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Screw assemblies

Screw assemblies
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Screw assemblies

Product catalog summary
Overview: The document from Bosch Rexroth AG provides comprehensive information on Ball Screw Assemblies (BASA) and Planetary Screw Assemblies (PLSA), focusing on their design for converting rotary motion into linear motion with high precision and efficiency.
Ball Screw Assemblies (BASA): These assemblies are noted for their efficiency in converting rotary to linear motion, offering high linear speeds, maximum load ratings, and minimal installed lengths. Key features include smooth operation, high load rating, and short nut length. Recent updates include the discontinuation of certain nut types, series expansion, introduction of ID numbers for screw drives, extended relubrication intervals, and the B flange.
Planetary Screw Assemblies (PLSA): PLSAs use planets as rolling elements to transmit high forces, offering smooth functioning, quiet operation, long service life, compact design, and easy installation. They are ideal for applications requiring high power density and positioning accuracy.
General Notes and Safety Instructions: The document emphasizes the intended use of assemblies in machines for moving and positioning, warning against misuse such as transporting people. It outlines safety instructions, including compliance with country-specific safety regulations and standards like ISO 3408 and DIN 69051.
Directives and Standards: References include DIN EN ISO 12100 for machinery safety, Directive 2006/42/EC for machinery design, and REGULATION (EC) No. 1907/2006 (REACH) concerning dangerous substances.
Product Overview: A comprehensive overview of the product range is provided, detailing various nut types, screw sizes, and accessories, along with specifications for miniature, speed, standard, and high-performance series.
Specifications and Ordering Information: Detailed specifications and ordering information for ball screw assemblies and components are provided, focusing on screw ends and end bearings, including technical data, part numbers, and assembly instructions.
Procedures: Instructions for ordering and assembling screw ends are emphasized, with a focus on correct allocation to bearing assemblies and technical dimensioning of permissible drive torque.
Standards and Norms: Several DIN standards for undercuts and keyways are referenced to ensure compatibility and standardization across components.
Recommendations: Following specified configurations and part numbers is recommended for optimal performance, highlighting the importance of technical dimensioning for drive torque and increased critical speed.
Key Data from Tables: Comprehensive data on dimensions, thread sizes, and part numbers for various screw end forms and bearing assemblies are provided, including centering hole sizes and wrench sizes required for assembly.
Technical Data: Ball screw assemblies offer high efficiency (up to 98%) and advantages over acme screw drives, such as higher efficiency, longer life expectancy, and more precise positioning.
Safety Information: For non-horizontal installations, protection against falling loads may be necessary.
Selection Criteria: Considerations include accuracy, load, service life, critical speed, buckling load, rigidity, and characteristic speed.
Load Ratings and Service Life: Calculations are based on ISO 3408-5, with dynamic load capacities exceeding ISO values.
Critical Speed and Buckling Load: High speeds up to 150,000 rpm are possible depending on nut type.
Material and Hardness: Components are made from high-quality, heat-treatable steel, with stainless steel options available on request.
Sealing and Temperature: Drives require protection from contamination, with standard versions coming with seals.
Acceptance Conditions and Tolerance Grades: Permissible travel deviation is according to ISO 3408-3.
Preload and Rigidity: Preloaded or adjustable-preload nut systems are available, with overall axial rigidity being a combination of bearing, screw, and nut unit rigidity.
Dynamic Drag Torque: Specifications for dynamic drag torque calculation are provided, including values for standard, reinforced, and low-friction seals.
Installation and Alignment: Key installation tolerances are outlined, emphasizing adherence to prevent premature failure.
Lubrication: General lubrication instructions recommend Dynalub 510 grease, with specific relubrication intervals and amounts.
Mounting Position: Vertical mounting is recommended, with specific guidelines for lubrication and travel direction.
Lubrication Specifications: Recommended greases include Dynalub 510, Castrol Longtime PD 2, or Elkalub GLS 135/N2 for assemblies with a diameter greater than 12 mm.
Lubrication Procedures: Initial lubrication and relubrication instructions are provided, emphasizing the use of a grease gun or progressive lubrication system for larger assemblies.
Recommendations and Notes: Special lubrication considerations are advised under extreme conditions.
Lubricant Properties: Dynalub 520 is recommended for its high performance and corrosion protection.
Oil Lubrication Specifications: Shell Tonna S 220 oil is recommended for machine bed tracks and tool guides.
Lubrication Procedures: The lubrication process involves using a single-line piston distributor system.
Norms and Recommendations: For double-threaded FED-E-B single flange nuts, lubrication quantities increase by 20%.
Load-Dependent Lubrication: Guidelines for load-dependent lubrication are provided, with a formula for calculating the relubrication interval.
Design Examples: Examples of lubrication for two-axis applications are provided.
Static Load Safety Factor: The static load safety factor is crucial for ensuring reliability under maximum load conditions.
Service Life Calculation: The service life of a ball screw assembly is determined by operating conditions and load cycles.
Critical Speed and Axial Load: Critical speed and permissible axial load are key parameters in screw assembly design.
Design Considerations for Driven Nuts: Driven nuts offer advantages such as reduced moment of inertia and improved dynamics.
Permissible Travel Speed: The permissible travel speed of a driven nut is significantly higher than that of a classical ball screw assembly.
Specifications and Parameters: Specifications for ball screw assemblies focus on parameters such as screw length, diameter, lead, end fixity, and permissible speeds.
End Fixity and Bearing Types: Different types of end fixity are discussed, with emphasis on critical speed limitations.
Drive Unit Design: The design of the FAR-B-S drive unit is detailed, focusing on improving performance with a driven nut.
Torque and Load Calculations: Formulas for calculating drive torque, axial load, and buckling load are provided.
Mounting and Installation: Guidelines for mounting bearings and housing are provided.
Lubrication and Maintenance: Lubrication requirements for bearings are discussed, emphasizing grease lubrication.
Conclusion: Comprehensive guidelines for the design, calculation, and maintenance of ball screw assemblies are provided, emphasizing the importance of considering various parameters and conditions.
Specifications for Planetary Screw Assemblies (PLSA): Detailed specifications for PLSA include dimensions, load capacities, and lubrication requirements.
Installation Procedures for PLSA: PLSAs are delivered prelubricated and should be handled with care to avoid contamination.
Lubrication Guidelines for PLSA: Lubrication is critical for longevity and performance, with Dynalub 510 recommended.
Alignment and Tolerances for PLSA: Proper alignment is crucial to prevent premature failure.
Cleaning and Maintenance for PLSA: Guidelines for cleaning involve using aqueous or organic agents.
Calculation and Design Considerations for PLSA: Formulas for calculating average speed and load are provided.
Service Life and Load Ratings for PLSA: The service life is calculated based on operating conditions.
Static Load Safety Factor for PLSA: The static load safety factor is calculated using the static load rating and maximum static load.
Critical Speed and Axial Load for PLSA: Guidelines for ensuring the operating speed does not exceed 80% of the critical speed are provided.
Lubrication and Bearing Design for PLSA: Lubrication requirements for bearings are outlined, with specific quantities for relubrication.
Resulting and Equivalent Bearing Loads for PLSA: Formulas for calculating resulting and equivalent bearing loads are provided.
Tools and Resources: Bosch Rexroth offers configurators and a dimensioning program called Linear Motion Designer.
Important Notes: The document highlights that the data provided is for product description only and does not guarantee suitability for specific uses.
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Catalog excerpts

