This approach from Renk AG allows manufacturers to form a network with their products, allowing operators and gear designers an accessible set of data and providing advantages to not only the end user but also to all involved in the purchase, design, commissioning, application, and maintenance.

During the past decades, the capacity of production machinery increased continuously in nearly all industries. A doubling of the capacity in a time span of 20 years is a coarse but helpful point to fathom. With machinery becoming more powerful, investments per unit increased significantly. Thus, in order to expedite the return on investment, machinery was required to be more reliable and operate continuously with minimum or zero downtime.

Machine Protection and Condition Monitoring Development

Starting in the oil and gas industry, developments have pushed forward. (See the progression of maintenance policies from 1960 to today, shown in Figure 1.)

Figure 1: Development of maintenance policies: from sensing to vision to automation to increase MTBM

Turbomachinery condition has been monitored for decades by measuring the housing first and then shaft vibration. Experts consulted end users by means of real-time analysis to support maintenance decisions. Automated and continuous machine protection at excessive sleeve and thrust bearing temperatures had been introduced earlier. Furthermore, due to high shaft speeds of the equipment, vibration values have been a threshold from the beginning to protect against major damage.

Automated machine protection has also been practiced since the eighties in the application of low-speed gears as applied in cement grinding, polymer mixing, extrusion, or hydropower generation. This was focused on oil pressure, temperature, flow, and filter condition.

It has been only recently that the adaptation of further measurements have been found valuable to display not only the condition of the gears but also the condition of the process, such as casing vibration, shaft location, and shaft torque (especially when facing applications with high torque dynamics). Table 1 shows how the individual measurements are evaluated.

Table 1: Measured values and processing in PLC and CMS

For those applications, it is useful to split the machine protection and condition monitoring with regard to hardware, software, and business approach: The protection needs to be locally installed using a specific set of hard alarm and shutdown values. However, the CMS (condition monitoring system) must not serve only to protect against personal injury or major damage — it is operated to monitor the application in the manner of the design criteria. This philosophy ensures the CMS prevents premature damage and, in the case of imminent damage, secure the operability of the equipment up to scheduled maintenance activities. To perfectly secure the CMS efficiency process, data must be displayed and observed together with the measurements used in the PLC (programmable logic controller). Therefore, the equipment and the process can both be optimized.

By proper use and extrapolations from the CMS data, interventions can be planned with regard to spare parts and scope of work. As a result, with the optimization and perfection of CMS, physical equipment inspections become increasingly expendable.

Automatization, Qualification, and Economics

The internet is the perfect means to carry any quantity of information from everywhere to anywhere. This allows specialists to be concentrated in one place, taking care of a worldwide fleet of applications. Using 4.0 means manufacturers can network with their products, and a new dimension of product experience can be accumulated in the Internet of Gears. Accumulating comparative data allows operators and gear designers a never-before accessible set of data taken on critical equipment even without going to the site and often without stopping and inspecting the equipment.

This partly means automatization of maintenance, optimization of the processes, and product development to the target.

The increasing need to save costs with the increasing efforts to employ qualified personnel, especially in locations where critical machinery is often operated, is a challenge for end users. The use of CMS is a solution and often most profitable when it is operated and monitored remotely by specialists. The alarm values on which a CMS is operated are established during the initial commissioning or after an overhaul of the equipment under the design criteria of the application. Those values have nothing to do with acceptance criteria of a specification or machine protection thresholds. Establishing and changing those values requires significant knowledge and experience with the product and the application. This is ideally done by an online connection to the CMS as shown in Figure 2.

Figure 2: Architecture of Renk VIBmonitor CMS

The focused CMS targets are:

  • Prevention against unplanned outage
  • Secure operation until planned outage
  • Optimization of the process
  • Optimization of the equipment
  • Extension of MTBM (mean time between maintenance) and MTBF (mean time between failures)
  • Making visual inspections and unplanned shutdowns greatly expendable

CMS requires expense for hardware and operation. Operation, in this case, means the care of the system, data handling, and data storage. CMS is most economical for equipment that is:

  • Applied in processes where an unplanned outage cannot be absorbed by redundant machinery and where the loss by an outage is in excess of 5.000 € per day.
  • Critically rated, up to physical and technical limits.
  • Based on uncertain specifications or applications or suffering wear of the driven machine, which ends up in a change of the torque dynamics.

In cases where more than one criteria are met, CMS is indispensable.

CMS Data Analysis: Understanding, Preventing, and Improving

Figure 2 shows the elements of the Renk VIB monitoring CMS. Here, a cement application is the example, but the makeup does not greatly differ for other applications. The main features include:

  • Measured data is stored centrally on a server with synchronous access for licensed parties.
  • Bidirectional data transfer between CMS and PLC (only with this, a PLC can display essentials of all the CMS systems of the installation).
  • High pickup rate for dynamic data.
  • Quick access and easy to operate software with various display and analysis levels.

Depending on the gear design and application, any amount and type of measured data can be processed. When designing the CMS, the expertise of the gear manufacturer is important, as excessive measurements are costly and can sometimes be confusing. However, it must be considered that for an optimized CMS omitting important measurements, for example, the torque function for many applications has a reduced value in respect of process and product optimization. It is also important to record process data to verify that the gear performance truly reflects the requirements of the application. This is the point where the OEM or engineering contractor of the driven equipment must be involved in the CMS strategy. Often, access to the data obtained from the driven equipment is of major use for the driven equipment manufacturer for its own performance review and development.

