A common question is why should I choose a professional graphics card such as NVIDIA Quadro over gaming cards such as GeForce? For one thing, professional users such as CAD designers and engineers have more stringent hardware requirements than those of average users or gamers. The primary concern of workstation professionals is stability and reliability. Professional graphics, such as NVIDIA Quadro, are designed to meet those needs by working closely with the software companies such as Autodesk, Dassault Systems, PTC and Siemens PLM to certify that both the Quadro hardware and drivers are optimized specifically for those applications and can handle the workload. For the CAD user, this can mean greater performance and, more importantly, rock solid stability. Because, as we all know, sitting in front of a non-responsive screen can be very frustrating.

Professional cards can often also expand the range of options available within applications. For example, in SolildWorks, gaming cards do not offer the ability to enable a high performance ultra-realistic viewing mode called RealView. This allows designers to view models with detailed shadows and reflections to show a more realistic representation of the design. Additional advantages of using a professional card in SolidWorks include expanded full scene anti-aliasing (FSAA) modes and performance, and enhanced performance displaying solid models with visible edges (Shaded with Edges).

Unlike consumer gaming cards which are designed by a wide range of board vendors, all Quadro graphics products are manufactured exclusively by NVIDIA and have a planned product availability of at least 18 months. This allows companies who standardize on a Quadro solution to be comfortable with the knowledge that units will continue to be available for an extended time period. Since NVIDIA controls both the board design and production as well as the drivers, it simplifies product support inquiries should they ever be necessary.

Additionally, Quadro boards support all the same functions available on consumer gaming products. While Quadro boards are designed for demanding professional applications, they are equally capable of providing afterhours fun by allowing users to play today’s top PC games.

How would it impact design if it were possible to completely eliminate off-lining rendering to a centralized cluster or an outsourced-company? NVIDIA Maximus lets users design and simulate or render at the same time on the same workstation. The technology features intelligent GPU job allocation; a single unified driver; full independent software vendor (ISV) application certification; and it works with a range of OEM workstations, including Dell. The technology uses the 3D graphics capability of NVIDIA Quadro® GPUs combined with the high-performance computing power of NVIDIA® Telsa™ GPUs The Telsa co-processors automatically perform the heavy lifting of rendering or CAE computations, freeing the Quadro GPUs to enable interactive graphics.

In this scenario, designers will have the capacity to work with and interact with components and assemblies with real-time feedback on the structural dynamics acting on the components or assemblies. Consider this: An automotive stylist can make important decisions based on how things look but traditionally they have not been able to understand the impact the decisions will have on the airflow over or around the car and what the resulting drag or wind noise results will be until much later in the vehicle development. In contrast, Maximus computational horsepower lets accurate fluid dynamics simulation be calculated and visualized in real time. This lets designers make educated decisions that affect the look of the vehicle and its performance in an intuitive, visual way. In addition, Maximus is enabling reality based design with its powered interactive raytracing. Users of CAD applications like SolidWorks or Inventor can remain interactive while performing photorealistic renders on the same system. And applications such as Dassault's CATIA V6 with its integrated GPU-powered Live Rendering feature provide interactive raytracing that lets users work through design revisions and drive to a final design in less time, so core engineering can begin sooner.

Engineers at General Dynamics Land Systems, Sterling Heights, Mich., faced a challenge when designing the Expeditionary Fighting Vehicle for the U. S. Marine Corps. The amphibious combat craft needed to be made mostly of a lightweight aluminum alloy so that it would meet its mission objectives. But aluminum is relatively soft, and fasteners used to attach components to the aluminum frame needed to satisfy several requirements. They had to be lightweight, create watertight seals, lock in place solidly, resist extreme vibrations and shock, and withstand extended exposure to saltwater. The Marines also wanted be able to remove and replace the fasteners in the field.

In search of an insert
The design team wanted to use threaded inserts, a common practice when putting bolts in soft metals like aluminum and magnesium. Inserts, usually made of a tough metal like stainless steel, are installed into pretapped holes and permanently locked in place. Their interior threads give a strong, wear-resistant interface to install bolts into.

Although engineers have a few basic types of threaded inserts to choose from, including key-locking, ring-locking, and helical-spring, none met the U. S. Marine Corps demands. For example, if a conventional insert needs to be removed for any reason, it must be drilled out. This risks damaging the hole in the parent material. Plus, drilling can be clumsy and difficult if the insert is not easily accessible.

Another limitation is that inserts typically cannot create air and watertight seals without using a thread-locking compound. And even when thread-locking compounds are used, many inserts don’t offer ‘blind’ internal threads, so there is still a leak path.

