End bearing D Machined end type FLBU A or A PLBU A or A BUF A or A For SD/BD - SX/BX - SN/BN/PN - SND/BND/PND Size d d d d d B B B B B B 6 B 7 B 9 d G G m d 6 c c b a d 7 r a Keyway to DIN 6 a N9 xl xb h7 h6 h6 h7 js js js H js 6g + 0, h h h fixed end fixed end + 0 (type A) (type A) 0 6 7 0 7 0 0 / / / / / / / 7 7 0 0 66 69 76 7 0 0 6 69 7 96 99 9 79 7. 7..7 9 9 6 6 67 67 9.... 0 0 0 0 0 0 0...7.. Mx0.7 Mx M7x Mx M0x. Mx. M0x. 7 7.....6.6. 9.6 9.6...6.6. 0. 0. 0. 0.. 0. 0. 0. 0. 0. 0......... 0. 0.. 0. / 0.. 0. /.. 0. / 0. 7. 0. /.. 0. /. 7. 0. / Axx Axx Axx Axx Ax7x Ax7x Axx0 Axx Axx Axx Axx Ax7x Ax7x Axx0 For SL/BL only Size d d d d d B B B B B B 6 B 7 B 9 d G G m d 6 c c b a d 7 r a Keyway to DIN 6 a N9 xl xb h7 h6 h6 h7 js js js H js 6g + 0, h h h fixed end fixed end + 0 (type A) (type A) x 7 / 7 66 0 96 6. 0.7 M7 x.. 0. 0... 0. Axx Axx x 7 / 7 66 0 96 6. 0. M7 x.. 0. 0... 0. Axx Axx x x x 7 7 7... 7 7 7 69 69 76 0 0 0 99 99 99 6 6 6... 7.. 6.9 M x M x M x......6 0. 0. 0. 0. 0. 0........ 0. /. 0. /. 0. / Axx Axx Axx Axx Axx Axx x x 0 0 / / 0 0 76 76 7. 7. 67 67 6. 6. 0 0..0 M0 x. M0 x..6.6.6.6 0. 0... 7. 7. 0. 0. Ax7x Ax7x Ax7x Ax7x 0 x 0 0 7 0 9 7. 67 9. M x. 7.6.6 0.... 0. / Ax7x Ax7x / for end types A or A
Standard machined ends Threaded length = total length - end length (n) : end length Type A For SL/BL only Type A Ra d G d For SL/BL only 0 C x B 7 x d 0 c x B 7 x d B c x b a x d 7 G (B ) B c x For other types Ra d G d For other types b a x d 7 c x c x G B (B ) B Type A d G For SL/BL only Type A B 7 x d B 9 x d B For SL/BL only m x d 6 c x r 0 a b a x d 7 c x B 7 x d G B 0 c x r a B c x d d G For other types B 7 x d B For other types m x d 6 d r a B b a x d 7 c x G c x B r a c x Type A B 7 x d B m x d 6 For SL/BL only Keyway d d // b // 0 c x B 9 x d r a c x c x c x B (B ) B 6 B 7 x d B m x d 6 For other types d d r a c x c x B (B ) B 6 c x a N 9 9
End bearings Axially locating flanged housing with SKF angular contact ball bearings (back to back arrangement). The FLBU flanged bearing unit consists of: precision housing, made of burnished steel two SKF preloaded angular contact ball bearings, 7 or 7 series two garter seals locknut, self-locking Nylstop type or, on demand, high precision KMT The FLBU flanged thrust bearing unit provides the following benefits: lubrication for life. very easy mounting (matched bearings, hand mounting on the shaft end) as well as easy disassembly with the optional high precision KMT nut. In standard version, the FLBU thrust bearing unit is assembled according to drawing page. If you require a different assembly, please indicate it when ordering. Angular contact ball bearing ( ) Lock nut Basic load rating SKF Bearing Self locking nut High precision nut / (axial) designation Size Flanged bearing C a (kn) C oa (kn) Designation Hook Designation Hook Tightening Grub screws unit designation spanner spanner torque (Nm) Size Max. tightening torque (Nm) FLBU.. 70 BECB / CN 70- HN KMT 0 HN / M. FLBU..7 7 BEGA / CN 70- HN KMT HN M. FLBU 7.9.9 70 BEGA / CN 70-7 HN KMT HN M 6.0 FLBU.6.9 7 BEGA / CN 70- HN KMT HN M 6.0 FLBU.9 9.6 76 BEGA / CN 70-0 HN 6 KMT 6 HN 6 M 6.0 0 FLBU 0. 79. 77 BEGA / CN 70- HN 7 KMT 7 HN 7 M 6.0 6 FLBU 6.0 96. 7 BEGA / CN 70-0 HN KMT HN / 60 M.0 / No backlash elimination / Light preload / Optional
