Additive and Subtractive Manufacturing

Emergent Technologies

J. Paulo Davim

• Publisher: De Gruyter
• Year: 2020
• Print ISBN: 9783110776775
• eBook ISBN: 9783110548334
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Automation in Engineering
• Index: Technology & Engineering

Additive manufacturing (AM) and subtractive manufacturing (SM) offer numerous advantages in the production of single and multiple components. They provide incomparable design independence and are used to fabricate products in several industries, e.g.: aeronautic, automotive, biomedical, etc. The book presents recent results of processes including 3D printing, SLS (selective laser sintering), EBM (electron beam melting) and Precise Cutting and Drilling.

1 Emerging trends in additive and subtractive manufacturing

Prasanta Sahoo

Suman Kalyan Das

Abstract

The manufacturing sector has experienced a rapid advancement in the last few decades. From the popularization of computer numerical control machines as the face of traditional machining to the development of additive manufacturing (AM), it has been an open field in a series of innovations. Although AM is promising in terms of material savings and generation of complex parts rapidly, it cannot be a replacement for the conventional machining process, which seems better in terms of mass production. Thus, a hybridization of both the technologies seems to offer an optimal solution with respect to increased productivity and efficiency. Besides, improvement in information and communication technologies, Internet of things (IoT), robotics, and so on makes the manufacturing process self-sufficient and fully integrated. Besides, collaborative manufacturing systems are now a reality that responds in real time to meet changing demands and conditions in the factory, in the supply network, and in customer needs. All these have paved the roadmap for the implementation of Industry 4.0 (4th industrial revolution).

Keywords: Additive manufacturing, subtractive manufacturing, 3D printing, stereolithography, fused deposition modelling,

1.1 Introduction

In the past few decades, few industries have been impacted by rapid advancement in technologies quite like manufacturing has. The ever-increasing demand for advanced products along with the pressure of cost reduction has led to a competitive attitude among the industrialists, which may be cited as one of the primary reasons for infusion of innovation in the manufacturing sector. Manufacturers have been faced with an “evolve-or-die” ultimatum as customers expect faster rates of innovation. Hence, apart from the traditional machining, things such as additive manufacturing (AM) techniques, smart manufacturing, and agile manufacturing, have been embraced by the manufacturing community, and continuous effort has been put to increase the effectiveness of these techniques. AM is the fast upcoming technology that has already proved its mettle and is responsible for transforming how products are designed and produced. It has gained popularity through other names such as 3-D printing, rapid prototyping (RP), additive layer manufacturing (ALM), and solid freeform fabrication (SFF) and has begun to be incorporated even in our daily lives. Subtractive manufacturing (SM) belongs to more of the conventional manufacturing techniques based on machining of materials. Computer numerical control (CNC) is the modern machine for carrying out SM. As the advancement in the field of AM has been phenomenal in the past couple of decades, this chapter emphasizes more on its current trends and techniques. Figure 1.1 illustrates the basic philosophy of SM and AM.

Figure 1.1: Basic principles of subtractive and additive manufacturing (source: GAO analysis).

The basic idea of AM is to first create the CAD (computer-aided design) model of the object to be build. The CAD model is sliced into individual layers. The object is then built by AM progressively layer by layer. Hence, it is obvious that costly jig and fixture, other equipment and processing which are normally required for any conventional production processes are eliminated in this case. According to the joint ISO/ASTM standard [1], AM is defined as the “process joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies,” which cuts, drills, and grinds away the undesired excess from a solid piece of material, often metal. AM processes, on the other hand, have some following commonalities, namely a pc to store and process the geometric information as well as to drive the fabricator, deposition of feedstock which is administered as points, lines, or areas to create a part [2]. Some of the advantages of AM include:

1. Complex parts can be fabricated without the need of costly tooling.
2. There is no issue of tolerances such as circularity, linearity, and perpendicularity, which requires a major share of attention in case of conventional machining.
3. Components can be produced as per requirement reducing the load on inventory as well as the lead time for critical or outdated parts that need replacement.
4. Material wastage is very less compared to SM.
5. Easy building of prototypes and optimizing the design.