Screw assemblies-1

Screw assemblies Ball screw assemblies BASA/Planetary screw assemblies PLSA

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Ball screw assemblies BASA Ball screw assemblies are the efficient solution for the precise conversion of rotary to linear motion. Building on our many years of experience and extensive engineering expertise, we have developed a product range that fulfills the most diverse requirements. No matter whether you need very high linear speeds, maximum load ratings, or minimum installed length, you will always find the right solution in Rexroth’s broad manufacturing spectrum. To make sure your application runs with the utmost accuracy and operational reliability, the individual components in our range...

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Ball screw assemblies BASA

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Notes General notes ▶▶ Non-horizontal installation There is no self-locking effect due to the low level of friction between the screw and the nut. The components of the product are designed to last for the product's service life; a major defect may nonetheless arise in exceptional cases, and if the moving part (i.e. the screw assembly nut) is not installed horizontally it may fall off. An additional protection against falling loads is therefore required for non-horizontal installation. ▶▶ Rexroth screw assemblies are components that are used to convert a rotary motion into a linear motion, and...

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Rexroth screw assemblies are suitable for dynamic linear applications that are moved and positioned reliably and precisely. The machine tool industry and other sectors must observe a series of standards and directives. These requirements can vary significantly worldwide. It is therefore essential to understand the legislation and standards that apply in each DIN EN ISO 12100 This standard is entitled Safety of machinery – General principles for design – Risk assessment and risk reduction. It gives a general overview and contains a guide to the major developments governing machines and their intended...

