Extrusion presses can cause a lot of wear and tear on the hydraulic components they utilize due to the hardworking nature of these machines. Proper maintenance can help to ensure the longevity of the hydraulics. But as one Bosch Rexroth customer learned, upgrading certain components could benefit the lifespan of an extrusion press and its hydraulics as well.
General Extrusions Inc. (GEI), a manufacturer of aluminum extrusions, decided to assess the performance of the drive and control components of its 1,675-ton aluminum extrusion press which has been in operation since 1967. Upon doing so, GEI determined upgrading key hydraulic and electronic control components could help to reduce maintenance and extend the life of its machine.
GEI worked together with Bosch Rexroth to implement a multi-phased approach, enabling the hydraulic and electronic components to be upgraded in a cost-effective manner and performance as well as machine life to be improved.
Overcoming Legacy Hydraulics Technology Issues
According to Jason Andre, General Manager at GEI, the 1,675-ton aluminum extrusion press is a key component within the company’s manufacturing operations. “We generally produce between 12 and 15 million pounds of product a year, so keeping the press healthy and operating at peak efficiency and productivity is crucial to our business and keeping customers satisfied,” he said.
Therefore, ensuring the pumps, spool valves and other hydraulic components utilized by the press perform as desired is critical.
Due to the age of the machine and the need to maintain its productivity, GEI decided an assessment of the hydraulic and control components was necessary. As part of this process, risks associated with maintenance downtime were assessed.
The aging hydraulics on the extrusion press were a concern as well. Not only were they impacting the efficiency of the machine but also causing an increase in fluid leaks as these older components were not able to withstand wear and tear like they used to. The original design of the machine’s hydraulics system also made it more susceptible to inherent shock during operation, leading to fluid leaks on a weekly and sometimes daily basis.
In addition, legacy spool valves on the extrusion press were an older technology which made it difficult to find replacement parts when needed.
“Once these factors started adding up, we made the decision that it was in the best interest to move forward with newer, modern hydraulic systems,” said Andre.
Benefits of a Phased Approach
To achieve the necessary hydraulic system upgrades for its extrusion press, GEI chose to work with Bosch Rexroth and implement a phased approach. Doing so would help the company better manage the costs of upgrading the hydraulics while also minimizing the downtime that would be needed to do so.
Besides its technology offering, GEI appreciated Bosch Rexroth’s support of a step-by-step upgrade program and help in establishing it.
“One of the things that Bosch Rexroth brought to the table, besides their hydraulic technology, was the concept of doing this project in stages,” said Andre. “Their ability to come in, work through with our team here so that we could lay out the project in a manner that was more doable in a shorter timeframe was a real positive.”
After working with GEI to assess its legacy hydraulics system and understand the company’s goals for the upgrade project, Bosch Rexroth aided with the following phases:
- upgrade the hydraulic fluid conditioning system,
- replace the line-mounted spool valves with a hydraulic manifold system,
- replace key piping elements,
- install new state-of-the-art hydraulic pumps,
- modernize the control system.
Bosch Rexroth recommended upgrading the hydraulic fluid conditioning system first. Doing so would help to ensure new pumps and other components added to the extrusion press would operate with peak efficiency and quality.
In addition, GEI replaced the pumps, filters and heat exchangers for its cleanliness system to ensure it would meet ISO targets as well as ensure performance of the new hydraulic components added to the press.
New Hydraulic Components Bring Performance Improvements
By upgrading specific hydraulic components in the extrusion press with newer technology, GEI was able to realize improvements in performance, efficiency, maintenance and more.
Manifold System Replaces Spool Valves
Replacing the line mounted spool valves in the extrusion press was the next step in the upgrade project. This was a major element as the valves had been an important component for controlling hydraulic flow throughout the press but also a key factor in the machine’s reduced efficiency and leakage issues.
The spool valves were replaced with a state-of-the-art manifold system. Michael Kramer, Press Application Engineer at Bosch Rexroth, said manifold systems reduce the number of potential leak points in a hydraulic system. As such, using a manifold instead helps to overcome the efficiency issues presented by the legacy spool valves.
Logic valves are integrated into the manifold system which can be independently tuned, enabling a reduction in hydraulic shock and a speed up in machine cycle times. Faster actuation is possible with this technology as well, aiding productivity improvements. In addition, the leak-free design of the manifold system allows for greater pressurization rates of the main ram.
