Additive Manufacturing for Industrial Applications

What are the main challenges and opportunities in developing applications to improve Industrial performance?

Industrial manufacturers in all sectors, from aerospace to everyday consumer goods, via medical applications and household appliances (to name only these), are looking for applications that will improve their industrial performance and agility to respond to changing needs. Industry 4.0, as it is referred to, is radically transforming how industrial companies design, manufacture, streamline and deliver products and services. To enable these improvements, they are integrating new, smart and self-learning technologies, including the use of collaborative production lines and machine learning using the Internet of Things (IoT), big data, cloud computing, analytics and AI into their entire processes and facilities throughout their operations.

For several years now, Additive Manufacturing has been an essential part of this revolutionary change in production. Its best-known and most widespread use has been upstream in the design process, enabling direct rapid prototyping using Computer-Aided Design (CAD) systems and data.

Downstream, in the actual physical production process, Additive Manufacturing has become a key technology for the fabrication of customized products which cannot be produced by traditional mass manufacturing methods. This means that companies can produce complementary customized parts in smaller batches to create especially sophisticated objects and parts with advanced features using new materials: complex shapes, specific mechanical properties, resistance to harsh environmental conditions, different degrees of hardness and/or flexibility, shape memory, etc.

Additive Manufacturing is useful in many operational applications, such as manufacturing spare parts rapidly close to the customer’s manufacturing facilities (or even within their facilities), retrofitting of critical parts with more durable and reliable materials, making new parts with enhanced aesthetic or comfort characteristics, etc.

Additive Manufacturing is therefore at the cutting edge of new manufacturing processes, but also driving the development of new business models, such as decentralized production, particularly important in our age of unstable supply chains, increased transportation costs and the need for companies to provide products on time to businesses and consumers.

Additive Manufacturing is not only more efficient but is also more sustainable since it is less wasteful, using only the materials that ultimately make up the final product.

Where is additive manufacturing most used in industrial applications and how does it provide added value?

The sky’s the limit

Historically speaking, Additive Manufacturing was first used in aerospace and defense applications as early as 1990. Initially used to make functional and rapid prototypes upstream and lightweight components downstream. The aerospace and defense industries have continued to be at the forefront of Additive Manufacturing innovation, with a multitude of applications including:

• Limited series of complex shapes and multiple materials, without the need to produce expensive tooling or molds
• Greater precision and reduced weight when using new materials such as silicones to replace certain thermoplastics, metals or alloys resulting in cost savings, reduction in energy consumption and lower costs per unit.
• Additive manufacturing is also increasingly used to provide the support structurers for thin-wired sensors or antenna which often must be lodged in small and hard-to-reach places, which are often subjected to high vibrations. In this case, silicone is the perfect material to meet all these needs.
• Flexibility, by enabling multiple parts into a single component and reducing assembly time.
• Lower maintenance costs, resurfacing of partly worn-out parts and the ability for retrofitting aircrafts that have been in service for long periods of time, both for functional parts and interior areas: new seats, wall panels, safety lighting, ventilation valves, etc.

Down to earth

The automotive industry was also an early adopter of Additive Manufacturing and is the fastest-growing sector for its use: moving from $1.4bn in 2019 to a forecast $5.8bn in 2025. With rapid prototyping still being the main application, it is increasingly being used for tooling, spare parts and customization. Beyond that, Additive Manufacturing is also being implemented for the production of complex shapes and parts using multiple materials, such as fine-mesh wiring in electrical vehicles (EVs) that need to be flexible, properly insulated and capable of withstanding extreme temperature changes. This gives designers greater freedom, but also contributes to streamlining assembly processes.

For all these reasons, silicone has become a material of choice for all areas of the automotive industry. Also, automotive manufacturers and parts suppliers have used silicones for several decades for a great variety of applications, such as waterproofing joints or gasketing and so have built up knowledge of its versatility and established a close relationship with silicone makers to develop innovative new applications collaboratively, a key consideration in choosing materials for Additive Manufacturing.

