Pneumatics

In every manufacturing industry, machine safety is always a top priority. When operating in Europe, utilizing machinery and components with CE certification is the best way to ensure the reliability of the equipment that benefits both production and the operators who use the equipment. 

What is the Machinery Directive?
First published in 1989, the Machinery Directive was designed to provide freedom of movement across Europe for machinery and safety of workers in an effort to reduce injuries. 

In 2009, the Machinery Directive 2006/42/EC became law in Europe, and its primary role is to ensure common safety levels of machinery placed on the market and put into service. 

Today this directive lays down the foundation and regulatory basis for the harmonization of Essential Health and Safety requirements (EHSR) in the field of machinery. It is unified with CE requirements and covers almost 21 distinct EN Standards to guide machine builders on safety requirements and has worked to harmonize with other safety organizations. Ultimately becoming the foremost authority on where to go to design a safe piece of equipment globally.

Directive qualities
A unique quality of the Machinery Directive is its broad coverage for machinery design. The standards start at concept of design or designing out risk. The directive mandates a technical file be kept on the machine to show its inception and what risk avoidance was implemented to create a safer machine. 

Guidance is provided to the machinery builder in the form of EN standards which mandate a risk assessment be conducted on machinery. Finally, the directive includes information on disposal at end of life of machinery. While broad, the directives do a great job of ensuring safety is addressed at every level and even account for “unintended use of machinery” at the design stage.

Safety
Another interesting note is given that one of the primary purposes of the Machinery Directive is to ensure common safety, the directive does not mandate the use of safety rated products. It does clearly differentiate standard components used in a safety application versus those products built and intended as safety rated products.

Safety rated products are classified separately and are subjected to more rigorous requirements, testing and expectations for performance. 

The directive does state that common sense strategies be employed on machinery such as the use of e-stop buttons, the removal of air in a machine to protect from unexpected movement (where safe to do so) and the addition of technical measures where risk cannot be designed out. Additionally, to meet enhanced safety levels on machinery, redundancy and monitoring must be included in the controls of the machine EN ISO 13849-1 as well as validation of the system EN ISO 13849-2.

Some manufacturers offer safety rated components, such as Parker’s P33 series of safety exhaust valves, which meet the needs of the directive to remove air from machinery during either an e-stop or a faulted condition on the machine. 

Knowing that products now exist which incorporate the needs of the directive and provide an enhanced level of certified safety can bring peace of mind to machinery designers and the engineers responsible for enhanced and integrated safety on machine. 

If you would like to find out more about Parker’s P33 series of safety exhaust valves and the benefits they can bring to your machine-building projects, please download our white paper What You Need to Know About Safety Exhaust Valves.

Article contributed by Linda Caron, global product manager for Factory Automation, Pneumatic Division.

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We are all witnesses to the fourth industrial revolution, or Industry 4.0 as it has been coined, as most of us will have seen robots, machines, vehicles or control systems connect to the Internet at some level or another. Of note here is the speed with which changes are taking place, a factor that has seen many new and exciting technologies come to market. In short, the union between the IT and industrial automation worlds is taking place in front of our eyes.

Of course, there are many levels of industrial communication and each requires different hardware and software features. Smart factories are looking to get a lot smarter, more flexible and dynamic, so networks need to respond to these goals. The high performance and reliable communication technologies that are entering the market are making it possible to transfer large amounts of data and connect a high number of individual devices both reliably, and with the highest data security standards.

Well, in the first instance, all levels of communication need to be involved. With Industry 4.0, the boundaries of the different levels shift from what is currently in place. The field level remains a dedicated layer, but the devices on it will incorporate more and more intelligence – including smart sensors – which are able to perform many processes autonomously.

Many efforts to develop IoT platforms have focused on the enterprise level with a top-down approach. Although this level is indispensable, it actually only collects about 10 percent of the available data, limiting the ability to support predictive maintenance and component performance optimisation. Unless a discrete IoT system is used for the remaining 90 percent of critical component data, enterprise systems cannot exploit their potential to truly transform business activities.

With its centralised ‘Voice of the Machine’ strategy, Parker provides an example of a company developing and implementing an Industry 4.0 solution which supports extensive autonomous monitoring and control. The strategy comprises hardware such as smart sensors and IO Link, plus a common set of standards, principles and best practices. Although Industry 4.0 is still in its relative infancy, the technology has reached a point of evolution that can provide significant value in many industrial applications.

