Halloween party ideas 2015

Over the past 15 years, robotics and automation specialist TRACLabs has used its 3T robot intelligence software to perform inspection tasks for the International Space Station (ISS). Robots programmed with the latest software are able to search for, find and recognise people, hunt for underwater mines and carry out repair and replacement tasks on earth or in space. Impressive so far, but wait, there's more.
Layered intelligence can now be utilised by any computer-controlled machine, even stationary ones. TRACLabs has also been busy developing intelligent control for advanced life support systems such as biological water processors, oxygen generation and CO2 recovery systems. The results of several of these efforts were used in human-related tests, including one with four people living and working in a NASA biosphere for three months. With a little more work, industrial automation might have the power to keep us alive in the most unfriendly environments imaginable.
In terms of the types of technology industrial automation is contributing to keeping the ISS up and running, we've not even scratched the surface. Supplier of industrial networking technology, Hirschmann is also in on the action, providing the ISS with industry-proven managed OCTOPUS switches, used in data communication.
On the ISS, the OCTOPUS switches are subjected to electromagnetic radiation that is around 100 times higher than on Earth, mostly caused by high energy protons. To ensure they were up to the job, the switches underwent extensive testing prior to being implemented. Luckily, the radiation-sensitive integrated switch circuits proved their suitability for their trip into space.
After proving their worth in the communication system of the Russian segment of the ISS, the OCTOPUS switches have also been in use since 2011 in the American segment. This part of the ISS is the home of the Cupola, the observatory module used to conduct experiments, dockings and observations of Earth. In addition, the OCTOPUS switches transport data from the space station's joint Local Area Network (LAN). In the future, videos in HD quality are to be transmitted from the Cupola to ground control.
Across the pond, leader in power and automation technologies ABB is in the midst of developing a new industrial sensor that will be used to study planetary rocks from a Mars or Moon Rover. The new design is around half the size of its predecessor with better performance and lower service requirements. It includes a solid-state laser designed to operate in space, without any servicing for more than 20 years. To compare, its predecessor needed servicing every three years.
With the help of the new sensor, ABB hopes to advance understanding of issues such as global warming, ozone depletion and the impact of pollution on air quality, as well as weather prediction and climatology.
Apart from the latest generations of robots and industrial automation technologies, the ISS also relies on more traditional industrial automation components like motors and drives. The critical process of cooling, for example, is heavily dependent on liquid ammonia pumps.

It’s fair to say that industrial automation plays a key part in humankind’s exploration of outer space. And it’s helping us go further and further every day. So there you have it, you can officially say that your industry is making its mark in space.

We've all seen Russian nesting dolls, each perfectly decorated doll giving way to a smaller one inside. Every one of those little dolls is hand turned, carefully decorated and finished with a fine gloss. Medical device design operates on a similar concept, layering smaller components together to form one machine, each component tailored to the needs of the original equipment manufacturer (OEM).Design verification and validation are akin to the finishing gloss, and aren't reserved for the largest doll - or completed product; each component gets the same gloss. Here, Gareth Hancox, engineering and commercial support manager at Accutronics, explains the layers of verification and validation.
The words verification and validation are a little overused, and it can be easy to confuse the two processes or even to think they are the same. However, they are distinct and important practices that OEMs can’t afford to take for granted, especially in medical device manufacturing. The possible repercussions of failing to ensure that your new device is effective, safe and fit-for-purpose in medical and healthcare applications can be severe.
So what’s the difference between the two? Design verification establishes whether you designed the device to the right specification, design validation ascertains whether you designed the right device to meet customer expectations and requirements. The distinction may be subtle, but it is significant.
There’s no room for error when supplying medical devices, so verifying and validating your design proves that you’ve developed the best possible solution to a specific need and that it is safe to use. However, did you know that OEMs designing the machine are not the only ones going through this process? Often, the smaller components within a device are bespoke designs created by another OEM, such as the all important battery.
Much like lining up your Russian nesting dolls in height order before tucking them away, successful design validation and verification requires order and planning. Treating this process as an afterthought will, at best, cause you a headache; at worst it could mean your device fails the procedure.
Testing the waters
The US Food and Drug Administration (FDA) guidelines on the topic stipulate that medical device verification activities must be “conducted at all stages and levels of device design” and say that the “basis of verification is a three-pronged approach involving tests, inspections, and analyses”. In addition, the guidelines state that devices should be “tested in the actual or simulated use environment as a part of validation”.
To ensure our customers’ devices meet all necessary regulatory requirements, we test our batteries in simulated conditions and, to make sure we can do this effectively, we recently upgraded our test facility. Automated testing cabinets linked to climatic chambers tirelessly test cells and batteries for applications ranging from portable instrumentation and medical devices to robotics and defence.
Our new test equipment allows us to really put cells through their paces based on real world usage. We are able to accurately replicate the demands the device will place on the battery so we know the cells will perform as needed.

