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Engineer's Toolbox: How to design the optimum hinge

Although many pin styles are available, Coiled Spring Pins are particularly well suited for use in both friction- and free-fit hinges. To achieve optimum long-term hinge performance, designers should observe these helpful design guidelines from SPIROL.
Read the full article.

Innovative new robo welding gun

Comau's newest N-WG welding gun is designed for high-speed spot welding for traditional, hybrid, and electric vehicles, in addition to general industry sectors. It features a patented, single-body architecture that enables rapid reconfiguration between welding types and forces, and it delivers consistent performance across a broad range of applications, including steel and (soon) aluminum welding. It supports both X and C standard gun configurations, has fast arm exchange, and universal mounting options. It is fully compatible with major robot brands and represents a significant advancement in spot welding performance and cost efficiency.
Learn more.

What's a SLIC Pin^®? Pin and cotter all in one!

The SLIC Pin (Self-Locking Implanted Cotter Pin) from Pivot Point is a pin and cotter all in one. This one-piece locking clevis pin is cost saving, fast, and secure. It functions as a quick locking pin wherever you need a fast-lock function. It features a spring-loaded plunger that functions as an easy insertion ramp. This revolutionary fastening pin is very popular and used successfully in a wide range of applications.
Learn more.

Engineering challenge: Which 3D-printed parts will fade?

How does prolonged exposure to intense UV light impact 3D-printed plastics? Will they fade? This is what Xometry's Director of Application Engineering, Greg Paulsen, set to find out. In this video, Paulsen performs comprehensive tests on samples manufactured using various additive processes, including FDM, SLS, SLA, PolyJet, DLS, and LSPc, to determine their UV resistance. Very informative. Some results may surprise you.
View the video.

Copper filament for 3D printing

Virtual Foundry, the company that brought us 3D-printable lunar regolith simulant, says its popular Copper Filamet™ (not a typo) is "back in stock and ready for your next project." This material is compatible with any open-architecture FDM/FFF 3D printer. After sintering, final parts are 100% pure copper. Also available as pellets. The company says this is one of the easiest materials to print and sinter. New Porcelain Filamet™ available too.
Learn more and get all the specs.

Copper foam -- so many advantages

Copper foam from Goodfellow combines the outstanding thermal conductivity of copper with the structural benefits of a metal foam. These features are of particular interest to design engineers working in the fields of medical products and devices, defense systems and manned flight, power generation, and the manufacture of semiconductor devices. This product has a true skeletal structure with no voids, inclusions, or entrapments. A perennial favorite of Designfax readers.
Learn more.

Full-color 3D-printing Design Guide from Xometry

With Xometry's PolyJet 3D-printing service, you can order full-color 3D prints easily. Their no-cost design guide will help you learn about different aspects of 3D printing colorful parts, how to create and add color to your models, and best practices to keep in mind when printing in full color. Learn how to take full advantage of the 600,000 unique colors available in this flexible additive process.
Get the Xometry guide.

Tech Tip: How to create high-quality STL files for 3D prints

Have you ever 3D printed a part that had flat spots or faceted surfaces where smooth curves were supposed to be? You are not alone, and it's not your 3D printer's fault. According to Markforged, the culprit is likely a lack of resolution in the STL file used to create the part.
Read this detailed and informative Markforged blog.

Test your knowledge: High-temp adhesives

Put your knowledge to the test by trying to answer these key questions on how to choose the right high-temperature-resistant adhesive. The technical experts from Master Bond cover critical information necessary for the selection process, including questions on glass transition temperature and service temperature range. Some of the answers may surprise even the savviest of engineers.
Take the quiz.

Engineer's Toolbox: How to pin a shaft and hub assembly properly

One of the primary benefits of using a coiled spring pin to affix a hub or gear to a shaft is the coiled pin's ability to prevent hole damage. Another is the coiled pin absorbs wider hole tolerances than any other press-fit pin. This translates to lower total manufacturing costs of the assembly. However, there are a few design guidelines that must be adhered to in order to achieve the maximum strength of the pinned system and prevent damage to the assembly.
Read this very informative SPIROL article.

What's new in Creo Parametric 11.0?

Creo Parametric 11.0 is packed with productivity-enhancing updates, and sometimes the smallest changes make the biggest impact in your daily workflows. Mark Potrzebowski, Technical Training Engineer, Rand 3D, runs through the newest functionality -- from improved surface modeling tools to smarter file management and model tree navigation. Videos provide extra instruction.
Read the full article.

What's so special about wave springs?

