Sciaky Inc., based in Chicago, Illinois, specializes in large scale welding systems; and a pioneer in an additive process called Electron Beam Additive Manufacturing (EBAM).
Sciaky’s Electron Beam Additive Manufacturing process utilizes an electron beam, within a vacuum environment, to melt metal wire in an additive manner to achieve near-net shape parts.
We connected with Kenn Lachenberg, Application Engineering Manager of Sciaky Inc., to gain his insight and understanding of EBAM in an exclusive AMazing® Q&A session.
AMazing®: Kenn, thank you for your participation. We are very excited to be featuring Sciaky’s Electron Beam Additive Manufacturing (EBAM) process. How does the process begin? How does EBAM work?
Kenn Lachenberg: The EBAM processing initially involves manipulating a 3D cad model such that it can be used to generate computer numerically controlled (CNC) tool paths for the electron beam (EB) system. The tool paths are programmed such that the part model is “sliced” into layers that when executed on the EBAM machine will result in a near net shape.
Once the tool paths are created the EB system is used to perform the deposition process. The EBAM process is typically conducted under vacuum conditions between 1×10-4 and 1×10-6 Torr. The EB gun is used to supply the energy required to melt and fuse the deposited material. The EB gun also provides for focusing and deflecting the electron beam by using programmable electromagnetic coils. A substrate plate provides a surface upon which to deposit material and in many instances becomes an integral part of the finished structure.
The EBAM process utilizes wire as the incoming feedstock material. Wire has several advantages in that it is readily available, results in minimal waste, and the feed rate can be precisely calculated and controlled. The wire is fed into the molten pool established by the electron beam through a guide nozzle whose position can be monitored and controlled. The result of depositing layer upon layer of material generates the near net shape component commonly referred to as a “preform”. The preform is finished machined to achieve the tolerances and surface finishes required by the application.
AMazing®: Within the last several years, EB welding technology has matured to meet demands of industry. What developments have been significant and how has it affected the EBAM process?
Kenn Lachenberg: Although Sciaky had previously built geometric structures using open loop controls and CNC motion, the most significant development change affecting the EBAM process was the implementation of the closed-loop control (CLC) to manage the deposition process.
In order to obtain widespread commercial acceptance of this technology, it is important that the EBAM processes are automated, such as by the CLC system, such that dependence upon human operators can be reduced. With a robust closed loop control system it is believed possible to save time, produce more uniform parts, control microstructure, and provide in situ verification that the proper parameters have been used in the build process.
AMazing®: What makes the combination of electron beam welding and additive manufacturing ideal for large-scale, near-net shape parts? What are some major benefits associated with the use of EBAM technology over conventional means?
Kenn Lachenberg: Sciaky’s electron beam direct manufacturing technology uses a highly focused stream of electrons rather than photons (used with Laser based system) to heat up and fuse the material. Additionally the process is performed within a vacuum chamber unlike most other additive technologies that require some type of inert gas.
The use of an electron beam allows for high power to be applied very efficiently that enables our process to scale to large size parts very easily and allows us to achieve material deposition rates that we believe are some if not the highest available in the marketplace today. When working with reactive materials such as titanium at high deposition rates, the vacuum chamber provides an ideal environment for processing these materials. The moving EB gun technology facilitates movement within a vacuum chamber to optimize the build envelope of large-scale components.
Many of the parts we have been asked to build are currently produced using a forging process. Typically with the forging process there is a need to purchase a (sometimes very large) rectangular billet of material and machine most of it away or wait for special forging tooling to be fabricated which can take upward of a year before the first parts can be produced.
With EBAM we can start with a 3D cad file of the prototype part, and typically within 3-4 weeks have all the plate and wire materials required to produce the initial preform. Typically the preform can save as much as 50% or more of the material that must be machined away when compared to starting with a large billet.
AMazing®: We understand EBAM can be used to repair worn or damaged parts? Is there a past project that stands out in your mind which best exemplifies EBAM as a repair option?
Kenn Lachenberg: EB with wire-feed has been utilized as an additive process for several years successfully performed at various jet engine overhaul and repair facilities for remanufacturing and refurbishing aircraft engine components.
One of the notable applications incorporated the build-up of worn knife edge seals to a selective height and width. This was accomplished by rotating the piecepart under the electron beam and feeding the wire continuously to the point of required edge build-up. For these applications, Hastelloy, Titanium and Nickel based alloys have been utilized with the additive process.
Also, Sciaky has worked with the Navy identifying and developing the EBAM process for the fabrication and repair of components for underwater warfare equipment; this initiative was put in place to target the reduction of replacement costs and extend the service lives of the Navy’s existing assets. Although the implementation of this development is not yet complete, many materials (Nickel Copper, Stainless Steel, Inconel, Aluminum, and Titanium) were successfully deposited as part of this EBAM repair process development.
AMazing®: As Sciaky’s standard build envelope is 19’ x 4’ x 4’ (L x W x H), can you recall a part that utilized the full build envelope? How long did it take to additively manufacture the part?
Kenn Lachenberg: Our larger EBAM machine does facilitate a maximum work envelope of 19’ x 4’ x 4’. However, most of our projects are bound by non-disclosure agreements between Sciaky and our customers. But we can state that we have built some large titanium airframe components targeted for a military jet that is nearly 10 feet in length. The preform build of this assembly took approximately 48 hours.
