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New 'breathable' rupture disk tech provides overpressure and vacuum relief

To increase equipment safety and reliability, a new rupture disk technology activates at a set burst pressure, but it can also "breathe" to relieve minor pressure fluctuations. The patent-pending, dual-function device from BS&B Safety Systems is ideal for use on low-pressure vessels that are susceptible to ambient temperature changes.
Read the full article.

Engineer's Toolbox: 9 considerations for specifying a slewing ring bearing

In applications that require a bearing to support a structure while it rotates (e.g., cranes, radar, tank turrets), premature bearing failure can put people and equipment at risk. While slewing ring bearings have proven themselves countless times in such applications, designers must consider many factors when specifying them. According to engineers at Kaydon, the bearing's support structure, mounting (including bolt strength, tensioning, and hole patterns), installation, and even storage are all factors in a bearing's success or failure.
Read the full article.

ClampDisk micro fastener is new alternative for automotive and consumer electronics

Designed as a unique alternative in assemblies for the automotive and consumer electronics markets, the ClampDisk Press-on Fastener is a new offering from PennEngineering that delivers a fast, simple way to achieve sheet-to-sheet clamped fastening while replacing the use of standard screws, nuts, and adhesives. The most common challenges that can be eliminated or reduced by using ClampDisk include over installation, cross threading, stripped screw heads, broken screws, and damaged product. This fastener can be removed easily with a sharp-edged tool.
Learn more and see how ClampDisk works.

New nylon constant torque hinge

Southco has expanded its line of E6 Constant Torque Hinges with a compact, nylon version designed for small applications. The newest addition to the company's E6 50 Constant Torque Position Control Hinge series measures 45 mm with a torque range of 4 to 16 in./lb and is 65% lighter compared to the standard E6 50 Hinge. It provides constant resistance throughout the entire range of motion, enabling users to easily position doors, display screens, and other mounted components and hold them securely at any desired angle.
Learn more.

What injection molding material do I use?

How do you decide what type of plastic to use for your next injection molding project? Xometry can help you narrow your choices. Discover the different strengths and applications for materials that could be ideal for your application by learning about the most common plastic injection molding materials in detail.
Read this detailed Xometry article.

What are carbon composite bellows springs?

The Carbon Composite Bellows Spring (CCBS) from MW Components is a system of carbon fiber elements that combine to work as a high-performance, lightweight, and design-flexible compression spring meant to replace coil springs or metallic Belleville disc springs. A functional spring is made from several individual elements paired and joined to make a stack. The stack spring rate is determined by the number of elements, the base rate of each element, and their series or parallel orientation in the stack. Applications include motorsports, aerospace, and high-performance activities.
Learn more.

Conductive Brush Ring overcomes current leakage in EV powertrains

SKF's new Conductive Brush Ring paves the way to greater reliability and longer life in high-performance electric vehicle powertrain systems. Using pure carbon fiber bristles, it provides a reliable electrical connection between an EV eAxle rotor shaft and its housing. When used in combination with SKF Hybrid ceramic ball bearings, it helps to alleviate parasitic current effects that can lead to premature failure in bearings and other components. Available in different configurations for wet (oil-lubricated) motor designs -- and soon for dry (sealed) applications.
Learn more.

hyperMILL 2024 CAD/CAM software suite

OPEN MIND Technologies has introduced its latest hyperMILL 2024 CAD/CAM software suite, which includes a range of powerful enhancements to its core toolpath capabilities, as well as new functionality for increased NC programming efficiency in applications ranging from 2.5D machining to 5-axis milling. New and enhanced capabilities include: Optimized Deep Hole Drilling, a new algorithm for 3- and 5-axis Rest Machining, an enhanced path layout for the 3D Plane Machining cycle, better error detection, and much more.
Learn more.

One-part epoxy changes from red to clear under UV

Master Bond UV15RCL is a low-viscosity, cationic-type UV-curing system with a special color-changing feature. The red material changes to clear once exposed to UV light, indicating that there is UV light access across the adhesive material. Although this change in color from red to clear does not indicate a full cure, it does confirm that the UV light has reached the polymer. This epoxy is an excellent electrical insulator. UV15RCL adheres well to metals, glass, ceramics, and many plastics, including acrylics and polycarbonates.
Learn more.

SPIROL Press-N-Lok™ Pin for plastic housings

The Press-N-Lok™ Pin was designed to permanently retain two plastic components to each other. As the pin is inserted, the plastic backfills into the area around the two opposing barbs, resulting in maximum retention. Assembly time is quicker, and it requires lower assembly equipment costs compared to screws and adhesives -- just Press-N-Lok™!
Learn more about the new Press-N-Lok™ Pin.

Why hybrid bearings are becoming the new industry standard

A combination of steel outer and inner rings with ceramic balls or rollers is giving hybrid bearings unique properties, making them suitable for use in a wide range of modern applications. SKF hybrid bearings make use of silicon nitride (twice as hard as bearing steel) rolling elements and are available as ball bearings, cylindrical roller bearings, and in custom designs. From electric erosion prevention to friction reduction and extended maintenance intervals, learn all about next-gen hybrid bearings.
Read the SKF technical article.

3M and Ansys train engineers on simulating adhesives

Ansys and 3M have created an advanced simulation training program enabling engineers to enhance the design and sustainability of their products when using tapes and adhesives as part of the design. Simulation enables engineers to validate engineering decisions when analyzing advanced polymeric materials -- especially when bonding components made of different materials. Understand the behavior of adhesives under real-world conditions for accurate modeling and design.
Read this informative Ansys blog.