x S Ø 0..6 E D D D D D.6 60 x L L L L Dimensions (mm) Size L L L L D D D D D S Fixing E Self locking High precision h7 Self locking High precision H screws nut nut / nut nut / 7 7.0 76 0 7 6 6.6 M6 x 0 6 7. 76 0 7 6 0 6.6 M6 x 0 7 6. 90 6 60 76 7 6.6 M6 x 0 9. 90 9 60 7 9.0 M x.0 0 0 0 9.0 M x 0 9.0 0 9 90 0.0 M x 60 9 6..7 6 6 7.0 M x 60 6 / Optional
End bearings Fixed plummer housing with SKF angular contact ball bearings (back to back arrangement) The PLBU plummer bearing unit consists of: precision housing, made of burnished steel, with precision reference edges on both sides two SKF preloaded angular contact ball bearings, 7 or 7 series two garter seals locknut, self-locking Nylstop type or, on demand, high precision KMT The PLBU plummer bearing unit provides the following benefits: lubrication for life. very easy mounting (matched bearing, hand mounting on the shaft ends) as well as easy disassembly with the optional high precision KMT nut. good rigidity guaranted by foot mounting with dowel pins. Angular contact ball bearing ( ) Lock nut Basic load rating SKF Bearing Self locking nut High precision nut / (axial) designation Size Flanged bearing C a (kn) C oa (kn) Designation Hook Designation Hook Tightening Grub screws unit designation spanner spanner torque (Nm) Size Max. tightening torque (Nm) PLBU.. 70 BECB / CN 70- HN KMT 0 HN / M. PLBU..7 7 BEGA / CN 70- HN KMT HN M. PLBU 7.9.9 70 BEGA / CN 70-7 HN KMT HN M 6.0 PLBU.6.9 7 BEGA / CN 70- HN KMT HN M 6.0 PLBU.9 9.6 76 BEGA / CN 70-0 HN 6 KMT 6 HN 6 M 6.0 0 PLBU 0. 79. 77 BEGA / CN 70- HN 7 KMT 7 HN 7 M 6.0 6 PLBU 6.0 96. 7 BEGA / CN 70-0 HN KMT HN / 60 M.0 / No backlash elimination / Light preload / Optional
Dimensions (mm) Size L L L L M B B B H H H H H S P Fixing S D Tapered pin js Self High js screws H Self High (hardened) locking precision locking precision or straight nut nut / nut nut / pin (DIN6) 6 6 7 7.0 9 0. M x 7.7 x 9 60 77 7 7. 6 7 9 0. M x 7.7 0 x 6 66 6 9. 7 9 7 9 0. M x 9.7 7 x 0 6 70 9 6 9 9. 77 7 0. M x 9.7 x 0 6 0 6.0 9 0. M x 0 9.7 9 x 0 0 0 9 7 9.0 6 0. M x 9.7 0 x 6 90 0 0 9.7 0 6 9 0. M x 6 9.7 6 7 x 6 / Optional
End bearings Axially free plummer housing with SKF deep-groove ball bearing The BUF plummer bearing unit consists of: bearing housing made of burnished steel, with one reference side grease-tight deep-groove SKF ball bearing, greased for life, type 6... RS retaining ring In standard version, the BUF thrust bearing unit is assembled according to drawing page. If you require a different assembly, please indicate it when ordering. Deep-groove ball bearing Basic load rating SKF Bearing Dimensions (mm) (radial) designation Size Plummer bearing C (kn) C o (kn) d D B unit designation (free) Retaining ring (DIN 7) BUF.07.6 60.RS 0 9 x BUF.07.6 60.RS 0 9 x BUF 9.6.7 6.RS 7 7x BUF 9.6.7 6.RS 7 7x BUF 9.. 66.RS 0 6 0x. 0 BUF 0 9.. 66.RS 0 6 0x. 6 BUF 6..6 69.RS 9 x.7
L H H ØS L M = B = H H H L L Dimensions (mm) Size L L L L M B H H H H H S Fixing js js H screws 6 6 9 M x 9 60 77 7 6 6 7 9 M x 6 66 7 9 7 9 M x 6 70 9 6 77 7 M x 6 0 6 9 M x 0 0 0 9 7 9 6 M x 6 90 0 0 9 0 6 9 M x 6
