Groundbreaking cold-formed aluminium leadscrews

In an age of automation and miniaturisation, mechanical drive elements have to meet continuously changing demands. Lightweight design, for example, has become one of the key future technologies in the aerospace, automotive and mechanical engineering fields. The rising demand for products that are both material- and energy-efficient is a driving force behind the continual development of manufacturing processes at Eichenberger Gewinde, a manifestation of which comes in the form of the company's aluminium leadscrew.

A leadscrew is actually a simple design element. However, if it meets the highest quality and dimensional tolerance requirements and is constructed from a groundbreaking material, it can create exceptional application opportunities, particularly in automotive and medical industry fields.


Material versatility


Aluminium is the most used metallic material after steel, and, through a broad range of alloys and alloying additions, such as the combination of aluminium with other metals, the material covers an enormous spectrum of properties. Among other characteristics, it has an extremely low density and is therefore very light in weight. Plain aluminium forms an oxide layer on its surface in air, which then makes it corrosion resistant. This self-passivation, the combination of light weight and stability, the outstanding machinability and the fact that aluminium is non-magnetic is increasing its importance in more and more new application fields. Over 70% of the aluminium ever extracted is still being used, making it an extremely recyclable material; its low depreciation being due to its high level of stored energy.

MRI application  


Magnetic resonance tomography is able to provide very detailed images of organs and tissue in order to assess them for potential changes. This examination method, also called magnetic resonance imaging, uses magnetic fields and high frequency electromagnetic waves instead of x-rays.

Magnetic resonance tomography devices employ powerful magnets and alternating magnetic fields that operate in the radio frequency range. It is obvious that these highly precise and complex systems must meet the highest requirements, one fundamental prerequisite of which is the use of non-magnetic individual components.

Eichenberger Gewinde was presented with the challenge of manufacturing a non-magnetic injector drive unit that can deliver a contrast agent safely, quickly and precisely into human tissue. What they developed was a cold-rolled, round thread (‘Rondo’) leadscrew made of aluminium, with a diameter of 12mm and a lead of 5mm.

This aluminium leadscrew system was found to be ideal at administering the medical contrast agent extremely precisely and quickly through the highly efficient translation of rotary movement into linear motion.

Customer-driven innovation

Eichenberger thread specialists look for non-standard thread geometries to solve problems. Depending on the requirements and dimensions, customised cold-formed high-helix and round thread leadscrews can be implemented with enormous lead values. Uniquely high linear speeds can be implemented with surprisingly low rotary speeds. Eichenberger high-helix Speedy leadscrews have a helix angle of over 60°. In comparison, a metric M20 thread only has a helix angle of 2.48°.

Exceptional customer solutions are developed upon request; to date the most extreme of which is a high helix leadscrew with a diameter of just 8mm, but a phenomenally long lead of 600mm. The combination of these properties with the lightweight, non-magnetic qualities of aluminium allows the Speedy and Rondo leadscrew series to access an even broader range of applications.


A step ahead


Eichenberger’s achievement in producing round (‘Rondo’) and high helix leadscrews out of aluminium may sound simple, but it's a big step forward that can only be possible when research, development, production and quality assurance work hand in hand.

When working with aluminium, there are two challenging obstacles to overcome. First, like all metallic materials, aluminium can be strengthened through alloying. Even small amounts of precipitated alloying elements affect the tensile strength, so it takes a lot to achieve ideal strength values. Secondly, while aluminium is a material known for its good machinability, its tendency to spall means that it can be quite demanding when it comes to the accurate and controlled cold-forming of threads. Intuition is needed, not only for the careful selection of optimal raw material and alloys, but also the geometry and design of the tooling used for the forming process is key to a technically high quality product.

Three times lighter than steel

With dwindling resources and a growing world population, the trend for searching for metallic lightweight construction materials will continue unabated. At 2.7Kg/dm³, the weight of aluminium is one-third that of conventional steel. Lower weight of material results in fuel savings, energy-efficient drive solutions and higher profitability. The perfect material combination of the corrosion-resistant aluminium leadscrew and plastic flange nut even guarantees unlubricated operation (dry running) for certain applications. The combination of an aluminium leadscrew and plastic flange nut is also distinguished by its high wear resistance, low coefficient of friction and lack of any reliance on maintenance. Depending on customer requirements, the friction and efficiency can be even further optimised through additional surface treatments.

The initial results and wisdom gained from this aluminium leadscrew milestone are remarkable and the designers at Eichenberger have recognised the extent of its applications. Encouraged by the communicative partnership with the customer and the solution-oriented exchange, further enhancements are ongoing. The dawn of the aluminium leadscrew age has arrived... watch this space for further developments!

Eichenberger products are available through Moore International.