April 2012
By Josef Schindler, Siemens Industry
A change in maintenance solution trends results in significant value added increases in production. Condition-based maintenance makes a sustained contribution to boosting productivity through increased plant availability. This is based on innovative diagnostics mechanisms that continuously update plant-wide centralized information hubs with diagnostics data, so you can carry out the right maintenance measure at precisely the right time – a leap forward in boosting maintenance efficiency in automated production plants.
Value added through maintenance
The production systems of the western industrial nations were leaned down on a massive scale in the 1990s. Productivity differences of up to 40% became apparent between Japan – where the Toyota production system with the KAIZEN Philosophy started back in 1950 – and Europe/US [1]. Value added chains were then consistently examined for activities that did not create value (waste), inventories were reduced, throughput times shortened, and response capability increased. System solutions for a detailed overview of the entire supply chain became necessary. Just-in-time production and lean thinking [2] were the buzzwords on everyone's lips.
Waste in value added chains
- Repairs / faults
- Inventories
- Waiting times
- Transport
- Over-production
- Journey times
- Space / area
For technological reasons, maintenance technology in automated plants was unable to keep pace. Sensors for the necessary device diagnostics were not available or were too expensive for widespread use. Diagnostics standards, too, have only in the last few years reached the necessary maturity for plant-wide, vendor-independent overall concepts. Regular preventive maintenance and extensive spare parts management were therefore the mantra for minimizing plant downtimes as much as possible.
Preventive maintenance increases availability
Both fault-correcting and preventive strategies are much in use today. They increase the availability of an automated plant and thus make a contribution to higher value added. The important thing is to remove occurring faults quickly and efficiently, and to minimize future fault potential so that the production process is only interrupted as briefly as possible. However, if it is possible through preventive measures to stop a fault happening in the first place, the economic damage is significantly less since a standstill does not occur. Maintenance work carried out at regular intervals helps in the following cases, for example:
- Oil loss
- Loose screws
- Dirty machinery
- Defective tools
- Vibration
- Swarf waste/transport
- Unsuitable workholders
- Maintenance faults
- Wear limits exceeded
- Overheated motors
- Motor noise
- Overflowing oil tanks
- and many more
Figure 1. Reduces costs and increases plant availability: Just-in-time maintenance
Figure 2. Increased productivity thanks to centralized information hub for maintenance
Figure 3. Maintenance at the right time, and fast response to faults thanks to centralized diagnostics and maintenance information in the Simatic Maintenance Station.
- Support for condition-based maintenance through plant-wide diagnostics
- Use of existing project data, no additional engineering overhead
- Support for vendor-independent standards and integration across all Siemens automation components (e.g.
- One central solution for continuous and discrete automated production processes
- Unique identification and status display of all connected devices ensures short response times
- Operating and monitoring integrated into one system
Ethernet, Profinet, Profibus, AS-i, HART, etc.)
Conclusion
In automated plants, the migration from cyclic preventive maintenance to just-in-time servicing with the help of condition-based maintenance systems is in full swing. Similar to energy-saving light bulbs, investments in diagnostics-enabled components pay off within a very short time. The components are easy to integrate into the Simatic Maintenance Station.
