June 08, 2021 Volume 17 Issue 22

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.

'Engineer of the Year' chosen by largest aerospace society

Humberto "Tito" Silva III, a Sandia National Laboratories researcher, has been named Engineer of the Year by the American Institute of Aeronautics and Astronautics (AIAA), the world's largest aerospace technical society.

Humberto "Tito" Silva. [Photo by Lonnie Anderson, courtesy Sandia National Laboratories]





Selected by a committee of his peers, Silva was cited for improving failure-rate predictions of aerospace flight systems as they reenter Earth's atmosphere. The work helps direct engineers to attack the worst problems first for reentry rockets, spaceships, and satellites.

Silva's procedure, which he has dubbed "Tito's full-circle analysis methodology," uses computer modeling to determine the fewest number of computer simulations and physical experiments needed to get trusted data on a project.

"We were able to have high statistical confidence in our results. These were analogous to those achieved by researchers using many orders of magnitude more computational simulations and physical experiments," Silva said. "Our method saves money and time."

AIAA president Basil Hassan, who is also the deputy chief research officer at Sandia, said, "Tito's work helps ensure the safety, security, and reliability of the nuclear deterrent by helping to understand potential uncertainties in extreme thermal environments. The methodologies developed here could also be used for other entry and reentry-type applications that similarly concern engineers."

Silva's award will be presented in August at the AIAA Aerospace Spotlight Awards Gala, an annual event the organization describes as "recognizing the most influential and inspiring individuals in aerospace."

Succeeding with failure
Silva credits his unusually varied background, which includes study in several engineering and science fields, for endowing him with a jack-of-all-trades outlook that connects with the deeper perspective of researchers who self-confine to particular research areas.

"Many scientists deep-dive into subfields," he said. "My bread-and-butter is that I bring a different perspective. Technical experts fill in my knowledge gaps, and I fill in ones they haven't thought of." He describes himself as an "inside consultant," bridging subcategories in computer science, project management, and aerospace, mechanical, chemical, and electrical engineering.

Acting as a catalyst in a variety of fields doesn't blur his research focus, which is thermal science -- "pretty much the jell for all the work I've done," he said.

His teams feed data from modeling and physical experiments -- limited in number to keep costs down -- into computer models expected to simulate the actual effects. Results from the models are then used in experiments to see how derived data matches that from physically harvested data.

The work often shows considerable overlap between theory-based and experimental graphs, which lends weight to Silva's failure-rate predictions.

Super-sleuthing the cosmos
Working from an Earth-bound lab, Silva doesn't minimize the difficulty of determining events in outer space. The sleuth-like deductions are similar, he says, "to determining why an iPhone thermally or electrically fails in a box, if the box is in a closet, the closet in a room, the room in a building, the building on a barge in the hold of an aircraft carrier ..."

His first move is to simulate the environment, including the season of the year and time of day.

Then, there's the equipment. "If the reentry body is made partly of stainless steel, we think we know its thermal conductivity. But there's material variability from different factories, so we have uncertainty in how that affects our vehicle. So, we use a range of possible figures," he said.

Solving questions about a particular system entering Earth's atmosphere, subspecialists were needed to find the sweet spot between different forms of heat transfer. "So, we did a computational experiment on how to use all the test equipment most frugally. We needed to determine the optimum amount of experiments and computer simulations, so we weren't running, say, 5 million computer simulations and 5,000 experiments."

Using these deliberately limited means, his team found a way to map the probability space of all possible outcomes. "Then we found a condition with our model that stressed the system. We used that in the computer domain and then again in the experimental domain in an iterative fashion. That gave us our result."

Said Darcie Farrow, a former systems engineer overseeing nuclear weapon sustainment, "The multiple technical advances initiated by Tito are improving nuclear safety assessments as well as aerodynamic models for a wide range of flight systems."

Silva also has initiated collaborations with Los Alamos National Laboratory resulting in nuclear weapon system models that capture the response of both labs' components in fire environments for the first time, she said.

A peaceful past and stimulating future
Belying the future complexity of his work, Silva grew up in the visually simple farming country around El Paso, TX. There were no big buildings; he could see for miles.

The open fields contributed to his interest in outer space, he says: "It's easy to dream about the stars, growing up with only cotton fields in your backyard."

But his life grew more complicated when he left astrophysics as he started graduate school: "At the time, there was too much uncertainty in [astrophysics]," he said. "You couldn't experimentally prove that there is such a thing as black hole -- or, at least, back then there wasn't any experimental or tangible proof as there is now."

The space shuttle Columbia disaster in early February 2003 got him back into studying space -- specifically, aerospace engineering -- to finish his graduate school education. Silva said he "saw it in real time across the sky" as he was driving across Texas.

The emotional impact of the sight, reinforced by Texas radio stations' repeated playing of Stevie Ray Vaughan's song "The Sky is Crying," created a memory that he feels forged his future path.

"I knew then," he said, "that I wanted to apply uncertainty quantification to safety-driven problems and that aerospace engineering was a perfect field for that application. It was like a homecoming for me ... coming back to what I always loved."

The earlier disaster of the space shuttle Challenger was Silva's initial propellant into thoughts of aerospace. "The memory of watching that disaster -- also in real time with my principal and my classmates while in school -- left a huge impression on me as a young boy."

He maintains his interest in a number of academic fields in which he still takes classes and teaches to this day, he said.

But in Silva's life, he said, "It's clear that aerospace tragedies have had their way with my destiny."

Source: Sandia

Published June 2021

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