The integrated, hybrid subtractive/additive (AM) manufacturing system made possible by Optomec's modular LENS metal print engine can now be monitored for quality control with the company's SmartAM (Smart Additive Manufacturing) option. During a build, this closed-loop control system monitors and adjusts key process parameters to help ensure consistent quality, and qualities, of metal parts.
The modular LENS print engine results from an America Makes project for making structural metal parts spearheaded by Optomec. Used for many years in military and aerospace applications for low-volume manufacturing and in-service product repair, the blown powder LENS metal AM technology in production-grade standalone 3D printers was originally developed by Sandia National Labs. The main goal of the project that puts the core LENS technology into a print module is to speed up the use of metals AM in US industry, as we reported last summer.
This Fadal Vertical Mill has been upgraded with Optomec's LENS metal print engine AM technology, resulting in a hybrid CNC machine tool. Now, a closed-loop feedback system using Optomec's SmartAM process control option for the print engine ensures higher quality parts in similar hybrid tools during 3D printing by controlling control melt pool size and adjusting key process parameters to help ensure consistent quality.
The relatively low-cost modular print engine can be installed on most machine tools to form a hybrid system. This can drastically reduce the amount of time it takes to machine parts, as well as materials costs, because printing and finishing can be done in one setup. When the LENS print head is in the idle position, the hybrid system maintains all of its CNC machining capabilities. When the cutting tool is idle, metal parts can be 3D printed for rapid prototyping. It's also easy to make design changes during product development.
During printing, though, heat can build up in the part, affecting the size of the melt pool. This, in turn, can change the microstructural properties and dimensional accuracy of the printed metal part. Real-time process monitoring to control melt pool size is a standard option for Optomec's standalone LENS metal 3D printers, and that technology is now available for the LENS print engine.
SmartAM technology comprises a melt pool sensor and special focusing optics in the print engine's deposition head. The sensor monitors the build process, while control software automatically adjusts laser power to keep the melt pool area constant. Several studies have demonstrated that this closed-loop method effectively controls heat input and cooling rate. This promotes uniformity of the microstructure that defines the mechanical properties of the printed metal part and ensures its geometric and dimensional integrity. From the first layer to the end of the build during actual operation, SmartAM has been shown to dramatically reduce laser power.
These studies were conducted by a variety of sources, Tom McDonald, Optomec's senior program manager, told Design News. Most of them have been performed on LENS systems independent of the company's direct involvement. "Fundamental studies were performed at Sandia Labs in conjunction with the original LENS cooperative research and development agreement," he said. "Subsequent work was conducted at Sandia in collaboration with industry and university research partners using LENS systems. Additional subsequent work has been performed correlating weld pool control for the LENS process to microstructure and/or residual stress control at Lehigh University, the Applied Research Lab at Penn State, Carnegie Mellon, and UC Davis, to name a few we are aware of."
Optomec also announced strategic investments in the company by GE Ventures and Autodesk. The proceeds will further the development, promotion, and deployment of its proprietary solutions for production applications including 3D-printed sensors and antenna, advanced electronics packaging, and 3D-printed metals. Optomec has previously worked with both companies. With GE, it has collaborated on directly printing 3D sensors onto high-value components. Optomec has used Autodesk's software tools to generate design data that ultimately drives its 3D printers, and both companies now intend to co-develop software tools to leverage the Spark 3D printing platform. Those tools will help better connect AM hardware and software so AM technology can be integrated into conventional production platforms.
Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 27 years, covering manufacturing materials & processes, alternative energy, and robotics. In the past, she's also written about machine vision and all kinds of communications.
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