When making Russian nesting dolls you start with the smallest one first and work out. She has to be perfectly formed and solid, or the rest simply doesn’t fit. Your battery is that tiny figurine; if it is not formed properly the rest of your device will fail. Choosing a battery OEM that can guarantee attention to detail, is the first step in getting your device verified and validated.

Despite the emergence of alternative control solutions, the popularity of the PLC endures. Mitsubishi Electric product manager Hugh Tasker offers ten reasons why you still need a PLC.
There was a time, not so long ago, when the PLC stood as the only viable option for control in industrial automation applications. Today engineers have more choice in the form of industrial PCs, soft PLCs and panel PCs that ape the functionality of the PLC/HMI combination. Engineers could even, if they felt so inclined, build their own custom controller around a Raspberry Pi board.
Despite the emergence of these new control options, there are still many compelling reasons to use a PLC. Here are just ten of them.
1. Peace of mind
Both PLCs and PCs have come a long way since their humble beginnings but there is a big difference in how these distinct control options continue to evolve and this has significant implications for long term support. The managed evolution of the PLC means that vendors can and do support their products over long periods of time, both in terms of hardware and software. That means, with Mitsubishi Electric for example, that we could take the application program for example, from a 20 year old FX PLC and import it straight into a brand new FX5U. A user could install the very latest controller and have the application back up and running almost immediately. How would you even contemplate doing the same with a PC based solution?
There are many industries where that level of support is not simply desirable but actually a baseline requirement. There is talk in the water industry, for example, of framework suppliers having to be able to assure support of control systems for up to 20 years. Of course the control hardware will change over that time but PLC users have the peace of mind of knowing that the software will always port to the latest controller.
2. Inherently robust and reliable
The modern industrial PC provides a stable computing platform and it would be unfair to suggest that it locked-up and crashed with the unerring regularity of a desktop PC. However, it is not on equal terms with a PLC.
The real time operating system that runs alongside Windows on a typical industrial PC has been designed to try to provide the same level of robustness as you get from a PLC CPU.
If a PC operated in complete isolation, perhaps that would be the end of the reliability debate. However no controller does; there are peripherals to connect, I/O to network and other components to talk to, each requiring their own drivers to be loaded into the PC. Will the drivers for all of these products have been tested in combination and thoroughly proved? It seems unlikely. Clashes can and do occur and problems can be exacerbated every time those drivers are updated.
It is almost inevitable, then, that an industrial PC will crash and what might that mean for the control process? By contrast, when did you last hear of anyone needing to reboot a PLC after a software crash – probably never…
3. Scalability
The biggest selling PLCs by volume covering the largest spread of applications are those offering 40 I/O or less. In such applications, the PLC represents a highly affordable solution, much more so than an equivalent PC-based system. However, the same essential platform is also scalable to tens of thousands of I/O, with users able to port control programs to bigger PLCs, benefit from the same programming environment and take advantage of completely modular hardware.
The customisation potential of the PLC is enormous, with numerous ways to expand the functionality but all without ever leaving a common platform.
4. Programming
Even today, for every engineer coming out of university who is fluent in structured text programming and for every engineer who is comfortable working in C or C++, there are probably ten more who only want to use ladder logic, particularly at the lower I/O end of the application spectrum.
In between, there are those applications that might start small, perhaps written in ladder but then grow as the application evolves – taking advantage of the scalability of the PLC platform – benefiting from the ability to write the control program in structured text and to drag and drop software function blocks that will take away much of the configuration effort.
At Mitsubishi Electric we offer a C++ programming option for our PLCs, so we marry a flexible hardware platform to high level language programming capability Of course these same programming options are available on a PC platform, but the levels of modularity and scalability that PLC software tools offer – in much the same way as with the hardware – simply aren’t there.
5. Integration of other automation equipment
For many automation engineers, there is never any need to move outside the product portfolio of a single vendor, with suppliers such as Mitsubishi Electric able to address every requirement from HMIs, drives, servos, motion control, safety and robotics to low voltage power distribution products, power management meters and CNC systems. Because all of these components have been designed to work together, engineers benefit from ‘plug and work’ integration.
