Using computer aided design (CAD) or 3D object scanners, additive manufacturing allows for the creation of objects with precise geometric shapes. These are built layer by layer, as with a 3D printing process, which is in contrast to traditional manufacturing that often requires machining or other techniques to remove surplus material.
Additive Manufacturing Technologies
AM technologies can be broadly divided into three types.
The first of which is sintering whereby the material is heated without being liquified to create complex high-resolution objects. Direct metal laser sintering uses metal powder whereas selective laser sintering uses a laser on thermoplastic powders so that the particles stick together.
The second AM technology fully melts the materials, this includes direct laser metal sintering which uses a laser to melt layers of metal powder and electron beam melting, which uses electron beams to melt the powders.
The third broad type of technology is stereolithography, which uses a process called photopolymerisation, whereby an ultraviolet laser is fired into a vat of photopolymer resin to create torque-resistant ceramic parts able to endure extreme temperatures.
Similar to standard 3D printing, AM allows for the creation of bespoke parts with complex geometries and little wastage. Ideal for rapid prototyping, the digital process means that design alterations can be done quickly and efficiently during the manufacturing process. Unlike with more traditional subtractive manufacturing techniques, the lack of material wastage provides cost reduction for high value parts, while AM has also been shown to reduce lead times.
In addition, parts that previously required assembly from multiple pieces can be fabricated as a single object which can provide improved strength and durability. AM can also be used to fabricate unique objects or replacement pieces where the original parts are no longer produced.
Material waste reduction
In conventional manufacturing processes, material is typically removed from a larger piece of work; think timber milling or cutting shapes from sheets of steel. In contrast AM starts from scratch, adding material to create a component or part. By using only the substance necessary to create that part, AM ensures minimal waste. AM also reduces the need for tooling, therefore limiting the amount of material needed to produce components.
Manufacturing and assembly
A significant benefit of additive manufacturing is the ability to combine existing multi-part assemblies into a single part. Instead of creating individual parts and assembling them at a later point, additive manufacturing can combine manufacturing and assembly into a single process. Effectively consolidating manufacture and assembly into one.
Additive manufacturing is appealing to companies that need to create unusual or complex components that are difficult to manufacture using traditional processes. AM enables the design and creation of nearly any geometric form, ones that reduce the weight of an object while still maintaining stability. Part flexibility is another major waste reduction aspect of AM. The ability to develop products on-demand, inherently reduces inventory and other waste.
AM has gifted companies the ability to recreate impossible-to-find, no longer manufactured, legacy parts. For example, the restoration of classic cars has greatly benefited from additive manufacturing technology. Where legacy parts were once difficult and expensive to find, they can now be produced through the scanning and X-ray analysis of original material and parts. In combination with the use of CAD software, this process facilitates fast and easy reverse engineering to create legacy parts.
Inventory stock reduction
AM can reduce inventory, eliminating the need to hold surplus inventory stock and associated carrying costs. With additive manufacturing, components are printed on demand, meaning there is no over-production, no unsold finished goods, and a reduction in inventory stock.
In conventional manufacturing, machinery and equipment often require auxiliary tools that have greater energy needs. AM uses fewer resources, having less need for ancillary equipment, and thereby reducing manufacturing waste material. AM reduces the number of raw materials needed to manufacture a product. As such, there is lower energy consumption associated with raw material extraction, and AM has fewer energy needs overall.
AM manufacturing offers design innovation and creative freedom without the cost and time constraints of traditional manufacturing. The ability to easily alter original specifications means that AM offers greater opportunity for businesses to provide customised designs to their clients. With the ease to digitally adjust design, product customisation becomes a simple proposition. Short production runs are then easily tailored to specific needs.
Production costs are high. Materials for AM are frequently required in the form of exceptionally fine or small particles that can considerably increase the raw material cost of a project. Additionally, the inferior surface quality often associated with AM means there is an added cost to undertake any surface finishes and the post-processing required to meet quality specifications and standards.
Cost of entry
With additive manufacturing, the cost of entry is still prohibitive to many organisations and, in particular, smaller businesses. The capital costs to purchase necessary equipment can be substantial and many manufacturers have already invested significant capital into the plant and equipment for their traditional operations. Making the switch is not necessarily an easy proposition and certainly not an inexpensive one.
Currently there is a limit to the types of materials that can be processed within AM specifications and these are typically pre-alloy materials in a base powder. The mechanical properties of a finished product are entirely dependent upon the characteristics of the powder used in the process. All the materials and traits required in an AM component have to be included early in the mix. It is, therefore, impossible to successfully introduce additional materials and properties later in the process.
A certain level of post-processing is required in additive manufacturing because surface finishes and dimensional accuracy can be of a lower quality compared to other manufacturing methods. The layering and multiple interfaces of additive manufacturing can cause defects in the product, whereby post-processing is needed to rectify any quality issues.
As mentioned, additive manufacturing technology has been around since the eighties, yet even in 2021, AM is still considered a niche process. That is largely because AM still has slow build rates and doesn’t provide an efficient way to scale operations to produce a high volume of parts. Depending on the final product sought, additive manufacturing may take up to 3 hours to produce a shape that a traditional process could create in seconds. It is virtually impossible to realise economies of scale.
New Applications of additive manufacturing
The rapidly innovating medical industry utilises AM solutions to deliver breakthroughs in functional prototypes, surgical grade components, and true to life anatomical models. AM in the medical field is producing advancements in the areas of orthopaedic implant and dental devices, as well as tools and instrumentation such as seamless medical carts, anatomical models, custom saw and drill guides, and custom surgical tools.
Material development in the medical industry is critical with the certified biocompatible materials potentially revolutionising areas of customised implants, and the life-saving devices and pre-surgical tools to increase patient results.
The transportation industry requires parts that withstand extreme speeds and heat, while still being lightweight enough to avoid preventable drag. The benefit of additive manufacturing’s ability to develop lightweight components has led to more efficient vehicles.
Many of the AM applications transforming the transportation industry include complex ductwork that is unable to be fabricated using conventional methods, resilient prototypes, custom interior features, grilles, and large panelling.
Marketing teams, designers, and graphic artists function to form ideas and deliver products to market as quickly as possible while adapting to fluctuating trends and consumer demand. Part of this process is spent simulating the look and feel of the final product.
With some of the most demanding industry standards in terms of performance, the aerospace industry was one of the first to adopt additive manufacturing. The commercial and military aerospace domain needs flight-worthy components that are made from high-performance materials.
Additive manufacturing’s innovation in producing efficient, on-demand, lightweight components has driven success in the energy sector. Centring on AM’s capability to quickly create tailored components and environmentally friendly materials that can withstand extreme conditions.
Key AM applications that have developed in the gas, oil and energy industries include various control-valve components, pressure gauge pieces, turbine nozzles, rotors, flow meter parts, and pump manifolds. With the capability to develop corrosion resistant metal materials AM has the potential to create customised parts for use under-water or other harsh environments, associated with the industry.