New FATH T-slotted rail components in black from AutomationDirect

Automation-Direct has added a wide assortment of black-colored FATH T-slotted hardware components to match their SureFrame black anodized T-slotted rails, including: cube connectors (2D and 3D) and angle connectors, joining plates of many types, brackets, and pivot joints. Also included are foot consoles, linear bearings in silver and black, cam lever brakes, and L-handle brakes. FATH T-slotted hardware components are easy to install, allow for numerous T-slotted structure configurations, and have a 1-year warranty against defects.
Learn more.

Weird stuff: Moon dust simulant for 3D printing

Crafted from a lunar regolith simulant, Basalt Moon Dust Filamet™ (not a typo) available from The Virtual Foundry closely mirrors the makeup of lunar regolith found in mare regions of the Moon. It enables users with standard fused filament fabrication (FFF) 3D printers to print with unparalleled realism. Try out your ideas before you go for that big space contract, or help your kid get an A on that special science project.
Learn more.

Break the mold with custom injection molding by Rogan

With 90 years of industry experience, Rogan Corporation possesses the expertise to deliver custom injection molding solutions that set businesses apart. As a low-cost, high-volume solution, injection molding is the most widely used plastics manufacturing process. Rogan processes include single-shot, two-shot, overmolding, and assembly. Elevate your parts with secondary operations: drilling and tapping, hot stamping, special finishes, punch press, gluing, painting, and more.
Learn more.

Weird science: Weaker bonds can make polymers stronger

By Anne Trafton, MIT

By adding weak linkers to a polymer network, chemists dramatically enhanced the material's resistance to tearing.

A team of chemists from MIT and Duke University has discovered a counterintuitive way to make polymers stronger: introduce a few weaker bonds into the material.

Working with a type of polymer known as polyacrylate elastomers, the researchers found that they could increase the materials' resistance to tearing up to tenfold, simply by using a weaker type of crosslinker to join some of the polymer building blocks.

As this polymer network is stretched, weaker crosslinking bonds (blue) break more easily than any of the strong polymer strands, making it more difficult for a crack to propagate through the material. [Credit: Courtesy of the MIT researchers/Edited by MIT News]

 

 

 

 

These rubber-like polymers are commonly used in car parts, and they are also often used as the "ink" for 3D-printed objects. The researchers are now exploring the possible expansion of this approach to other types of materials, such as rubber tires.

"If you could make a rubber tire 10 times more resistant to tearing, that could have a dramatic impact on the lifetime of the tire and on the amount of microplastic waste that breaks off," says Jeremiah Johnson, a professor of chemistry at MIT and one of the senior authors of the study, which appeared June 22, 2023, in Science.

A significant advantage of this approach is that it doesn't appear to alter any of the other physical properties of the polymers.

"Polymer engineers know how to make materials tougher, but it invariably involves changing some other property of the material that you don't want to change. Here, the toughness enhancement comes without any other significant change in physical properties -- at least that we can measure -- and it is brought about through the replacement of only a small fraction of the overall material," says Stephen Craig, a professor of chemistry at Duke University who is also a senior author of the paper.

This project grew out of a longstanding collaboration between Johnson, Craig, and Duke University Professor Michael Rubinstein, who is also a senior author of the paper. The paper's lead author is Shu Wang, an MIT postdoc who earned his PhD at Duke.

The weakest link
Polyacrylate elastomers are polymer networks made from strands of acrylate held together by linking molecules. These building blocks can be joined together in different ways to create materials with different properties.

One architecture often used for these polymers is a star polymer network. These polymers are made from two types of building blocks: one, a star with four identical arms, and the other a chain that acts as a linker. These linkers bind to the end of each arm of the stars, creating a network that resembles a volleyball net.

When force is applied, a modified polyacrylate elastomer (top) takes longer to tear than the same material made in the traditional way (bottom). [Credit: Courtesy of the MIT researchers]

 

 

 

 

In a 2021 study, Craig, Rubinstein, and MIT Professor Bradley Olsen teamed up to measure the strength of these polymers. As they expected, they found that when weaker end-linkers were used to hold the polymer strands together, the material became weaker. Those weaker linkers, which contain cyclic molecules known as cyclobutane, can be broken with much less force than the linkers that are usually used to join these building blocks.

As a follow-up to that study, the researchers decided to investigate a different type of polymer network in which polymer strands are cross-linked to other strands in random locations, instead of being joined at the ends.

This time, when the researchers used weaker linkers to join the acrylate building blocks together, they found that the material became much more resistant to tearing.

This occurs, the researchers believe, because the weaker bonds are randomly distributed as junctions between otherwise strong strands throughout the material, instead of being part of the ultimate strands themselves. When this material is stretched to the breaking point, any cracks propagating through the material try to avoid the stronger bonds and go through the weaker bonds instead. This means the crack has to break more bonds than it would if all of the bonds were the same strength.

"Even though those bonds are weaker, more of them end up needing to be broken, because the crack takes a path through the weakest bonds, which ends up being a longer path," Johnson says.

Tough materials
Using this approach, the researchers showed that polyacrylates that incorporated some weaker linkers were nine to 10 times harder to tear than polyacrylates made with stronger crosslinking molecules. This effect was achieved even when the weak crosslinkers made up only about 2% of the overall composition of the material.

The researchers also showed that this altered composition did not alter any of the other properties of the material, such as resistance to breaking down when heated.

"For two materials to have the same structure and same properties at the network level, but have an almost order of magnitude difference in tearing, is quite rare," Johnson says.

The researchers are now investigating whether this approach could be used to improve the toughness of other materials, including rubber.

"There's a lot to explore here about what level of enhancement can be gained in other types of materials and how best to take advantage of it," Craig says.

Published July 2023

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