July 02, 2019 Volume 15 Issue 25

Mechanical News & Products

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Round vs. square rails -- which are better for you?

Thomson invented the world's first anti-friction linear ball bushing bearings in 1946. For many years, these round-rail linear guides satisfied every linear motion control requirement. However, as machines required closer tolerances, the round rail didn't always fit the bill. Learn the pros and cons of each design type.
Read this informative Thomson blog.


New bearings reduce wear in heavy-duty applications

igus has introduced a new bearing with an improved iglide material, called TX2, that offers self-lubricating and maintenance-free properties for heavy-duty applications. TX2 increases wear resistance by a factor of 3.5 in load ranges with more than 100-MPa surface pressure. The material is ideal for components in machines that serve construction and agriculture, which can require more than 50 liters of lubricant annually. The material is also very resistant to temperature, chemicals, moisture, corrosion, and seawater, which opens up the applications base for its use substantially.
Learn more.


Aerospace fastener hole drilling and countersinking all in one step

Kennametal has introduced the HiPACS drilling and countersinking system for aerospace fastener holes. Designed to drill and chamfer holes in one operation, the high-precision tool meets the aerospace industry's stringent accuracy requirements while delivering increased tool life in machining composite, titanium, and aluminum aircraft skins. With an industry-standard interface, HiPACS can be utilized on any CNC machine. Three components eliminate the need for custom tooling: a reducer sleeve with a built-in high-precision pocket seat, a PCD countersinking insert, and two series of solid carbide drills.
Learn more.


Why precision metrology is critical for electric vehicle gearing

As the shift from internal combustion engines to electric motors in vehicles continues, the number of drivetrain components will dramatically lessen too. The remaining components will be even more critical to a vehicle's operation and longevity. One such area is the gear components necessary to convert the high-force torque from electric motors to the RPMs at the wheel.
By Michael Schmidt, Zygo Corporation
Read the full article.


Master CNC machining tolerances eBook

Need a refresher on the basics of applying tolerances to custom machined metal and plastic parts? In this ebook, Xometry provides some pointers on designing mating parts and parts for specific functions. Chapters include: general machining tolerances, clearance and interference fit, how to avoid over-tolerancing, CAD drawing prep and specs, and an inspection report cheat sheet.
Get this valuable resource from Xometry.


Specifying metal inserts for molded plastics

Teaming with insert manufacturers that offer engineering expertise throughout the design and manufacturing process can be worth its weight in gold. Learn how two OEMs overcame their metal insert challenges by using advice and products from Tri-Star Industries, including specialty stainless steel parts and modifying the knurling on some inserts.
Read the full article.


Posi-Lok keyless shaft bushings for secure shaft-to-hub connection

Zero-Max offers a variety of options within the Posi-Lok keyless shaft bushings (PSL) product line that allow users to rigidly and reliably secure shaft-mounted components into position for optimal operating results in their machines. Options include material choices, plating, and different mounting methods. Posi-Loks are a superior shaft-hub locking solution, eliminating the need for keyways that can weaken or cause excess wear to shaft components. All Posi-Lok models easily slide onto a shaft for mounting and provide reliable, zero-backlash performance.
Learn more.


Automation: ECONOmaster drilling units -- affordable, flexible, get the job done

Suhner's ECONO-master® is a low-cost, high-output automated drilling unit that puts holes in light metal, composite, thermoplastic, and even wood substrates at high speed with excellent accuracy. It features low power and air consumption. On a recent project for Mid-State Engineering, Suhner custom ECONOmaster drill units -- featuring selectable drill heads that can be used in combination or individually -- were used to automatically drill holes into fiberglass panels for truck trailer bodies.
Read the full article.


Great Resources: Ultimate Guide to Injection Molding

Xometry has put together a comprehensive resource for injection molding -- from the basic principles to applications, tooling, materials, design features, and more. Learn how to optimize your part designs and choose the right surface finishes, textures, and post-processing for your projects. A super-handy resource worth bookmarking.
Read the Xometry Ultimate Guide to Injection Molding.


