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Daimler is exploring a number of 3D printing options for plastic and metal parts. (image: Mercedes-Benz Trucks)

Adding 3D printing to design, manufacturing processes

Additive manufacturing is beginning to transform operations from early development through fulfilling requests for obsolete components. Integrating 3D printing into the design and manufacturing operations can be a slow process, since a broad range of parameters must be examined, sometimes on a case-by-case basis.

Additive processing has already altered many fields, but it’s still fairly new in the high reliability world of commercial vehicles. The technology is often used for prototypes, since production times are far shorter than for parts made with conventional manufacturing techniques. Companies are striving to understand the nuances of components and expand their usage of additive processes.

“We are piloting six 3D-printed plastic, non-safety critical parts,” said Angela Timmen, Manager of Interior/Exterior Cab and Major Components at Daimler Trucks North America. “DTNA partnered with the 3D printing service bureau, Technology House, to produce the parts via selective laser sintering. The pilot parts were selected based on their long lead times and their lack of tooling. They also provide a safe way to explore and learn the 3D printing process.”

Additive processes have become more common in the last few years, so many companies are expanding their capabilities to produce a broader range of prototypes. They’re also looking to see how additive parts can be put into production machines.

Caterpillar opened its Additive Manufacturing Factory in 2015 to focus on changing manufacturing environments. This operation helps Caterpillar understand the many different 3D printing technologies and explore how they can be used in conjunction with other manufacturing technologies.

“The Additive Manufacturing Factory has two primary functions,” said Stacey M. DelVecchio, Additive Manufacturing Product Manager at Caterpillar’s Innovation & Technology Development Division. “First, it’s a mini-production factory with the ability to fulfill production orders on production-capable 3D printing equipment. Second, it’s a lab for our engineers to train on this equipment.”

Interest is not just from OEMs. Engineering and technical consulting groups are quite interested, since they’re often designing a number of different solutions for OEM projects. When they can make a range of different options without taking the time to set up conventional manufacturing equipment, design engineers can try out far more options, often using creative concepts.

“With additive processes, new geometries which are not possible with conventional forging or casting can be produced, such as piston bowls, honeycomb structures and cooling channels in pistons or cylinder heads with web cooling structures,” said IAV Automotive Engineering spokesperson Pia Shah. “There’s far less machining effort for products like cylinder heads with integrated oil channels or without closing plugs.”

There are many factors to be understood. There are a range of different manufacturing technologies, including selective laser sintering, stereolithography, direct metal laser sintering, multi-jet fusion, fused deposition modeling and continuous liquid interface production.

Additionally, the properties of components made with powdered raw materials can be different depending on the selected production technology. Some companies address this complexity by working with specialized contract manufacturers, while others forge links with equipment suppliers.

“It is very important to partner with equipment suppliers,” Timmen said. “We use supplier partners now who have the flexibility to keep up with the changing technology to print our parts.”

Alter or start from scratch?

Design strategies are among the many questions surrounding the technology. When new designs have honeycombs or other elements that can’t be made using conventional design techniques, engineers must use 3D design techniques from the beginning. When prototypes or volume designs mimic existing parts, it’s often helpful to design the part for additive manufacturing, but that’s not always necessary.

“In some cases, we can use a design that was intended for a conventional manufacturing process,” DelVecchio said. “In other cases, we can’t. The real question, though, before 3D printing a part that was designed for conventional processes isn’t, ‘Can we print it?’ it’s ‘Should we print it?’ As the cost to 3D print a part continues to come down, we’ll see more and more cost-effective applications for additive manufacturing.”

The decision to redesign an existing part or start afresh varies widely depending on complexity and whether alterations are needed. Sometimes, it’s simple to add features when parts are made with additive processes. Other times, it’s expedient to use the existing data files.

“If the full potential of additive parts can be used with a dedicated/optimized design approach and integration of new functions and features, then we usually design from scratch,” IAV’s Shah said. “If a client wants to use the additive process only to reduce the lead time for prototypes and produce the series parts, for example pistons, with conventional processes like forging, then we use a rather conventional design for the additive prototypes.”

Additive technologies are also being used as a way to fulfill demand for outdated components, especially when volumes of older parts are too low to warrant full production runs. The printers can also help companies alleviate backlogs.

“3D printing is useful for sourcing parts for older truck models,” Timmen said. “This technology can also provide a solution for backordered parts, which would otherwise cause long delays. DTNA has made significant enhancements to its supply chain ecosystem including processes and new parts distribution centers. Our current supply chain strategy is a rapid recovery system that allows us to deliver parts next day to most of our dealer order volume.”

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