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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. Proto Labs provides valuable tips on designing these (sometimes thin and fragile) parts.
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Bottom tapped rails available for quick ship

Bottom tapped rails are useful for mounting from the bottom of a base, as well as when contamination protection is required -- eliminating the need for bolt-hole caps. See the available models from THK, including standard and radial LM guides and standard and radial caged ball. All units are available for quick shipping.
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Non-marring blowoff nozzle protects expensive equipment

EXAIR's new PEEK 1/2 NPT Super Air Nozzle™ has been engineered to produce powerful blowoff without damage to expensive equipment. It features PEEK plastic construction and excellent resistance to damage from harsh chemicals and temps up to 320 F (160 C). The PEEK Super Air Nozzle is great for blowoff, cooling, and drying applications located in general industrial or corrosive environments.
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Flex thixotropic one-component dual-cure epoxy

Master Bond UV23FLDC-80TK is a moderate viscosity, cationic-type system that offers both UV light and heat curing mechanisms. It cures readily within 20 to 30 sec when exposed to a UV light source. The adhesive can also undergo a secondary heat curing for shadowed areas, typically curing in 60 to 90 min. The system's adaptability to varying depths and applications, such as encapsulation and bonding, enhances its versatility. Well suited for uses where low stress is critical.
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Standard parts with signal feedback included

JW Winco standard parts are becoming even more functional -- multifunctional, to be precise. From smart stop bolts that report whether workpieces are precisely positioned in the machining process to cabinet handles with signal lights and fluid level indicators with electronic REED contact signals, intelligent standard parts from JW Winco ensure greater safety, higher efficiency, and increased stability. Many more very useful options available for a wide range of applications.
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Particle foam perfectly distributed thanks to simulation with Ultrasim

BASF's Ultrasim simulation solution now includes Infinergy, an expanded thermoplastic polyurethane (E-TPU) that is used in a wide range of applications to make components with particle foam -- from bicycle tires to the soles on shoes. Identify and solve problems related to pneumatic filling when distributing particle foams in molds, even taking gravity and mold closing into consideration. Avoid those pesky air pockets.
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Best practices for making technical drawings

Ambiguities in technical drawings can cost extra money when a part must be redone or reworked, leading to unexpected project delays. It is essential to create clear technical drawings the first time around. Did you remember to include an isometric view if possible? Did you limit the number of hidden lines? Xometry lays out 14 tips that to help engineers create clear and professional manufacturing drawings. A solid review.
Read the full Xometry article.

NEW! Semi-automatic pin installation technology from SPIROL -- Better, faster fastening

SPIROL's new video showcases their updated Model PR and Model CR Semi-Automatic Installation Machines for Pins, Alignment Dowels, and Bushings. The video demonstrates how to operate the machine, details standard features, and optional quality and error-proofing enhancements. More than 80% of the components in this installation equipment are standard, pretested, production-proven, off-the-shelf parts. This translates into faster delivery, greater reliability, and lowest cost for equipment of comparable quality.
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Are fasteners over-torqued in your assemblies?

According to Mountz, if you currently use a click wrench for your bolting application, you should proceed cautiously because click wrenches are easily misused, which leads to over-torque events. Replacing a click-wrench with a Mountz FGC cam-over wrench helps prevent operator anomalies and over-torque occurrences, because a cam-over mechanism physically prevents the operator from over-torquing fasteners.
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Tools for robotic metal weld grinding

There are many ways to automate grinding processes, but according to ATI Industrial Automation, "Compliance is the key to successful robotic grinding applications." Learn about the pneumatic compliance built into ATI's tools -- the CGV Compliant Angle Grinder and the PCFC Passive Compliant Force Control device -- that exerts a constant force and compensates for surface irregularities to ensure consistent results and facilitate easier robot programming.
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How BMW Group uses ExOne binder jetting tech to make parts

3D-printer maker ExOne and BMW have worked together for more than two decades on additive manufacturing projects. This video showcases how the premium automaker uses ExOne binder jet sand 3D-printing technology to manufacture water jacket cores in serial production. Binder jetting is one of the fastest 3D-printing methods for producing high-quality and complex precision parts in high volume.
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NEW: Build parts together with Teamspace from Xometry

Xometry's Digital Manufacturing Marketplace has just launched Teamspace, a new product feature that makes it easy for you and your team to build big ideas together. Teamspace is a collaborative workspace within your Xometry account that gives you and members of your team quick and easy access to quotes, order placement, part status, tracking info, and more. Turbocharge the way you make custom parts using additive manufacturing, CNC machining, sheet and tube fabrication, plastics, metals, and more.
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Clean in Place Latches save time and money

Spend less time and money on cleaning and cleaning media with two new standard parts from JW Winco. The new GN 1150 latches are designed to repel dirt and can be cleaned in place. The Hygienic Design latches support the machine and system cleaning concept known as clean in place, or CIP for short. Two versions available: front hygiene (FH) for applications such as switch cabinets that must comply with hygiene requirements only on the outside, and full hygiene (VH) with additional seals for HD quality, even on the latch arm side.
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Flex Locators for quick changeover of small and large fixtures