And finally, there’s a limited range of standard threaded inserts on the market, and custom lengths or materials are typically accompanied by high prices and long lead times. This lack of flexibility often means engineers must alter their designs to accommodate available insert sizes or material options.

Faced with requirements it could not meet with commercially available threaded inserts, General Dynamics began internal design and development of an insert that would do the job without adding cost. Led by a talented and now-retired tool engineer named Fred Wheeler, the team came up with the Fredsert after 12 months of development, testing, and redesign. Ultimately, more than 6,000 Fredserts were installed on each Expeditionary Fighting Vehicle, and Fredserts have been used on several other General Dynamics vehicles and weapons, including the Mk 46 naval-gun turret, the Army’s Future Combat System and Joint Light Tactical Vehicles, the Navy’s Littoral Combat Ships built by Austal, Mobile, Ala., as well as more than 12,000 upgraded Humvees made by AM
General, South Bend, Ind.

Fredserts’ advantages
A Fredsert combines a tapered thread profile, 100% thread engagement, cutting flutes, and a flanged head to create a friction fit with material compression to reliably lock it in place. External threads are slightly oversized compared to other inserts and tapered in certain areas so that they create a friction-fit when installed into the parent material (such as aluminum). And all of the Fredsert’s threads are engaged with the parent material, much like the way taps interface with threaded holes. Other inserts use standard bolt threads that end up with significantly less contact with the parent material in terms of surface area.

The flanged head also helps in that it gets torqued down onto the parent material and contributes to the locking action. Fredserts are designed to exceed the tensile strength of bolts installed in them. In tests, bolts break before the Fredsert ever budges from the parent material.

For example, in tests at General Dynamics Land Systems Test Lab, inserts with M12 × 1.75 internal threads were put into 0.5-in.-thick plates of 6061 aluminum. In torque-out tests, Grade 8 bolts broke at about 160 lb-ft. In pull-out tests, the bolts broke at about 21,000 lb. In neither tests were the Fredserts damaged.

The combination of a tapered thread profile, 100% thread engagement, and a flanged head also deliver air and watertight seals on the insert’s internal threads. In addition, “blind” Fredserts deliver air and watertight seals on its internal threads because they don’t break through the bottom of the insert.

Although Fredserts can handle high torques and pull-out forces, they are not permanently locked in place. Instead, its patented geometry lets it “break away” when technicians apply approximately 80% of the recommended installation torque. If the insert is reinstalled into the same hole, the breakaway torque drops slightly to 70% of the original installation torque. This is because the Fredsert’s external threads remove small amounts of parent material when initially installed. Subsequent reinstallations will not cut any material. But the friction fit and material compression will still lock the insert in place. Fredserts have a generous safety factor, so even at the 70% level, the insert has more than twice the breakaway torque of the bolt, even if thread-locking compound is applied.

This lets soldiers or technicians quickly remove and replace bolts and inserts in the field, given they have a torque wrench and Fredsert drive tool, which is designed to mate with a Fredsert. By comparison, other inserts can only be removed by drilling them out and, in some cases, retapping to the next largest size.

Fredserts are available as standard components in several sizes and materials. In addition to those made from stainless steel, there are also titanium versions which are 40% lighter than stainless-steel inserts of the same size and more corrosion resistant. Inconel Fredserts handle high-temperature application such as well drilling, engine installations, and nuclear-power plants. And phosphor-bronze Fredserts offer a high level of corrosion resistance in saltwater, are nonmagnetic, and make excellent electrical conductors.

While designing the initial amphibious attack vehicle, General Dynamics engineers determined that the vast majority of Fredserts would have no problems with corrosion. But about 10% of them are in areas where saltwater can become trapped, leading to galvanic corrosion of the aluminum. To prevent this, General Dynamics coated the head (flange) of those Fredserts with Alodine ec2, which was developed and patented by Henkel Corp., Cleveland, and independently proven effective by General Dynamics through salt-fog and durability testing. The electroceramic coating creates a barrier between the titanium and aluminum. Because Fredserts create their own seal upon installation, there is no need to coat external threads or any other part, only the head. The initial amphibious vehicle has been the only application where this coating was deemed necessary. Other vehicles have used uncoated titanium and stainless-steel Fredserts with no corrosion issues.

