June 12, 2018 Volume 14 Issue 22

Mechanical News & Products

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Build a mini synchronous drive system

With the Miniature Synchronous Drive System from Stock Drive Products (SDP), you can put your own 1-, 2-, or 3-mm design together in a snap. The tiny timing belts and pulleys are engineered and manufactured to give high accuracy and smooth, dependable operation in 3D printers, moving security cameras, med devices, robotic surgical equipment, self-service machines, and more. Advantages include no-slip synchronization, accurate positioning, high torque transmission with low backlash, quiet operation, and long belt life.
Click here to learn more.


How colorants affect plastic characteristics

If you're starting a custom plastic injection molding project, you'll want to select a material with the properties most suitable for the function of your parts. One aspect of polymer characteristics that doesn't always get the consideration it deserves is the addition of colorant. Believe it or not, there is a whole scientific body of knowledge about the ways in which adding color to plastic can affect the behavioral properties of the plastic. This short article by Denny Scher of ICO Mold takes a high-level look at some of the different, and surprising, ways colorants can have an effect on plastics.
Read the full article.


New hybrid nylon TPEs are tough, flexible, and more

Nylon Corporation of America has launched an extended product family of nylon (polyamide) -based thermoplastic elastomers (TPEs), also known as polyether-block-amides (PEBA), for a range of applications in the automotive, sporting goods, personal electronics, composite, and specialty films markets. These materials are block copolymers of nylon segments and polyether segments. The nylon block is the hard segment and the polyether block is the soft, flexible segment. NY-FLEX grades are thus hybrid materials, offering a unique combination of rubber-like elastomeric properties and thermoplastic-like processing capabilities. By varying the type and the ratio of these two blocks, a wide range of NY-FLEX grades can be offered.
Learn more.


New 3M metal bonding adhesive

3M Scotch-Weld Metal Bonder Acrylic Adhesive DP8407NS delivers strength, corrosion resistance, and reliable performance for bonding metal without extensive surface prep. This high-strength, fast-curing structural adhesive offers high peel and durability, and maintains its strength at temps as low as -40 F. With the ability to bond active metals like steel, copper, brass, and bronze, 3M's Metal Bonder is ideal for a wide range of assemblies in metal fabrication, transportation, specialty vehicle, architectural panels, appliances, and office furniture. It bonds plastics and composites for multi-material bonding and is also well suited for bonding metals prior to powder coating and paint processes.
Click here to learn more.


Clamping levers with eccentrical cam

JW Winco now offers GN 927 Clamping Levers with Eccentrical Cam in Tapped Type and Threaded Stud versions. The RoHS-compliant clamping levers are used for rapid clamping and releasing operations. In contrast to a clamping operation utilizing threads, these levers permit torque-free clamping. The zinc die-cast, plastic-coated lever has been designed to ensure its movement cannot exceed the maximum clamping position. In addition, there are no loose components, since all are assembled and mounted in their correct order. Thrust forces up to 1.8 lb (8 N) can be obtained.
Learn more.


Replace traditional fasteners: 50+ retaining ring applications

The benefits of a Rotor Clip Retaining Ring are simple: The ring is made from less material than traditional fasteners, eliminating machined shoulders, threads, cover plates, and heat-formed studs -- so you save. Using a retaining ring to fasten your assembly instead of a traditional fastener not only reduces your costs, but also saves the environment. Fewer parts and less material means cost savings for you and less waste for the planet. This quality part offers lot traceability. Want to know what you can do with a Rotor Clip Retaining Ring?
View more than 50 application examples.


Top Technical Tips: Noisy bearings?

Smalley wave springs are ideal for bearing preload. The wave spring preloads the bearing through its outer race, taking up play in the bearing. Preloading will reduce bearing damage, wear, noise, and vibration. The wave spring prevents sliding between the rolling elements. Smalley has over 150 standard springs available, from .188" to 16". Customs are available for unique bearing sizes with No-Tooling-Charges™.
Learn more. You can also request samples.


Metal bonding: Solvent-free activators from DELO speed up curing time

DELO, one of the world's leading manufacturers of industrial adhesives for automotive, consumer, and industrial electronics applications, has developed two solvent-free activators that speed up the curing time of metal adhesives like DELO-ML. These new activators prevent solvent vapors escaping into the environment, potentially causing both health and environmental hazards. DELO's low-viscous DELO-QUICK 5910 and the higher-viscous DELO-QUICK 5975 can be dispensed together with adhesive, without having to evaporate first. Components can be joined and processed immediately after dispensing of the activator, reducing cycle time in the production process.
Learn more.


