*4.3.2 Porsche's revolutionizing product development*

Porsche has used 3D-printing technology to produce 3D-printed pistons, spare parts, and sports seats. Porsche has developed the lightweight, better thermal resistance, high-performance pistons for the twin-turbo boxer engine of the 911GT2 RS

**Figure 6.** *3D-printed finished spacer panel, [Source: Materialise].*

**Figure 7.** *Airbus 3D metal-printed bionic titanium bracket [Source: Airbus].*

model leading to a 30-horsepower gain. This process used the laser printing or laser metal fusion process in collaboration with MAHLE & TRUMPF which uses the highprecision machine, TruPrint 3000 with a 500-Watt fiber laser and high-purity metal special aluminum alloy powder which melted to print 1200 layers ending into the desired shape (**Figure 8**) [31, 32].

Porsche has been manufacturing spare parts using selective laser melting since 2018 but recently, Porsche has started manufacturing personalized bodyform fullbucket sports seats for Porsche 911 and 718. Porsche has also invested in 3D-printing specialist INTAMSYS (**Figure 9**).

#### **Figure 8.**

*Pistons of the twin-turbo boxer engine of 911GT2 RS [Source: Porsche AG].*

**Figure 9.** *3D-Printed bodyform full-bucket sports seats [Source: Porsche AG].*

Porsche has also produced its first complete housing for its electric drive using the additive laser fusion process which has opened the possibilities for 3D printing in the highly stressed electric sports cars sector (**Figure 10**) [33].

### **4.4 Post-processing advancement**

**Achieving Good surface quality:** As it was mentioned in section 3, there is a discrepancy with the surface quality whenever multiple materials are used because of the layer stair-stepping effect, but there have been numerous advancements done in this field to achieve the good surface quality such as mask-image-projection-based stereolithography (MIP-SL) which is a hybrid AM stereolithography process. In the

#### **Figure 10.** *Prototype for small series production [Source: Porsche AG].*

MIP-SL process, Digital Micromirror Device (DMD) is used instead of a laser, unlike stereolithography. DMD is an electromechanical device that can control ~1 million small mirrors simultaneously to turn on or off a pixel at over 5kHz [18] which results in the projection of masked images on a surface area. MIP-SL process is faster than the SLA process. MIP-SL was developed to spread the liquid resin on the smooth ultrathin layer surface which basically used the meniscus equilibrium method for building the smooth up-curved surfaces [18]. There have been several approaches used to achieve the good surface quality, such as blasting, sanding, chemical finishing, which has differentiation influence on the surface quality. There is another post-processing step to achieve good surface quality is the coating method on the 3D-printed parts. For instance, there is a chemical coating XTC-3D was used because it was lost cost, easy to work on any 3D-printing surfaces (FDM, SLS, SLA) which showed that coating has filled up the gap between the layers and improved the final finished surface quality of the product [34].

**Protecting Intellectual Property and AM standardization:** To protect the intellectual property rights of any process, material, and file information, there has been advancement where information is either encrypted or embedded into the structure domain such as infraStructs which literally means below the structures where tags including all the information are embedded inside the digitally fabricated structure which can be read only by Terahertz (TZ) imaging system. It is not visible outside the surface and can be read only by advanced imaging systems [35]. Similarly, there is an advancement where watermarks can be extracted from the 3D prints by changing the original 3D print mesh [36, 37].