Although most commercial inserts are only available in female configurations, there are several styles of Fredserts that meet a variety of needs. Female, the most common style, creates a wear-resistant bolt interface. Male versions let designers place threaded studs on soft metals. Appurtenance Fredserts are similar to female versions, except that they have a specified flange thickness that lets them be used as standoffs for armor plates or electronic boxes. Appurtenance Fredserts let designers eliminate or limit the use of aluminum weld bosses. Hex Fredserts let bolts be installed from the opposite side of the metal plate as the inserts. This is useful in areas where threads are needed, but access and reach are limited. And fitting Fredserts create hydraulic or pneumatic connections through metal plates or housings

Simplifying installation
One of the most important features that differentiate Fredserts from other threaded inserts is that installation will soon be automated. General Dynamics is currently working to develop ways to install Fredserts with CNC machines and robots. The CNC method will use a toolholder similar to a tension/compression tap holder to take a Fredsert from a tray and install it into a pretapped hole. This approach will let companies combine machining and insert installation in one setup, a major step toward Lean Production. Essentially, the user would machine a part as they do today, but after the holes are tapped, the machine would pull the Fredsert installation tool from the tool magazine and install Fredserts while the part is still set up in the machine. Other threaded inserts on the market would be difficult or impossible to automate, due to the mechanical clamping aspect of their installation. Fredserts are simply installed with torque, so a CNC machine has all the necessary abilities to install them.

General Dynamics is also developing a robotic installation cell consisting of a robotic arm with an electric nut-runner that picks Fredserts from a tray and installs them into pretapped holes. Such a setup would let manufacturers install inserts into several surfaces of a component in a single setup. This would be a plus for applications where a CNC machine cannot reach all the installation locations due to part size or shape. Automated threaded-insert installation could dramatically change the way aluminum components and structures are assembled in aerospace, defense, automotive, and other industries.

Other future developments include a Fredsert designed for composites. Such an insert should overcome limitations in traditional “potted” inserts which use epoxy-type resins to permanently bond inserts to composite parent materials. A less-costly and more-effective insert for composite applications will save time and money for companies building lightweight aircraft, mobile shelters, and other composite structures.

While General Dynamics has used Fredserts in military platforms for nearly a decade, the company has only begun offering it to commercial markets in the past several months. The Fredsert design and configuration are controlled by General Dynamics using a 3D model tied to a 2D manufacturing drawing. This lets designers plug in key dimensions to the model to create custom insert designs, as well as a fully dimensioned manufacturing drawing, in seconds.

Fredserts are manufactured by Miller Precision Industries in Ohio, and marketed through sales representatives across the U. S. Standard metric sizes range from M4 × 0.7 to M36 × 4.0 internal threads. Standard inch sizes go from #8-32 to 1-8 internal threads. At production quantities, stainless-steel Fredserts cost $5 to $25 each, depending on size. Titanium versions typically cost 30 to 40% more, based on the cost of titanium.

The introduction of Fredserts gives engineers and designers new fastening and joining choices. The inserts have also simplified vehicle design, improved producibility, and reduced logistical costs.

© 2012 Penton Media, Inc.

Ethernet, once thought to be the sole province of computer networks, has found itself linked to applications and devices far beyond its original scope. Aside from the normal computer to computer communications, Ethernet today links many diverse devices, including cameras, motor controls, VoIP phones, intercom paging and public-address systems, industrial devices for sensing, monitoring, and control, and wall clocks synchronized to network time protocols, to name just a few.

In many cases, Ethernet-connected devices must also connect to power sources of some type, typically standard ac power. But unless wall outlets are handy, this usually means running power, along with the Ethernet cabling, to the device, which adds cost and complexity. So one can see the advantage of a device that only needs one cable connection to provide both signal and power. Such was the case when IEEE created the original Power-over-Ethernet (PoE) 802.3af standard in 2003.

A new standard
The 802.3af standard details a method of transmitting up to 15.4 W of electrical power at a minimum of 44 V and 350 mA, along with Ethernet signals, in a single Cat-5 (or earlier Cat-3) cable. However, only 12.95 W is available for the device due to power losses in the cable. As more devices demanded greater power, the IEEE created a new standard, 802.3at, in 2009. The updated standard, called PoE Plus or PoE+, almost doubled the available power to 25.5 W and applied new terminology to the equipment used for PoE applications.

Power-sourcing equipment (PSE) identifies those pieces of equipment that supplies power to the Ethernet system. The source may be built into equipment, such as routers or switches, which are called endspans. Or it can be an add-on pass-through connection known as a midspan that adds PoE capability to non-PoE devices.

