NSK Linear Guides A roller guide series employing advanced analysis technology offers super-high load capacity and rigidity. The RA series includes a complete lineup to handle a wide range of applications. Extended series
The fruits of comprehensive technology of NSK RA series roller guides handle a diversity of applications The RA series of roller guides is the product of a combination of NSK s extensive experience in roller bearings and linear guide technologies. The result is an optimal design that takes full advantage of NSK s unique expertise to realize super-high load capacity, rigidity and motion accuracy, plus smooth motion. Capable of handling a variety of applications, the RA series supports high machine performance. RA series features support high machine performance Super-long Life Super-high load capacity NSK has realized super-high load capacity, now the highest performance in the world, and achieved unprecedented operating life. Maintenance-free Installing an NSK K1 lubrication unit assures long-term, maintenance-free operation. Highly dust-proof The high performance seals as standard equipment completely block the entry of foreign matter and maintain primary performance over the long term. Optimal design through integration of NSK technologies Smooth motion by use of retaining pieces Roller Guide RA Series Balanced four-directional iso-load specifications NSK executed a comprehensive, detailed performance simulation of roller guides by integrating its analysis technology and the tribology technology that the company had been developing over many years. Down to the dimensions and shapes of component details, we have attained an optimal design completely. 4 4 Example of roller slide deformation analysis Analysis example of contact pressure distribution of rollers Contribution to High-precision Manufacturing Super-high rigidity Super-high rigidity provides high-precision manufacturing. Super-high motion accuracy Coupled with NSK s unique design approach, the vibration caused by roller passage has been substantially reduced. This will greatly contribute to improve machining quality. Smooth motion The installation of a retaining piece achieves smooth motion, resulting in stable positioning accuracy. Five sizes (RA1, RA2, RA2, RA3 and RA6) have been added to the RA series. NSK also introduces a low-profile size (doesn t apply to RA2 and RA6). Used in Many Fields Complete series Series includes a full lineup from small to large, including low-profile sizes. You can choose the model according to the application. Interchangeable mounting dimensions Outside dimensions and mounting dimensions conform to standard dimensions for the market, so RA series roller guides can be used without having to alter machine design. (See page 1 for mounting surface dimensions) Low friction Uses rollers for rolling elements to hold down dynamic friction. 1 2
A variety of contributions to improve the performance of machine NSK roller guide RA series exhibits the world s highest load capacity and enhance the performance of machine through a variety of features, including super-high rigidity, super-high motion accuracy, and low friction variation. Features Super-high load capacity By installing rollers that are the largest possible diameter and length within the existing standard cross-section dimension in a rational layout based on analysis technology, we have realized the world s highest load capacity, far superior to conventional roller guides. Super-long