Precision rolled ball screws catalogue

Ewellix is a global innovator and manufacturer of linear motion and actuation solutions used in assembly automation, medical applications and mobile machinery. Formerly part of SKF Group, the Ewellix Group consists of 16 sales units and eight factories. External net sales are approximately 2.3 SEK billion and we employ around 1200 people. Ewellix is headquartered in Gothenburg, Sweden and is owned by Triton. Technology leadership Global presence and local support Our journey began over 50 years ago as part of the SKF Group, a leading global technology provider, with the world’s first precision...

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....

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...

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

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

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...

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...

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...

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...

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...

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...