AMazing®: As the part builds layer-by-layer, how does the electron beam and subsequent molten metal affect the solidified layers beneath it? Is there a key hole effect similar to conventional electron beam welding?
Kenn Lachenberg: With the thousands of pounds of layer-by-layer build, the empirical research and testing has shown that the interfaces of the layers with the EBAM process are fully dense and homogeneous in microstructure. With the EBAM process, the beam is rastered in a heat pattern serving to uniformly melt the wire and substrate/layer, and a beam key hole is not generated like that in conventional EB welding.
AMazing®: As with conventional EB welding, there are risks of voids or porosity. How are these same risks mitigated when using Electron Beam Additive Manufacturing?
Kenn Lachenberg: Unlike EB Welding titanium where cleanliness and fit-up of the faying surfaces as well as the keyhole welding process parameters play a significant role on the generation or minimization of porosity, the bead on bead deposition method used in EBAM appears to produce higher overall material quality.
While randomly distributed spherical gas pores have been found in some titanium EBAM material, the size of these pores are predominantly below the detectability limits of conventional ultrasonic testing technology. No correlation to a loss in mechanical strength has been made between EBAM titanium material properties and porosity. Sciaky is also currently engaged with industry leaders to identify the mechanism responsible for generating pores in titanium to further reduce their presence in EBAM deposited material.
AMazing®: What types of materials can be used with the EBAM process? How do the mechanical properties compare with wrought or cast materials?
Kenn Lachenberg: Materials that are expensive and difficult to machine currently make the best business cases for EBAM. The majority of our work has targeted aerospace applications involving titanium, but we have worked with other materials in more limited amounts such as aluminum, niobium, tantalum, tungsten, Inconel, copper-nickel, nickel-copper, and stainless steels.
We recently started working with a handful of tool steels which may be used for building or repairing dies in industries outside of aerospace. Since the EBAM process is typically operated within a high vacuum environment, this provides for an oxygen-free atmosphere to best ensure the chemical integrity of the material. The majority of EBAM material evaluated has been titanium which is superior to cast titanium and is within a few percentage points of wrought material mechanical properties in beta annealed titanium.
AMazing®: What types of EBAM post-processing operations are necessary?
Kenn Lachenberg: As previously referenced, the EBAM preform is post machined to achieve the tolerances and surface finishes required by the application. Also depending upon the application requirements, the preform may go through thermal stress relieve, solution heat treatment and non-destructive examination prior to finish machining.
AMazing®: Shifting gears to education, what career advice would you offer an individual interested in working with additive manufacturing technologies?
Kenn Lachenberg: The Additive Manufacturing industry today covers such a vast range of materials (metals, ceramics, thermoplastics, etc.) and processes (Electron Beam, Laser, Plasma Arc, etc.). I would recommend a person interested in AM to research the various technologies to hone in on their specific material and process of interest. Then follow up through web based searches to best connect with like organizations and academia that best specialize in the target AM areas of interest to further engage with expert personnel and learn more. This engagement could open some good doors for opportunity. “The more you learn, the more you like, the more you learn.”
AMazing®: Finally, how will Sciaky’s Electron Beam Additive Manufacturing process evolve over the next three years? What do you hope to see?
Kenn Lachenberg: To date, the thrust of the EBAM process for Sciaky has been driven by the aerospace industry to target affordability initiatives; specifically to refine the process utilizing titanium material for airframe structures. Over the next few years, Sciaky’s EBAM process should further advance from development/qualification to production in this segment. Also, the EBAM process should expand into other markets and industries (Space, Oil & Gas, and other commercial entities). We are hoping to see much more EBAM work with different material alloys and a greater need for EBAM equipment internationally.
AMazing®: This concludes our interview. Thank you very much Kenn. We are very grateful for the opportunity to learn about Sciaky’s Electron Beam Additive Manufacturing (EBAM) process.
About Kenn Lachenberg:
Employed at Sciaky Inc. for over 30 years with experience that spans over four department operations; manufacturing, engineering, customer support and application/sales, and currently manages the Application Engineering department.
An active member with the American Welding Society serving on the C7 and C7B committees for high-energy beam and electron beam welding processes. Co-authored and acted as a contributing editor on the AWS C7.1 (an American National Standard – ANSI) manual “Recommended Practices for Electron Beam Welding”. Also, co-authored with Lockheed Martin Aeronautics Co. on applications using the Electron Beam Process for Free Form Fabrication, and authored “Nontraditional Applications of Electron Beams” as a section of the ASM Handbook, Volume 6A (Welding Fundamentals and Processes.
Presented at various sessions including the ASM Aerospace & Defense Industrial Sector sponsored “AeroMat” 2004 & 2007 conferences covering details on Electron Beam Additive Manufacturing (EBAM) process.
Sciaky Inc. Contact
Kenn W. Lachenberg
Manager, Application Engineering
4915 W. 67th Street Chicago, IL 60638
Phone 708-594-3800 ext. 342
About Sciaky Inc.
Sciaky, Inc., United States: As an Additive Manufacturing (AM) pioneer of large-scale, high-value metal applications, such as titanium parts for aircraft, Sciaky is a key player in AM advances for the aerospace and defense markets. Our groundbreaking AM process, which uses state-of-the-art EB welding technology, saves manufacturers time and money on the creation of production parts and prototypes. Sciaky, Inc.
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