There are some automation vendors that sell industrial PCs who can claim to offer a broadly similar product portfolio but certainly not many. However, the real challenge comes when engineers need to look outside of a single brand and integrate third party components.
With the modern PLC, integration of third party hardware is a breeze; can the same be said for integration on a PC platform? Are the drivers for those third party modules guaranteed to work? How much configuration effort will be required? Perhaps more importantly, will there be the same assurance of ongoing compatibility through the operational lifespan of the control platform?
6. Performance
In terms of power and performance, Moore’s law of computational capability is just as applicable to PLCs as it is to PCs – indeed many people forget that the modern PLC is a powerful computer in its own right. The latest incarnation of the Mitsubishi Electric FX PLC, for example, is 150 times faster than the original.
Just how powerful the modern PLC is only really becomes apparent when you look at the speed of execution of instructions, with the latest designs offering sub-nanosecond performance. You might be able to ‘pimp’ a PC to offer similar performance but the PLC offers you that straight out of the box. Then there is the increased bus speed and the ability to synchronise multiple I/O in a high speed system, delivering a much more responsive control system. Again, this is much more difficult to achieve outside of the PLC environment.
7. Security
The arrival of high profile viruses such as stuxnet have made us all realise that automation systems have become targets, as malicious hackers look to cripple the operations of big companies or vital utilities. With its familiar operating system and inherent network vulnerabilities, the PC can represent the soft underbelly of the control system for anyone trying to break in. The operating systems of PLCs, by contrast, are much less visible to the outside world and this has traditionally offered a layer of insulation against malicious intent. This does not mean, however, that PLC manufacturers take security for granted. Mitsubishi Electric, for example, enables programs to be password protected, with different levels of access granted to different levels of user.
Further remote access preferences can be set such as access only being granted to specific IP addresses, protecting PLC software and the wider automation system even in heavily networked applications.
8. Intellectual property
Extending the security argument, a concern for companies with global development teams or where the end system will be installed overseas is that the control software will be copied by unscrupulous third parties and all too quickly developed as a competitive, lower cost product.
Where this is a valid concern across all control platform options, the PLC manufacturers have taken significant steps to address the problem. With Mitsubishi Electric products, encrypted code embedded in hardware and software can be set to execute at a given time. That might mean that the system is open to developers and installers right through to the end of commissioning of the application, but then switches on to protect the system from further interaction.
9. Maintenance
Every automation system, regardless of platform, needs routine maintenance; perhaps to manage hardware or software upgrades, as part of scaling up the system as the application evolves, or, to swap out faulty components. The ease with which this can be accomplished is a major attraction of the PLC. Programs and configuration settings for just about any connected component can be stored to SD card via a slot in the PLC CPU, simplifying any maintenance requirements.
Indeed, even if the PLC CPU itself were to fail, a new unit could be snapped onto the backplane and the original program loaded direct from a bootable backup on the SD card, getting the system back up and running straight away.
At the same time, there are none of the requirements for ongoing firmware updates that plague PC-based systems, with the constant worry that any one of these will clash with another and bring the system to its knees. The very fact that the PC is a multi-purpose system is one of its greatest weaknesses in the automation environment.
10. Reduced IT requirements
One of the questions in any automation system, even more so as integration between the plant floor and higher level systems comes into the equation, is the allocation of responsibility between the automation engineering team and the IT team. This can be a source of friction but perhaps more importantly there is the almost inevitable lack of understanding from each about the requirements of the other.
With PLC-based automation, the demarcation between engineering and IT is clear, with little or no need for the IT team to have to get involved on the plant floor. Further, with products such as Mitsubishi’s Electric’s MES module – which plugs into the PLC backplane and provides direct connection with higher level databases – whole layers of PC products can be eliminated from the automation system altogether, making the demarcation between automation and IT even clearer.
We can see, then, that there are many good reasons why the PLC will continue as the mainstay of automation system control and that’s before we’ve even considered issues such as redundancy, safety and more, plus the capability of the modern PLC to perform many of the complex maths functions that could once have only been performed in a PC-based system.