Due to these host of advantages, AM has found wide acceptance across a variety of domains, such as aerospace and aviation industry, medical and surgical devices, electrical and electronics industry, defense and military applications, automotive applications [3]. Fuel injector nozzles are of complex shapes and require multicomponent assembly, which is now preferably produced through AM resulting in significant cost savings [3]. It is also reported [3] that burner tips for mixing and swirling result in energy savings as well as their service life extends if the same are made of high-temperature materials. Now, with AM it is possible to give complex shapes to high-temperature materials. Automobile sector has been one of the major adopters of 3D printing. Apart from various spare parts of brakes, clutches, and other subsystems of a vehicle, AM has had two major points of influence on automotive applications: as a source of product innovation and as a driver of supply chain transformation. AM has also penetrated medical and dental sector, where various organs, namely, liver, kidney, heart, ear, and nose have been produced by AM. Biocompatibility of the produced organs have been significantly improved. Besides, AM has the advantage of producing individually matched organs that can be derived from the patient’s own medical imaging.

The inception of AM was based on production of nonmetallic parts, especially made of plastics. This posed a hindrance in its wide acceptability as most of the practical engineering components are metallic. However, substantial development in AM metal processing techniques over the past couple of decades has changed this scenario. Production of low-cost lasers, cheap high-performance computing devices, and development in feedstock technology (for producing metal powder) have made AM a front-runner production method [3] in today’s world. This is also evident from the rapid movement of the commercial AM machines out of the shelves. Although AM technique is found to be a champion among all the production methodologies, some optimization and fine-tuning with respect to material of feedstock, produce tailor-made materials, AM processes, surface finish, properties of the produced part in order to be able to yield defect-free, sound, and reliable AM components. Figure 1.2 shows some actual photographs of parts being manufactured by machining and 3D printing.

Figure 1.2: Parts being manufactured by (a) machining and (b) 3D printing (creative commons).

1.2 Evolution of additive manufacturing

1.2.1 Development of 3D printing

Modern AM technology or 3D printing, as it is known, was first realized around 1975 [2]. 3D Systems which was founded in 1986 is credited with selling the first commercial AM machine SLA-I. SLA-1 as the name suggests was based on stereolithography (SLA) technique of 3D printing. Progress in laser technology and material research paved the way for the first successful demonstration of this process. According to Bandyopadhyay and Bose [4], “SLA is a system where an ultraviolet (UV) light source is focused down into an UV photo-curable liquid polymer bath where upon contact, the polymer hardens. Patterns can be drawn using the UV source to semi-cure the polymer layer. Uncured polymer stays in the bath and provides support to the part being built. After a layer of printing is done, the hardened polymer layer moves down on a build plate in the liquid medium and the next layer of polymer is available on top for the following layer. This process continues until the part is finished based on the CAD design and is removed from the liquid medium. In most cases, further curing is needed before the part can be touched.” The first patent of an RP system (using SLA) was obtained in 1986 [4].

1.2.2 Advancement in other rapid prototyping techniques

Apart from development of SLA-based system, other techniques of 3D printing were also developed parallelly. Advancement ...

Table of contents

• Title Page
• Copyright
• Contents
• Preface
• About the Editor
• 1 Emerging trends in additive and subtractive manufacturing
• 2 State of the art of the fused deposition modeling using PLA: improving the performance
• 3 Development of the basic drill design for cored holes in additive and subtractive manufacturing
• 4 Additive manufacturing of magnesium alloys
• 5 Additive manufacturing for patient-specific medical use
• 6 Stereolithography and its applications
• 7 Ultrasonic-assisted deep-hole drilling
• 8 Information and computational modeling for sustainability evaluation and improvement of manufacturing processes
• Index