life is achieved and impact load can be sufficiently handled. Super-high motion accuracy NSK has developed its own unique method of simulating rolling element passage vibration and method of designing optimal roller slide specifications for damping roller passage vibration. These developments have dramatically enhanced roller slide motion accuracy for the RA series. Change of attitude (pitching) Automatic collimator NSK RA3BN Compared with products of the same size, as of September 1, 23, researched by NSK. C, kn 14 12 1 8 NSK RA4BN Co, kn 3 3 2 NSK RA4BN Linear guide Movement at a given speed Conversion to the overhang point of 1 mm Displacement 1 m 2 4 6 8 1 Comparison of measured motion accuracy 6 2 Basic static load rating Basic dynamic load rating The basic load rating which is shown in the figures complies with ISO standards. Standards for basic dynamic load rating: ISO14728-1 Standards for basic static load rating: ISO14728-2 Smooth motion Installing a retaining piece between rollers and restraining the skew peculiar to roller bearings achieve smooth motion. The reduction of friction variation provides stable tracking in the complicated trajectory control. Motion smoothness of RA series equivalent to competitor s product Motion smoothness of RA series Super-high rigidity Using NSK s advanced analysis technology, we pursued a complete, optimal design, down to the detailed shape of roller slides and rails, thereby realizing super-high rigidity superior to that of competitor s roller guides. Direction of tension Direction of compression Retaining piece Roller Recirculation can be conducted smoothly by maintaining roller attitude. Rail Friction force, N 3 2 1 Without retaining piece 2 4 6 Friction force, N 3 2 1 With retaining piece 2 4 6 2 Direction of compression 2 Direction of tension Measured motion smoothness 1 1 1 NSK RA4BN 1 NSK RA4BN Mounting dimensions compatibility The outer and mounting dimensions of RA series are based on market standards. RA series can be replaced without altering equipment design. (See page 1 for mounting surface dimensions) 1 1 2 1 1 2 Comparison of measured rigidity 3 4
Specifications Low friction Using rollers for rolling elements helps minimize dynamic friction. Conventional linear guide for machine tools #3; medium preload (Z3) Measurement conditions Lubrication: Oil (VG68) Feeding speed: 1 m/min RA3AN; medium preload (Z3) 1. Roller Slide Types and Shapes Two types of roller slides are available in this series: one with a mounting flange and a square type with tapped holes and no flange. A compact, low-profile square type is now available. On the mounting hole of the flange type, the tapped part is used to fix the roller slide from the top surface, and the minor diameter can be used as a bolt hole from the bottom. This provides mounting from both directions, top and bottom. Roller slide length can be specified by standard high load type or special long, super-high load type. 4 3 4 3 Fig. 1 Square type Roller slide shape code Friction force, N 2 1 1 2 3 Friction force, N 2 1 1 2 3 AN (High load) 4 4 2 4 6 8 1 1 2 2 4 6 8 1 1 2 Comparison of measured dynamic friction force BN (Super-high load) Highly dust-proof and maintenance-free operation Roller slides include high performance seals as standard equipment. The seal completely blocks the entry of foreign matter in to the rolling surface and prevents loss of performance. In addition, rail covers are also available for severe operating conditions. (Rail