The use of industrial networks to make sensors and actuators more intelligent has become common across modern factory environments, and the use of continuous position sensing is a pathway to achieving smart motion control in pneumatic systems.

Continuous position sensors are more sophisticated sensor devices with two-way data flow that help to bring intelligence to pneumatic motion control and provide necessary continuous data to help facilitate a true Industry 4.0 environment. 
Using contactless technology to continuously detect the linear position of a piston in its cylinder, the quick, precise and high-resolution sensing of the piston magnet is achieved without the need for separate position encoders or additional mechanics, therefore minimising the cost of implementation.
The data communicated by the sensor allows for monitoring, and when information flows in both directions and actuators are employed, control. The result is that positional data is made available for fast detection of any issues that might cause downtime or potential loss of productivity.

Another critical part in the success of Industry 4.0 manufacturing strategies is choosing the right protocol to connect sensors with controllers and actuators. Here, IO-Link provides the ideal solution, allowing two-way communications to receive data and then download a parameter to the device/actuator. As a result, processes can be adjusted remotely.

The advantages of IO-Link include the automatic detection and parameterisation of the IO-Link device, device monitoring and diagnostics, changes on the fly and reduced spare part costs.

Ultimately, the key to unlocking the power of smart sensors is in making diagnostic information easy to access. IO-Link allows for cyclic data exchange capabilities so that programmers can easily send the information directly to where it is required, either to an HMI screen, a signal light or a maintenance request. If sensor or actuator parameters need to be changed or calibrated, this can be done remotely, even while the production line is still running, ensuring that shutdowns, stoppages and unnecessary costs are avoided.

Watch this video to know more about IO-Link:

Article contributed by Manuel Finotto, business development manager IoT, EMEA 

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Installing a pneumatic cylinder correctly is a vital design consideration. Failure to address this properly can result in inaccurate operation, compromised reliability and premature failure.

Depending on the specific application, cylinders such as those from Parker’s P1F series, are either going to be rigidly fixed to the structure of a machine bench, or allowed to swivel to form part of a linkage. The two fixing points will be the cylinder body and its piston rod end. In many applications, the mechanism attached to the piston rod end will be allowed to hinge in one or more planes. In a few applications however, the piston rod end is left free, such as in a simple pushing application.

The mechanics of cylinder installations will vary considerably from one application type to another. A cylinder should be installed so that side loads on the piston rod bearing are reduced to an absolute minimum or eliminated entirely. A side load is a force component acting laterally across the axis of the bearing and can cause premature wear and failure.

A cylinder can be rigidly fixed by side mountings, or front or rear flange plates. Alternatively, if the cylinder has a thread on the front or rear end cover, it can be clamped to a structure with a locknut. Special tie rod ISO or CNOMO cylinders can be fitted with tie rod extensions for fixing through a flat plate.

Rigid mounting options for the cylinder are shown in the diagram below using components annotated 1-9. A semi-rigid trunnion option can be achieved using supports (10 or 11), pivots and clevis brackets (3 & 5, 7 & 8 & 4, 5 & 6) allowing the cylinder to rotate by following the piston rod extension or retraction during the work task of the cylinder.

If the cylinder is forming part of a linkage, then it must be free to swivel in one or more planes at the mounting point. Different degrees of balance can be achieved for the cylinder and load system by choosing between a rear hinge, front clevis, and central trunnion (using mountings 12, 13 & 14). A front hinge, clevis or universal eye allows swiveling attachments at the end of the piston rod.

There several areas where caution is appropriate when installing a cylinder.

• Avoid attaching an unsupported load to the piston rod; wherever possible support the load on a slide or roller guides.

• The weight of a long out-stroked piston rod alone can produce a high bending moment. It may be possible and prudent to hang the rod end from a roller track or provide other external guidance to minimise bending moments.

• Misalignment of the cylinder and a guided load can easily jam the cylinder completely. The installation of a front fork and slot will eliminate this type of side load on the front-end cap bearing in the cylinder. 

• An offset load is a common source cause of a bending moment on the piston rod of the cylinder. Installing external bearings will relieve the side load as well.

