June 16, 2020 Volume 16 Issue 23

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.


Air Force Research Lab improving processes for fabricating aircraft engine inlet ducts

The Kratos XQ-58 Valkyrie is an experimental stealthy unmanned combat aerial vehicle designed and built by Kratos Defense & Security Solutions for the United States Air Force Low Cost Attritable Strike Demonstrator program, under the USAF Research Laboratory's Low Cost Attritable Aircraft Technology project portfolio. [Photo: AFRL]

 

 

 

 

By Donna Lindner, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio

Aircraft engine inlet ducts provide the engine compressor with a constant supply of air to prevent the compressor from stalling. Since the inlet is directly exposed to the impacting airflow, it must create as little drag as possible. The smallest gap in airflow supply can cause major engine problems as well as significant efficiency losses.

Part of the Air Force 2030 Science and Technology strategy includes the deployment of low-cost Unmanned Aerial Systems in mass to assist in future near-peer engagements. In order to realize this vision, new manufacturing strategies need to be identified that can support the rapid manufacturing of high-quality aerospace components at costs that are lower than what are currently available using legacy manufacturing processes.

If the inlet duct is to retain its function of providing sufficient air with minimum turbulence, it must be clean and flawless.

The Air Force Research Laboratory's Manufacturing and Industrial Technologies Division and the contractor team of Cornerstone Research Group, A&P Technology, and Spintech LLC conducted research to quantify the benefits of replacing legacy manufacturing processes with novel processes for the fabrication of an 11-ft-long, S-shaped engine inlet duct.

An 11-ft-long unmanned aircraft system inlet duct preform is shown prior to resin infusion. [Photo: AFRL]

 

 

The legacy fabrication process for the inlet duct consists of composite material preimpregnated with a synthetic resin, applied by hand, to a multi-piece steel mandrel. The mandrel is packaged and placed in an autoclave for processing. An autoclave is essentially a heated pressure vessel that supplies heat to activate resin curing and pressure to ensure there is minimal absorbency in the fully cured composite part.

The approach replaces the hand-applied composite prepreg with an automated overbraid process that applies dry fiber to a mandrel. The very heavy multi-piece steel mandrel was replaced with a light-weight, single-piece shape-memory polymer (SMP) mandrel, and the dry braided carbon fiber was processed with a low-cost epoxy resin using a vacuum-assisted resin transfer molding process.

One of the primary goals of this program is to understand part cost and production time benefits from introducing the new tooling and processing solutions.

The team completed element analysis finalization of the overbraid architecture, fabrication of a shape-memory polymer forming tool, and construction of the SMP mandrel that will serve as the tool during the preform overbraid process.

Because of inlet duct geometrical complexity, multiple iterations will be necessary to optimize the overbraid machine settings and thus minimize composite material wrinkling. A total of four inlet ducts will be fabricated, and legacy part cost and production time will be compared to the new design.

"We believe that the introduction of a reusable shape-memory polymer mandrel together with the automated overbraid process and an oven-based VARTM composite cure will lead to significant cost and cycle time reductions," said Craig Neslen, manufacturing lead for the Low Cost Attritable Aircraft Technology Initiative in the Manufacturing and Industrial Technologies Division. "Quantifying the manufacturing benefits and validating structural integrity will be critical to establishing a positive business case and convincing designers and manufacturers that the new materials and processes should be incorporated into future low-cost engine inlet duct designs."

The final inlet duct will be delivered to the government for further integration into the Aerospace System's Directorate's complementary airframe design and manufacturing program. Personnel at the Aerospace Vehicles Division will conduct static ground testing of the integrated braided fuselage and inlet duct structure.

"While we have yet to define all of the implications of attrition tolerance on design criteria and the resulting manufacturing materials and processes utilized, we do have a baseline with threshold requirements for strength and stiffness which we will assess via full-scale airframe ground tests," said Ray Fisher, aerospace engineer in the Aerospace Vehicles Division.

Published June 2020

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