Adhesives formulated in different colors

Master Bond epoxy systems are formulated in a variety of standard colors, including black, red, green, blue, gray etc. Many optically clear grades are also available. Upon request, compounds can be manufactured in custom colors in order to meet specific requirements. This task requires blending multiple RoHS-compliant pigments in precise proportions to ensure no color variation and uniform appearance. These colored adhesives can be formulated to meet industrial certifications such as medical grade, NASA low outgassing, ISO 10993-5 for cytotoxicity, and more. Compliance testing is performed by independent testing laboratories.
Click here to learn more.


New 3M tape tackles high-temp fastening applications

Since 1980, 3M VHB Tapes have opened the door to faster and easier assemblies. Now, the new GPH series from 3M combines the extreme, permanent bonding power and convenience of 3M VHB Tapes with high-temperature resistance. It can withstand operating temperatures up to 450 F, with long-term durability in conditions up to 300 F. Users will experience excellent adhesion to high and medium surface energy materials, as well as coated or painted surfaces. 3M VHB Tapes, including the new GPH series, replace traditional mechanical fasteners, subsequently eliminating processes like drilling, grinding, refinishing, screwing, welding, and associated rework/clean-up.
Click here to learn more.


Permanent threads in thin sheet applications -- with only one-sided access

ATLAS SpinTite blind threaded inserts from Penn-Engineering provide strong, permanent, and reusable threads in thin sheet materials where only one side is accessible for hardware installation. Installation is performed from the accessible "front" side using spin-spin tooling technology. The inserts then become permanently mounted on the "back" side to accept a mating screw for final component attachment. This "blind" installation capability especially suits applications such as tubing, extrusions, and others where access to the back side is either limited or nonexistent. These steel, aluminum, brass, or stainless steel inserts support close-to-edge applications and can be installed at any stage during the production process (even after assemblies have been painted).
Click here to learn more.


Heavy-duty air-powered conveyor resists wear and transports more

EXAIR's new 2-1/2-in. and 3-in. Heavy Duty Line Vacs are powerful in-line conveyors that transport high volumes of material through ordinary hose or tube -- at a rate that is typically twice that of ordinary air-powered conveyors. Designed for rugged, industrial applications, Heavy Duty Line Vacs have a hardened alloy construction that prevents premature wear when transporting abrasive or heavy materials like shot blast, tumbling media, or metal fittings. These units feature large throat diameters that make it possible to convey more material over longer vertical and horizontal lengths. Seven sizes available.
Learn more.


High-gain rubber-type coupling

In 2007, NBK took the lead in the industry with the launching of the High-Gain Rubber Coupling. With the XG-Series, you can increase the productivity and control of your Servo System with higher gain compared to when using traditional couplings. These High-Gain Rubber Couplings shorten manufacturing time through the reduction of vibration even in high-gain surroundings by an innovative molding technique within the internal structure of the couplings.
Click here to learn more.


Completely updated new full-line catalog of fasteners

Micro Plastics introduces its new 300-page catalog #41 containing thousands of fastening solutions for engineers and product designers. Find hundreds of new problem-solving products including Spacers, Washers, Clips, Clamps, Ties, Bushings, Screws, Nuts, Rivets, and Plugs. Micro Plastics specializes in Nylon threaded fasteners, but the company also offers extensive product lines for wire management and circuit board hardware. Samples are available upon request.
Check out the new online catalog.


Instant quoting for on-demand manufacturing

Xometry, a popular on-demand manufacturing platform, has released a new version of its Xometry Instant Quoting Engine. Key features include a redesigned summary view to help users quickly review their quotes, a part-level modification page that captures all changes in real time, and an always-visible 3D viewer with instant design feedback displayed directly on the model. Xometry provides instant quotes on CNC Machining, Sheet Metal Fabrication, 3D Printing, and Urethane Casting.
Check it out on the Xometry website.


Novel transmitter protects wireless devices from hackers

Today, more than 8 billion devices are connected around the world, forming an "internet of things" that includes medical devices, wearables, vehicles, and smart household and city technologies. By 2020, experts estimate that number will rise to more than 20 billion devices, all uploading and sharing data online.

But those devices are vulnerable to hacker attacks that locate, intercept, and overwrite the data, jam signals, and generally wreak havoc. One method to protect the data is called "frequency hopping," which sends each data packet, containing thousands of individual bits, on a random, unique radio frequency (RF) channel, so hackers can't pin down any given packet. Hopping large packets, however, is just slow enough that hackers can still pull off an attack.

Now MIT researchers have developed a novel transmitter that frequency hops each individual 1 or 0 bit of a data packet, every microsecond, which is fast enough to thwart even the quickest hackers.

The transmitter leverages frequency-agile devices called bulk acoustic wave (BAW) resonators and rapidly switches between a wide range of RF channels, sending information for a data bit with each hop. In addition, the researchers incorporated a channel generator that, each microsecond, selects the random channel to send each bit. On top of that, the researchers developed a wireless protocol -- different from the protocol used today -- to support the ultrafast frequency hopping.

