What is in this article?:
- Hydraulic Upgrade Brings New Life to Extrusion Press
- Factor Three: energy efficiency
Factor Three: energy efficiency
Another challenge for aluminum extruders is to reduce the amount of energy expended in powering the press hydraulics without sacrificing productivity.
One retrofit opportunity in this area is to evaluate the electric motor driving the hydraulics pump. In many older systems, these motors tended to be oversized to compensate for inefficiencies downstream in the hydraulics system (leaks, pressure drop-offs, etc.). New regulations, such as the Energy Independence and Security Act of 2007 (EISA 2007), call for “right-sizing” manufacturing systems with the use of more energy- efficient motors.
These motors can be utilized in conjunction with a systems design concept called “energy on demand,” which integrates sophisticated controllers and variable speed pumps with properly sized electric motors to deliver only as much energy as is needed to accomplish the press cycle.
Hydraulic pump efficiency is also worth assessing for a retrofit. All hydraulic pumps utilize a portion of the fluid flowing through them for lubrication. To generate the required force in a hydraulic motion sequence, more energy needs to be drawn from the electric motor powering the pump to compensate for this fluid, since it is not actually contributing force to the press ram. Less efficient, older-generation pumps require more lubrication. They also generate higher levels of waste heat which adds more loads on the cooling systems and can lead to unnecessary energy consumption.
The latest generation of hydraulic pumps is more efficient and requires less lubrication and places lower loads on the cooling system, which in turn can provide significant energy savings. Newer generation pumps also feature integrated sensors and diagnostic ports to check hydraulic system pressure.
Factor Four: working environment
Safety for the machine operator and protection for the press itself have become more significant in today’s manufacturing environment. Older presses may not handle the safety aspects of a press as well as new control systems. For example, new systems can set unique upper limits on pressure for each die in the press to help protect the die (and other press components) from damage. Upgrading to controls with these capabilities can enhance plant safety and lengthen the life of your equipment.
Two other complaints associated with extrusion press hydraulics are fluid leaks and noise. Hydraulic leaks create hazards such as slippery floors, dirt, even fire risks. Plus, persistent leaks require more frequent and costly refilling of the hydraulic fluid reservoir. Much of the noise typically associated with hydraulic presses comes from the high-power electric motor driving pumps, as well as the pumps themselves.
It’s often assumed that these issues are inherent to the power and force dynamics that only hydraulics can deliver—even if it means increased maintenance and an unsuitable operating environment.
Many of these issues arise from outdated or poorly designed and/or maintained hydraulics systems—and can be easily resolved through a retrofit. For example: presses that utilize older inline valves have far more seals and points where leaks can occur than systems retrofitted with hydraulic manifolds.
In addition, limited control system design, or older controllers, may be introducing high levels of hydraulic “shock” through the press motion cycle, overstressing valves and seals. Newer electrohydraulic controls offer much finer control of the hydraulic axis, minimizing stress on the system. To reduce noise, simple enclosures of pumps and motors, or reorienting motor-pump assemblies to redirect noise, can resolve excess noise issues with minimal cost as part of an intelligently designed and cost effective retrofit.
Factor Five: overall operating costs
Many press operators incrementally expend time and resources on repeated repairs and maintenance efforts. These include maintaining spare parts inventories, repair and service contracts with outside hydraulics and controls service providers, and more frequent maintenance cycles—all of which can also reduce press availability. The costs are not just related to time and materials, but also to opportunity costs. There is more risk of losing potential business with less efficient or problem-prone extrusion operations. A new press would alleviate these issues, but these problems could be solved with significantly less cost through a retrofit.
A key goal is also to reduce the extrusion press “dead cycle,” or the time when the press is not extruding parts. A hydraulics and controls retrofit has the potential to directly reduce the extrusion press dead cycle.
New life for extrusion pressess
Preserving and extending the value of existing manufacturing equipment makes fundamental sense; the challenge is to determine which solution offers the most reliable and measurable return on investment. The age and performance of your existing systems needs to be analyzed. Although no one factor can solely justify a significant retrofit, it makes sense to consider all aspects of the systems that affect extrusion press performance, uptime and part quality.
It also makes sense to consult with experts who have in-depth experience designing high-efficiency hydraulics and controls solutions for both new extrusion presses and retrofit/ upgrade projects. You may discover inefficiencies in your production platform that can be addressed through a cost-efficient retrofit.
Jeff Grube is Manager, Press and Heavy Industry, Bosch Rexroth, Charlotte, N. C. For more information, visit www.boschrexroth-us.com.