• A horizontal mounted rear hinged cylinder will cause the weight of the body cylinder to create a bending moment. This will be helped if a central trunnion is fitted at the point the cylinder balances.

It is difficult to eliminate side loads completely, but by employing good practice and basic mechanical design knowledge, they can be reduced to a minimum helping to increase the lifetime and performance of the cylinder in the application.

Parker’s P1F series pneumatic cylinders are ISO15552-certified and suited to a wide range of industrial applications with bore sizes ranging from 32 to 125mm. The smooth profile version P1F-S cylinder is complemented by the P1F-T tie-rod version, with the P1F-C version for ‘clean’ applications due for release soon. A wide range of cylinder and piston rod mountings and sensors can be supplied for use with the P1F series to suit all customer applications.

For further information download P1F catalogue.

Article contributed by Franck Roussillon, Product Manager for Actuators Europe, Parker Hannifin, Pneumatic Division Europe

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Pneumatics have always played an important role in achieving maximised productivity for manufacturing automation applications and the technology is constantly evolving to solve engineering challenges. 

One such evolution is the development of rodless cylinders.

The disadvantages of rod-type cylinders

The limitations of conventional rod-type cylinders are widely recognised, particularly where long strokes are required. Being unsupported, the cylinder rod has a tendency to flex in the extended position which can cause excessive wear on rod seals and bearing leading to the need for additional engineering to avoid premature wear.

Space constraints may also limit the use of rod-type cylinders with the overall length being more than double the stroke length. This can cause problems when designing or mounting cylinders to machinery. In long travel situations, rod-type cylinders can also sag under its own weight and this misalignment can cause the cylinder rod to bind or buckle. 

The disadvantages of rod-type cylinders are:

• Overall length is more than double the stroke length.
• Risk of the piston rod bending, resulting in excessive wear.
• Bad positioning features due to two different piston areas.
• Unequal velocities in forward and return strokes.
• Designed for short stroke length.

The development of slot-type rodless cylinders was designed to eliminate all of these disadvantages.

The construction of rodless cylinders

The rodless pneumatic cylinder has been engineered to be a self-contained linear actuator with a unique design that offers greater design flexibility. With a unique design that uses only four main components, rodless cylinders, such as Parker's OSP range, offer a robust and reliable solution in operation that is simple to maintain; providing long trouble free service. Operated by compressed air, rodless cylinders combine controlled and precise movement with integral support and guidance in any plane.

The rodless cylinder consists of four main parts:

1. The cylinder barrel of extruded anodized aluminium has a slot along its entire length.
    
2. A flexible hardened stainless steel inner band running the entire length of the bore and passing through the piston provides a metal to metal seal. An outer band of the same material acts as a cover over the slot preventing foreign particles from entering into the cylinders interior.
    
3. The aluminium piston is fitted with synthetic bearing rings. The power transmission outwards takes place through a positive, physical connection through the slot to the external piston mounting. This solid guide permits the acceptance of external forces and moments and minimizes frictional losses.
    
4.  End caps providing connections to the air supply, and housing cushioning adjustment screws.

When to use rodless cylinders

The double acting operation of pneumatic rodless cylinders is advantageous in applications where space is limited.

This is because the installation length of a rodless cylinder is only slightly longer than the cylinder’s stroke. For example, 25mm diameter rodless cylinder with 1000mm stroke would only occupy 1200mm of space, opened or closed.

When specifying, a pneumatic rodless cylinder would be the ideal choice over a pneumatic rod-type cylinder to meet the following requirements:

• A source of repetitive linear movement is needed.
• Cleanliness and minimal risk of contamination from lubricants must be assured.
• Space savings are a major design consideration, e.g. long stroke applications.
• Reliability and minimal component maintenance is needed to safeguard against downtime.
• Overall length can present problems when designing or mounting cylinders to machinery.

When optimally selected and applied, the latest generation of smart sensors can have a positive impact on predictive maintenance strategies for fluid power applications.

Real-time data collection via smart sensors can influence decisions about when to schedule downtime to carry out maintenance operations, helping to maximise productivity. 

Maintenance operations are traditionally based on being either reactive or preventative. A reactive strategy means a loss in production and incurring unforeseen costs, while a preventative strategy often sees systems or parts repaired simply because they are listed on the general maintenance procedures, rather than when they actually need it. 