“Initially, we were mainly interested in how using manifolds to replace the spool valves would reduce our leakage issues and some of the issues related to shock,” said Andre. “A real bonus was how the manifolds helped improve our dead cycle time: we have documented roughly a three-second reduction, and that translates into approximately 200 additional production hours on an annual basis, giving us increased capacity to fill customer orders.”
Bosch Rexroth LC-LFA cartridge control valves integrated into the manifold system help to minimize shock and improve efficiency as they can be independently controlled to open in the appropriate sequences to achieve these results, an aspect not possible with the legacy spool valves. These cartridge valves are also readily available off the shelf, making repairs easy when necessary.
According to Andre, hydraulic shock was greatly reduced through the addition of the manifold system to the extrusion press because it helped to minimize wear and tear on hydraulic and other components on the machine. It also allowed GEI to upgrade piping from a welded network of pipes to a weldless system. This enabled better shock absorption and reduced leak points.
Modern Pump Design Enables Efficiency Gains
The next step in the upgrade process was replacing the two hydraulic pumps used to power the press with newer, more modern models. Doing so would help to ease future repairs as the legacy pumps used in GEI’s extrusion press were both difficult and expensive to repair.
These pumps were also much less efficient than currently available hydraulic pump designs. The legacy versions could require as much as 30-40% more energy than modern pumps, leading to higher operational costs for GEI. The pumps were also known to generate a greater amount of heat which had to be removed, further adding to the company’s operational expenses.
“Not only would new pumps be easier and less costly to operate and maintain, pump replacement offered us the opportunity to increase the hydraulic flow rate and power input to the press to increase productivity,” said Kramer.
Rexroth AA4VSO 355 axial piston variable pumps, designed for high-pressure industrial applications, were chosen for the GEI machine. This hydraulic pump model is capable of operating at 355 cc and 1,800 rpm. Andre said the legacy pumps produced 108 gpm but the new AA4VSO pumps will provide a 30% increase in pump output.
“In hydraulics, volume is directly related to the speed you can run your press at,” he said. “By going to a higher volume, the new pumps will help reduce dead cycle time on top of the improvements we’ve seen with the new manifold, once the new pumps are installed.”
Upgrading to a manifold system first made it easier to then upgrade the hydraulic pumps. The legacy pumps used two pressure ports which required a complex valve arrangement. Use of a manifold system allowed conversion to a one-way operation for the hydraulic circuit, allowing for easier installation of the new hydraulic pumps.
Installation of the new pumps was done during a weekend shutdown, helping to minimize downtime that would negatively impact productivity for GEI. The two pumps were also replaced one at a time, allowing the downtime and costs to be spread out over time.
The new hydraulic pumps are vertically mounted and submerged in a tank, providing significant space savings compared to the legacy pumps which were mounted horizontally on top of the extrusion press. This mounting design also helps to ease installation and service.
“That space savings lets us open up 20-25% of that space, and from a maintenance standpoint, everything is housed in a very compact, localized space,” said Andre. “Plus, installation time is very short – [it took] about 4 hours to remove the legacy pump and install the new Rexroth pumps, keeping our downtime to a minimum.”
Industry 4.0 technology is integrated into the new pumps as well, enabling GEI to gain performance insights and other information from its upgraded hydraulics system.
Collaboration Ensures Successful Upgrades
The final step in the upgrade process will be updating the controls platform for the extrusion press. With an upgraded controls platform, there is the potential to improve the control of press force and velocity, among other aspects which will enable overall performance and productivity benefits.
Additionally, new controls can help to improve maintenance through collection and analysis of Industry 4.0 data – offering the potential for predictive maintenance to be employed – as well as machine communication capabilities.
GEI will work closely with Bosch Rexroth on this part of the project as well. The close collaboration between the two companies benefited the entire hydraulic system upgrade process by enabling the right technologies to be chosen which would meet GEI’s needs.
“Mike and his team were able to come in and show us how this project could be split into phases that would minimize any downtime we might have to face,” concluded Andre. “That, combined with the history of the company within the aluminum extrusion business, their reputation within the industry, their size and ability to meet our needs – so we could continue to meet our customers’ needs – really gave us the confidence that this would be a success.”