Additive Manufacturing (AM) or 3D Printing technologies involve various manufacturing processes that enable building objects layer by layer. It gives way to complex designs and heightened performance. 

The automotive industry was among the first to use AM processes, including laser powder bed fusion (L-PBF), fused filament fabrication (FFF), and, more recently, inkjet printing and stereolithography for developing prototypes and test pieces. As time has passed, there have been significant improvements in the accuracy, quality, repeatability, and dependability of the parts produced through additive manufacturing. However, these metrics are still not considered adequate for the automotive industry, which demands standardized, consistent, and automated operations. Moreover, this transition period for AM processes is concurrent with a significant transformation in the automobile sector.

The automotive sector is currently experiencing new changes, largely because of an increased need for electric mobility as a renewable substitute to locomotion powered by internal combustion engines, which have been the norm since the car was first invented. The transformation of concepts such as ride-sharing and automated driving reinforces this progress. This article examines the acceptance and viability of metal and polymer-based 3D printing methods in automotive production as 3D printing shifts from prototyping to production and the automotive industry moves towards electric and smart mobility.

Metal-based AM 

For commercial and research purposes, the most commonly used metal-based additive manufacturing techniques are Laser Powder Bed Fusion (L-PBF) and Electron Beam Melting (EBM). This progress is attributed to the availability of high-performance alloys that can be printed, which cannot be economically machined using other fabrication processes. In particular, titanium and nickel alloys offer impressive mechanical traits, such as superior fatigue strength, in a lightweight form. 

Researchers have made significant progress in developing superior-quality metal parts through enhanced research in refining Additive Manufacturing processes. This has given rise to more business models for AM processes and a greater uptake within the automotive sector. Notably, the size of metal components produced through AM processes has grown considerably, allowing for larger production runs and quicker manufacture. 

Recent developments in the automotive sector, such as electric mobility, have made metal additive manufacturing a very attractive and practical choice. Laser powder bed fusion has enabled the fabrication of parts created through generative design and topology optimization, allowing one to design the internal structure of the component precisely. This is especially beneficial as it allows computer algorithms to optimize the component and improve its performance using less material.

Metal Additive Manufacturing 

Another motivation to use metal Additive Manufacturing is to improve the heat efficiency and decrease the weight to increase performance-to-weight ratios. Front-end automotive components can direct air towards higher temperature battery and brake systems. By utilizing 3D printing, it is possible to modify metal part designs to increase cooling, thereby enhancing heat efficiency during operation. Heat efficiency is paramount for electric vehicles since greater efficiency equates to better battery performance and range, which is essential for all types of electric vehicles, such as small cars, luxurious cars, and high-performance vehicles.In addition to heat management, 3D printing can address other challenges such as the need to reduce weight without compromising strength. Studies have suggested that using 3D-printed components in load-bearing parts could provide better cooling, both actively and passively. 

Experts anticipate that metal Additive Manufacturing components will soon enrich cars, trucks, and other vehicles, as they become integrated into hybrid process chains. This integration will enhance the strength-to-weight ratio through advanced component design and a reduction in sub-assemblies.

Polymer-Based AM

The emergence of layer-wise manufacturing technologies has given rise to novel terminologies such as “functional printing” and the recently coined “industrial printing”. The term “functional printing” refers to the development of additive manufacturing techniques to the point where a single manufacturing session can produce fully functional printed devices.

Technically, “industrial printing” is an integral component of the manufacturing process chain, intended to contribute by providing additional capabilities to the already created part or improving existing ones. Inkjet printing stands out among other polymer-based additive manufacturing technologies due to its capacity to create complex 3D components with various materials. Its ability to jet digitally and on-demand ensures the fabrication of components with high precision and integrated functions.

For the past few decades, the industrial world has taken advantage of the benefits of inkjet printing for a wide range of applications, such as printed electronics, smart sensors, bioinspired elements, micro- and 4D active gadgets, and drug delivery. Industries have effectively utilized inkjet technology due to its limitless design options, high throughput, and flexibility. Producing a single lot size with specialized features is feasible with the ability to switch from one design to the other quickly. Researchers discovered the capability of inkjet printers to print and develop adaptable touch-sensitive sensors by printing conductive patterns, which they then vacuum shaped around a 3D element.

Advancements in Inkjet Printing Technology for Automotive Applications

One can employ vacuum foaming to map sensors onto various shapes and forms. This allows for incorporating sensing capabilities onto complex geometries externally and internally for a vehicle, like a door handle or the cabin interior. Automotive infotainment applications can also benefit from the application of this technology. Moreover, researchers can further investigate and enhance new automotive-specific functions and characteristics by incorporating the advanced touch-sensing ability into 3D devices such as Human Machine interfaces (HMI). Inkjet technology finds application in printing flexible sensors, which can be utilized for observing the levels of carbon monoxide (CO) inside the car and the exhaust gas. The inkjet process can also produce sensors that detect other gases in automotive applications. 

As the automotive industry is transitioning to sustainable fuel sources, hydrogen gas is a feasible option. Manufacturers use the inkjet printing technique to produce several components of a hydrogen fuel cell, which results in cost reduction and enhanced fuel cell efficiency. A recent study has explored the potential of using inkjet printing to create polymer organic light-emitting diodes (PLED). The researchers found the accuracy of inkjet printing to be satisfactory, and they also discovered that the PLEDs were flexible. This could be a valuable step forward in developing hydrogen fuel cells for cars in the future. Furthermore, combining it with flexible touch sensors enables the creation of touchscreen displays that are not limited to a flat shape.

Inkjet printing can create respiratory sensors for automotive applications which are both cost-efficient and effective. By integrating these wearable sensors into the seat belt, we enable real-time monitoring of the driver’s respiratory system, which allows us to utilize the data for safety features.

Future directions

Metal Additive Manufacturing technologies could be extremely beneficial for automobiles, as the capacity for optimized parts would lead to greater efficiency. This could result in higher fuel efficiencies and extended range capabilities for electric cars. The automotive industry can significantly benefit from the use of Polymer Additive Manufacturing technologies in its journey towards becoming green, smart, and electric. These technologies can be employed in applications such as human-machine interfaces, sensors, hydrogen fuel cells, polymer organic light-emitting diodes, and respiratory sensors for drivers.

The future of additive manufacturing (AM) and its association with the automotive sector appears bright, and experts anticipate its continuous growth across all metrics. Furthermore, merging with other digitalization technologies, such as AI and machine learning, will enhance the growth potential of both AM and automotive manufacturing. Consequently, further research needs to be conducted and encouraged in these areas.