Of course the requirements of every automation system should lead to the selection of the appropriate control solution on merit but the PLC offers many reasons to be the platform of choice.

Virtual reality isn’t just at the heart of a new era of entertainment. It’s also for serious business.
That’s why we’re helping developers, businesses, OEMs and independent software vendors with our NVIDIA ‘VR Ready’ program, which ensures they have the tools and technologies to create and enjoy the best possible VR experience.
“Enterprise adoption will outpace consumer adoption for some time,” said Bill Briggs, chief technology officer for Deloitte Consulting, in a recent Tech Trends 2016 report spotlighting VR and augmented reality.
We’re working with top OEMs such as Dell, HP and Lenovo to offer NVIDIA VR Ready professional workstations. That means models like the HP Z Workstation, Dell Precision T5810, T7810, T7910, R7910, and the Lenovo P500, P710, and P910 all come with NVIDIA-recommended configurations that meet the minimum requirements for the highest performing VR experience.
Quadro professional GPUs power NVIDIA professional VR Ready systems. These systems put our VRWorks software development kit at the fingertips of VR headset and application developers. VRWorks offers exclusive tools and technologies — including Context Priority, Multi-res Shading, Warp & Blend, Synchronisation, GPU Affinity and GPU Direct — so pro developers can create great VR experiences.
An Industry First for Mobile VR
We’re also enabling the industry’s first professional-class mobile workstation, which lets users take a great VR experience wherever they go.
The MSI WT72 is the first NVIDIA VR Ready professional laptop. It lets designers, engineers and others run VR-powered design reviews anywhere, improving product quality and speeding workflows. With it, companies can use immersive technology to train remote employees. And architects like those at McCarthy Building Companies Inc. can let customers visualise concepts and designs. They can even walk through complete virtual buildings.
“Providing customers with a high-fidelity VR experience during design review allows them to realistically visualise and make informed decisions, which can prevent costly design changes after construction has started,” said Alex Cunningham, VDC engineer at McCarthy Building Companies. “With NVIDIA Quadro driving VR at high frame rates, the VR Ready MSI laptop lets us bring virtual reality to our clients’ locations and communicate designs more effectively.”
NVIDIA GPUs are the keystone of VR because graphics requirements are so high. Head-mounted displays, for example, require 90 frames per second, with a display for each eye.
The MSI WT72 VR Ready laptop is the first to use our new Maxwell architecture-based Quadro M5500 GPU. With 2048 CUDA cores, the Quadro M5500 is the world’s fastest mobile GPU. It’s also our first mobile GPU for NVIDIA VR Ready professional mobile workstations, optimized for VR performance with ultra-low latency.
With features like these, scientists, product designers, educators and filmmakers can use the MSI WT72 to tackle the most challenging visual computing tasks. Plus, it comes certified for Autodesk VRED to create amazing, immersive 3D design environments.
“We’ve certified the MSI professional ‘VR Ready’ laptop with the NVIDIA Quadro M5500 mobile GPU because it delivers an amazing Autodesk VRED VR experience wherever our customers need it,” said Lukas Faeth, product manager, Autodesk VRED.

Come see the latest VR technologies from our partners and professional applications developers — along with Quadro VR Ready Workstations and the MSI WT72 professional VR Ready laptop —at NVIDIA’s annual GPU Technology Conference, April 4-7, at the San Jose Convention Centre in Silicon Valley.

