The AM Applications Series: Moving Parts

2019-07-17

Aya Bentur  

Bowman Additively Manufactured Bearing Cages

One of the advantages of additive manufacturing is the ability to create moving parts, either by creating a single piece with linked components or the ability to change material characteristics through geometry within the printing process. The third installment in our #AMapplication series looks at how companies tap into this potential. Today we explore additively manufactured applications related to movement, which are in use today.

Movement through Material

Creating moving parts is somewhat of a design challenge. A hinge, for example, is an assembly of parts connected in a way that allows the parts to move in a controlled, directed yet free manner. While usually hinges are created as an assembly, for certain applications hinges are created as a single part. In injection molding, for example, thinner material in a designated area can create a hinge. This type of hinge is often called a living hinge – when different material characteristics are achieved within the same material, (commonly seen in plastic boxes). This logic does not only apply for additive manufacturing (AM) but is enhanced by it. With AM the direction and location of the movement (i.e thinner material) aren’t constrained by the rules of injection mold making.  The material characteristics can also be adjusted through density, porosity, and lattice structure. In the Adidas sole 3D printed by Carbon, for example, the lattice structure varies in order to create different functional properties, in different zones within the same print. The sole reacts differently, moves differently depending on the requirements – some areas call for a more rigid support to the foot, while in others movement and flexibility are needed (below).

Adidas X Carbon Multiple functional zones showing varying lattice structures within the same midsole

Movement through Geometry

As additive manufacturing allows for complex material structures it also allows for complex shapes, the possibilities to achieve different characteristics through geometry are almost endless. An example can be seen in eyewear. Typically eyewear hinges are separate components inserted into the frame. Additively manufactured frames, on the other hand, allow for integrating the hinge, frame, and temples – producing them as a single part, similar to the Adidas sole. Hoet has created such a hinge in their additively manufactured titanium frames, and so has SEIKO, Ron Arad and Mono. This eliminates a big part of the assembly process, simplifying production. It also enables the creation of unique designs making the hinge a focal point rather than pure necessity.

Hoet 3D Printed Titanium Frame - Detail

Movement through Optimization

In an entirely different industry, EDAG together with Voestalpine Additive Manufacturing and Simufact Engineering additively manufactured a lightweight hood hinge with integrated pedestrian protection. Here additive manufacturing enabled optimization of the part – reducing the weight of the part (by 51%) as well as the number of components (from 19 to 6), and by doing so reaching increased efficiency. An optimized part brings optimized movement.

EDAG Additively Manufactured Lightweight Hood Hinge

Movement through Assembly

Smooth movement can also be reached by ensuring the components fit together in the best way possible. This isn’t always possible with traditional manufacturing. In the manufacturing process of ball bearings, the cage is traditionally produced using subtractive methods. While ball bearings have been around for many years (hundreds) and can be found in numerous applications, traditional manufacturing methods have their limitation in terms of creating the optimal fit between ball and cage. That’s why Boman, a UK manufacturer specializing in bearings created a division named Bowman Additive Production where they now additively manufacture ball bearings cages (up top). According to the company, their AM ball bearings can withstand a 30-40% extra load-bearing capacity as well as extend the overall lifespan of the product due to the reduced friction enabled by AM. They currently deliver customized bearings in production runs of 20 to 20,000 units. (below and in this video).

Bowman Additively Manufactured Bearings

Creating moving parts always seems to the untrained eye a bit like magic, but the truth is that it requires precision, carefully planned designs, and geometrical ingenuity. AM is an enabler of all those.

It’s always exciting to see new applications for AM, but it’s even more exciting to see them mature into industrialized processes and business models. Tell us about the AM applications you encountered, we’ll try to feature them here and follow us for more #AMapplications. For more insights and information follow us on LinkedIn or subscribe to our newsletter for weekly updates.

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