BUS606: Operations and Supply Chain Management

As has been discussed throughout this paper, additive manufacturing (AM) processes are considered in many applications as a new industrial revolution. This article conducts an exhaustive study of the current state of additive manufacturing. As is shown in Table 2, the technologies and processes that currently exist are very diverse and, therefore, producing a classification that unites and differentiates all of them being truly complex. Thus, this paper proposes several types of classifications.

Over recent years, many names have arisen to encompass these technologies, such as "rapid prototyping", "rapid tooling", "3D printing", and "freeform fabrication". All of these are commonly accepted; however, "additive manufacturing" is probably that which best brings them all together.

The main advantages associated with these technologies are the high precision, the possibility of using different materials, and the ability to obtain impossible prototypes using conventional means. The current limitations include the high cost of the processes, the time required to obtain the prototypes, and perhaps the lower resistance they have. Active work is underway to improve these limitations in order for additive manufacturing to be competitive with regard to other more conventional means.

It is important to note that within additive manufacturing there is no perfect technology for all purposes, rather what we need to do is to determine the most suitable technologies for a specific use.

For example, in the dental sector, as is discussed by Jiménez et al., in order to manufacture the models used in the thermoforming of correction splints, technologies based on printing by injecting resin (IJP-UV), digital light processing (DLP), and fused deposition modeling (FDM) are the most suitable as they offer the best price-quality ratio of the model for thermoforming.

Among the agents in the aviation market, metal material additive manufacturing technologies, such as 'Electron Beam Melting' (EBM), 'Sintering Laser Melting' (SLM), or 'Laser Cladding' (LC), are those that attract most interest, in particular, for part manufacturing, case of the OEM or Tier1; or for part repair, case of the 'Maintenance and Repairing Overhaul' (MRO). These manufacturing technologies provide many advantages in comparison with other conventional metal transformation processes.

Changing sector, 3D printing of architectural models will lead to a reduction in the number of steps, an improved design timeframe, and the preservation of the finer details of the final architectural design, and therefore its market niche is on the rise. As discussed by Domínguez et al., fused deposition modeling machines appear among the most suitable for obtaining working models, given their low cost (especially in the case of the RepRap models), the speed of the process, and the possibility of recycling the material. Machines projecting binding agent would also be suitable for obtaining models for the client, thanks to their competitive prices, good surface finish, wide range of colours, and lack of support fixtures, among other qualities. Although, perhaps, the method most used for architecture is printing via the sintering of composite powder, this material requires a postprocess to harden it and give it the necessary consistency and finish for an optimum result. In any case, it is certainly true that, right now, no technology fully meets all of the requirements of the work specifications in the field of architecture and construction. Thus, this sector still has quite a long way to go.

PolyJet technology produces ultradetailed prototypes, moulds, and even final parts that incorporate smooth rigid, transparent, and flexible materials, which is why it has been the technology most used in the jewellery sector in recent years. Multimaterial 3D printers produce lifelike models with a variety of properties on a single build tray. Regarding jewellery, one of the advantages of using 3D printers is speed. The plastic parts take 7 to 10 days to be made, whereas metal parts take 10 to 15 days. Other positive points include the cost saving and the fact that it is possible to retouch the jewellery while it is being printed.

4.1. Immediate Future of Additive Manufacturing

In production lines, one of the main focal points for improvement in additive manufacturing consists of optimizing its features in order to be competitive with regard to conventional manufacturing processes in different production lines. In comparison with the traditional means, the use of additive manufacturing technologies continues to be too costly.

An important niche for saving in the industrial sector would be the so-called virtual libraries. There is a large number of fixed assets in all industrial platforms within what is known as physical replacement parts, spare parts, etc. Many of these items could be saved by means of a virtual parts library, which could print suitable parts or components as and when required.

Another important section is that of the study of new materials. Cellulose, the plant material we have used for centuries to make paper, has emerged as a new resource for better, faster, and cheaper three-dimensional printing, in addition to providing an alternative that is recyclable and biodegradable by nature, according to new research by the MIT, published in Advanced Materials Technologies. At present, the key raw material for 3D printing is polymers, compounds that are largely synthetic and which use inks to create three-dimensional objects in accordance with the models via a computer used to execute the three-dimensional printing.

A particularly interesting field and one for study is that of the space sector, where additive manufacturing should also play an important role. The National Aeronautics and Space Administration of the US (NASA) is seeking a habitat design built using a 3D printer that can be used as a base to build houses on the surface of Mars. The final objective is to achieve a space design that allows astronauts to stay on the red planet for long periods at a time. Different projects are being carried out to conduct research on materials and explore the possibilities of 3D technology, which would mean many of the necessary infrastructures could be directly built on the Moon using, moreover, resources that are already there. This would speed up this large undertaking, as it would notably reduce the amount of parts that would need to be taken to the Moon and then later to Mars. 3D technology and the use of resources may help reduce costs both in the long and in the short term.

