Introduction to Manufacturing Techniques of Composites

Introduction to Manufacturing Techniques of Composites

Every material possesses unique physical, mechanical, and processing characteristics and therefore a suitable manufacturing technique must be utilized to transform the material to the final shape. One transforming method may be best suited for one material and may not be an effective choice for another material. For example, wood is very easy to machine and therefore machining is quite heavily utilized for transforming a wooden block to its final shape. Ceramic parts are difficult to machine and therefore are usually made from powder using hot press techniques. In metals, machining of the blank or sheet to the desired shape using a lathe or CNC machine is very common. In metals, standard sizes of blanks, rods, and sheets are machined and then welded or fastened to obtain the final part. In composites, machining of standard-sized sheets or blanks is not common and is avoided because it cuts the fibers and creates discontinuity in the fibers. Exposed and discontinuous fibers decrease the performance of the composites. Moreover, the ease of composites processing facilitates obtaining near net shape parts. Composites do not have high pressure and temperature requirements for part processing as compared to the processing of metal parts using extrusion, roll forming, or casting. Because of this, composite parts are easily transformed to near-net-shape parts using simple and low-cost tooling. In certain applications such as making boat hulls, composite parts are made at room
temperature with little pressure. This lower energy requirement in the processing of composites as compared to metals offers various new opportunities for transforming the raw material to near net shape parts.

There are two major benefits in producing near-net- or net-shape parts. First, it minimizes the machining requirement and thus the cost of machining. Second, it minimizes the scrap and thus provides material savings. There are cases when machining of the composites is required to make holes or to create special features. The machining of composites requires a different approach than machining of metals.

Composite production techniques utilize various types of composite raw materials, including fibers, resins, mats, fabrics, prepregs, and molding compounds, for the fabrication of composite parts. Each manufacturing technique requires different types of material systems, different processing conditions, and different tools for part fabrication. production success relies on the correct selection of a manufacturing technique as well as judicious selection of processing parameters. The main focus of this is to describe emerging and commercially available manufacturing techniques in the field of thermoset and thermoplastic based composite materials. Various composites manufacturing techniques are discussed in terms of their limitations, advantages, methods of applying heat and pressure, type of raw materials used, and other important parameters. The basic knowledge of these processes will help in selecting the right process for an application.