As industry becomes more automated and robotised the need for high precision gearboxes in machinery and plant engineering grows. Ian Carr, managing director of Drive Lines in Bedford, explains how planetary gearheads have precision and power designed into them.
Machinery and systems such as robots, packaging machines, pick and place units, tool changers in machine tools, printing presses and welding systems all rely on precision motion. Likewise, medical equipment, navigational aids and astronomical telescopes also need cutting edge motion systems.
While at first glance some of these applications may seem to have little in common, in fact their power and motion systems are based on similar fundamental principles.
Looked at as a drive system, the main requirements are in fact very similar: high torque must be provided, whilst low backlash is essential. To achieve this, torsional stiffness is required, and high acceleration and braking are often demanded. More often than not, there is also the need for a compact design, or the need to fit within a demanding space envelope.
Such drive systems have a high design content. Many are truly bespoke, one-off designs, while others may be customised variations of a standard design. However, like all drives systems they are typically made up in large part from standard components, servomotors, gearheads, couplings etc.
Thus a precision drive system designer will select components, optimising one with the next with the ultimate goal of achieving each project’s performance specification. They will also be aware that each type of component has certain characteristics and advantages, so will know, for instance, when to specify a servo motor rather than a stepper or which type of coupling to use in given situations.
It is fair to say that precision drive system designers make regular use of planetary gearheads. In fact they are used almost exclusively as the major joints in both articulated arm and delta robots, are ideal for many bespoke machines and are a firm favourite for medical scanners. So let us look first at how they work, then at why they are good for precision drives.
Operating principle
Planetary gears are also called epicyclic gears or sun-and-planet gears, the latter being useful for helping visualise - their operating principle. Dismantle a planetary gear and at first it looks complicated, but you can soon identify a central sun gear, surrounded by, and meshing with, some planet gears. (Typically there are three or four planet gears, but it could be fewer or more.) Holding the sun and planet gears together are an outer ring gear with internal teeth that mesh with the planets. There is also a planet gear carrier, but this does not transmit power rather being a structural element that keeps the gears in place.
If the sun gear is turned, the meshing teeth cause the planet gears to turn, which then cause the ring gear to turn. It sounds complicated and looks hypnotic, but in fact is very simple. It is also notable that the ring gear turns in the same direction as the sun gear.
Significantly, while the sun gear rotates relatively quickly, the outer ring gear rotates more slowly. In fact the ratio of their two speeds is derived from the ratio of their two diameters – the planet gears act as idlers, their role being to transmit power between the sun and ring, in other words their diameter does not affect the overall speed ratio between input and output.
This configuration offers some very significant advantages over other gear layouts. For instance, all the parts fit inside the ring gear making it a compact unit. Because there are a number of planet gears, there are many teeth meshing with one another, each pair transmitting power and adding together to give a high torque capability in a compact unit. The multiple meshing of teeth also helps to significantly reduce backlash compared to a gear system where there is only one meshing pair. Also, because the power transmission is spread equally across each planet gear, there is an innate symmetry which helps prevent the gearhead from flexing under load.
Thus it can be seen that planetary gearheads have a lot to attract designers of precision drive mechanisms. They are compact, powerful, accurate and robust.
In order to make planetary gearheads even more attractive to potential users, manufacturers such as Premium Stephan make them in a range of formats, so that individual requirements can be met from a standard model or one that has been only slightly modified. Premium Stephan can supply their gearheads as sub-assemblies, enclosed gearboxes or fitted to a motor to form a unitary component. They are available in a range of sizes and can be supplied with either solid shafts (with shaft length to match the application) or hollow shafts, the latter allowing a feed-through of cables. Generally they are designed for use with standard mineral oils, although specials are available.
Now to look in more details at a particular planetary offering, let’s take the Melior Motion range, again from Premium Stephan. This has many design details that help ensure performance is as precise and reliable as possible. For instance, the gear teeth have a unique profile that guarantees backlash is less than 0.6 arcmin and will not change by more than 10% over the nominal operating lifetime of 20,000 hours. This reduces the costs associated with initial set up and subsequent servicing and replacement.
Further, the Melior Motion’s torque capacity is exceptional for such a small footprint, so energy efficiency is high. Thus heat generation is low, allowing standard lubricating oils to be used rather than expensive specialist ones. It also leads to low starting torque, inertia and braking loads, and therefore smooth and reliable operation.
Tilting and torsional stiffness are high, leading to precise positioning and high repeatability. In fact the Melior Motion was designed with robot applications very much in mind, hence its compact size, low maintenance, and high performance.