Any device that draws power from the Ethernet is known as a powered device or PD. In many cases, PDs also have auxiliary power connectors that supply the devices external power in case of PoE failures.

When 802.3at was adopted, IEEE split PDs into two types. Type 1 devices draw less than 13 W of power, making them compatible with the older standard. PDs that need more than 13 W, up to the 25.5-W maximum, are classified as Type 2 devices. A PSE that handles Type 2 devices can also run Type 1 devices, for backward compatibility.

A PoE power path is defined as having three components: the power of the PSE, the power delivered to the PD, and the power sent on to the application, which is obviously less than that delivered to the PD. This has led to some confusion as different manufacturers market different power levels. For example, a switch maker might hype its product’s PSE capacity, while a PD vendor would tout the power needed by the PD (the power delivered to the PD). And a sensor maker using PoE would be more concerned with the power available to the application to operate the sensor. When comparing power ratings, always be sure to verify which power point the manufacturer is speaking about.

Benefits of PoE
One major advantage of PoE is that it eliminates “wall warts,” the plug-in power transformers and supplies typically needed in remote situations. These transformers are notoriously inefficient, often poorly designed, and can be easily damaged by surges and brownouts.

Many PoE installations have been sold on its “green” merits alone. However, it’s possible to lose that efficiency without carefully planning the installation.

For example, a standard 48-port Ethernet switch with PoE capability typically uses a power supply between 60 to 80 W that provides power for the switch electronics. But it may need an additional 370 W (for 802.3af) or 740 W (for 802.3at) to supply maximum power to all PoE devices connected to the switch. As Cat-5 Ethernet cabling is usually 24-awg wire (23 awg for Cat-6), long runs tend to lose a greater portion of power. However, the advantage of not needing to run ac power sources to the PD justifies these losses. In addition, when ac power is readily available, the PD can be externally powered, improving efficiency at the PD and reducing the load on the PSE. The trade-off may be a slightly higher loss at the PD power supply.

PSEs may contain active, smart, or managed power features that reduce the draw of all powered devices. For instance, automatic power-down and cable-length detection lets the switch accept lower signal strengths, reducing power needs. And power can be shutdown to devices that do not need the PoE feature.

How it works
Delivering power from the PSE to the PD depends on the type of Ethernet connection. For example, 10Base-T and 100Base-TX connections use only two of the four pairs in a standard Cat-5 Ethernet cable. In such cases, PoE can be sent using either Mode A or Mode B transmissions. Mode A sends power in what’s known as “phantom” mode. PoE power is injected into the center-tap of the two active pair transformers in the PSE and removed via similar connections in the PD. Pins 1 and 2 of a standard 8C8P (aka RJ-45) connector share one polarity, while pins 3 and 6 provide access to the opposite polarity.

Mode B, on the other hand, relies on the two remaining inactive pairs as direct power wires, keeping each pair a single polarity. Pins 4 and 5 become one polarity, while pins 7 and 8 provide the return. Diode bridge rectifiers steer incoming voltages for proper polarity within the PD.

When working over 1000Base-TX, all four wire pairs transmit signals. Therefore, both Mode A and B are implemented using the phantom technique.

The PSE determines if the system runs Mode A, B, or both. It does this by detecting a 25-kΩ resistor between the powered pairs. If the PSE detects a resistance that is too high or low, no power is applied to the circuit. This protects the PSE from trying to power shorted wires, an open circuit, or a non-PoE-compliant Ethernet connection.

To stay powered, a PD must continuously use 5 to 10 mA for at least 60 msec but no more than 400 msec since its last use. Some PDs incorporate an optional “power class” feature that lets the PD indicate its power needs.

Negotiating power demands between the PSE and PD follows a specific sequence of operations. First the PSE tests the PD to make sure it’s properly connected and a good device. If the PSE is satisfied, the PD is powered. The PD then sends the PSE two pieces of information: its maximum power needs and the amount of power it’s requesting to use. The PSE responds with the maximum power it lets the PD use. The PD now uses the power specified by the PSE.

The negotiations are carried out according to a set of rules that starts with the PD never requesting more power than permitted by 802.3af (the 13-W level). It may also never draw more than the maximum power allocated by the PSE. The PSE may deny (turn off) any PD that draws more power than the PSE’s allowed maximum. But the PSE cannot reduce the power given to a PD that’s in use. Finally, a PSE may request reduced power via conservation mode, which usually happens when the system switches to a battery-powered supply in a power outage.

More power
A number of nonstandard PoE implementations have been created by different manufacturers. Some were developed before the standards were created, but still find use today. Others were developed as a method to supply more power to the PD than permitted by the standard.