"With the current existing [transmitter] architecture, you wouldn't be able to hop data bits at that speed with low power," says Rabia Tugce Yazicigil, a postdoc in the Department of Electrical Engineering and Computer Science and first author on a paper describing the transmitter, which is being presented at the IEEE Radio Frequency Integrated Circuits Symposium. "By developing this protocol and radio frequency architecture together, we offer physical-layer security for connectivity of everything." Initially, this could mean securing smart meters that read home utilities, control heating, or monitor the grid.

"More seriously, perhaps, the transmitter could help secure medical devices, such as insulin pumps and pacemakers, that could be attacked if a hacker wants to harm someone," Yazicigil says. "When people start corrupting the messages [of these devices], it starts affecting people's lives."

Co-authors on the paper are Anantha P. Chandrakasan, dean of MIT's School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science (EECS); former MIT postdoc Phillip Nadeau; former MIT undergraduate student Daniel Richman; EECS graduate student Chiraag Juvekar; and visiting research student Kapil Vaidya.

Ultrafast frequency hopping
One particularly sneaky attack on wireless devices is called selective jamming, where a hacker intercepts and corrupts data packets transmitting from a single device but leaves all other nearby devices unscathed. Such targeted attacks are difficult to identify, as they're often mistaken for poor a wireless link and are difficult to combat with current packet-level frequency-hopping transmitters.

With frequency hopping, a transmitter sends data on various channels, based on a predetermined sequence shared with the receiver. Packet-level frequency hopping sends one data packet at a time, on a single 1-megahertz channel, across a range of 80 channels. A packet takes around 612 microseconds for BLE-type transmitters to send on that channel. But attackers can locate the channel during the first 1 microsecond and then jam the packet.

"Because the packet stays in the channel for long time, and the attacker only needs a microsecond to identify the frequency, the attacker has enough time to overwrite the data in the remainder of the packet," Yazicigil says.

To build their ultrafast frequency-hopping method, the researchers first replaced a crystal oscillator -- which vibrates to create an electrical signal -- with an oscillator based on a BAW resonator. However, the BAW resonators only cover about 4 to 5 megahertz of frequency channels, falling far short of the 80-megahertz range available in the 2.4-gigahertz band designated for wireless communication. Continuing recent work on BAW resonators -- in a 2017 paper co-authored by Chandrakasan, Nadeau, and Yazicigil -- the researchers incorporated components that divide an input frequency into multiple frequencies. An additional mixer component combines the divided frequencies with the BAW's radio frequencies to create a host of new radio frequencies that can span about 80 channels.

Randomizing everything
The next step was randomizing how the data is sent. In traditional modulation schemes, when a transmitter sends data on a channel, that channel will display an offset -- a slight deviation in frequency. With BLE modulations, that offset is always a fixed 250 kilohertz for a 1 bit and a fixed -250 kilohertz for a 0 bit. A receiver simply notes the channel's 250-kilohertz or -250-kilohertz offset as each bit is sent and decodes the corresponding bits.

But that means, if hackers can pinpoint the carrier frequency, they too have access to that information. If hackers can see a 250-kilohertz offset on, say, channel 14, they'll know that's an incoming 1 and begin messing with the rest of the data packet.

To combat that, the researchers employed a system that each microsecond generates a pair of separate channels across the 80-channel spectrum. Based on a preshared secret key with the transmitter, the receiver does some calculations to designate one channel to carry a 1 bit and the other to carry a 0 bit. But the channel carrying the desired bit will always display more energy. The receiver then compares the energy in those two channels, notes which one has a higher energy, and decodes for the bit sent on that channel.

For example, by using the preshared key, the receiver will calculate that 1 will be sent on channel 14 and a 0 will be sent on channel 31 for one hop. But the transmitter only wants the receiver to decode a 1. The transmitter will send a 1 on channel 14, and send nothing on channel 31. The receiver sees channel 14 has a higher energy and, knowing that's a 1-bit channel, decodes a 1. In the next microsecond, the transmitter selects two more random channels for the next bit and repeats the process.

Because the channel selection is quick and random, and there is no fixed frequency offset, a hacker can never tell which bit is going to which channel. "For an attacker, that means they can't do any better than random guessing, making selective jamming infeasible," Yazicigil says.

As a final innovation, the researchers integrated two transmitter paths into a time-interleaved architecture. This allows the inactive transmitter to receive the selected next channel, while the active transmitter sends data on the current channel. Then, the workload alternates. Doing so ensures a 1-microsecond frequency-hop rate and, in turn, preserves the 1-megabyte-per-second data rate similar to BLE-type transmitters.

Source: Massachusetts Institute of Technology

Published June 2018

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