The Vimercate-based group, with a leading role in countless important innovations in process technology, simplifies the hydraulic system of the press using the PE. Energy Saving System, which offers a significant energy cost reduction in the short and long terms, along with a reduction in operating, maintenance and after-sales service costs
by Roberto Guccione
A careful and capable designer and manufacturer of plants for the extrusion of non-ferrous metals should never forget two essential elements for the creation of an excellent product: productivity and efficiency. Productivity guarantees the qualitative and dimensional properties of the finished product, in compliance with the client’s specific requests. But how can the constant and progressive improvement of productivity and efficiency be achieved while manufacturing a product aligned with the modern demands of the market?
This is only possible if time and resources are invested in research and development activities, consolidating know-how without ever abandoning experiments and the use of new technologies, thereby allowing the final client to receive a timely and knowledgeable support. This is the approach used by Presezzi Extrusion, which ever since its establishment constantly invests in research and development activities and in a constant and earnest after-sales service.
The company’s mission regards research and development as being aimed towards the evolution of machines and plants, ensuring the best productivity (qualitative and dimensional properties of the finished product) and highest efficiency by means of the reduction of energy costs in the short and long terms, as well as the reduction of costs and time necessary for maintenance and after-sales servicing. For Presezzi Extrusion research and development is one of the most important investments, which involves the best internal resources and some of the most qualified external organizations, having as its main objectives energy saving, complete production management programs, excellent quality of extrusions and reduction of production costs.
The PE. Energy Saving System
New technologies allow the company to maintain its leadership on the market, and this condition is acknowledged by clients even thanks to the presence of solutions which always keep abreast with state-of-the-art technology and of the creation of original solutions aligned with new production requirements, which are rapidly evolving for aluminium, copper and brass alloy applications. Confirming this constant and fruitful effort aimed at a constant improvement, in 2007 Presezzi Extrusion began to develop a new type of hydraulic system. Presses designed and produced until then all used, with no exception, variable displacement pumps coupled with servo-valves and standard-type electric motors. In 2009, after 18 months of research and development activity, stemming from the company’s choice of providing clients with a considerable energy saving while maintaining and/or improving the production performances and the quality of the extrusions, Presezzi presented the PE. Energy Saving System (PE. E.S.S.).
The system is based on two pillars: savings and technological innovation. The savings concept does not only imply energy saving, but also a lower number of components needed for its operation which make press production and setup leaner while at the same time ensuring that the machine is less subject to downtimes and maintenance. Thanks to the synergy with one of the most important Italian manufacturers of hard alloy extrusions, a first group prototype was manufactured which confirmed the initial intuition and the successive technical and technological development, until a more than significant energy saving was obtained with “field testing”. The first press equipped with this system was a 33 MN Front Loading press (in 2009): ever since, almost all of the presses installed have been equipped with the PE. E.S.S. system; we are talking about over 80 presses in all, with considerable success and satisfaction on clients’ part.
Low inertia motors for a next-generation hydraulic system
Let us see in detail what can cut down the energy consumption of an extrusion press by 26% (between 13 and 80 MN on average, depending on the different types of production) with respect to a hydraulic press equipped with a conventional modern hydraulic system.
The PE. E.S.S. system reduces energy consumption by placing the hydraulic pumps in standby mode when the press is not functioning or when they are not necessary in a particular phase of the extrusion cycle. Without the PE. E.S.S. system, all pumps are continuously functioning with traditional drive systems, using up energy when they are not needed and wasting money as a consequence. On the contrary, PE. E.S.S. only uses the amount of energy which is really necessary.
In order to understand the advantages of the PE. E.S.S. system it is necessary to understand what really goes on during the extrusion process. The hydraulic plant in a traditional press is generally sized to obtain reduced downtimes and normally only 20-30% of the capacity is used for extrusion. In a traditional press, during the extrusion phase, in order to obtain a regular and constant speed the amount of oil needed is supplied by the pump group by means of the pump flow regulation system, managed by the servo-valves. This means that, besides the use of energy due to the pumps dedicated to the command of the servo-valves, there are conditions when the main pumps are underused and continue rotating, wasting energy and heating up the oil. The PE.E.S.S. system allows the press to generate only the exact amount of oil which the system really needs to obtain the force and speed needed for extrusion. The low inertia motor is controlled by inverters and, by means of the fixed pump connected to it, the volume of oil supplied is exactly what is necessary for the movement of the press during every operation. The advantage which these low inertia motors provide is considerable and this system allows better performances compared to a system with servo-valves and variable flow pumps. According to requirements, the pumps turn on and off automatically and the number of revolutions is regulated as a consequence.
Pumps which are not necessary during the extrusion phase are completely at rest, no dedicated or auxiliary pumps are envisaged to send oil to various services or pump the excess oil to the discharge system. Further savings are also obtained during the stops of the press or during matrix change. The energy saved compared to a traditional press may be calculated as being in the 25%-30% range, depending on the product and the cycle required.
Revamping of existing presses
It is worth mentioning that the PE.E.S.S. system may also be installed on existing presses and as a matter of fact in recent years Presezzi Extrusion successfully completed the revamping of many presses in this way: after studying the type and properties of the press, the existing hydraulic plant is replaced with the new PE.E.S.S. system, with all the changes and integrations needed for the new parts, such as pipes, electric system, electronics and software. The advantages which such a solution provides may be summarized as follows:
• Reduction in the power and size of the motors.
• Decrease in the amount of oil used.
• The high-efficiency pumps used enable the system to have a reduced need for spare parts and maintenance
• The installation in the pump room requires less space and makes less noise while the plant is functioning
To conclude, Presezzi Extrusion designed, manufactured and installed successfully as from 2007 a system characterized by a completely new design concept and which can be summarized by the use of low inertia electric motors. Up to that moment nobody had thought of using this type of motor for this application, today only Presezzi Extrusion may talk about high production quality extrusion presses associated with an actual energy saving. During the past few years press manufacturers have tried to simplify the hydraulic plants necessary for the press, but Presezzi Extrusion was the first global concern to reach an aim pursued by many and with a fantastic result: simplification and energy savings.