covers reduce the amount of foreign matter to 1/1 that of conventional linear guide for machine tools.) The highly regarded NSK K1 lubrication unit is also available to satisfy customer needs for long-term, maintenance-free operation. Amount of foreign matter passing through, g.6..4.3.2.1. Conventional linear guide for machine tools RA series with rail cover Fig. 2 Low-profile type AL (High load) BL (Super-high load) Example results of foreign matter invasion test Fig. 3 Flange type Low noise A retaining piece is provided between rollers to prevent collision of rollers to minimize noise. Noise level, db (A) 8 7 7 6 6 RA4BN Competitor s product EM (High load) Microphone position: mm above rail Lubrication: Oil (VG68) 4 4 1 1 1 Speed, m/min Example measurement of noise test GM (Super-high load) 6
2. Accuracy Four accuracy grades are available: ultra super precision P3, super precision P4, high precision P, and precision P6. : Difference in roller slides on the reference side roller guide. Table 1 Accuracy standards Accuracy grades Accuracy standards Ultra super precision Super precision High precision Precision P3 P4 P P6 Mounting height: Dimensions in mounting height H ±.8 ±.1 ±.2 ±.4 Mounting width: Dimensions in mounting width W 2 or W 3 ±.1 ±.1 ±.2 ±. Variation of mounting height dimension H.3..7.1 Variation of mounting width dimension W 2 or W 3.3.7.1.2 Running parallelism of face C against face A Running parallelism of face D against face B Refer to Table 2 Unit: mm 3. Preload and Rigidity Preload is set for the RA series by slightly changing the size of the roller used. Applying preload enhances rigidity and minimizes elastic deformation. With the characteristics of the roller guide, there is minimal variation in rigidity according to amount of preload. Because the RA series offers stable, high rigidity, only medium preload type Z3 (preload: 1% of C, where C is the basic dynamic load rating) is set. Typical measurements for preload and rigidity are as follows. Table 3 Preload and rigidity Model No. High load capacity type AL, AN, EM Preload (N) Medium preload (Z3) Ultra high load capacity type BL, BN, GM RA1 1 3 1 3 Fig. Direction of load Load in direction of compression Table 2 Running parallelism Unit: µm RA2 1 92 2 4 Rail length Ultra super precision Super precision High precision Precision (mm) P3 P4 P P6 RA2 2 92 3 4 RA3 3 89 4 76 Over or less 2 2 2 4. 8 2 2 3 8 12 2 2 3.. 12 2 2 2 4 6 2 2 2 2. 7 RA3 33 6 74 RA4 9 28 6 RA 12 9 16 8 RA6 21 28 8 2 31 2 2. 8 31 4 2 3 6 9 4 2 3 6 1 Fig. 6 Rigidity measurement data 63 2 3. 7 12 63 8 2 4 8 14 8 1 2. 4. 9 16 1 1 2 3 1 17 1 2 1 6 4 6 19 1 6 2 4. 7 13 21 2 2 8 1 22 2 3 6 9. 17 2 2 2 1 1 RA3BN measurement values in compression direction 2 2 1 1 RA3BN measurement values in compression direction Fig. 4 Specifications of accuracy 1 1 1 C D C D RA3BN RA3BN H H 2 2 1 1 RA4BN measurement values in compression direction 2 2 1 1 RABN measurement values in compression direction A B W 2 A W 3 B 1 1 2 1 1 2 Standard Semi-standard RA4BN RABN 7 8
