Retrofitting as a way of restoring press efficiency
Replacing the electrical drive and automation elements of production systems (retrofitting) is frequently the most effective way of maximizing their availability. However, for this to be an option, regular preventive maintenance of the mechanical components of such systems is vital.
Retrofitting is often a cost-effective alternative to buying a new press. Depending upon the performance parameters, it has the potential to raise a system’s capabilities to current levels. In addition, it can also be a way of ensuring compliance with the applicable legal provisions regarding work safety and also the relevant EU standards.
A case study from decorative gravure printing
The following case study illustrates the practical possibilities of the retrofit approach. It looks at a decorative gravure printing press made by Kochsiek and installed in the US company with the following main components:
- Non-stop unwinder
- Infeed station
- 4 print units
- Visual inspection
- Outfeed station
- Non-stop rewinder
Prior to the refit, the press had been controlled by means of the digital, programable memory Simatic S5 (subsequently S7-400) control system, and drive control was handled by the modular Simadyn control system in combination with Simodrive or Masterdrive drive controllers. All of these systems were manufactured by Siemens. Register control was provided by systems from such well-established third-party suppliers as Eltromat and Bobst.
The Simatic S5, including ET200U/B peripherals, the Simadyn and Simodrive/Masterdrive as well as the older servo motors such as the 1FT5 are no longer commercially available. The availability of spare parts was therefore becoming critical in some cases and manufacturer support had largely ceased.
In view of this lack of availability combined with enhanced safety requirements, systems like the decorative gravure press referred to above, that were mostly manufactured between 1980 and 2010, are currently being modernized all around the world by the team from Lebbing engineering & consulting GmbH. Based in Bocholt, the company is a member of the Jagenberg Group.
Over the course of these systems’ lives the mechanical components, apart from those subject to wear, have altered little and in most cases there is no need for any kind of retrofitting.
During the retrofit carried out in this case study it was therefore the critical components that were swapped out and replaced by currently available ones. The key tasks were to replace the old Siemens Masterdrive converter along with the associated Simadyn components, the 1FT5 synchronous motors and the control system. The operator panels were also completely replaced, since some of their components were also no longer available.
After six months of preparation, the actual retrofit at the customer’s facility in the USA took just three weeks. The drive controllers and converters were assembled and pre-wired on special mounting plates in advance to that they could then be rapidly integrated into the existing control system on-site. However, all the components (converters, I/O stations and controls) were electrified and pre-commissioned before leaving the Lebbing workshop. The new operator controls were also installed in panels that matched the customer’s so that they could then be taken pre-assembled to the site, tested and integrated. The actual electrical and mechanical refit took about a week and around two weeks were required for the commissioning of all the components.
Step by step retrofit
- Such a retrofit could also be carried out in a series of stages, such as the following:
- Stage 1: Replacing the Simadyn control system
- Stage 2: Replacing the Simatic S5 and the press controls (PP17, TD17)
- Stage 3: Replacing the drive system (Simodrive, Masterdrive as well as the ‘old’ servo motors)
- Stage 4: Replacing the ET200B-I/Os of the Simatic control system
- Stage 5: Replacing the fan frequency converters
Retrofit or new system
Lebbing estimates that the financial and time cost of a retrofit is substantially lower than the purchase of a new press and retrofitting offers a really cost-effective alternative to a new buy. In essence, the Lebbing approach is to work with the customer to determine the best and most reliable way of retrofitting the press in question. In order to achieve this, the company, which was founded in 1998, is able to draw on a substantial body of experience accumulated through numerous successful retrofits for its customers.