In conclusion we can say that planetary gearheads are enabling more and more potential users to think about adopting precision servo drive technologies for their machines and systems. First time users in particular may appreciate technical support from a company like Drive Lines, which not only supplies gearheads and associated equipment but also has a wealth of expertise and experience in specifying precision drives for a wide range of applications. Established over 30 years ago, Drive Lines has worked on applications as diverse as hot drape formers, golf buggies, lifting systems, laboratory equipment, cement mills drives and a door closure for a medieval cathedral.

Adding new design features or applying special techniques and coatings to bearing components can optimise the performance of bearings for challenging applications, providing unique bearing solutions to clients’ problems.
  • Adding value and improving bearing performance by incorporating new design features such as special flanges, shafts and housings.
  • Optimising bearing performance by replacing traditional bearing materials with special materials for high speed, high temperature or harsh operating environments.
  • The use of surface coatings such as sub-micron sputtered coatings to further optimise bearing performance and to make bearing behaviour more predictable/consistent in harsh environments.
There are many different design features and techniques that can be applied to a bearing to optimise and improve its performance in order to meet particularly challenging (i.e. high speed, high temperature, harsh operating conditions) applications. These techniques include applied coatings, altering the geometry of a specific bearing component or replacing conventional bearing materials with high performance alternatives.
Silver-plating of metal cages
In some high speed, high temperature applications, steel cages can be coated with silver to improve lubrication performance and reliability. Silver plating improves the lubricity of the bearing, making it more robust and resistant to oil-off events. In the case of lubricant failure/starvation, the silver-plating acts like a solid, dry lubricant, allowing the bearing to continue running for a short period of time or in an emergency situation. Application examples include aerospace starter generator bearings and bearings for air conditioning units on trains.
Ceramic hybrid bearings
For high-speed applications, replacing the steel balls with ceramic (silicon nitride) balls can radically improve bearing performance in several ways. First, because ceramic balls are much lighter than steel balls, reducing centrifugal forces and improving dynamic conditions whilst their surface finish is almost perfectly smooth, they exhibit vibration levels two to seven times lower than conventional steel ball bearings. At higher speeds, internal loading in the bearing is also reduced.
Secondly, ceramic hybrid bearings also run at significantly lower operating temperatures, which in conjunction with the lower mass allows running speeds to increase by as much as 40 to 50%. Lower operating temperatures and reduced heat build up inside the bearing helps extend lubricant life, sometimes up to five times longer than conventional steel ball bearings.
Examples of applications for ceramic hybrid bearings include high-speed vacuum pumps, medical/surgical hand tools and aerospace fans and generators.
In materials technology, the most appropriate bearing materials can be selected to maximise bearing performance. Special ring materials are used successfully in aerospace and non-aerospace applications, combining superior corrosion and wear resistance with the ability to withstand higher dynamic loads than conventional bearing steels. When used in conjunction with ceramic balls, significant gains in bearing life and performance can be achieved.
Ring materials can be optimised for specific applications. The four predominant ring materials used by Barden are AISI 440C (corrosion-resistant steel), SAE 52100, AISI M50 and Cronidur 30. For high temperature applications (up to 345°C) AISI M50 tool steel or a special tempered version of Cronidur 30® are suitable and are widely used in high temperature aerospace accessory applications such as bleed valve systems on aircraft.
Cronidur 30 is martensitic through-hardened, high nitrogen, corrosion-resistant steel that can also be induction case hardened. This material enhances corrosion-resistance and improves the fatigue life and wear resistance.
Full complement bearings
Full complement bearings capitalise on the space normally occupied by the ball retainer. This allows for more balls, which in turn provides an increase in load capacity, either predominantly radial, in the case of filling notch designs, or axial and in the case of angular contact designs. The use of preloaded angular contact pairs can also allow bi-directional axial loads to be applied. Applications here range from high temperature valves for aerospace applications, to missile fin supports and emergency touch down bearings.
Sub-micron coatings
The role of surface engineering in rolling bearing technology is also becoming increasingly important as bearings get progressively smaller, but are still required to run faster, at higher temperatures, carry higher loads and operate reliably for longer periods. Advanced coatings and surface treatments can be applied to bearings that combat friction, prevent corrosion and reduce wear, even under the harshest operating conditions. The resulting benefits are higher power density, improved performance, more predictable/consistent bearing behaviour (particularly in harsh environments), lower running costs and longer service intervals.
Multi-layer sub-micron (sputtered) coatings, for example, can be employed to enhance the physical and tribological characteristics of bearing surfaces. The success of such techniques relies on the avoidance of distinct layers by generating a graduated or diffused interface between different materials. Similarly, keying layers such as nickel or copper are frequently used to improve the adhesion of soft films to hard or passivated substrates.
Sub-micron coatings can be applied to the internal and external surfaces of bearing rings and rolling elements if required. For example, molybdenum disulphide (MOS2) or tungsten disulphide (WS2) can be sputter coated to the surface of bearing components in order to make bearing behaviour more predictable in harsh environments.
Special polymers
In some high speed applications, the ball separators or cages can be supplied in special polymer materials. These components are vacuum-impregnated with oil to increase the life of the bearing. The special polymer material retains the oil in a controlled manner when vacuum impregnated. Application examples include bearings for high speed aircraft gyros. Other special polymers can be provided for high speed harsh environments where the bearings require high resistance to chemicals or thermal attack.
Adding value through new design features
Pressure to reduce costs in all areas of manufacturing means that the integration of bearing systems into mating components is becoming more common. The resulting assemblies are neater, more compact, faster to put together and offer the additional benefits of reducing space and mass, whilst resolving the issues of tolerance stack-up.

