Health check-ups reap big rewards01 February 2007

In the age of lean, condition monitoring of capital equipment is an obvious aid to efficient operation, as opposed to waiting for something to break down. As Chris Haines, Rockwell director of customer support and maintenance UK and Ireland observes, "in an effort to improve business performance and meet shareholder expectations, many engineering, operations and maintenance departments are faced with the reality of having to do more with less. A manufacturer who views maintenance operations as a long-term investment can reap the benefits of significant returns and process improvements".

Haines also argues that manufacturers of all sizes need to focus on what they do best, "making products", and should consider outsourcing maintenance.

The best way to achieve these goals - ie, do more with less and possibly outsource maintenance - is to have machinery report directly and automatically on their own state of health, and any required actions, to somebody who can apply the appropriate remedies. Nowadays, that person could be in a data centre on the other side of the world.

The technology to do this marches on. This year's Hannover Fair, for example, again features a special pavilion devoted to condition monitoring (in Hall 24), offering insights into how visitors can:
- Minimise the effects of technical faults
- Prevent follow-on damage
- Schedule repairs
- And prevent future occurrences.

One of the application areas highlighted will be wind turbines, which are particularly difficult to access for major repair, especially when offshore, and where the early detection of bearing and gearbox problems can prevent major catastrophic breakdowns.

For those not wishing to travel quite so far, Festo will be demonstrating a new web-based monitoring tool at Mtec at the NEC Birmingham on 14 February. Designated 'CPX Web Monitor', it facilitates the online retrieval of digital and analogue statistical data from any Ethernet-equipped Festo CPX series valve terminal or I/O module. Capable of handling static and dynamic data, it accommodates a wide variety of process-related functions, including individual pneumatic valve diagnostic and condition monitoring, pressure, temperature and I/O status monitoring, and power supply condition monitoring. The software can be installed on any standard PC-based web server and users can retrieve data via any standard web browser by specifying the IP address of the CPX terminal controller. The web monitor can be accessed directly via system network, company intranet or the Internet, depending upon the user's IT network configuration. Users with mobile devices that support HTML-based web browsing, such as phones and PDAs, can access the system while on the move, and the system can also be set up to send text messages and email alerts.

Appearing at the same event and presenting a workshop on 14 February (from 11am to 12.30pm) will be the Profibus Group. The group has recently released the 'Profinet and MES (Manufacturing Execution Systems) Maintenance Operations' guideline, which is said to make it much easier to switch from preventive maintenance to condition monitoring in systems and machines. Profinet uses an extended traffic light model to display device states, which, as proposed in NAMUR recommendation NE107, features not only the status, 'failure', but also the pre-warning levels 'maintenance required' and 'maintenance demand'. Up to 30 additional states can be defined for communication for each device profile.

For the majority of readers who have no intention of trying to set up their own systems, companies such as t-mac Technologies, working with FAW Electronics, produce turnkey solutions that gather relevant data from electrical and electronic sensors, send it over the Internet and present it to users in a manner they can easily understand. Both t-mac, which has 106 I/O channels, and its smaller version, MINI t-mac, with eight inputs and four outputs, are Modbus compatible. T-mac units monitor a number of inputs and store data that is periodically uploaded to a central Internet database. They can also send SMS or email updates to selected personnel when pre-defined parameters have been breached. Data can alternatively be presented automatically on 'Digital Dashboards', removing the need for users to log on to the t-mac web page.

The most common data input indicating machinery condition is temperature. Bearings and mechanisms that are running hot have been seen to indicate impending trouble since the steam age. The other commonly used parameter is vibration. The Armstrong DLW Group, a German maker of linoleum, has reduced maintenance times at its Delmerhorst factory by using Schaeffler's FAG Detector III units. The devices are hand-held, combining vibration measuring, data collection and operational balancing in the same units. Previously, the company carried out balancing checks on its machinery manually, which took on average 4.5 hours to complete. After purchasing the new units, this has been reduced to 30 minutes. Built-in software, 'FAG Trendline', includes a database of more than 20,000 bearing products from different suppliers, so that users can deduce what a measured value actually means, in terms of bearing and machine condition.

Sometimes, however, specialist techniques are required. Corus Northern Engineering Services uses a variety of techniques, including acoustic emissions monitoring. "Many companies rely on vibration monitoring systems to check the condition of plant and machinery," explains Ian Taylor, business development engineer, plant condition monitoring, "but this method is not as accurate as acoustic emissions monitoring, especially when it comes to slow speed, fluctuating load applications.

"It's horses for courses really. Vibration monitoring is fine for high-speed motors, fans and pumps. The equipment is cost effective, easy to use and the data is easier to interpret. However, where components of machines rotate at less than 80rpm and operate under fluctuating load conditions, or only move through a part revolution, it is more difficult to collect meaningful data from methods such as vibration monitoring."

Top Tips for tip-top conditioning
- Focus on what you do best - manufacturing - and consider outsourcing your maintenance
- View maintenance and condition monitoring as a long-term capital investment, rather than an expense (Rockwell)
- Minimise the effects of technical faults
- Prevent follow-on damage
- Schedule repairs
- Prevent future occurrences (Hannover Fair organisers)

Corus Northern Engineering Services uses: thermal imaging; vibration analysis; balancing and laser alignment; rotor bar testing; remote visual inspection; acoustic emissions monitoring; and contamination monitoring and debris analysis of lubricants and hydraulic fluids

SOE

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