Sealing fasteners may optimize your designs

Highly specialized sealing fasteners include sealing screws, sealing nuts, sealing bolts, and sealing washers. Unlike ordinary fasteners, sealing fasteners are configured with a rubber O-ring (or a rubber element) that, when squeezed, permanently seals out a wide range of contaminants from entering and damaging equipment while preventing leakage of toxins into the environment. ZAGO sealing fasteners are designed to withstand harsh weather and extreme temperatures and are vibration and pressure resistant.
Learn all about ZAGO's wide selection of sealing fasteners.


Spirit levels with adjustment and cross-measurement

They may seem like relics from the past, but spirit levels remain indispensable tools in everyday industrial operations. Two new types from JW Winco now offer even better and faster alignment. The cross spirit levels GN 2276 combine two perpendicular linear levels within a single, round aluminum housing to show the alignment in two planes at once, making installation and leveling easier and faster. The new screw-on spirit levels GN 2283 are used to check the horizontal position of jigs, machines, devices, appliances, and instruments. These are available in a directly mountable, flat version (AV) and as an adjustable version (JV) with an alignment cam.
Learn more.


New cast urethane materials and finishes

Xometry has added new urethane resins and finishes as options for quick and affordable low- to mid-volume production. Urethane casting is used to make end-use, highly durable parts with robust mechanical properties. It is considered a "soft-tooled" process, where a silicone mold is formed around a master pattern -- usually 3D printed. Xometry has materials in two main durometer classes, rigid (Shore D) and rubber-like (Shore A). Finishes include matte/frosted, semi-gloss, high-gloss, and custom.
Read this informative Xometry blog.
Get the Xometry Urethane Casting Design Guide.


New molded-in aluminum threaded inserts for plastics

SPIROL has introduced a new, high-performance series of Molded-In Inserts for plastics assemblies. The rugged design of the Series 63 Through Hole Inserts and Series 65 Blind End Inserts consists of multiple bands of helical knurls to maximize torque resistance, balanced with radial undercuts to achieve high pull-out (tensile) force. These Molded-In Inserts are designed to be placed in the mold cavity prior to plastic injection. They offer exceptional performance due to unrestricted plastic flow into the retention features on the outside diameter of the Inserts.
Learn more.


How to avoid premature linear screw actuator failure

At their core, electric linear screw actuators deploy mechanical technology such as ball bearings, ball screws, and roller screws that have a finite life. These components do not last forever -- even though that is the expectation of some customers. But how long will an actuator really last? Tolomatic engineers provide a way to calculate, estimate, and size the electric linear screw actuator to achieve the desired life for your applications.
Read this informative Tolomatic blog.


3D Printing: Desktop Metal qualifies 316L stainless steel for high-volume manufacturing -- thousands of parts per week

3D-printer machine maker Desktop Metal has qualified the use of 316L stainless steel for its additive manufacturing platform called the Production System, which provides some of the fastest build speeds in the market for mass production and can make thousands of parts per week. This article includes very useful cost-per-part and time-to-manufacture information using five different application examples.
Read the full article.


Sun-soaking device turns water into superheated steam

The high-temperature steam might be used in remote regions to cook, clean, or sterilize medical equipment.

MIT engineers have built a device that soaks up enough heat from the sun to boil water and produce "superheated" steam hotter than 100 degrees Celsius, without any expensive optics.

On a sunny day, the structure can passively pump out steam hot enough to sterilize medical equipment, as well as to use in cooking and cleaning. The steam may also supply heat to industrial processes, or it could be collected and condensed to produce desalinated, distilled drinking water.

The outdoor experiment on the MIT roof. Steam-generating device is mounted over a basin of water, placed on a small table, and partially surrounded by a simple, transparent solar concentrator. Researchers measured the temperature of the steam produced over the course of the test day, Oct. 21, 2017. [Credit: Courtesy of the researchers, Thomas Cooper et al.]

 

 

 

 

The researchers previously developed a sponge-like structure that floated in a container of water and turned the water it absorbed into steam. But a big concern was that contaminants in the water caused the structure to degrade over time. The new device is designed to be suspended over the water to avoid any possible contamination.