Cisco’s original PoE scheme for their WLAN access points and IP phones was developed many years before the IEEE standard. While the original Cisco PoE could only deliver 10mW, it is not upgradable to the 802.3af standard.

Another incompatible PoE make is PowerDsine, now a Microsemi brand. It’s original “Power over LAN” setup was created in 1999 and is used by a number of different companies, including Polycom, 3Com, Lucent, and Nortel.

A new entry in the nonstandard category is Linear Technology’s LTPoE++, which promises up to 90 W of power delivered to the PD. The advantage of the LTPoE++, however, is that it is backward compatible to both 802.3af and 802.3at standards. This lets their system work within a standards-compliant architecture, while still supplying more power to devices that can use the LTPoE++ architecture.

The LTPoE++ system comes in selectable power levels of 35, 45, 70, and 90 W with all power levels capable of running the two power standards. The higher power levels expand the field of Ethernet-powered devices, enabling PoE designs that were only possible before with external power available.

The use of PoE continues to grow, along with the power demands of the PDs in the system. One can only assume that the next IEEE standard will double the power levels again. Until then, proprietary techniques such as the LTPoE++ format can fill the power gap where needed.

© 2012 Penton Media, Inc.

Planetary gearheads are high-precision, motion-control devices that generate substantial torque for their size, have high torsional stiffness, and low backlash — making them suited for wide-ranging tasks. For instance, specific types of planetary gearheads:
• Run around the clock, seven days a week, for more than 30,000 hr in cartoning applications. The lubricated-for-life gearheads require no maintenance, and high torque-to-size ratios permit compact envelopes and small machine footprints.
• Help attain accuracy within a few ten-thousandths of an inch on plasma-cutting machines, thanks to exceptionally low backlash. Helical crowned gearing provides fast positioning and smooth movement, and sealed gearboxes keep out abrasive dust generated during cutting.
• Limit noise and vibration and meet strict backlash requirements in scanning tables for cardiovascular patients.
• Let food-processing equipment slice meat, bread, and frozen foods at speeds up to four slices/sec. Also available are slim, right-angle designs to fit within the machine envelope and provides quiet, smooth operation.

Planetary basics
A planetary gearhead takes a high-speed, low-torque input, say from an electric motor, then increases torque and reduces speed at the output by the gearhead ratio. This lets motors run at higher, more-efficient rpms in equipment that operates at low speeds. It also reduces inertia reflected back to the motor, increasing stability. And using a planetary gearhead often lets machine builders reduce the size and cost of motion-control hardware.

Planetary units with helical gears, rather than spur gears, have a larger contact ratio. The contact ratio is the number of teeth in mesh at any given moment. While typical spur gearing has a 1.5 contact ratio, helical gearing more than doubles it to 3.3. Benefits of higher contact ratios include:

• 30 to 50% more torque capacity than equivalent spur-type planetary gearing.
• Better load sharing, which increases life.
• Smoother and quieter operation.
• Backlash reduced by as much as 2 arc-min.

The gearhead’s helix angle also has a significant impact on performance because the greater the angle, the more teeth in the mesh at any one time. So increasing the helix angle from the typical 12° up to 15° raises torque capacity by 17 to 20%; and by as much as 40% over straight-cut spur gears. Gears with a 15° helix angle also emit less noise.

Helical-gear teeth generate axial loads on the motor shaft. Gearhead bearings must compensate for these loads. Helical gearheads using ball bearings with little or no axial load capabilities can suffer premature motor-bearing or gear failure. A better approach uses tapered roller bearings, such as in Micron Helical gearheads, to completely compensate for axial loads.

Single-stage planetary gearhead ratios range from 3:1 to 10:1. Gear ratios cannot exceed 10:1 because pinion gears can be made only so small. Gear ratios greater than 10:1 are possible with an additional planetary stage, although this normally increases length and cost. Planetary designs also cannot have ratios less than 3:1 because then the pinion and outer ring gear would need to be nearly the same size, leaving no room for the planet gears. Ratios between 4:1 and 8:1 provide the best combination of pinion and planet-gear size, performance, and life.

Crowning involves slightly modifying the gear-tooth profile to improve gear mesh alignment, increasing torque capacity and reducing noise. It also improves load distribution on the tooth flank, thereby minimizing high-stress regions that can cause surface pitting.