4.2. Connected Industry: Future Prospects of Additive Manufacturing in the 4.0 Environment – A Study Is Conducted on the Possibility of Positioning Additive Manufacturing in a Service Environment

The term Industry 4.0 was coined to describe the smart factory, a vision of computer-aided manufacture with all of the processes interconnected through the Internet of things (IOT). It is what we know as the industrial Internet of things, I2OT.

It is hoped that the new concept of industry 4.0 will be able to drive forward fundamental changes on the same level as the steam-powered first industrial revolution, the mass production of the second, and the electronics and proliferation of information technology that characterised the third.

According to Mark Watson, associate director for the industrial automation of IHS, "The challenge for the fourth industrial revolution is the development of software and analytical systems that turn the deluge of data produced by intelligent factories into useful and valuable information".

Factories with fully computerized production processes are better prepared to respond faster to changes in the market, as they have integrated greater flexibility and individualization in their manufacturing processes.

However, in order to obtain real improvements in manufacturing efficiency and flexibility, manufacturers must be able to manage and analyse large amounts of data, the biggest challenge of which will be regarding software. Companies should implement Big Data systems capable of managing large amounts of data from the manufacturing environment and conducting an intelligent real-time analysis, providing valuable information for decision-making, thus optimizing the processes and increasing business intelligence.

Industrial companies have to take the technological leap to Industry 4.0, in the field of additive manufacturing. The concepts and experiences being accumulated in companies and research institutes need to be passed on to companies by means of guided visits to leading facilities, induction and practical training, guided training, diagnosis, specific advice, testing, and prototypes.

Why should additive manufacturing be introduced in companies in a connected industry setting? The answer is simple: because the following can be achieved:

1. Creative product design
2. More customised products with high quality and performance
3. DDM (demand driven manufacturing) with less waste generated and efficient use of energy
4. Internet (EICTs in general) as a tool with a high potential to support new supply chain models
5. The consumer as designer and "customiser"
6. Additive manufacturing as enabling technology
   

4.3. Additive Manufacturing and B2C/B2B

The majority of the work on systematizing and disseminating sales experience and on the techniques, methods, texts, and sales and marketing courses focuses on selling to the consumer, what we call B2C (Business-to-Consumer). However, the volume of business generated by sales to other companies, B2B (Business-to-Business), is much higher, not to mention complex and different.

Additive manufacturing can take the shape of a service activity and, therefore, it needs to adapt to ensure that the companies that are willing to provide this service obtain higher growth and profitability on sales to other companies and organizations and also on sales to the consumer, taking into account the final destination of the additive manufacturing service.

The current problem is that there is no vertical platform that organises the advanced manufacturing technologies and customised manufacturing based on additive manufacturing (3DP.)

Current service providers partially facilitate the transaction for 3DP solution companies. It must be ensured that additive manufacturing is on the cloud as a reliable service based on the fact that clients manage the details of their manufacturing project in real time: material, size, delivery time, quality, price, location, and catalogue payment (direct e-commerce selection), by means of a quotation or offer.

A global platform must be configured as a network of 3DP services: marketplace for B2B vertical offering (Figure 1). The service portfolio should be built around the following activities:

Business model: marketplace, all agents, all orders (large series focus), matrix selection, web location, and real-time all-agents capacity management.

1. Market: B2B focus (could do B2C), KPI-customised orders.
   
2. Value Chain: global E2E services to B2B vertical clients.
   
3. Technology: E2E open API connecting in real-time clients and provider's ERP.
   
4. Product: Manufacturing and high quality / high definition.
   
5. Expertise: Institute 3DP: industry, research centres, universities ecosystem.
   

However, the development of additive manufacturing does not stop there; the following step was what is now called "bioprinting", which is the printing of cells and living tissues. The interest in this is mainly due to the shortage of organs available for transplant and the possibility of avoiding rejection if the organ required can be successfully printed using the individual's own cells. Nevertheless, its use is very important in research on new drugs in order to reduce the use of laboratory animals.

3D printing of living cells usually requires the deposition of cells and also the deposit of the support element or matrix. This matrix, the place where the cells are going to grow, where nourishment will be found and on which the structure is to be formed, may be liquid, usually called bioink, paste-like, rigid solid, or elastic solid. Also, solid materials in particular may or may not be biodegradable.

The issue of biodegradation is an added factor in this technology, as if this biodegradation occurs too quickly; we will not obtain the desired results; however, if it occurs too slowly, there is a possibility that the structure will prevent the development of the cells and so, in the end, we will not obtain the desired results this way either. This is why bioprinting is currently the focal point of the majority of research projects: it is anticipated that bone regeneration, printing different vital organs, printing human skin, etc., will be functionally viable in the near future, as prostheses currently are.