Calculation formulas Calculation formulas. Dynamic load rating (N) and Basic life rating C a L = ( ) or C req = F m (L ) / F m req L = life (million of revolutions) C a = basic dynamic load rating C req = required dynamic load rating F m = cubic mean load (N). Cubic mean load (N) F m = (F L + F L + F L + ) / (L + L + L + ) / Axial Load F F F L L L stroke F m = F min + F max Axial Load F min F max stroke. Critical speed of screw shaft (no safety factor) (rpm) (a factor of 0, is generally recommended) n cr = 90.. f d l d = root diameter (mm) l = free length, or distance between the two support bearings (see page 6) f = 0,9 fi xed, free, fi xed, supported,6 fi xed, fi xed. Speed limit of the mechanism (maxi speed applied through very short periods) For instance : n x < 0 000 with recirculation by tubes/inserts (SH-SD/BD- SX/BX-SN/BN/PN-SND/BND/PND) n x < 90 000 with recirculation through flange (SL/BL-SLD/BLD) if > 0 000/90 000, consult SKF n = revolutions per minute = screw shaft nominal diameter. Buckling strength (with a safety factor: ) (N) F c = 00. f. d l d l f = root diameter (mm) = free length, or distance between the two support bearings = mounting correction factor 0, fi xed, free supported, supported fi xed, supported fi xed, fi xed 6
Calculation formulas Calculation formulas 6. Theoretical effi ciency direct ( h ) motor Rotation result Translation h = + p. P h µ µ = 0,006 for SH µ = 0,006 for SD, SX, SL, SN, SND, BD, BX, BN, BL, PN, PND = nominal diameter of screw shaft = lead (mm) P h indirect ( h ) motor Translation result Rotation h' = - h 7. Practical effi ciency ( h p ) h p = h. 0,9 The value 0,9 used is an average value between the practical effi - ciency of a new screw and that of a properly run in screw. It should be used for industrial applications in all normal working conditions. For extreme cases, call us.. Input torque in a steady state (Nm) T = F. P h 00.p.h p F P h h p = maximum load of the cycle (N) = lead (mm) = practical effi ciency 9. Power required in a steady state (W) P = F.n.P h 60000.h p n = revolutions per minute. Preload torque (Nm) F T pr = pr.p h ( - ) 00.p h p F pr = preload (N) 7
Calculation formulas Calculation formulas. Restraining torque (Nm) (considering system backdriving) T B = F.P h.h' 00.p F = load (N) For safety, we can use the theoretical indirect effi ciency h = indirect effi ciency. Nominal motor torque when accelerating (Nm) For a horizontal screw T t = T f + T pr + For a vertical screw T t = T f + T pr + P h F + m L.m f.g 00.p.h p P h F + m L.g 00.p.h p. + ws!. + ws! T f = torque from friction in support bearings, motors, seals, etc... (Nm) T pr = preload torque m f = coeffi cient of friction h p = real direct effi ciency w = angular acceleration (rad/s ) m L = mass of the load (kg) g = acceleration of gravity (9, m/s ) S! =! M +! L +! S. l. -9. Nominal braking torque when decelerating (Nm) For a horizontal screw T' t = T f + T pr + For a vertical screw T t = T f + T pr + P h.h'. F + m L.m f.g 00.p P h.h'. F + m L.g 00.p. + ws!. + ws!! L = m L ( P h ) -6 p h = theoretical indirect effi ciency! M = inertia of motor (kgm )! S = inertia of screw shaft per metre (kgmm /m) l = length of screw shaft (mm) For additional information, please contact SKF