Some clearance is needed for a planetary gearhead to work effectively. Clearance prevents excessive heat and gear wear and ensures good lubrication. But the small gap between gear teeth leads to lost motion. Real-world gearheads also cannot have infinite torsional stiffness, so windup (flexing) in the gearhead generates additional lost motion.

Understanding how different manufacturers measure backlash is important when choosing a gearhead. There are no strict standards regulating how to measure backlash. This can lead to confusion and misconceptions. Some manufacturers measure and average four or more points on the output shaft to produce a backlash specification. Using this method, a unit with backlash measurements of 4, 6, 10, and 12 arc-min would have a rating of 8 arc-min. Thomson engineers believe backlash should be based on the largest measurement on the output shaft, so the above example would yield a 12-arc-min rating.

In addition, some manufacturers apply 2% of the rated torque to generate backlash ratings, while others apply less. The latter produces lower backlash measurements and doesn’t provide true backlash ratings over the life of a product.

Backlash will increase over time. A planetary gearhead might have 8 arc-min of backlash out of the box but 15 arc-min after six months of use, for example. So how well a planetary gearhead maintains accuracy over its life is an important consideration for most users.

Sizing and selection
Choosing the right gearhead and accurately sizing it is critical to long and reliable life. As a starting point, designers can approximate required gearhead size from:

T_r = T_m × r × e

where T_r = application torque, T_m = continuous torque, r = ratio, and e = efficiency.

To precisely size a gearhead, however, engineers must consider the complete motion profile, including speed, torque, acceleration, deceleration, and cycle rate. And they should apply a derating factor for high-cycling conditions. (Typical values are shown in the table.)

Nonstop, continuous-duty applications do not require derating factors. In those cases, the most common problem is overheating that breaks down the lubricant and causes gear failure. High-performance gearheads, such as Micron EverTrue, are designed to run 24/7, operate under 140°F, and last more than 30,000 hr.

Online selection and sizing tools can save time by letting engineers find and compare planetary gearheads that fit a particular application. (See the accompanying sidebar for more details.)

Troubleshooting
Several problems can crop up in gearheads that aren’t sized and installed properly:

Noise. Inappropriate input speed, gearhead ratio, output torque, radial and axial loads, and mounting errors can all contribute to gearhead noise. But proper mounting is critical to minimizing noise and maximizing performance. Many gearheads must be mounted to the servomotor while positioned vertically. This lets the motor shaft center the gearhead. After mounting to the motor, the gearhead can be used in any orientation.

Friction. Too much grease, out-of-tolerance components, and poor gear or bearing quality can cause excessive friction and drag. Look for gearhead manufacturers that test every gearhead for input drag before shipment. Each size and ratio has an acceptable range for drag, and peak levels should be measured in both directions.

Sealing. For applications that require protection against dust, dirt, and water, be aware that combining an IP65 motor and an IP65 gearhead does not always provide IP65 protection. Look closely at how the interface between the motor and gearhead is sealed. The best approach is to use O-ring seals between all housings for IP65 protection on the full assembly.

A new type of planetary gearhead, the Micron AquaTrue, meets IP67 requirements for food and beverage handling, packaging, and dispensing, thanks to a round stainless-steel housing with no external seams. Such gearheads can withstand caustic cleaning chemicals and high-pressure wash downs, giving engineers the flexibility to mount it without the added cost and complexity of components such as enclosures, shielding, and mechanical transmissions.

Lubrication. Oil or grease can effectively lubricate planetary gearheads. Grease has the advantage of providing lubrication for the life of the gearhead, eliminating a lot of maintenance. Grease permits mounting in any orientation and eliminates concerns about leakage.

Oil requires maintenance and relubrication, usually every few thousand hours. And leaks are always a concern with oil lubrication. Orientation with oil lubrication is usually restricted, must be specified when ordered, and usually cannot be changed. A common misconception is that oil-filled units always run cooler than grease-lubricated gears. Actually, the sealing required for an oil-filled gearhead often generates more heat than the oil saves.

© 2012 Penton Media, Inc.

People lucky enough to hitch a ride on a Gulfstream G550 private jet outfitted by industrial designer Stefan Radev find the plane is equipped with iPads. But the iPads aren’t for reading ebooks or playing games. They actually control the passenger-compartment climate and entertainment systems.

Radev’s luxury jet exemplifies a trend in mobile platforms: smartphones and tablets increasingly are taking on roles as data displays and even operator terminals. And they aren’t just managing consumer goods. Several controls makers let mobile platforms work with the controls running industrial processes.

