Adaptive Manufacturing: Reinventing Design and Manufacturing
ISO/ASTM 52900 defines additive manufacturing as the process of joining materials to make parts from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing and formative manufacturing methodologies. Additive manufacturing is also considered as a natural process like plant growth. It is now used in industries to manufacture engineering components.
A process that qualifies the below five criteria can be called additive manufacturing.
a. Process of joining of materials.
b. Sharing from three-dimensional (3D) model data.
c. Layer-by-layer build up approach.
d. Not subtractive manufacturing methodologies.
e. Not formative manufacturing methodologies.
Additive manufacturing is one of the nine technologies derived from the Industry 4.0 (I4.0) or the fourth industrial revolution. I4.0 is characterized on manufacturing and services by highly developed automation and digitalization processes, electronics and IT. It is a merger of the physical and virtual worlds to create a more holistic and better-connected ecosystem for manufacturing and supply chain management. It focuses on interconnectivity, automation, machine learning, and real-time data.
Why do we need additive manufacturing?
Additive manufacturing can help improve current manufacturing scenario and satisfy customer requirements. The technology used in additive manufacturing is quite advanced and it is known that with the use of superior technology, the success rate increases tremendously.
There’s cut-throat competition in the industry because of the presence of more players and models but reduced volume per product. In order to increase efficiency, the industry is fast moving towards adverse duty conditions and additive manufacturing can address this major concern.
Additive manufacturing offers an immediate delivery of the best quality product with maximum features at the lowest price. It eliminates a number of stages like procurement, documentation and quality control resulting in saving cost and time. Therefore, it is more efficient as compared to other conventional manufacturing methods.
Comparison with other manufacturing processes
Table 1: Comparison of Additive Manufacturing with other processes
Additive Manufacturing Methodology
It involves 3 stages – pre-processing, processing, and post processing. In the first stage, we create a 3D model from different sources which is then sliced into different layers. In the processing stage, the machine settings are adjusted and then the material is added in a layer-by-layer fashion. The post processing stage involves a treatment method which tailors the properties of the component as per the requirement of the customer to get the final desired product.
Image 1 – Additive Manufacturing Methodology
Classification of Additive Manufacturing
As per the American Society for Testing and Material (ASTM), it has been classified into 7 different processes.
a. Vat Photo-polymerization is defined as “an additive manufacturing process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization”. The major advantage of this process is high accuracy along with it being simple, compact, and high in quality. It is used for tooling applications, microfluids and medical purposes.
b. Material jetting is defined as an additive manufacturing process in which droplets of build material are selectively deposited. This process has high accuracy and offers great surface finish. It is used for medical, automotive, jewellery and electronics.
c. Material extrusion is defined as an additive manufacturing process in which material is selectively dispensed through a nozzle or orifice. This process costs low and doesn’t cause material wastage. It is simple and safe. On top of the applications alike material jetting, it is also used in aerospace, concept models and functional testing.
d. Binder Jetting is defined as an additive manufacturing process in which a liquid bonding agent is selectively deposited to join powder materials. This process doesn’t cause warping or require supports. It has great applications in biomedical, electrical, coloured prototypes and decorative art.
e. Sheet lamination is defined as an additive manufacturing process in which sheets of material are bonded to form a part. The advantage of this process is that there’s no thermal stresses involved, and we can have multiple materials as we are adding sheets in a layer-by-layer fashion.
f. Powder Bed Fusion is defined as an additive manufacturing process in which thermal energy selectively fuses regions of a powder bed. It’s the most commonly used metallic manufacturing process because of its ability to build highly complex engineering components.
g. Directed Energy deposition (DED) is an additive manufacturing process in which focused thermal energy is used to fuse materials by melting as they are being deposited. The source of the energy could be a laser, wire, an electron beam or an arc. This is the second most commonly used technique. This process has a high deposition rate and is used for repairing of components and biomedical.
Image 2: Classification of Additive Manufacturing
Design for additive manufacturing
The conventional manufacturing doesn’t give us the design freedom whereas additive manufacturing can be used to design complex components.
Three methods are designed for additive manufacturing, namely Direct part replacement, adapt for additive manufacturing and design for additive manufacturing. These methodologies are three stages of implementing additive manufacturing in industries and are analogous to crawl, walk, and run for companies.
In Direct part replacement, only the manufacturing process is changed from conventional to additive manufacturing. For example: Reverse Engineering and fabrication of spare parts. In adapt for additive manufacturing, form as well as the process changes, but the functionality remains untouched. The non-functional parts are modified to reduce the cost and material usage. The final stage of the process involves a change in form, fit, function, and process using the complete freedom. The designer has complete freedom to redesign the component from scratch. This can transform the designing process from ‘Design for manufacturing’ to ‘Feature-based Design and Manufacturing’.
Advantages and Limitations
Complexity doesn’t affect the cost of additive Manufacturing. Since it’s a contactless process, part fixturing is simple. Other advantages of additive manufacturing include, mass customisation, integrated components, reduced wastage, material design freedom, and logistics freedom.
There are some limitations attached to additive manufacturing such as high production costs, limited build volume, different mechanical properties, requires post processing treatment and stair stepping effect.
Table 2: Challenges and Opportunities
Conclusion
Additive Manufacturing is a process of joining materials to make parts directly from 3D Model following layer-by-layer approach. The advantages of additive manufacturing cannot completely replace other manufacturing processes, but can co-exist with other existing manufacturing processes, where it has distinct techno-economic advantage. Additive Manufacturing is one of the nine pillars of Industry 4.0 which has its own unique challenges and opportunities that are important to understand before taking this technology forward.