4. Basic Load Rating and Rated Life Basic dynamic load rating that expresses load capacity is established by ISO standards (ISO14728-1) for linear guides. With basic dynamic load rating, direction and size do not fluctuate so that rated fatigue life is 1 km. Load rating for NSK linear guides complies with ISO standards. With the RA series, dynamic load rating is the same in both the vertical and horizontal directions (4-way equal load specs.). Rated fatigue life L is calculated by the following formula when load F is applied to the roller slide in the horizontal or vertical direction only. This life formula is different from that for linear guides with ball rolling elements. fw is load factor. Refer to the respective value from the following table 4 as a guideline according to potential vibration and the impact of the machine in which the linear guide is used, and select the load factor. L =1 ( C fw F ) 1 3 (km) When load R in the horizontal direction and load S in the vertical direction are simultaneously applied, use the following dynamic equivalent load F for the calculation: F = R +.S (R> = S) F = S +.R (R<S). Lubrication Specifications With standard specifications, grease fittings are mounted on the side of the roller slide for the RA series, but can also be mounted on the side of the end cap with optional specifications. A lubrication hole can also be provided on the top of the end cap. Openings are not provided on the top or side with standard specifications in order to prevent dust. Contact NSK for more information. 6. Dust-proof RA series is equipped with side, inner and bottom seals to prevent foreign matter from entering the inside of the roller slide. Under normal applications, the RA series can be used without modification. For severe usage conditions, optional rail covers are available. Contact NSK for information on how to mount the cover. The linear guide can also be equipped with a lubrication unit (NSK K1 ) that has already proven its effectiveness with other NSK linear guides. Table Optional parts for dust-proofing Name NSK K1 Double seal Protector Rail cover Bolt hole cap Objective Porous part containing oil enhances lubrication function. Sealing effect is enhanced by using pairs of side seals. Table 3 Load factor fw Fig. 7 Two directional load Inner seals for RA1 and RA2 are available as options. Rail cover is applicable to RA2 to 6. Fig. 8 Optional lubrication hole positions Fig. 9 Rail cover Removes large dust particles and protects side seals from hot and hard dust particles. Covers top of rail to prevent foreign matter from getting in the rail mounting holes. Impact and/or vibration Lubrication hole on top Prevents foreign matter such as cutting dust from collecting in the rail mounting holes. R Load factor No impact and vibration from the outside 1. 1. With impact and/or vibration from the outside 1. 2. With heavy impact and/or vibration from the outside 2. 3. S Grease fitting on side 7. Installation (1) Mounting tolerance Mounting tolerance results in harmful effects such as shortened operating life, deterioration in motion accuracy, and friction variation. NSK particularly focuses on operating life, and sets an operating life value of more than 2 km calculated under the following conditions as mounting tolerance: The load per roller slide is 1% of basic dynamic load rating C. The rigidity of machine is infinite. The tolerance in Fig. 1 is shown in the Table 6 as typical tolerance. Fig. 1 Mounting tolerance e 2 (2) Shoulder height and corner radius of mounting surface When using the shoulders, which rise perpendicularly to the mounting surface, for accurate installation of a roller guide, refer to Fig. and Table 7 for the dimensions. Fig. Datum face of roller guide and shoulder 9 1 Rail r a r a H Roller Slide r b r b H e 1 Model No. RA1 RA2 RA2 RA3 RA3 RA4 RA RA6 Handling Precautions Table 6 Mounting tolerance of RA series Unit: µm Parallelism tolerance of two roller guides e 1 7 9 13 17 19 3 Table 7 Shoulder height and corner radius of attachment Height tolerance of two roller guides e 2 1 µm / mm Model No. Shoulder Height Chamfer (maximum) H H r a r b RA1 3 4.. RA2 4.. RA2 4. 