Flex Locators from Fixtureworks are designed for quick changeover of small and large fixtures, automation components, and more. They are ideal for applications that require frequent disassembly, providing excellent repeatability for locating and clamping in a single operation. Manual and pneumatic versions are available. Just turn the handle, knob, or screw!
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Injection-molded heavy-duty plain bearings for high mechanical loads

igus has introduced a new two-component plain bearing for high mechanical loads called the iglide Q3E series. With this new, greaseless offering, igus has, for the first time, found a way to manufacture heavy-duty bearings made of two layers of high-performance plastic using the cost-effective injection molding process. Applications include the construction and agricultural machinery industries.
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A metal that behaves like water: Graphene exhibits out-of-this-world characteristics

In a new paper published in Science, researchers at the Harvard and Raytheon BBN Technology have advanced our understanding of graphene's basic properties, observing for the first time electrons in a metal behaving like a fluid. [Credit: Peter Allen/Harvard SEAS]

 

 

 

 

Graphene is going to change the world -- or so we've been told.

Since its discovery a decade ago, scientists and tech gurus have hailed graphene as the wonder material that could replace silicon in electronics, increase the efficiency of batteries, the durability and conductivity of touch screens, and pave the way for cheap thermal electric energy, among many other things.

It's one atom thick, stronger than steel, harder than diamond, and one of the most conductive materials on Earth.

But, several challenges must be overcome before graphene products are brought to market. Scientists are still trying to understand the basic physics of this unique material. Also, it's very challenging to make -- and even harder to make without impurities.

In a new paper published in Science, researchers at the Harvard and Raytheon BBN Technology have advanced our understanding of graphene's basic properties, observing for the first time electrons in a metal behaving like a fluid.

In order to make this observation, the team improved methods to create ultra-clean graphene and developed a new way to measure its thermal conductivity. This research could lead to novel thermoelectric devices as well as provide a model system to explore exotic phenomena like black holes and high-energy plasmas.

This research was led by Philip Kim, professor of physics and applied physics in the John A. Paulson School of Engineering and Applied Sciences (SEAS).

An electron super highway
In ordinary, three-dimensional metals, electrons hardly interact with each other. But graphene's two-dimensional, honeycomb structure acts like an electron superhighway in which all the particles have to travel in the same lane. The electrons in graphene act like massless relativistic objects, some with positive charge and some with negative charge. They move at incredible speed -- 1/300 the speed of light -- and have been predicted to collide with each other 10 trillion times a second at room temperature. These intense interactions between charged particles have never been observed in an ordinary metal before.

The team created an ultra-clean sample by sandwiching the one-atom thick graphene sheet between tens of layers of an electrically insulating perfect transparent crystal with a similar atomic structure of graphene.

"If you have a material that's one atom thick, it's going to be really affected by its environment," said Jesse Crossno, a graduate student in the Kim Lab and first author of the paper. "If the graphene is on top of something that's rough and disordered, it's going to interfere with how the electrons move. It's really important to create graphene with no interference from its environment."

The technique was developed by Kim and his collaborators at Columbia University before he moved to Harvard in 2014 and now have been perfected in his lab at SEAS.

Next, the team set up a kind of thermal soup of positively charged and negatively charged particles on the surface of the graphene, and observed how those particles flowed as thermal and electric currents.

What they observed flew in the face of everything they knew about metals.

A black hole on a chip
Most of our world -- how water flows (hydrodynamics) or how a curve ball curves -- is described by classical physics. Very small things, like electrons, are described by quantum mechanics, while very large and very fast things, like galaxies, are described by relativistic physics, pioneered by Albert Einstein.

Combining these laws of physics is notoriously difficult, but there are extreme examples where they overlap. High-energy systems like supernovas and black holes can be described by linking classical theories of hydrodynamics with Einstein's theories of relativity.

But it's difficult to run an experiment on a black hole. Enter graphene.

When the strongly interacting particles in graphene were driven by an electric field, they behaved not like individual particles but like a fluid that could be described by hydrodynamics.

"Instead of watching how a single particle was affected by an electric or thermal force, we could see the conserved energy as it flowed across many particles, like a wave through water," said Crossno.

"Physics we discovered by studying black holes and string theory, we're seeing in graphene," said Andrew Lucas, co-author and graduate student with Subir Sachdev, the Herchel Smith Professor of Physics at Harvard. "This is the first model system of relativistic hydrodynamics in a metal."

Moving forward, a small chip of graphene could be used to model the fluid-like behavior of other high-energy systems.

Industrial implications
So we now know that strongly interacting electrons in graphene behave like a liquid -- how does that advance the industrial applications of graphene?

First, in order to observe the hydrodynamic system, the team needed to develop a precise way to measure how well electrons in the system carry heat. It's very difficult to do, said co-PI Dr. Kin Chung Fong, scientist with Raytheon BBN Technology.

Materials conduct heat in two ways: through vibrations in the atomic structure or lattice; and carried by the electrons themselves.

"We needed to find a clever way to ignore the heat transfer from the lattice and focus only on how much heat is carried by the electrons," Fong said.

To do so, the team turned to noise. At finite temperature, the electrons move about randomly: the higher the temperature, the noisier the electrons. By measuring the temperature of the electrons to three decimal points, the team was able to precisely measure the thermal conductivity of the electrons.

"Converting thermal energy into electric currents and vice versa is notoriously hard with ordinary materials," said Lucas. "But in principle, with a clean sample of graphene there may be no limit to how good a device you could make."

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

Published February 2016

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