Fast-moving innovations

Additive Manufacturing is also a key contributor to meet one of the biggest and most added- value trends in consumer goods: personalized products. To begin with, Additive Manufacturing is a true accelerator of prototyping and upstream market testing, enabling the production of small batches of attractive and high-potential products for customer appreciation before ramp-up to serial production. Once launched onto the mass market, products can then be customized to meet individual needs. This is especially interesting for sport, leisure and luxury products, but is also being extended to various other consumer sectors, such as cooking and kitchenware, household appliances, fixtures and furniture, etc. From an industrial standpoint, Additive Manufacturing opens new horizons and, from a consumer standpoint, it means greater choice, but also meets their increasing desire for more environmentally friendly and sustainable products, since waste is greatly reduced in the fabrication process.

The human touch

Silicones have been used for medical and dental applications for a long time and Additive Manufacturing has become a key technology in developing new ways of making prostheses and other personalized treatment systems. For more in-depth information on the use of Additive Manufacturing in healthcare, we invite you to check out our fourth blog in this series.

What are the benefits of using silicones for Additive Manufacturing?

While we have looked at Additive Manufacturing in general, we would like to focus briefly on why silicone elastomers are increasingly becoming a material of choice in this new and exciting area of industrial production. Silicone polymers, to begin with, offer enormous versatility thanks to their unique molecular structure, based on silicate derivatives that integrate both inorganic and organic molecules, such as carbon, hydrogen and oxygen. This provides scientists, designers, developers and manufacturers with the possibilities of creating customized solutions that provide a wide range of characteristics, including:  

• Greater resistance to temperature variations in functional parts, ranging from -50°C to 250°C and beyond
• Enhanced chemical stability, even when exposed to harsh and aggressive substances
• Efficient electrical and thermal insulation
• High abrasion and vibration resistance
• Long-term weatherability when exposed to wind, precipitation, sunlight, UV rays and Ozone
• Low toxicity and higher biocompatibility than most other elastomers
• Strong mechanical properties, including maximum elongation and tensile strength, resulting in durable and efficient elasticity.

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What is the particular advantage of silicone elastomers in Additive Manufacturing?

Elastomer materials are available in various formats that can be adapted to different Additive Manufacturing processes. In our previous blog, we compared silicone-based elastomers to TPEs. We explained that one of the most significant advantages of silicone elastomers is that they are available in many formats and with customizable features to meet different processing specifications and end-product requirements. For example, silicones are available as liquids (in various viscosities) and pastes, are non-meltable (therefore withstanding high temperature variations) and are irreversible because of their covalent crosslinks.

Manufacturers have used and continue to use silicone elastomers in many types of processing – including injection molding, calendaring, cast molding, spraying, coating, sheet lamination, etc. They have grown to trust and appreciate silicones and know that they can be adapted to Additive Manufacturing or 3D printing when properly formulated and when used with the right printers.

ISO (International Organization for Standardization) has categorized seven types of Additive Manufacturing processes, three of which are particularly well suited to the use of silicone polymers:

• UV-Vat (also known as stereolithography)
  • Higher viscosity silicone materials
  • Curing by photopolymerization
• Material Jetting
  • Very low viscosity silicone materials
  • Choice of curing methods, including photopolymerization, condensation or hydrosilytation (polyaddition
• Material Extrusion
  • Highest viscosity silicone materials
  • Choice of curing methods, including photopolymerization, condensation or hydrosilytation (polyaddition)

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To summarize the advantages for Additive Manufacturing, the variable viscosity of silicone elastomers allows the material to flow at the required speed, is easily cured (usually at room temperature) and is appropriate for both prototyping or end-use. Silicone elastomers offer different degrees of hardness and are flexible, with the capacity to be deformed according to different criteria and return to their original shape. They can be therefore designed to meet a very wide range of needs: resistance to heat and extreme conditions, conductivity, insulation, etc.

As Additive Manufacturing techniques evolve and as applications in an increasing number of industries are developed, elastomers (and silicones in particular) are becoming materials of choice for end-to-end solutions, from rapid prototyping to serial manufacturing, via customized batches to spare parts replacement. Elastomers must be carefully assessed and tested through collaboration between silicone makers and design and manufacturing experts so that they are adapted to current or future manufacturing processes.