1. RA3 6 1. 1. RA3 6 1. 1. RA4 6 8 1. 1. RA 7 1 1. 1. RA6 1. 1. ➀ If oil lubrication is used, the oil may not pervade the rolling surface according to the roller slide mounting conditions such as upside down mounting and wall mounting. In these situations, consult with NSK. ➁ Operating temperature limits should normally be less than 8 C. ➂ If using NSK K1, service temperature should not exceed C (or 8 C instantaneously). Make sure the unit does not come in contact with organic solvents with that can be used for degreasing. Do not place the unit in a location exposed to white kerosene or rust prevention oil containing white kerosene. Unit: mm
Dimension table Square type (tapped mounting holes) RA AL (High load type) RA AN RA BL (Super-high load type) RA BN M YO Example of specification number: RA 3 1 AN C 2 P4 3 M RO M PO Series code Size No. Rail length (mm) Accuracy grade : two rails per axis No code: single-rail Preload code Z3: Medium preload (Without NSK K1): P3, P4, P, P6 (With NSK K1): K3, K4, K, K6 T W L 1 B 1 B 6-M Pitch Depth J D T 1 ( N ) J 1 L Roller slide shape code AL, AN, BL, BN Material and surface treatment code, C: Special carbon steel (NSK standard) Design number Number of roller slides per rail ( H K ) H 1 h Please note that the appropriate design number will be inserted into the reference number and the tag end code ( II) will be omitted. E B 3 W 2 W 1 G d F n F ( G ) L Assembly Roller slide Model No. Height Width Length Tapped hole Grease nipple H E W 2 W L B J M Pitch B 1 L 1 J 1 K T Mounting hole T 1 N RA1AL 24 M4.7. 2 4 7 44.8 9.4 RA1AN 28 M4.7 6 24 8 4 9. 34 26 26 4 8 3 RA1BL 24 M4.7. 2 4 8.4 6.2 17.1 RA1BN 28 M4.7 6 24 8 RA2AN 86. 36 7. 1.7 3 12 44 32 M.8 6 6 RA2BN 16.3 77.3 13.6 2 12 3 4 3 RA2AL 36 M6 1 8 31 6 97. 3 6. 1.2 RA2AN 4 M6 1 9 3 1 12. 48 3 6. 12 M6.7 RA2BL 36 M6 1 8 31 6. 83. 16.7 RA2BN 4 M6 1 9 3 1 RA3AL 42 3. 7.8 4 74 17 RA3AN 4 38. 1 6. 16 6 4 M8 1.2 1 14 M6.7 RA3BL 42 3. 7 13.4 6 98.6 19.3 RA3BN 4 38. 1 RA3AL 48 41. 8 123.8 83.2 16.6 RA3AN 48. 1 6. 18 7 M8 1.2 12 1 1 M6.7 RA3BL 48 41. 8 12 72 1.4 19.7 RA3BN 48. 1 RA4AL 6 M1 1. 16 2 1 14 6 1.4 22.7 RA4AN 7 M1 1. 17 62 2 8 2. 86 6 13 17 R C 1/8 RA4BL 6 M1 1. 16 2 1 19 8 141.4 3.7 RA4BN 7 M1 1. 17 62 2 RAAL 7 61 184 7 128 26. RAAN 8 71 21 9 23. 1 7 M12 1.7 18 12. 18 R C 1/8 RABL 7 61 234 9 178 41. RABN 8 71 21 RA6AN 228.4 7 1.4 42.7 9 13 31. 126 76 M16 2 2 2 RA6BN 32. 12 229. 4.7 Either 6 mm or 3 mm of bolt pitch F is applicable for RA1 and RA2. 6 mm bolt pitch will be provided if not specified. 3 14 14 77 22 R C 1/8 19 14 Rail Basic load rating Weight Rail width Rail height Bolt pitch Bolt hole G Maximum Dynamic Static Static moment (N m) Bearing Rail length W 1 H 1 F d D h B 3 (recommended) L max C (N) C (N) M R M P M Y (kg) (kg/m) 1 16.3 2 2.8 6 4. 7..3 7. 2 2 (3) 1 3 27 26 21 21 13 37 3 37 37.17.21.2.3 6 19 2 2 66.38 6 9. 8. 1 2 3 (3) 24 7 89 9 9. 23 24 3 7 9. 2 3 28 28 4 9 14 12 14 2 3 34 31 4 9 14 12 17 2 3 4 38 2. 14 2 17 22. 22. 3 3 43. 6 16 23 2 26. 3 3 63 7 18 26 22 31. 3 3 29 2 72 7 97 76 76 3 4 92 9 1 24 1 24 1 24 38 9 93 1 67 1 14 1 14 47 6 121 2 17 1 9 1 9 3 3 129 2 81 1 8 1 8 67 4 17 3 81 3 2 3 2 92 8 229 6 18 4 8 4 8 6 3 8 24 7 1 7 1 129 33 1 2 7 6 7 6 168 462 14 3 13 6 13 6.4.6.8.91.8 1. 1.1 1.3 1.2 1.6 1.7 2.1 2. 3. 3.4 4.1 4.1 4.9.7 6.7 21 4 19 2 12 7 12 7 9.3 288 76 28 7 28 6 28 6 12.2 The basic load rating complies with ISO standards (ISO14728-1, ISO14728-2). If the above basic dynamic load rating (1 km rating) is converted into km rating, use the following formula: C km =1.23 C 1 km If the rail length exceeds the above limitation, you may be able to cope with the problem by rails for butting connections. Contact NSK for more information. 1.6 2.6 3.4 4.9 6.8 1.9 14.6 22. 12