Attention has been gradually shifting to predictive maintenance, spurred on by the emergence of Industry 4.0 and sophisticated ‘smarter’ technologies. For fluid power systems, this means a whole new level of condition monitoring, to the extent that maintenance personnel can determine whether something out of the ordinary has occurred. 

Ultimately, every process has a ‘heartbeat’, so the question to ask is has that heartbeat changed over a certain period of time? Maybe it has become slower or faster, for instance. This is where smart sensor technologies begin to pay dividends. 

The latest sensor technology available for fluid power systems, such as the P8S CPS series from Parker, have evolved to offer high quantities of data which offer the opportunity for plant managers to transform how they operate and maintain industrial equipment. 

Embedded smart sensors can today be integrated with numerous different low-level fluid power products, from connectors, hoses and tubing, to pumps, motors, actuators and filters – all as part of an Industry 4.0 installation. One of the principal opportunities arising from this concept relates to predictive maintenance. For example, some of the diagnostic data generated from control valves could be invaluable in troubleshooting power issues. 

Among the common concerns in fluid power systems is voltage sags that can occur downstream on long runs, which sometimes lead to misfiring valves. Normally, without an oscilloscope, there are no means of diagnosing the root cause of the problem. In contrast, if each valve manifold node included voltage sensing, a ‘sweeper’ program could be written to record voltage levels across the machine during certain periods of the cycle.

Of course, selecting an Industry 4.0-enabled sensor is one thing, but ensuring that it can communicate with other such devices is quite another. For this reason, it is imperative to select a sensor vendor that operates a centralised strategy to ensure that its smart devices and sub-systems share open communications standards and best practices. IO‑Link is the first I/O technology for communicating with sensors and actuators to be adopted as an international standard (IEC 61131-9). This open protocol is bringing the world of Industry 4.0 to component level and already proving essential in ensuring interoperability across multiple technologies and manufacturers.

Consider a pneumatic device, for example, which is being used to grip workpiece blanks and load them into position on a machine tool. Here, the voltage of the coils across the solenoid valves can be monitored for signs of impending failure. In such a scenario, IO-Link can offer budget-friendly communication with low-level devices, connecting them to motion controllers that subsequently connect to a factory network and, if required, to the cloud. 

Smart sensors and other Industry 4.0-enabled devices must work in co-operation with products from other manufacturers. In fact, the value of any connected digital solution is directly proportional to its interoperability. There is no place for proprietary solutions; an open, exchange-based architecture that enables interoperability with third-party products, applications and platforms is essential.

Talk about Industry 4.0 and one recurring area of concern arises - security. Indeed, this issue has been central in discouraging many plants from taking the decision to connect machines and devices to the cloud and gaining the insight required to predict failures and optimise performance at the component level. 

For any company concerned about this issue and seeking guidance on how to move forward, this is the point where choosing the right vendor is of the essence.

It is critical to choose suppliers who can share technical knowledge and hands-on experience gained from working across a wide range of advanced applications.

With a specific focus on fluid power installations, the selected vendor should be able to offer advice on where sensors need to be integrated to obtain optimal insight, the type of data to collect, and how to present the results to MRO (maintenance, repair and operations) personnel in the way that is most useful. Progressive, forward-thinking vendors are striving to bake in best-practice data encryption in motion and storage to create secure end-to-end Industry 4.0-enabled systems. 

Using the latest sensor intelligence is now about far more than simply monitoring factors such as position and speed. It’s about using data, collected in real time, to provide vital information concerning service life that can help facilitate the implementation of predictive maintenance. This data can be used to identify when a machine or system is not functioning correctly, or at its optimum efficiency. Early sensor notification of issues allows system operators to investigate, consider, plan and schedule the required corrective maintenance for a time when production throughput is either low or can be stopped. This could be overnight, during a larger planned plant maintenance shutdown, or whenever there is the least impact on those all-important customer delivery schedules.

Continuous position sensing devices can make a significant contribution to creating a smarter, more efficient factory environment. To find out more, download our CPS Smart Sensing Brochure that covers continuous position sensing using analogue signal or IO-Link communication for linear actuators, and discover how you can better schedule corrective maintenance and reduce your downtime.

Article contributed by Franck Roussillon, product manager, actuators, Pneumatic Division Europe, Parker Hannifin Corporation.

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