There are two different ways of letting smartphones or tablets communicate with controls: by devising a downloadable app that communicates with the control network, or by creating a mobile-enabled Web site that provides information about the control system. When the scheme involves a mobile-enabled Web site, the smartphone or tablet functions as a thin client, mainly serving as a display device and relying on the Web site for most number crunching of data. But in some cases, a mobile-enabled Web site won’t provide the kind of performance an application demands.

That was the case for iRule LLC, Farmington Hills, Mich., makers of an iPhone app that lets the phone function as a universal remote control for home theaters and audio/visual equipment. “We did tests and found that the Web added at least 250 msec of delay when you punched a button,” explains Itai Ben-Gal, iRule CEO and cofounder. “It was noticeable among people who have picked up a remote to change a volume for 30 years.”

iRule’s universal remote app communicates with AV equipment through a gateway device which typically learns the control protocols of individual remotes by sensing the data on their IR beams. The gateway, in turn, hooks up to a Wi-Fi connection to communicate with the iPhone. But iRule’s app can also work with home-automation systems, even when out of range of the home Wi-Fi. In this case, the phone uses a 3G data network from a cellular carrier to make a mobile virtual private-network (VPN) connection to the gateway. The VPN provides a level of security and lets the phone user roam across networks without losing a connection to the home-automation system.

Several industries commonly place cabinets full of control, communication, and monitoring electronics outdoors. Telecom companies, electric utilities, as well as municipalities that need to safely manage traffic on highways, bridges, and rail systems rely on outdoor cabinets. Additionally, wind and solar farms are now becoming major users of outdoor control cabinets.

On wind farms, electronic controllers and safety subsystems monitor the turbine, generator, tower and environment to keep the turbine operating safely and within prescribed limits. On solar farms, electronics help solar-tracking towers follow the sun.

In all these applications, outdoor electronics enclosures can be hard to reach, rarely visited by maintenance technicians and exposed to harsh weather conditions year round. The hardware must withstand high winds, storms of all kinds, heat, solar radiation, and other severe conditions that can damage electronics if they are not fully protected.

Consequently, it’s critical to specify enclosure latches and hardware that will withstand the weather, without complicating the jobs of the technicians who do visit to fix problems or upgrade equipment. Engineers should consider five factors when specifying access hardware for outdoor control cabinets: durability, ability to withstand vibration, corrosion resistance, ease of use, and ease of installation.
Long-lasting latches

Select latches that will hold access doors firmly closed and last as long as the enclosure. One option is compression latches that consistently compress gaskets surrounding enclosure openings. Compression varies from latch to latch, but one important aspect to consider is the clamping range of the latch. For instance, Dirak Inc., Sterling, Va., carries compression latches with clamping ranges as short as 3 mm to as long as 20 mm.

Fixed-compression latches have fixed cams, so they consistently compress and decompress gaskets to a specific depth. Or designers can choose latches with adjustable compression. These latches allow a user to change the initial and, consequently, the final position of the locking cam. This allows a single compression latch to be used in a variety of applications or to adjust compression on a cabinet over time.

Compressing the gasket along its entire length is important because without consistent force, gaps in the housing perimeter can let in water, dirt, or insects; any of which can damage the sensitive electronics within the enclosure.

Most robots in operation today are industrial types that engage in repetitive tasks. Robots assemble automobiles, weld sheet metal, and load widgets into CNC machines, among other jobs. Price, payload, reach, and speed are some of the design parameters that determine the best robot used for a particular industrial work cell.

Industrial robots are loaded with software that serves as “functional experience modules” and provide data or directions for how a robot will react when executing a task. The modules also let engineers choose particular features to generate programs that perform specific processes.

That said, the humanoid robots of sci-fi films closely resemble humans in almost all respects except that the robots lack emotion. With nimble “hands” and high-powered “brains,” the robots move seamlessly from task to task. Researchers are making progress in developing machines that are more humanlike, but they have a way to go to develop a truly versatile domestic robotic servant. Still, an interesting question arises: Are robots capable of evolving, or are they forever limited to merely executing programs?

On the flip side of the coin, human limitations don’t apply to robots. Consider the number and size of components needed to populate the printed-circuit board found in most cell phones. Unlike humans, robots are not limited by the size of their fingers. Robots can be outfitted with tiny pinchers instead. Nor do they place components in the wrong location. Robots shine at consistently performing repetitive tasks.

Of course, industrial robots are not intelligent in the sense of having conscious thought. They can, however, make decisions that impact their performance. Most tasks robots handle involve moving around physical objects. Robots can be made to be “self-aware” in responding to objects via options for “sight” and “touch.”