Dimension table Flange type (for both tapped and bolt mounting holes) RA EM (High load type) RA GM (Super-high load type) M YO J 3 J 2 Example of specification number: RA 3 1 EM C 2 P4 3 Series code : two rails per axis No code: single-rail Size No. Rail length (mm) Accuracy grade Preload code Z3: Medium preload (Without NSK K1): P3, P4, P, P6 (With NSK K1): K3, K4, K, K6 M RO 2-M Pitch M PO Roller slide shape code EM, GM Design number Material and surface treatment code, C: Special carbon steel (NSK standard) Number of roller slides per rail Please note that the appropriate design number will be inserted into the reference number and the tag end code ( II) will be omitted. T B 1 ( ) 2 W B Q 1 4-M Pitch D T 1 (N ) J 1 L L 1 J H ( K ) H 1 h E B 3 W 2 W 1 G d F n F (G) L Assembly Model No. Height Width Length Tapped hole, Fixing bolt Roller slide H E W 2 W L B J J 2 M Pitch 1 ( 2) Q 1 ( 2) B 1 L 1 J 1 J 3 K T RA1EM 7 44.8 7.4 9.4 24 4 16 47 38 3 26 M.8 8. (6.) 4.4 8. (6.) 4. RA1GM 8.4 6.2 1.1 17.1 RA2EM 86. 7. 8.7.2 3 21. 63 3 4 3 M6 1 9. (8).3 9. (8) RA2GM 16.3 77.3 18.6 21.1 RA2EM 97. 6. 1.2 12.7 36 23. 7 7 4 4 M8 1.2 1 () 6.8 1 () 6. RA2GM. 83. 19.2 21.7 RA3EM.8 74 1 42 6. 31 9 72 2 44 M1 1. 12 (12.) 8.6 12 (12.) 9 RA3GM 13.4 98.6 23.3 27.3 RA3EM 123.8 83.2 1.6 1.6 48 6. 33 1 82 62 2 M1 1. 13 (7) 8.6 13 (7) 9 RA3GM 12 1.4 24.7 29.7 RA4EM 14 1.4 12.7 22.7 6 8 37. 12 1 8 6 M12 1.7 1 (1.) 1. 1 (1.) 1 RA4GM 19 141.4 3.7 4.7 RAEM 184 128 16. 29 7 9 43. 14 6 9 7 M14 2 18 (13) 12. 18 (13) 12 RAGM 234 178 41. 4 RA6EM 228.4 1.4 22.7 36.7 9 13 3. 17 142 82 M16 2 24 (18.) 14.6 24 (18.) 14 RA6GM 32. 229. 9.7 73.7 Either 6 mm or 3 mm of bolt pitch F is applicable for RA1 and RA2. 6 mm bolt pitch will be provided if not specified. 2 8 2 1 31 3. 41. 12 2 13 61 1 77 22 Rail Basic load rating Weight Grease nipple Rail width Rail height Bolt pitch Bolt hole G Maximum Dynamic Static Static moment (N m) Bearing Rail length Mounting hole T 1 N W 1 H 1 F d D h B 3 (recommended) L max C (N) C (N) M R M P M Y (kg) (kg/m) 3 4 3 1 16.3 3 4 3 2 2.8 6 1 3 27 26 21 21.21 4. 7..3 7. 2 2 (3) 13 37 3 37 37.28 6 19 2 2 66.4 6 9. 8. 1 2 3 (3) 24 7 89 9 9.6 M6.7 6 23 24 3 7 9. 2 3 M6.7 7 28 28 4 9 14 12 14 2 3 M6.7 8 34 31 4 9 14 12 17 2 3 R C 1/8 1 14 4 38 2. 14 2 17 22. 22. 3 R C 1/8 14 3 43. 6 16 23 2 26. 3 3 R C 1/8 19 14 63 7 18 26 22 31. 3 3 29 2 72 7 97 76 76.8 3 4 92 9 1 24 1 24 1 24 1.1 38 9 93 1 67 1 14 1 14 1.3 47 6 121 2 17 1 9 1 9 1.7 3 3 129 2 81 1 8 1 8 1.7 67 4 17 3 81 3 2 3 2 2.3 92 8 229 6 18 4 8 4 8 3.2 6 3 8 24 7 1 7 1 4.3 129 33 1 2 7 6 7 6.4 168 462 14 3 13 6 13 6 7. 21 4 19 2 12 7 12 7 12.2 288 76 28 7 28 6 28 6 16. The basic load rating complies with ISO standards (ISO14728-1, ISO14728-2). If the above basic dynamic load rating (1 km rating) is converted into km rating, use the following formula: C km = 1.23 C 1 km If the rail length exceeds the above limitation, you may be able to cope with the problem by rails for butting connections. Contact NSK for more information. 1.6 2.6 3.4 4.9 6.8 1.9 14.6 22. 13 14