**4.8 Additive manufacturing**

Additive manufacturing is also known as 3D printing technique. Additive manufacturing is a step change in the development of rapid prototyping concepts that were introduced more than 20 years ago. This is a process for making a solid object from a three-dimensional digital model, typically by laying down many successive thin layers of a material. Manufacturing a composite structure with a single nozzle uses polymer composite filament and contains polymer and additives such as rubber microspheres, particles of glass or carbon fibre, wood flour, etc. as shown in **Figure 12**. This more recent form of composite part production grew out of efforts to reduce the costs in the design-to-prototype phase of product development, taking aim particularly at the material-, labour-, and time-intensive area of toolmaking [53–56].

#### **4.9 Composite properties**

The polymer composite materials are lightweight, which increases the fuel efficiency of vehicles manufactured from composites and gives them structural

**Figure 12.** *The schematic of the 3D printing process for polymer composites.*

The wetted bundle is pulled into heated dies, and the cross-sectional shape of the pulled fibre is formed by these dies. The resin is cured, and the composites are formed. Parts are then made by slicing the long-cured piece. This process is limited to straight parts with a constant cross-section, such as I-beams, T-beams, or frame sections and ladder rails. **Figure 10** shows the schematic of the pultrusion process [49, 50]. Pultrusion is used in the manufacture of linear components such as ladders

*Composite and Nanocomposite Materials - From Knowledge to Industrial Applications*

Automated fibre placement (AFP) is one of the most advanced methods for fabricating and manufacturing of composite materials as presented in **Figure 11**. This method is used almost exclusively with continuous fibre-reinforced tape. A robot is utilised to place fibre-reinforced tape and build a structure one ply (layer) at a time. A band of material comprised of multiple narrow strips of tape (tows) is placed where these tows are commonly 0.125 and 0.25 inches wide. The use of robotics gives the operator active control over all the processes critical variables, making the process highly controllable and repeatable. This method allows the fabrication of highly customised parts as each ply can be placed at different angles

Advantages of fibre placement are processing speed and reduced material scrap and labour costs. Often, the process is utilised to fabricate large thermoset parts with complex shapes. Similar to ATP process, automated tape laying (ATL) is an even speedier automated process in which prepreg tape, rather than single tows, is

and mouldings.

**18**

**Figure 9.**

**Figure 10.**

**4.7 Automated fibre placement**

*The schematic of the pultrusion process.*

*The schematic of the filament winding process.*

to best carry the required loads [51, 52].

laid down continuously to form parts.
