To produce complex titanium parts more cost-effectively, machine shops are increasingly integrating advanced forging equipment to complement their existing CNC capabilities to create near-net-shaped parts that only require machining. minimal. In some cases, the forging process is so precise that no additional machining is required.
There are significant benefits to including forging in a machine shop’s repertoire. Thanks to recent advances in the controls and automation of hydraulic forging presses, precision titanium parts can be forged to extremely tight tolerances and at relatively high volume. Forging also significantly reduces titanium input costs by up to 50%.
However, to forge titanium to precise specifications, machine shops require the right equipment with extremely tight control of production parameters. Fortunately, advancements in the design, controls and automation of hydraulic presses are helping to optimize component quality, production and price.
To cost-effectively produce large, complex titanium parts, Pennsylvania-based FPD Company, a machine shop that produces aerospace and medical components, decided to invest in a unique new custom press capable of greater control with a higher tonnage.
“We wanted to increase our forging envelope, and that required a larger press with more sophisticated controls for the titanium parts. We already had a 2,500 ton press, which is relatively small for titanium. At the same time, we needed to improve control, quality and cycle times,” said Jeff Speicher, general manager of FPD.
To achieve its production goals, FPD has partnered with Erie Press Systems, a manufacturer of individually designed mechanical forging presses and hydraulic presses since 1895 that is now part of the largest supplier of forging equipment in North America: Ajax-CECO-Erie Press.
Although Erie Press engineered, designed and built the system, FPD provided significant input into the design requirements. The result was a custom high-speed hydraulic press capable of producing 3,000 tons at a fully controlled and programmable speed and load profile over the entire stroke.
“The custom press, along with our engineering and tooling, allows us to maintain extremely tight tolerances when creating titanium parts for the aerospace and medical industries,” Speicher said. “With the right equipment, forgings are extremely consistent, and we can produce near-sharp shapes that require little or no machining. If a part requires additional machining for holes, bores, and other secondary features, we can do that too.”
Precise control of Forge Stroke, Force
According to Speicher, Erie Press forging equipment is designed with a unique servo-hydraulic system that allows for better control of forging stroke and applied force.
Press control modulates servo-proportional accumulator dump valves to maintain set speed regardless of load, ensuring consistent forging performance. This arrangement provides flexibility for forging parts over a wide range of speeds not possible with a mechanically adjusted accumulator discharge rate setup.
For some part geometries, the strain rate of titanium may require varying velocity profiles throughout the forming process. Changing the rate of strain allows the FPD to improve die life while creating more detail by filling the webs and corners of the die cavity later in the stroke.
According to Speicher, the servo-hydraulic system allows extremely high resolution in setting these parameters. Additionally, the press position controller publishes (to FPD’s factory server) a high-speed plot or digital signature corresponding to each part’s forging cycle for historical records and reference.
FPD can also control the press to strike the part at a specific force or preset tonnage limit. In addition, the press can reach a programmed position with a position accuracy of less than 0.01″.
Erie Press’ Human-Machine Interface (HMI) allows operators to see how the press is performing and anticipate its performance. This is accomplished with dynamic animated models and diagrams, live trends and diagrams.
HMI is a software application that graphically presents information to operators about the status of various processes in a format that resembles the actual machine or display panel. The information can be viewed locally (on the machine) or remotely (in the factory or offsite) via a PC, laptop or smartphone.
“Erie Press has integrated a very user-friendly graphical HMI into the design that can guide even someone unfamiliar with the forging process step by step,” Speicher said, adding that the forging press manufacturer’s HMI system is a “digital virtual”. twin” of the real machine as it works.
“The press is equipped with sensors that monitor cylinder position, pump flow, valve positions, etc. and all of these parameters are monitored in a digital representation of the press. With the HMI, the operator sees the performance of the machine in real time.”
The HMI also helps operators monitor what is happening with enough information to successfully resolve issues and quickly bring equipment back online if needed.
For example, operators can quickly “drill” into a top-level animated schematic to examine the performance of specific components, such as valves and pumps, and locate information on part numbers and wiring diagrams.
Up-to-date PDF technical documents and schematics for each machine component are also searchable and can be quickly displayed as needed.
Erie Press forging equipment incorporates automation that allows the operator to change hot dies in less than ten minutes. A change of forging is completely automatic, requiring only inputs on the HMI. Billets and titanium parts are preheated in an electric furnace, while tooling is preheated offline.
The operator, working behind an interlocking door system for safety, uses a joystick to transfer the tooling into the press, which is hydraulically fixed in place. A barcode is scanned at the production router, which calls a part-specific forging program into the controller.
FPD worked with Erie Press to incorporate safety features such as preventing the program from running if the tool and part barcodes do not match the router, and a safety run that the operator must run before switching to automatic mode.
“Because we produce a lot of small series, we can set up several times a day and that gives us enormous production capacity,” Speicher said.
Extend longevity, reduce costs
Stroke speed control also helped extend tool life.
“With the hydraulic servo, the operator can vary the stroke speed of the press with much more control, which extends the life of the tool. According to our internal statistics, the new press extended tool life by approximately 50%,” Speicher said.
There are also significant cost savings compared to the conventional machining approach.
“Depending on the geometry of the part, we can normally reduce the unit price by 30% to 50% compared to a raw part [machined from bar, plate or billet]. This is due to the use of fewer input materials – and titanium is very expensive,” Speicher said.
For machine shops, adding advanced titanium part forging to their existing machining capability can not only help improve production speed and control, but also significantly reduce manufacturing costs. entry, which increases the results.
Del Williams is a technical writer based in Torrance, California.