Precision rolled ball screws catalogue
Precision rolled ball screws catalogue
This document provides an overview of Ewellix's precision rolled ball screws, emphasizing their efficiency, precision, durability, and cost-effectiveness compared to ground ball screws. Ewellix's expertise in manufacturing ensures high-quality products.
Ewellix offers a range of precision rolled ball screws for demanding applications, manufactured using precision rolling and specific heat-treatment processes.
- Basic Dynamic Load Carrying Capacity (Ca): Determines the nominal fatigue life of ball screws based on axial load.
- Nominal Fatigue Life (L10): Defined by ISO as the life achieved by 90% of ball screws under identical conditions.
- Service Life: Actual life achieved before failure due to factors like inadequate lubrication or contamination.
- Equivalent Dynamic Load: Calculated based on external forces to determine the hypothetical load affecting screw life.
- Basic Static Load Carrying Capacity (Coa): Considered for screws under shock loads or low-speed conditions.
The catalogue details various product families, including SD/BD/SH miniature screws, SP/BP high-performance screws, and SX/BX universal screws, each designed for specific applications and performance requirements.
Ewellix ensures high precision in manufacturing, offering products with lead precision and adherence to DIN standards.
Details on ball screw support bearings and their configurations are provided, ensuring optimal performance and integration into systems.
Guidelines for mounting, lubrication, and alignment are included to ensure proper installation and maintenance of ball screws.
Ewellix, with a history rooted in the SKF Group, emphasizes engineering excellence and innovation. Now part of the Schaeffler Group, Ewellix continues to drive advancements in linear motion and actuation solutions.
Ewellix offers global support with local expertise, providing standard and custom-engineered solutions to enhance productivity and reliability while reducing costs.
The document outlines the static load carrying capacity of ball screws, determined by the permanent deformation caused by the load at contact points. The static load is the axially and centrally applied load resulting in a deformation equal to 0.0001 times the diameter of the rolling element. The basic static load rating must be at least equal to the product of the maximum axial static load and a safety factor.
The critical speed of screw shafts is calculated by treating the shaft as a cylinder with a diameter equal to the root diameter of the thread. A safety factor of 0.8 is applied due to potential inaccuracies in mounting.
The permissible speed limit is the maximum speed a screw can reliably handle, generally limited by the recirculation system in the nut.
High speed with high load requires significant input power and results in a shorter nominal life. Preload must be calculated to prevent internal sliding during movement reversals.
The column loading of the screw shaft must be checked under compression loading using Euler's formulae, with a safety factor of 3 to 5.
Proper lubrication is crucial for operation, especially at high speeds. Monitoring temperature can help optimize lubrication frequency.
Ball screws are generally reversible, and a braking mechanism is necessary to prevent back-driving.
Preload torque exists even without external load. Axial play versions are available, with reduced play and preload options for increased precision.
The static axial stiffness is the ratio of external axial load to axial displacement.
Standard screw shafts are made from carbon steel, surface hardened by induction. Various coatings are available for improved performance.
Standard screws operate between -20 to +110°C. Above 130°C, special steel is recommended.
Ewellix offers support bearings for ball screws, designed for easy mounting and quick delivery.
Standard machined ends are recommended, with considerations for strength and dimension limits.
Optional steel inserts and safety rings are available for severe applications.
Products are not developed for explosive environments.
Includes formulas for basic life rating, critical speed, speed limit, buckling strength, efficiencies, input torque, and power requirement.
The document provides detailed specifications for precision rolled ball screws, including nominal diameters ranging from 16 to 63 mm and leads from 5 to 40 mm. It includes standard composite recirculation inserts and optional steel inserts.
The product range includes various screw and nut combinations with specific dimensions and load ratings.
The screws are designed with compact nuts and integral flanges for easy assembly, suitable for positioning screws with G5 lead precision.
The design is economical and well-suited for transport screw applications. The optional features enhance safety and performance in demanding applications.