Don't settle for ordinary springs. Opt for Rotor Clip wave springs. A wave spring is a type of flat wire compression spring characterized by its unique waveform-like structure. Unlike traditional coil springs, wave springs offer an innovative solution to complex engineering challenges, producing forces from bending, not torsion. Their standout feature lies in their ability to compress and expand efficiently while occupying up to 50% less axial space than traditional compression springs. Experience the difference Rotor Clip wave springs can make in your applications today!
View the video.

New Standard Parts Handbook from JW Winco

JW Winco's printed Standard Parts Handbook is a comprehensive 2,184-page reference that supports designers and engineers with the largest selection of standard parts categorized into three main groups: operating, clamping, and machine parts. More than 75,000 standard parts can be found in this valuable resource, including toggle clamps, shaft collars, concealed multiple-joint hinges, and hygienically designed components.
Get your Standard Parts Handbook today.

Looking to save space in your designs?

Watch Smalley's quick explainer video to see how engineer Frank improved his product designs by switching from traditional coil springs to compact, efficient wave springs. Tasked with making his products smaller while keeping costs down, Frank found wave springs were the perfect solution.
View the video.

Top die casting design tips

You can improve the design and cost of your die cast parts with these top tips from Xometry's Joel Schadegg. Topics include: Fillets and Radii, Wall Thicknesses, Ribs and Metal Savers, Holes and Windows, Parting Lines, and more. Follow these recommendations so you have the highest chance of success with your project.
Read the full Xometry article.

Elastic polymer that is both stiff and tough resolves long-standing quandary

Polymer science has made possible rubber tires, Teflon and Kevlar, plastic water bottles, and nylon jackets, among many other ubiquitous features of daily life. Elastic polymers, known as elastomers, can be stretched and released repeatedly and are used in applications such as gloves and heart valves, where they need to last a long time without tearing. But a conundrum has long stumped polymer scientists: Elastic polymers can be stiff, or they can be tough, but they can't be both.

This stiffness-toughness conflict is a challenge for scientists developing polymers that could be used in applications including tissue regeneration, bioadhesives, bioprinting, wearable electronics, and soft robots.

In a paper published Oct. 7 in Science, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have resolved that long-standing conflict and developed an elastomer that is both stiff and tough.

"In addition to developing polymers for emerging applications, scientists are facing an urgent challenge: plastic pollution," said Zhigang Suo, the Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials, the senior author of the study. "The development of biodegradable polymers has once again brought us back to fundamental questions -- why are some polymers tough, but others brittle? How do we make polymers resist tearing under repeated stretching?"

Polymer chains are made by linking together monomer building blocks. To make a material elastic , the polymer chains are crosslinked by covalent bonds. The more crosslinks, the shorter the polymer chains and the stiffer the material.

"As your polymer chains become shorter, the energy you can store in the material becomes less and the material becomes brittle," said Junsoo Kim, a graduate student at SEAS and co-first author of the paper. "If you have only a few crosslinks, the chains are longer, and the material is tough but it's too squishy to be useful."

To develop a polymer that is both stiff and tough, the researchers looked to physical, rather than chemical bonds to link the polymer chains. These physical bonds, called entanglements, have been known in the field for almost as long as polymer science has existed, but they've been thought to only impact stiffness, not toughness.

But the SEAS research team found that with enough entanglements, a polymer could become tough without compromising stiffness. To create highly entangled polymers, the researchers used a concentrated monomer precursor solution with 10 times less water than other polymer recipes.

"By crowding all the monomers into this solution with less water and then polymerizing it, we forced them to be entangled, like tangled strings of yarn," said Guogao Zhang, a postdoctoral fellow at SEAS and co-first author the paper. "Just like with knitted fabrics, the polymers maintain their connection with one another by being physically intertwined."

With hundreds of these entanglements, just a handful of chemical crosslinks are required to keep the polymer stable.

Each polymer chain has a large number of entanglements along its length (left) and a cross-link at each end. A stretched polymer (right) showing transmission of the tension to other chains. [Credit: Suo Lab/Harvard SEAS]

 

 

 

 

A highly entangled hydrogel (left) and a regular hydrogel (right). [Credit: Suo Lab/Harvard SEAS]

 

 

 

 

That high fatigue resistance and high wear resistance increases the durability and lifespan of the polymers.

"Our research shows that by using entanglements rather than crosslinks, we could decrease the consumption of some plastics by increasing the durability of the materials," said Zhang.

"We hope that this new understanding of polymer structure will expand opportunities for applications and pave the way for more sustainable, long-lasting polymer materials with these exceptional mechanical properties," said Kim.

Harvard's Office of Technology Development has protected the intellectual property associated with this project and is exploring commercialization opportunities.

Source: Harvard John A. Paulson School of Engineering and Applied Sciences

Published October 2021

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