Only a properly designed CMS provides the assurance that the machine condition can be properly interpreted and understood. Here, effective failure prevention starts, and continuous product improvement is secured.

Models for CMS Operation

The following provides an overview of the aspects of product design and observation with and without CMS. (See Figure 3.)

Figure 3: Wider prospects for all stakeholders by CMS application

Under the focus of 4.0, CMS enables a strong and desirable third column in product care and in product design. Using CMS will make products not just more economical and reliable in application but also better with more valuable feedback to the product designer.

The advantages are not limited to the end user but to all parties involved in the process of purchase, design, commissioning, application, and maintenance. From this, CMS powers progress for critical equipment and is to be deemed indispensable for all parties.

The following outlines how the best results can be garnered from the use of CMS.

Three different CMS models are considered.

Figure 4 shows Model 1, the oldest model. Experienced end users understood the use of condition monitoring early and installed a mix of equipment that they dedicated to this purpose.

Figure 4: CMS Model 1

Figure 5 shows Model 2. Based on the success of this model, companies that mostly specialized in the production or marketing of instrumentation designed hardware dedicated to the condition monitoring use and created the product class of CMS. At the beginning, the systems were local and not linked. Quickly, it became clear that a local data storage capacity is too small and not capable for continuous condition monitoring. Modems were then installed, and wide area networks were erected. Often, the CMS makers not only provided hardware but also consulted technical services.

Figure 5: CMS Model 2

Both models have their advantages, but they have a distinctive drawback: The maker of the machinery, which is actually being monitored, is out of the loop of information. With this, the industry can neither contribute to solutions nor improve their service or their products. The use of CMS in those models is limited to just predictive maintenance.

Figure 6 shows Model 3. It shows the decision-makers planning critical equipment to the most recent and latest model of CMS operation.

Figure 6: CMS Model 3

The most efficient and effective CMS is one provided by the manufacturer of the equipment as opposed to an “add on” by a third party. With an inherent knowledge of the equipment, they can design, build, commission, and operate it optimally. A further important aspect is the system design. The current optimum is materialized by systems designed as in model 3, as Renk VIBmonitor. The key advantage is the safe server-based information platform, which is accessible for every licensed party with no need to operate any additional software. Interaction with VIBmonitor is via the shareware application CITRIX viewer. All displays, analysis, and settings can be accessed from anywhere with any sort of data terminal.

The VIBmonitor is based on an international manufacturer’s hardware and its software, which is run on a Renk server located in a secure environment outside the plant. The cost of the server, the software license, software updates, and software configuration to the equipment is borne by Renk. Using mass-produced standard equipment ensures low costs and secures spare parts availability and software support over decades.

Optionally, VIBmonitor can be utilized without the server information platform for strictly confidential operations, such as military use. In this case, VIBmonitor can be judged as a system of the first generation with additional makers support — a mix of models 1, 2, and 3.

Digital and Customary Services

Evidently, by taking the idea of the Internet of Gears to the next level, there is more to the CMS than just the consulting service previously discussed.

Internet of Gears 4.0 shows how up-to-date communication enables closer cooperation of the gear-maker with the OEM of the driven machine and especially the end user. The digital services are provided to facilitate the management of the equipment at all levels of the end user, whether it’s the operator, the maintenance team, the engineering groups, or the purchasing departments. (See Figure 7.)

Figure 7: CMS is a part of digital services focused on a platform shared between supplier and client

The target is to provide all the important news and operational information for a fleet of products, as well as for the individual gear in a clear structure with a structured accessibility. Customers deem the gear vita (development of measured values over a long period and reflected under maintenance activities and visual observations over the entire product life), as well as maintenance recommendations drawn from this vita, a valuable digital service. The access to spare part logistics and training/qualification is an additional service.

Special care is paid to confidentiality for both customer data and regarding Renk data. One prerequisite to secure confidentiality is the use of a secure server that is providing the data to licensed users only with no way to copy or distribute them. The visibility is strictly limited and protected.

The fundamental requirement to protect and maintain the equipment is at the core of customer service. However, unlike the traditional, reactive approach, CMS offers a more proactive approach and accelerates the decision of interventions. Historically, an end user calls the service when abnormal behavior of equipment is registered, for example, after an unusual filter inspection, after visionary or acoustic inspection is carried out, or when alarm values are reached in the PLC. This is often too late, and any remedy has to start with a detailed inspection or measurement site visit.

The results of this visit are converted in a site activity through an engineering consideration, which requires a lot of time.

With CMS in place, customer service calls the customer with a proposal for a process change or a maintenance measure immediately and usually early enough to prevent any damage or significant machine downtime.

Customer Requirements for Digital Services Covered

Renk contacted customers and collected information on their requirements to set up a digital service program around the CMS as previously discussed. Table 2 is a shortlist and its coverage.

Table 2: List of requirements and coverage


Including Renk VIBmonitor into a critical equipment project guarantees an up-to-date automatized maintenance tool with Renk digital and customary services, drastically reducing the total cost of ownership with little investment and minimum operating cost. With the Renk VIBmonitor, online monitoring means an availability increase in process and product development.

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is president of Artec Machine Systems in North Branford, Connecticut.
is head of sales and application support for stationary gears at Renk AG, in Augsburg, Germany.