New Directions in Additive Manufacturing

Penn State has a strong history in traditional manufacturing techniques, such as casting and machining. Now Penn State has emerged as a leading US center in additive manufacturing (AM) expertise through the Center for Innovative Materials Processing through Direct Digital Deposition (CIMP-3D). Additive manufacturing, commonly referred to as 3D printing, uses three-dimensional digital models to produce structures of varying complexity one layer at a time from materials such as metals, plastics, ceramics, glass, and even biological tissue.

“Penn State is really good at both additive and traditional manufacturing,” says Guha Manogharan, assistant professor of mechanical engineering. “CIMP 3D is the focal point for additive manufacturing nationally, if not worldwide.”

Manogharan has a background in both additive and traditional manufacturing technologies, and his current work involves bridging the technologies to bring some of the subtractive technologies, such as machining, and the casting technologies, such as sand casting, into the field of additive manufacturing. 

He leads a national consortium charged with developing a technological roadmap for integrating the additive processes with traditional manufacturing processes. Called CAM-IT, which stands for Consortium for Advanced Hybrid Manufacturing - Integrating Technology, the NIST-sponsored initiative is now headquartered at Penn State. “CAM-IT brings together suppliers from across the value chain, the machine tool and AM machine manufactures, cutting tool and CNC manufacturers, the software providers, and eventually the aerospace and defense end users,” Manogharan says.

Industry leaders provide the types of applications for which they would like to use AM, but are currently unable to use it for, and university researchers will address the technological issues and what is needed to overcome them. Now in its final stage, the consortium is moving from road mapping into a research project phase based on industry inputs, which ranks applications vs. time-line vs. technological priorities.

Within Penn State, Manogharan leads the SHAPE (Systems for Hybrid-Additive Process Engineering) lab, which includes a new metal additive hybrid system that integrates AM and direct digital subtractive manufacturing operations in both a single machine and across different machine envelopes. The lab will be located in the CIMP-3D space in Penn State’s Innovation Park.

The purpose of hybrid manufacturing is to overcome some of the limitations of AM that are often overlooked in the excitement of the new technology, according to Manogharan. These challenges include achieving a high precision tolerance, a smooth surface, and uniform directional mechanical properties. The latter problem which is affected by the build direction of 3D printing, can strongly affect the strength and reliability of parts, and will likely require intensive modeling, heat-treatment studies, and nondestructive testing to resolve. But hybrid technologies can solve the high precision and smooth surface challenges that need to be overcome in order to make parts that can fit seamlessly into a jet engine or automobile chassis.

One of Manogharan’s major research efforts is the design and development of a hybrid system that incorporates machining, abrasive flow polishing, and grinding with a laser scanner in a series of multi-axis CNC machines that seamlessly integrate AM and post-processing to get the best of both technologies.

“Our research group is focusing on developing both digital and advanced processing tools for hybrid manufacturing that would greatly enhance both the traditional and growing AM value chains,” he says.

3D Sand Printing

With funding from America Makes, Manogharan is combining one of the oldest methods of manufacturing, known as sand casting, with one of the newest methods, additive manufacturing. He calls this new combined process 3D sand printing.

“Penn State has always had a very good casting program,” he says. “We recently got a grant based on how we can combine two completely different areas of manufacturing in metal casting and 3D printing.”

Sand casting is a little like making a sand castle. Wetted sand is packed around a pattern made out of a material such as wood or plastic, much like ice trays are used to make ice in the shape of the tray. The pattern is removed and molten metal is poured through a hole in the top into the core, where it takes the shape of the part. When the metal cools, the sand is broken away to retrieve the cast part. It is estimated that 70 percent of all metal castings per year are produced via sand casting. The number of parts produced by metal casting is huge, including the engine blocks of all the cars on the road.

In 3D sand printing, the molds and cores for metal casting are printed directly on layers of sand in a powder bed process that deposits an adhesive binder onto layers of sand until an entire mold is fabricated.  

“With 3D sand printing, you spread a layer of sand and deposit glue as a binder in the spaces you want. Keep doing it until you have every layer of the box except where you have the shape you want for the metal to be poured into,” he explains.

 In traditional sand casting, the pattern has to be removed before the metal is poured, which limits the shape of the mold.  With 3D sand printing, almost any complex shape is possible, and consolidation of cores makes it even more economical.

“We did a project with an auto manufacturer in Detroit working on redesigning the engine block and the manifold,” Manogharan says. “We were able to reduce the weight by 20 percent, which may not sound like much. But on a truck designed to run for 400,000 miles, that adds up to a lot of fuel saved.”

3D Custom Orthopedic Implants

“My father was in a bike accident and had to get a shoulder implant. When you buy a shirt or coat, you typically only have a choice of small, medium, large, extra-large. But if it is a very important ceremony, you might go to a tailor and have it custom made. Shouldn’t we do that for something that’s going into our body?” Manogharan wonders.

To answer the question, he has begun working with Penn State’s Milton S. Hershey Medical Center on 3D printing of shoulder and knee implants. This is an area he believes is especially suitable for 3D printing because it fits three important criteria for 3D: complex design, customizability, and low cost. Their collaboration was recently awarded a grant to design and develop 3D printed metal implants for pediatric oncology studies.   

“The U.S. is far behind in this area, which is mostly due to regulations. My goal for the next three to five years is to reach out to colleagues with a range of biomedical and clinical expertise in order for us to be the leading university to develop 3D printed custom metal implants for patients,” Manogharan concludes.

Prof. Manogharan is an active member of ASME, IISE and SME and was named the 2016 Outstanding Young Investigator by the IISE- Manufacturing and Design Division and the 2017 Outstanding Manufacturing Engineer by the SME- Society of Manufacturing Engineers. Contact: gum53@psu.edu