Dimensional drawings are provided for different screw models, illustrating the design and assembly with support bearings and pillow blocks.
For high-load applications, specific types of support bearings and pillow blocks are recommended.
This document provides detailed specifications and features of precision rolled ball screws, focusing on different types such as PN preloaded screws, SL/TL long lead screws, and SLT/TLT rotating nut screws.
- PN Preloaded Screws: Nominal diameters range from 16 to 63 mm with leads from 5 to 10 mm.
- SL/TL Long Lead Screws: Designed for high linear speed with nominal diameters from 25 to 50 mm and leads from 20 to 50 mm.
- SLT/TLT Rotating Nut Screws: Aimed at minimizing inertia with nominal diameters from 25 to 50 mm and leads from 20 to 50 mm.
- Compact design for easy assembly and high rigidity.
- High rotational speed capabilities, resulting in high linear speeds.
- Backlash elimination options available.
- Reduced inertia for lower motor power requirements.
- For high load applications, use the FLRBU type and refer to the roller screws catalogue for end shaft and support bearings definitions.
The document includes detailed tables with dimensions, load ratings, and other technical specifications for various screw and nut combinations.
The document contains dimensional drawings for different screw types, illustrating the design and machining details for shaft ends.
Ewellix offers quick service facilities in Europe and North America for precision rolled ball screws, stocking standard screw shafts, nuts, and accessories.
After cleaning, fitting, and lubricating the assembly, the nut should make several full strokes at low speed and light load to ensure proper positioning of limit switches or reversing mechanisms.
Orders can be fulfilled within a couple of days to two weeks under certain conditions.
Customers are required to provide detailed project information, including company details, application type, and design parameters.
The document outlines the necessary details for operating conditions, including duty cycle description, mounting conditions, maximum loads, lubrication, operating temperature, and required service life.
The document includes a disclaimer about the accuracy of the catalog and notes that product specifications are subject to change without notice.
Catalog excerpts
Precision rolled ball screws catalogue
Open the catalog to page 1
Ewellix is a global innovator and manuacturer of linear motion and actuation solutions. f Our state-of-the-art linear solutions are designed to increase machine performance, maximise uptime, reduce maintenance, improve safety and save energy. We engineer solutions for assembly automation, medical equipment, mobile machinery, distribution and a wide range of other industrial applications. Technology leadership Schaeffler Group – We pioneer motion We earned our reputation through decades of engineering excellence. Our journey began over 50 years ago as part of the SKF Group, a leading global technology...
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Trusted engineering expertise Our industry is in motion; pushing towards solutions that reduce environmental impact and leverage new technology. We provide technical and manufacturing expertise to overcome our customers’ challenges. We work in a wide range of industries, where our solutions provide key functionality for business critical applications. We have a unique understanding of linear equipment and how it’s integrated in customers’ applications to provide the best performance and machine efficiency. For the medical industry, we provide precision components for use in core medical equipment....
Open the catalog to page 5
Product description This catalogue describes Ewellix expertise, technology and solutions related to precision rolled ball screws. Thanks to our lengthy experience with manufacturing ball screws and continuous product and process development, Ewellix provides customers with precision rolled ball screw solutions that fulfil their most demanding applications in terms of efficiency, precision, durability and value. In many cases, these ball screws can replace ground ball screws, offering a similar level of performance and precision at a lower cost. The high quality of Ewellix rolled ball screws is...