The suspended device is about the size and thickness of a small digital tablet or e-reader, and it is structured like a sandwich: The top layer is made from a material that efficiently absorbs the sun's heat, while the bottom layer efficiently emits that heat to the water below. Once the water reaches the boiling point (100 C), it releases steam that rises back up into the device, where it is funneled through the middle layer -- a foam-like material that further heats the steam above the boiling point, before it's pumped out through a single tube.

"It's a completely passive system -- you just leave it outside to absorb sunlight," says Thomas Cooper, assistant professor of mechanical engineering at York University, who led the work as a postdoc at MIT. "You could scale this up to something that could be used in remote climates to generate enough drinking water for a family, or sterilize equipment for one operating room."

The team's results are detailed in a paper published in Nature Communications. The study includes researchers from the lab of Gang Chen, the Carl Richard Soderberg Professor of Power Engineering at MIT.

A clever combination
In 2014, Chen's group reported the first demonstration of a simple, solar-driven steam generator, in the form of a graphite-covered carbon foam that floats on water. This structure absorbs and localizes the sun's heat to the water's surface (the heat would otherwise penetrate down through the water). Since then, his group and others have looked to improve the efficiency of the design with materials of varying solar-absorbing properties. But almost every device has been designed to float directly on water, and they have all run into the problem of contamination, as their surfaces come into contact with salt and other impurities in water.

The team decided to design a device that instead is suspended above water. The device is structured to absorb short-wavelength solar energy, which in turn heats up the device, causing it to reradiate this heat, in the form of longer-wavelength infrared radiation, to the water below. Interestingly, the researchers note that infrared wavelengths are more readily absorbed by water, versus solar wavelengths, which would simply pass right through.

For the device's top layer, they chose a metal ceramic composite that is a highly efficient solar absorber. They coated the structure's bottom layer with a material that easily and efficiently emits infared heat. Between these two materials, they sandwiched a layer of reticulated carbon foam -- essentially, a sponge-like material studded with winding tunnels and pores, which retains the sun's incoming heat and can further heat up the steam rising back up through the foam. The researchers also attached a small outlet tube to one end of the foam, through which all the steam can exit and be easily collected.

Finally, they placed the device over a basin of water and surrounded the entire setup with a polymer enclosure to prevent heat from escaping.

"It's this clever engineering of different materials and how they're arranged that allows us to achieve reasonably high efficiencies with this noncontact arrangement," Cooper says.

Full steam ahead
The researchers first tested the structure by running experiments in the lab using a solar simulator that mimics the characteristics of natural sunlight at varying, controlled intensities. They found that the structure was able to heat a small basin of water to the boiling point and produce superheated steam, at 122 C, under conditions that simulated the sunlight produced on a clear, sunny day. When the researchers increased this solar intensity by 1.7 times, they found the device produced even hotter steam, at 144 C.

On Oct. 21, 2017, they tested the device on the roof of MIT's Building 1 for the first time, under ambient conditions. The day was clear and bright, and to increase the sun's intensity further, the researchers constructed a simple solar concentrator -- a curved mirror that helps to collect and redirect more sunlight onto the device, thus raising the incoming solar flux, similar to the way a magnifying glass can be used to concentrate a sun's beam to heat up a patch of pavement.

With this added shielding, the structure produced steam in excess of 146 C over the course of 3.5 hours. In subsequent experiments, the team was able to produce steam from sea water, without contaminating the surface of the device with salt crystals. In another set of experiments, they were also able to collect and condense the steam in a flask to produce pure, distilled water.

Chen says that, in addition to overcoming the challenges of contamination, the device's design enables steam to be collected at a single point, in a concentrated stream, whereas previous designs produced a more dilute spray.

"This design really solves the fouling problem and the steam collection problem," Chen says. "Now we're looking to make this more efficient and improve the system. There are different opportunities, and we're looking at what are the best options to pursue."

Source: MIT

Published January 2019

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