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Supercar of the skies: Autodesk Alias design

Learn how Hill Helicopter is using Autodesk Alias to design the innovative HX50, the "supercar of the skies." The next-gen, private copter marries high-end automotive and aero design and materials to create a futuristic flying five-seat SUV for a discriminating clientele. A neat insider look.
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CNC machining: How to avoid high costs on thin walls

Parts that are light and strong are crucial to nearly every industry. To achieve better performance without risking part failure, parts must maintain a specific wall-height-to-thickness ratio and wall-height-to-length ratio. Additionally, some geometries and supports can support thin walls to achieve a lighter component weight. Dive deeper into the cost drivers behind CNC-machined thin walls in this Xometry design-for-manufacturing article.
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Before you design your next application, try this

Smalley's industry-leading Spirolox^® Retaining Rings feature a gapless design with 360° of retaining surface. Unlike other rings, Spirolox has no protruding ears to interfere with mating components in your assembly! The highly versatile Spirolox rings are also groove-interchangeable with circlips, meaning they can replace circlips without any design changes. Are you ready to try the Smalley Advantage? Request your free samples today!
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No-cost courses in fastener technology

Master the theory of fastener design to expand your product knowledge and become an even better and more efficient design engineer. PennEngineering's PEM FastenerClass^® courses aim to give participants insight into peer and competitor techniques, a better understanding of loads and stress analysis, and enhanced career opportunities -- all beyond the basics of fastener design, selection, and installation. Self-clinch, threads, press-in inserts, surface-mount options, and sheet-to-sheet are only a few of the many topics covered.
See what courses are offered.

Engineer's Toolbox: The secret to living hinges that fold flat

Living hinges are often used to produce a container and its lid as a single molded part. If properly designed, they can open and close thousands of times without ever losing strength or flexibility. Protolabs provides valuable tips on designing these (sometimes thin and fragile) parts.
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EXAIR's new Catalog 36: BETE products and a comprehensive guide to industrial solutions

EXAIR is excited to introduce Catalog 36 -- a full-color, in-depth resource designed to help businesses tackle conveying, cooling, cleaning, blowoff, drying, coating, and static control challenges. This latest edition features an expanded selection of products, technical guides, certifications, and expert insights to help manufacturers optimize their operations. A new addition is BETE's robust lineup of precision spray solutions. Catalog 36 is also a valuable reference for industry standards, safety best practices, and energy conservation techniques in compressed air systems.
Get your EXAIR Catalog 36 today.

Telescopic rail system is PTFE-free

igus has introduced an aluminum version of its drylin NT-60 telescopic rail, eliminating the use of polytetra-fluoroethylene (PTFE) and over 100 per- and polyfluoroalkyl substances (PFAS). This rail system extends up to 2 m and is suitable for many applications, including vehicles, furniture, and medical technology. Despite incorporating a new, PTFE-free plain bearing, the drylin NT-60-4 telescopic rail does not compromise performance.
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Top Product: 3M Friction Shims -- Why have more than 300 million been sold?

3M Friction Shims are small, thin steel shims with a big impact. They can increase maximum load and peak torque in bolted connections without additional fasteners or redesigns. What else makes them so popular -- and so useful?
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Improving high RPM performance with Revolox self-locking rings

Join a Smalley engineer as they explore innovative solutions for high RPM applications. This video delves into the challenges of high rotational speeds and highlights the unique features that make the Revolox^® self-locking retaining ring a reliable choice. Smalley's retaining rings are designed to enhance performance and longevity in demanding applications.
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Now available: Boker's new 2025 Catalog & Calendar

Boker's, Inc. has two new valuable resources available to help design engineers and procurement managers overcome engineering challenges: the 2025 Stampings & Washers Catalog and the 2025 Scheduling Calendar. The Catalog outlines the company's expansive line of more than 32,000 non-standard washer sizes, spacers, and shims that are available with no tooling charges, and the company's vast stamping capabilities. The Scheduling Calendar offers an at-a-glance, 15-month view of January 2025 through March 2026. Reverse side has a metric conversion chart.
Get your catalog and calendar today.

What are Crossed Roller Bearings?

Learn all about HIWIN Crossed Roller Bearings that are three to four times more rigid than standard bearing solutions and are capable of handling loads in the axial, radial, and moment directions. They consist of an outer ring, an inner ring, and a plurality of rollers and spacers. The roller lies between the inner and outer ring with the spacers placed between the rollers to prevent the mutual friction between them, thereby decreasing the torque resistance for rotation. Many options are available depending on the level of rigidity needed.
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How Reell electric wrap spring clutches work

Electric wrap spring clutches are ideally suited for critical timing applications requiring consistent, repeatable engagement and disengagement performance. Wrap spring technology used in Reell clutches provides the capability to transmit a large amount of torque in a small size -- package sizes smaller than other clutch technologies such as friction disk, tooth, or magnetic particle. Reell's technology has very positive engagement characteristics and also limits the effects of wear.
Read this informative Reell article.

Engineer's Toolbox: All about lead screws and how to apply them

Lead screws use the helix angle of the thread to convert rotary motion to linear motion. Learn all about their benefits, performance characteristics, design choices, lifecycles, and more in this in-depth article from Thomson Industries.
Read the full article.