Special design features can be incorporated into the bearing to improve its performance. These features include flanges, shafts and housings, which make fitting easier, faster and more accurate, which in turn, reduce assembly time and overall operating costs.

The results from a series of in-depth studies on the vibration monitoring of rolling bearings in wind turbine gearboxes and generators, have been published in a report by Dr Steve Lacey, Engineering Manager at Schaeffler UK.
As greater demands are being placed on existing plant assets, either in terms of higher output or increased efficiency, the need to understand when things are starting to go wrong is becoming more important than ever.
As plant and equipment becomes more complex and automated, the need to have a properly structured and funded maintenance strategy is critical. There is a need to properly understand the operation of equipment such that improvements in plant output and efficiency can be realised.
Rolling element bearings
Almost every type of rotating equipment uses rolling contact bearings to locate and allow accurate rotation of the shaft. During operation, equipment reliability very much depends on the type of bearing selected as well as the precision of all associated components i.e. shaft, housing, spacers, nuts, etc. Bearing engineers generally use fatigue as the normal failure mode based on the assumption that the bearings are properly installed, operated and maintained.
Today, due to improvements in manufacturing technology and materials, generally bearing fatigue life, which is related to sub-surface stresses, is not the limiting factor and probably accounts for less than 3% of failures in service.
Unfortunately, many bearings fail prematurely in service because of contamination, poor lubrication, misalignment, temperature extremes, poor fitting/fits, unbalance and misalignment – factors that can all lead to an increase in bearing vibration. Condition monitoring has been used for many years to detect degrading bearings before they catastrophically fail with the associated costs of downtime or significant damage to other parts of the machine.
Vibration monitoring
Vibration monitoring is probably the most widely used predictive maintenance technique and with few exceptions can be applied to a wide variety of rotating equipment. Since the mass of the rolling elements is generally small compared to that of the machine, the velocities generated are typically small and result in even smaller movements of the bearing housing, making it difficult for the vibration sensor to detect.
Machine vibration comes from many sources such as bearings, gears, imbalance, etc. and even small amplitudes can have a severe effect on the overall machine vibration, depending on the transfer function, damping and resonances. Each source of vibration will have its own characteristic frequencies, which can manifest itself as a discrete frequency or as a sum and/or difference frequency.
At low speeds it is still possible to use vibration but a greater degree of care and experience is required and other techniques such as measuring shaft displacement or Acoustic Emission (AE) may yield more meaningful results although the former is not always easy to apply. Also, while AE may detect a change in condition it has limited diagnostic capability.
Vibration monitoring has now become a well-accepted part of many Predictive Maintenance regimes and relies on the well-known characteristic vibration signatures which rolling bearings exhibit as the rolling surfaces degrade. However, in most situations bearing vibration cannot be measured directly and so the bearing vibration signature is modified by the machine structure and this situation is further complicated by vibration from other equipment on the machine i.e. electric motors, gears, belts, hydraulics, structural resonances, etc.
This often makes the interpretation of vibration data difficult other than by a trained specialist and can in some situations lead to a misdiagnosis resulting in unnecessary machine downtime and costs.
Wind turbine drive train
Vibration-based condition monitoring systems have become well established for monitoring the mechanical condition of a wind turbine drive train (rotor, gearbox and generator) during operation. However, vibration signals from this type of equipment can be very complex as they often contain a number of different bearing types and gears, which can include multi-stage planetary systems. At times, this can make the detection and diagnosis of a problem very difficult and often several different techniques may have to be used to diagnose a problem.