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Ball screw assemblies BASA | Screw assemblies 7 Ball screw assemblies BASA Ball screw assemblies BASA

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Screw assemblies | Ball screw assemblies BASA New features at a glance New features at a glance Discontinuation of 4 nut types In the standard series, single nuts with flange with recirculation cap FSZ-E-S and FSZ-E-B have been discontinued, Introduction of the B flange The C flange in the series FEM-E-C and FDM-E-C is replaced by the B flange. The nuts of the new design are available now under the designation FEM-E-B and FDM-E-B. All technical data remain unchanged. This change is necessary as the market and DIN favor the B flange.

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Ball screw assemblies BASA | Screw assemblies 9 Table of contents Product overview 10 Nuts and Nut Housings 10 Screws 12 Bearing 14 Accessories 15 Definition of ball screw assembly 16 Ball screw assemblies for all applications 18 Sample applications Nuts, miniature series Overview of formats Single nut with flange FEM-E-B Single nut with flange FEM-E-S Adjustable-preload single nut SEM-E-S Cylindrical single nut ZEM-E-S/ZEM-E-K Screw-in nut ZEV-E-S Nuts, Speed Series Single nut with flange with recirculation caps FEP-E-S Nuts, standard series Overview of formats Single nut with flange FEM-E-S...

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Screw assemblies | Ball screw assemblies BASA Product overview Nuts and Nut Housings Nuts Miniature series FEM-E-B / FEM-E-S / SEM-E-S / ZEM-E-S / ZEM-E-K / ZEV-E-S Adjustable-preload single nut DIN 69051, Part 5 SEM-E-C Cylindrical single nut ZEM-E-S/ZEM-E-K/ ZEM-E-A Double nut with flange FDM-E-S Double nut with flange DIN 69 051, Part 5 FDM-E-B Standard range, right-hand lead Size SEM-E-S Adjustable-preload single nut SEM-E-S Single nut with flange DIN 69 051, Part 5 FEM-E-B Single nut with flange FEM-E-S ZEM-E-S ZEM-E-K Standard series Single nut with flange with recirculation caps FEP-E-S...

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Ball screw assemblies BASA | Screw assemblies 11 Product overview High-performance series Driven single nut with flange FAR-B-S MGS for standard series FEP-E-S FEM-E-S SEM-E-S FDM-E-S MGA for cylindrical single nut ZEM-E-S ZEM-E-K ZEM-E-A MGD for standard series FEM-E-B SEM-E-C FDM-E-B FED-E-B Ball screw assemblies BASA Single nut with flange DIN 69051, Part 5 FED-E-B

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Screw assemblies | Ball screw assemblies BASA Product overview Screws Precision screw BAS Tolerance grades: T5, T7, T9 Screws in tolerance grade T3 (longer versions and larger sizes available on request) Standard, available at short notice on request

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Ball screw assemblies BASA | Screw assemblies 13 Product overview Precision screw BAS Tolerance grades: T5, T7, T9 Ball screw assemblies BASA Standard, available at short notice On request Maximum length (assembled) on request Screw ends

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Screw assemblies | Ball screw assemblies BASA Product overview Bearing Pillow block unit SEC-F A = SEB-F and SEB-L B = SEC-F and SEC-L C = SES-F and SES-L D = SEE-F

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Ball screw assemblies BASA | Screw assemblies 15 Product overview Accessories Single parts Slotted nut NMA, NMZ The load capacities of bearing and ball screw drive must be kept in reasonable balance. Page 124 Assembly tool for NMA/NMZ/NMG Front lube unit Measuring pads Acceptance conditions Ball screw assemblies BASA

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Screw assemblies | Ball screw assemblies BASA Product overview Definition of ball screw assembly ISO 3408-1 defines a ball screw assembly as follows: A unit consisting of a ball screw shaft, ball nut and balls which is able to convert rotary motion into linear motion, and vice versa. The basic functioning of a ball screw assembly is easy to describe, but there are numerous different designs and requirements for practical applications. Several innovations and adaptations have contributed to the extension of the product portfolio. Rexroth ball screw assemblies provide design engineers with diverse...

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Ball screw assemblies BASA | Screw assemblies 17 Product overview Ball screw assemblies BASA Smooth functioning due to the principle of internal recirculation Especially smooth running due to the optimal pick-up of balls from the raceway Adjustable-pre-tensioned single nut High load rating due to large number of balls Short nut length No protruding parts, nut is easily mounted Smooth outer shell Effective, wiping sealing Large range of series available ex stock

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