Why Composites and Additive Manufacturing?
Advanced Additive Manufacturing for Composites (AAMC): Given the order of improvement in additive manufacturing (AM), it holds the potential to bring change to many industries. This is mainly due to its capability of producing parts with high geometrical complexity, short manufacturing lead times, and suitability for customization as well as for low-volume production. If you're new to AM, check out our article called Additive Manufacturing (AM): From Prototyping to Production.
On the other hand, composites have already proven performance and durability, as evidenced by aircraft fuselages; where weight reduction combined with the demanding physical properties is of utmost importance. Modern technical requirements need composite materials with unusual combinations of properties that cannot be solely provided by metals, polymers, or ceramics.
In this case composite materials, consisting of two or more individual components, allow having the preferred combined properties all at once. Thus, AM of composites is a key component of Advanced Additive Manufacturing and is becoming more and more important for critical applications.
What are the key technologies behind AAMC?
The AM Approach
Fused deposition modeling (FDM) is one of the AM technologies and a widely used method for fabricating thermoplastic parts with advantages such as low cost, minimal waste, and ease of material change. Some of the key players who have brought commercial solutions to the market are:
Markforged: Nylon reinforced with continuous fiber, 2D layer
9T Labs: PA12 reinforced with continuous fiber, 2D layer
Arevo Labs: PLA/ABS reinforced with continuous fiber, 3D layer
BAAM, ORNL: PLA/ABS reinforced with chopped fiber, 2D layer
Selective laser sintering (SLS) is one of the AM technologies that uses a laser as the power source to sinter powdered material (typically nylon or polyamide), aiming the laser automatically at points in space defined by a 3D model, binding the material together to create a solid structure. Some of the key players who have brought commercial solution in the market are
Impossible objects’ composite-based AM (CBAM) technology
EnvisionTEC thermoplastic reinforced woven composite printer, SLCOM (Selective Lamination Composite Object Manufacturing)
Limitation of the AM approach
Although the additive manufacturing of polymer matrix composites has gone through a significant improvement in recent years, it is still not widely adopted by various industrial sectors for functional applications. Several limitations that need to be overcome are demonstrated in Figure 1 below. These problems are very similar to other AM techniques, such as direct metal laser sintering, which are more mature and overcome these restrictions for a wider infusion into the industry. There is a wide application of AM, and the amount of interest in industry and academia for producing polymer matrix composites has been growing significantly, and this is expected to continue exponentially in the coming years.
Proven digital composite production
High-quality composites parts with proven applications are already running in most performance-critical industries e.g. Space, Aerospace and Defense. The main automated system is Automated Tape Laying (ATL) system. This utilizes a single, wide, unidirectional, slit tape to layup simple, gentle contours or flat parts. There are two broad categories, first with traditional large part size players, second is the new entrants focusing on smaller and more complex shapes.
Traditional large part size ATL providers
MTORRES: Thermoset/Thermoplastic plastic on Gantry
Mikrosam: Thermoset/Thermoplastic on Gantry/Robotic Arm
Electroimpact: Thermoset/Thermoplastic on Gantry
Coriolis: Thermoset/Thermoplastic on Robotic Arm
Broetje-Automation: Thermoset/Thermoplastic on Robotic Arm
Airborne: Thermoset/Thermoplastic plastic on Robotic Arm
Automated Dynamics: Thermoplastic on Robotic Arm
Key highlights of traditional ATL systems
High quality and repeatability in production
High capital investment in the equipment and facility
Limited in shapes: Can do only very gently curvature or flat parts
Long lead times of system acquisition
New entrant small part size complex shapes ATL provider
The entrants are focusing more on the compact systems that can be operated by much smaller robots.
Addcomposites: Thermoset/Thermoplastic plastic (low temp) on Robotic Arm
Conbility: Thermoset/Thermoplastic (high temp) on Robotic Arm
Cevotec: Thermoset on Robotic-arm for geometrically complex reinforcements
Key highlights of new entrant ATL systems
Quick and easy to get started
Low to No Capex with the subscription model
Small part size; typically 1–2 sq. m.
Relatively low throughput
Why should companies apply advanced additive manufacturing of composites in their production?
Be it from the AM approach or proven digital composite production approach, there are key benefits of applying lightweight digital production in your workshop.
Product quality and reliability
In a world where social media has made the voice of the customer far more public, warranty returns and defective materials that elude quality assurance practices and make it into the field can be very damaging to the reputation of manufacturers. Additionally, the cost and time associated with rework parts during the manufacturing process is delaying production. If the matrix is applied too thick, the surface becomes susceptible to cracking – too thin and the gel coat won’t cure correctly, resulting in durability and appearance concerns. A robotic solution provides a repeatable outcome that can improve these product quality and performance issues through increased consistency and uniformity.
Material savings and wastage
Reducing waste at the point source of origin is the key to material savings. Robots and their dispensing systems are very accurate, with precise trigger timing and constantly repeatable motion dramatically reducing variance in the amount of material used. A robotic application pattern reduces excess material placement, leading to material optimization and a reduction in material waste. Closed loop material delivery systems can be included in a robotic solution to monitor and provide consistent fiber application, adjusting the material feed delivered in line with minor changes in the manufacturing environment.
Shorter cycle times
A robot can repeat difficult ergonomic tasks with speed and accuracy. Normally, the robot is limited by the application speed, which best practice may dictate as 500 mm/s, however the robot is able to transition between trigger ON and OFF points at much greater speeds. Assuming consistent operation, it is typical that a robotic cycle time will be less than compared with manual operation, and the layer application is typically more uniform. A robotic solution is often able to operate across multiple shifts, amortizing the value of the equipment and the factory when competing on a global platform for manufacturing economies of scale.
Increased employee safety and the environment
Removing manual operators from potentially hazardous fumes in a resin or fiber application can support improvements in workplace safety. Robots can be designed to operate in Class 1 Division 1 environments, meaning potentially hazardous tasks can be completed in a far safer manner, reducing the exposure of employees in a manufacturing facility to potentially hazardous environments.
The environmental, financial and quality benefits of introducing