Vibration monitoring can also be used to assess the condition of the drive train components prior to installation. Consequently, over a number of years, Schaeffler UK conducted a series of in-depth vibration monitoring studies on wind turbine gearboxes and generators, prior to these systems being installed on the wind turbine.
Wind turbine gearbox study
Rolling element bearings are manufactured to high accuracy and great care is taken over the geometrical accuracy, form and surface finish of the rolling surfaces. It is important therefore, that all associated bearing components i.e. shafts, housings, spacers, etc are all made to these high standards. In addition, assembling the bearings and associated components in a clean and controlled environment with the correct tools is also critical, as failure to do so can seriously compromise the performance and reliability of the bearing in service.
Assembling large gearboxes is a skilled task and it is not uncommon to find that some damage has been introduced to the bearing rolling surfaces during the assembly process.
While it is easy to introduce damage, detecting it is almost impossible without conducting some form of operational test. This often takes the form of running the gearbox on a purpose built test stand under a range of operating conditions. In some cases, only operating temperatures may be measured to quality assure the gearbox, but often this is not sufficient and any damage to the bearing rolling surfaces may go undetected.
Vibration measurements obtained from various positions on the gearbox e.g. input shaft, intermediate shaft and output shaft are often the best approach, enabling any damage to the bearings or gears to be detected.
Figure 1
An example of such a vibration measurement is shown in Figure 1. As part of Schaeffler UK’s studies, a 1.2MW gearbox was run at 1500rpm on a purpose built test stand and vibration measurements were obtained at various positions on the gearbox housing.
The vibration spectrum obtained from the housing close to the high speed shaft (HSS) is shown in Figure 1.
The calculated BPFI (Ball Pass Frequency of the Inner race) for the type NU228 cylindrical roller bearing on the high speed shaft (HSS) was 271.26Hz and present in the spectrum is a large amplitude vibration at 270.64Hz, which matches very closely with the calculated frequency. Either side of the vibration at 270.64Hz are a few sidebands at shaft rotational speed (fs = 25Hz). In the envelope spectrum, Figure 2, the BPFI is also evident at 272.50Hz, along with the third harmonic (817.52Hz).
Figure 2
This indicates that some damage may be present on the inner ring raceway and the absence of any significant harmonics of BPFI suggests that the damage is fairly localised. This is further supported by the impulsive nature of the time signal, Figure 3(a), showing impulses at the output rotational speed (40ms, 25Hz).
Figure 3 (a and b)
Figure 3(b) shows the expanded time signal where during one revolution of the inner ring, the contact of the roller with the defect is clearly visible (~3.52-3.9ms).
As a result, the gearbox was dismantled and examined and a localised fault was found on the inner ring raceway of the type NU228 cylindrical roller bearing.
This damage occurred during the assembly process, the most likely cause being misalignment between the inner ring and outer ring/rollers as the inner ring-shaft and outer ring-housing were aligned and assembled together.
During running of the gearbox on the test stand, all the operating temperatures were normal and this damage would otherwise have gone undetected without the vibration measurements. Such damage would result in a shortened service life and premature failure of the gearbox. In this case, the value of a detailed vibration analysis is obvious; in the long run, this saves the customer both time, money and reputation.
Other studies

Other vibration monitoring studies were carried out by Schaeffler UK, the results of which can be viewed in a full, 34-page report. These studies include the vibration monitoring of rolling bearings on a 2MW wind turbine generator prior to delivery to the customer. In addition, by working closely with a number of different rail fleet operators, Schaeffler UK conducted six separate vibration monitoring studies to assess the condition of traction motors without the need to remove equipment from the train bogie. These studies were undertaken on a variety of high-speed passenger trains and involved a wide range of traction motor makes and sizes, from 8MW high speed trains down to light rail-vehicles.

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