Designation Designation SN x R 0/ G7 L - HA + K **/** WPR Nut type SD = Miniature screw, axial play, internal recirculation nut SDS = Miniature screw, axial play, stainless steel BD = Miniature screw, backlash elimination by oversize balls BDS = Miniature screw, backlash elimination, stainless steel SH = Miniature screw, axial play, recirculation by integrated tube SHS = Miniature screw, axial play, stainless steel SX = Universal screw, axial play BX = Universal screw, backlash elimination by oversize balls SN = Precision screw, axial play BN = Precision screw, backlash elimination by oversize balls SND = Precision screw, axial play, DIN nut BND = Precision screw, backlash elimination by oversize balls, DIN nut PN = Precision screw with optimal rigidity PND = Precision screw with optimal rigidity, DIN nut SL = Long lead screw, axial play SLD = Long lead screw, axial play, DIN nut BL = Long lead screw, backlash elimination by oversize balls BLD = Long lead screw, backlash elimination by oversize balls, DIN nut SLT = Rotating nut with axial play BLT = Rotating nut with backlash elimination Nominal diameter x Lead Hand R = Right L = Left (on request) Threaded length / Total length, mm Lead precision: G9, G7, G Nut orientation Threaded side or flange of nut towards shorter (S) or longer (L) machined end of shaft. In case of same end machining : ( ) Machined end combination See page 6 Required lengths for: AA - SA (both side) See page 6 WPR: with wipers NOWPR: without RING: safety ring (for SH-SD only) REDPLAY : Reduced axial play 9
The robust screws for long life in tough conditions. Ø = to mm Ph = to mm * high load carrying capacity * ability to survive occasional blows and shock loads * highly reliable, even in hostile surroundings and at high rotational speed. Planetary roller screws Recirculating roller screws The fine screws for ultimate positioning accuracy. Ø = to mm Ph = to mm * fi ne resolution * high rigidity 0
Electro-mechanical cylinders They are designed for long life, high acceleration and high force applications. The cylinders use brushless servomotor technology, with an in-line direct drive as standard. SKF high performance electro-mechanical cylinders using planetary roller screws are expanding the limits of linear actuators. The high performance Electro-Mechanical cylinders consist of an SKF planetary roller screw directly driven through a coupling by a brushless motor. The roller screw converts rotary motion into linear movement. The new standard for high performance motion Compact Electro-Mechanical cylinders (CEMC) are designed to deliver the combination of a dynamic fl exible actuation packaged with powerful performance. Cylinders for heavy loads High loads and heavy working cycles: long life in adverse environments such as in steel industry.
Actuation Ball & Roller screws Contacts www.ball-rollerscrews@skf.com transrol.france@skf.com Represented by: SKF is a registered trademark of the SKF Group. SKF Group 0-0 The contents of this publication are the copyright of the publisher and may not be reproduced (even extracts) unless prior written permission is granted. Every care has been taken to ensure the accuracy of the information contained in this publication but no liability can be accepted for any loss or damage whether direct, indirect or consequential arising out of the use of the information contained herein. Publication EN - 0-0 Printed in France on environmentally friendly paper