Materials and design advantages of rolled threads
This blog article is a continuation of part 3/9 on the basics of thread rolling. In this article, you will learn more about the materials steel, non-ferrous metals, and the design advantages of rolled threads.
Steel
Nowadays, steel is the most commonly used material for rolled threads. Steel is an alloy and therefore a combination of several metals, with iron making up the largest proportion. Different strength classes are created depending on the quality of the material used. The strength class of screws is indicated on the head, whereas for threaded spindles there are attempts to standardize the material specification, but these have not yet become established. Each manufacturer still has its own designation. Both non-alloyed and alloyed steels (quality and stainless steels) are used. Alloyed steels often have considerably poorer elongation properties than unalloyed steels. Screws of VA quality (stainless steel) are therefore problematic in many application areas.
Non-ferrous metals
Non-ferrous metals include all metals except iron. In addition to steel screws, screws are also made of aluminum, brass, and even titanium. However, the disadvantage of aluminum and brass is that they are far inferior to ordinary steel in terms of either ductility or strength. Screws made from these materials are therefore only used in non-load-bearing threaded fasteners. Although titanium is comparable to steel in terms of ductility and strength, it is so expensive that it is only used for the production of screws or nuts in special cases (implants in medicine, aerospace, aircraft technology). Only much less than 1% of all rolled threads are therefore made from non-ferrous metals.
Design advantages of rolled threads
Thread rolling as a chipless shaping process does not interrupt the material fibers, but merely diverts them. The thread is anchored in the core cross-section by bundling the longitudinal fibers of the base material. The material is compacted and smoothed at those points that are most stressed. This enhances its resistance to wear, significantly increases the strength, and ensures very good roughness (the unevenness of the surface height which is standardized in ISO 25178) on the thread flanks and in the radius of the thread root. The notched impact strength also increases significantly.
Fig. 1: Every spindle drive has a certain amount of play.
But there are special designs that have been preloaded: a spring tensions the two parts of the nut against each other and therefore eliminates play.
From the designer's point of view, rolled threads have three main advantages:
- They have greater strength than threads produced using machining processes.
- They have a significantly more favorable price/performance ratio than comparable threads produced by machining.
- A special design enables a drive screw with zero backlash (Fig. 1).
Learn more about the benefits of rolled screw drives from Eichenberger here
Eichenberger – your service provider right from the start
With Eichenberger, you can implement your individual requirements for a screw thread right from the start of development. Don't hesitate to contact us before you even know what you need. We will be happy to work with you to develop a customized solution for your thread system. Contact one of our experts directly, we are there for you right from the start.
> Contact us now without any obligation and find out more
With state-of-the-art production methods, many years of expertise and a tool inventory of over 1,000 rolling tools, we produce rolled screw drives that meet even the most unusual requirements:
- Gradients up to 6x in diameter
- Slope accuracy class G5
- Spindle lengths up to 6 meters
- Spindle diameter from 2 to 160 millimeters
- All standard profiles (M, Tr, UNC, UNF, UNEF, Whitworth)
- Multi-start threads, also as right/left-hand threads
- Steep thread profiles
- Ball screw profiles
- Special profiles
- Worm thread profiles (special quality and price advantages!)
- Serrations and knurling
- Conical thread
- Threads on prefabricated and/or bulky parts, e.g., also on forged parts
- Freely designed thread geometry
- Responding to customer requirements, such as tailored nut geometry
Eichenberger leaves nothing to chance and places the highest value on quality. This is what has been impressing our customers since 1953. See for yourself!
> 100% Swiss Quality
> Thread specialist since 1953
Fig. 2 Threads on bulky parts, conical threads
Literature and sources
The nine blog articles contain excerpts from the Library of Technology, Volume 286, Thread Rolling. This book was compiled with the expert support of Kurt Husistein and published by Verlag Moderne Industrie, ISBN 978-3-937889-30-6.
Kübler, Karl-Heinz, Mages Walter J. Handbuch der hochfesten Schrauben, 1. Aufl. Essen: W. Girardet Buchverlag, 1986.
http://www.hp-gramatke.de/ Hans-Peters Mathematisch-Technisch-Algorithmisch-Linguistisches Sammelsurium.Verein Deutscher Eisenhüttenleute (Hrsg.): Werkstoffkunde Stahl, Bd. 1 Berlin: Springer, 1984. Apel, Heinz: Gewindewalzen: Kaltverformen von Präzisionsgewinden und Spindeln, München: Hanser 1952.
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Abbildungen: Nr. 1, 23-25 RWT Rollwalztechnik GmbH, Engen; Nr. 2 Foto Deutsches Museum, München; Nr. 3 Musée du tour automatique et d'histoire de Moutier, Moutier (Schweiz); Nr. 16 Fette GmbH, Schwarzenbek; Nr. 18 Meinrad Plaz, Staufen (Schweiz); Nr. 26 Habegger SA, Court (Schweiz); Nr. 34-36 FBT Fahrzeug- und Maschinenbau AG, Thörigen (Schweiz); Nr. 37, 38 Schleuniger AG, Thun (Schweiz); Nr. 39, 40 Max-Planck-Institut für Physik (Heisenberg-Institut), München; Nr. 41 Saurer AG, Arbon (Schweiz); Nr. 42 Line Tech AG, Glattbrugg (Schweiz); alle übrigen Eichenberger Gewinde AG, Burg (Schweiz). Satz: abavo GmbH, D-86807 Buchloe. Druck und Bindung: Sellier Druck GmbH, D-85354 Freising. Printed in Germany 889030.