Open the catalog to page 7
Product overview Screw assembly External, by integrated tube Stainless steel optional 2) SND/BND/PND SND/BND/PND SND/BND/PND SND/BND/PND SND/BND/PND SND/BND/PND SND/BND/PND SX/BX SX/BX SX/BX SX/BX SX/BX SX/BX SX/BX SP/BP SP/BP SP/BP SP/BP Internal, by inserts Stainless steel optional 1) SD/BD/SDS/BDS SD/BD/SDS/BDS SD/BD SD/BD/SDS/BDS SD/BD/SDS/BDS SD/BD/SDS/BDS SD/BD SD/BD – SDS/BDS
Open the catalog to page 8
Screw assembly SN/BN/PN SN/BN/PN SN/BN/PN SN/BN/PN SN/BN/PN SN/BN/PN SN/BN/PN Ball screw support bearings FLBU, PLBU, BUF FLBU/PLBU/BUF FLBU/PLBU/BUF FLBU/PLBU/BUF FLBU/PLBU/BUF FLBU/PLBU/BUF FLBU/PLBU/BUF FLBU/PLBU/BUF SLT/TLT rotating nuts SLT/TLT SLT/TLT SLT/TLT SLT/TLT SL/TL – SLD/TLD SL/TL SL/TL SLD/TLD SL/TL SL/TL Complete ball screw assembly wi
Open the catalog to page 9
Technical concepts Introduction to Ewellix ball Nominal fatigue life L10 Nominal fatigue life is, according to the ISO definition, the screws life achieved or exceeded by 90% of a large-enough group Ball screws convert rotary motion into linear motion, and vice-versa, and loads are transferred from the screw shaft to the nut through a ball set: in this sense, ball screws relate to general bearing technology. Various types of bearing steel are used to attain the hardness and material fatigue properties required for carrying heavy application loads over extended periods of service. Some bearing...
Open the catalog to page 11
Equivalent dynamic load 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 up by linear bearing systems. It is extremely important to resolve these problems at the earliest possible design stage. These forces are detrimental to the life and the expected performance of the screw (⮑ fig. 1). When the load fluctuates during the working cycle, it is necessary...
Open the catalog to page 12
High speed associated with high load requires a large input power and yields a relatively short nominal life1). In the case of high acceleration and deceleration, we recommend either working under a nominal external load or applying a light preload to the nut to avoid internal sliding during reversal of movement. The preload for screws subjected to high velocity must be calculated to ensure that the rolling elements do not slide1). Excessive preload will create an unaccep able increase in t the internal temperature. Screw shaft buckling The column loading of the screw shaft must be checked when...
Open the catalog to page 13
Static axial stiffness of a complete assembly Materials, heat treatment and coatings The static axial stiffness of a complete ball screw assembly is the ratio of the external axial load applied to the system and the axial displacement of the face of the nut in relation to the fixed (anchored) end of the screw shaft. Please see calculation formulae (⮑ pages 14 to 15). Standard screw shafts are manufactured from carbon steel which is surface hardened by induction. For standard screws, Nut stiffness: Rn When a preload is applied to a split nut, the internal play is eliminated. Additionally, the...
Open the catalog to page 14
Operating temperature Screws made from standard steel and screws operating under normal loads can operate from –20 to +110 °C. Between 110 °C and 130 °C, Ewellix must be notified for adaptation of the annealing procedure and for review of the application with hardness below the standard minimum value. Above 130 °C, steel adapted to the temperature of the application should be selected (100Cr6, special steel, etc.). Please consult Ewellix for advice. Operation at high temperatures will lower the steel hardness, alter the thread accuracy, may increase the oxidation of the materials and change the...
Open the catalog to page 15
Calculation formulae Basic life rating L10= Note: it is generally recommended to apply a safety factor of 0,8 to the calculated value of the critical speed ncr of the screw shaft. Speed limit of the mechanism (maximal speed applied through very short periods) Required load rating With recirculation by inserts / tubes (SD/BD/SH-SDS/BDS/ SHS-SX/BX-SND/BND/PND-SN/BN/PN): With recirculation through flange (SL/TL-SLD/TLD): = life [million revolutions] Ca = basic dynamic load rating [N] Fm = cubic mean load [N] If n d0 > 50 000 or 90 000 respectively, please consult Ewellix Creq = required dynamic...
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