Achieve higher loads with a round wire Wave Spring

Wavo^® springs are produced from round-section wire to provide higher loads while maintaining the accurate loading found in wave springs. As an alternative to Belleville Springs, the Wavo provides similar loads but with an accurate, predictable spring rate. Available in carbon and stainless steel from stock, sizes range from 1/2" to 6" diameters. Free samples are also available!
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Eco-friendly thermoplastic: Light, rigid, strong, damping

Polyplastics has launched PLASTRON^® LFT (Long Fiber-Reinforced Thermoplastic) RA627P, an eco-friendly composite of polypropylene (PP) resin and long cellulose fiber that delivers low density, high specific rigidity, high impact strength, and excellent damping for a range of applications including audio components and housings of industrial components. LFT exhibits 10% lower density than 30% short glass fiber-reinforced PP resin, roughly the same flexural modulus, and a specific rigidity that is higher.
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Simple method discovered to break down plexiglass for recycling

Polymer chemists at research university ETH Zurich in Switzerland have discovered a surprising way to fully break down PMMA plastic -- commonly known as acrylic glass or plexiglass -- into its monomer building blocks. The process remains unaffected by the presence of additives.

By Daniel Meierhans for ETH Zurich

Today, plastics recycling is primarily limited to the collection of sorted PET or polyethylene beverage bottles. The plastic collected is of identical chemical composition, with polymer molecules of similar lengths. The additives used to enhance properties such as color, softness, or sunlight resistance are also similar.

This process enables plastic to be melted down and reformed into new bottles. In contrast, plastics of various types and qualities (known as mixed plastics) are usually incinerated (to generate heat in cement plants, for example).

A team of scientists led by Athina Anastasaki from the Laboratory of Polymeric Materials at ETH Zurich has discovered a method that enables the near-complete breakdown of acrylic glass into its monomer building blocks. By using additives, these building blocks can be easily purified through distillation into virgin-grade starting products for the synthesis of new plexiglass polymers.

The potential implications are significant: With a global annual production of around 3.9 million tons, acrylic glass (chemically known as PMMA or polymethyl methacrylate) is a durable and lightweight material. It is gaining in popularity in the aerospace and automotive industries, in the manufacture of screens and monitors, and in the construction industry.

The process developed by the ETH researchers and presented in the journal Science is highly robust. It is also effective with very long polymer chains made up of 10,000 monomer building blocks. Additionally, the presence of additives such as copolymers, plasticizers, dyes, and most other plastics has minimal impact on chain scission. Even when using multicolored acrylic glass from the DIY market, the yield remains between 94 and 98%.

Surprisingly simple process
"Our process is extremely simple," says Anastasaki. "All we need is a chlorine-based solvent and to heat the dissolved recycling mixture to a temperature between 90 and 150 degrees Celsius to start the depolymerization reaction with the aid of UV or visible light."

The ETH professor was amazed at how straightforward the process is. Like many other important plastics, such as polyethylene or polypropylene, acrylic glass polymers consist of a polymer chain of carbon atoms with various side groups branching off, depending on the type of plastic. Until today, these uniform carbon chains have posed an insurmountable chemical challenge for targeted splitting into monomers, as they do not provide specific points of attack for splitting reactions.

The only method currently used in industry that completely breaks down homogeneous carbon chains is pyrolysis. This involves the thermal decomposition of carbon chains at around 400 C. However, these reactions are non-specific, resulting in a mixture of various cleavage products. The large amount of energy required for this process, along with the costs associated with purifying the resulting mixture, severely limits the economic efficiency of pyrolysis.

For several years, various research groups have been experimenting with modified polymers. They have introduced easily detachable molecular groups at the ends of the polymer chains, which then trigger deconstruction from the end of the chain. In this way, the researchers have achieved yields up to 90%.

However, these designer polymers have various major disadvantages. In addition to the need to be first integrated into established plastic production, their reactive end groups significantly limit the thermal stability of the polymers -- and thus their possible uses. Furthermore, many of the commonly used plastic additives reduce the yield of the reactions, with the result that depolymerization only works to a limited extent, even in the case of the long polymer chains that often occur in commercial plastics.

The solvent determines the reaction
As is so often the case in chemistry, the new method was discovered by chance. As Anastasaki explains, "We were actually looking for specific catalysts that would promote the targeted breakdown into monomers. But a control experiment led to the surprising revelation that the catalyst was not even necessary." The chlorinated solvent in which the crushed acrylic glass sample was dissolved was enough to virtually completely split the polymer with the help of UV light.

When the researchers had a closer look at the splitting reaction, they came across a surprising mechanism. They discovered that the chemically active particle in the reaction was a chlorine radical that is split off from the chlorinated solvent when excited by UV light. What was unexpected was that the high-wavelength light can break the chlorine's bond with the solvent molecule. This happens as part of a relatively esoteric photochemical phenomenon, whereby a very small fraction of the solvent molecules absorbs high-wavelength UV light.

Anastasaki was able to count on the help of specialists from other ETH research groups to investigate the mechanism behind the splitting reaction. Tae-Lim Choi from the Laboratory of Polymer Chemistry calculated the theoretical electronic states of the molecules involved, while Gunnar Jeschke from the Institute of Molecular Physical Science carried out electron paramagnetic resonance measurements, which were used to experimentally verify the theoretical predictions.

The chlorine must go
In the future, however, Anastasaki wants to dispense with the chlorinated solvent in her recycling process. "Chlorinated chemical compounds harm the environment. Our next goal is, therefore, to modify the reactions to enable them to work without the chlorinated solvent," she says.

It is still unclear how and when the ETH method will be implemented in practice. In any case, Anastasaki and her team of researchers have opened the door to new recycling methods that can be used to bring about the targeted breakdown of previously chemically inaccessible carbon chains of plastics.

Published March 2025

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