A flexible printed circuit is as much a mechanical device as it is an electrical device. Conductors must be laid out such that the circuit functions properly and reliably. Unlike a rigid printed-circuit board (PCB), flexible circuits bend, flex, and otherwise contort to fit the final assembly. These bending and flexing operations can severely strain improperly routed internal conductors.

The industry standard IPC-T-50 of the IPC Association Connecting Electronics Industries defines a flexible circuit as, “A patterned arrangement of printed wiring utilizing flexible base material with or without flexible cover layers.” A typical flexible circuit is formed by stacking four different types of primary layers: the base layer, a metal foil or conductor layer, an adhesive layer that bonds the other layers together, and outer insulating (cover) layers. Multilayer boards stack these four basic layers as needed to complete the circuit design.

The base and cover layers are typically a flexible polymer film that creates the foundation of the flexible circuit and provides most of the physical and electrical properties of the circuit. A number of materials may be used as base films, but most flexible circuits today use polyimide films because of their excellent electrical, mechanical, chemical, and thermal properties.

Normal base-material thickness typically falls between 12 and 125 μm (0.5 to 5 mils), but thinner and thicker bases are possible. It should be obvious that as the base material gets thinner, the circuit becomes more flexible.

The metal foil layer provides electrical connectivity for the circuit. While different metals may be used, the most common metal found in flexible circuits is copper. Its high malleability, along with good conductivity, makes it an ideal material for flexible applications.

Rolled and annealed (RA) foils are the most common choice, though thinner foils may use electrodeposited (ED) copper.

The bonding-adhesive film, as its name implies, affixes the metal foil layer to the base material, bonds base layers to each other, and also adheres covers to the circuit. As with base films, adhesive films are available in different thicknesses, which are usually determined by the application. For example, different adhesive thicknesses are used in the creation of cover layers to meet the fill-needs demanded by different thickness copper foils. The most-common adhesive films used today are made from a modified acrylic or epoxy base.

When circuits bend or flex, material towards the outside of the bend must stretch to cover the expanded radius, placing that material in tension. Materials inside the bend, however, see the force of compression as the inside-bend circumference shrinks.

At some point in the middle of the material stack is an area that sees little to no tension or compression. This area is called the neutral-bend axis. In a flex circuit, it’s loosely defined as an imaginary planar region with no thickness that undergoes neither tension nor compression during bending or flexing. As different layers in the flexible circuit move further away from the neutral-bend axis, the forces of tension and compression become more severe and damaging.

This February, NASA will launch NuSTAR (nuclear-spectroscopic telescope array) for a two-year mission exploring space using an advanced X-ray telescope. It will be the first orbiting telescope capable of focusing on and viewing this high-energy portion of the electromagnetic spectrum.

Previous X-ray telescopes, such as Chandra and the X-ray Multi-Mirror Mission (XMM), were limited in that they could not focus. Instead they used specially constructed apertures to image X-ray signals, and these structures had intrinsically high background noise and limited sensitivity. The two earlier X-ray telescopes were also limited to looking at low-energy X-rays (15 keV and lower). NuSTAR will be able to handle X-rays with up to 79 keV. According to NASA, NuSTAR will also have 10 to 100 times the sensitivity and spatial and spectral resolution of previous X-ray telescopes sent into space.

The spacecraft

To keep costs down on the NuSTAR mission, the spacecraft will be shot into space aboard a Pegasus launch vehicle, so it must fit in that rocket vehicle’s cargo bay. This limits NuSTAR to a 2-m-long, 1-m-diameter envelope. But this raises a problem: A focusing X-ray telescope needs focal lengths in the 10-m (33-ft) range. Both Chandra and XMM, for example, measure 10-m long and weigh about 9,000 lb. But it took the Space Shuttle to put Chandra in space and an Arianne 5 to take the XMM into orbit.

NASA engineers’ solution is an extendable mast, a scaled-down version of the 60-m mast used on a Shuttle-based radar topography mission. NuSTAR’s 10-m version, which collapses for storage, should provide a relatively stiff, stable, and reliable platform for the optics or focusing lenses, putting the necessary separation between the optics and detectors to focus the telescope and get clear images.

To ensure the optics and detectors are aligned, an adjustment mechanism is used when the mast is first deployed after the spacecraft is in orbit. Then to compensate for small, but inevitable, motions at the optics end of the mast, a pair of lasers will send light beams to three sensors mounted on the detector end of the telescope. Real-time measurements from the lasers will be used to correct X-ray images, which would otherwise be blurred.