Automated Fiber Placement
Automated Fiber Placement (AFP) is an additive manufacturing process that has three different inputs: fiber/polymer tape, heat, and pressure. The end-effector expertly handles the tape and deposits it onto a surface with the help of heat and pressure. The process allows the fabrication of highly customized parts as each ply can be placed at different angles to best carry the required loads. The use of robotics gives the operator active control over all of the process's critical variables, making the process highly controllable and repeatable. This process can result in additively manufactured composites parts that are two times stronger than steel at one-fifth of the weight.
Where does it belong in the composites manufacturing processes landscape?
Automated Fiber Placement is part of a family of manufacturing techniques, which refer to the precise laying of continuous fiber tapes to manufacture multi-layered composite products, typically with significant strength.
These techniques include:
Automated Tape Laying (ATL) – manufacture of products typically using a single wide tape (up to 300 mm). Typically used for the manufacture of large flat parts, such as the skins of aircraft wings
Automated Fiber Placement (AFP) – manufacture of products using narrow tapes (usually 1/4'' to 1'' inch). The use of narrow tapes allows for more complex layup geometries than ATL.
AFP vs. ATL
Automated Tape Laying (ATL) is the precursor to Automated Fiber Placement (AFP), and in many ways is similar to AFP. For example, both processes achieve high levels of material deposition on a form and feature increased levels of reliability, repeatability, and capability when compared to the hand placement of material. The types of material used in both AFP and ATL are similar, usually, both are pre-impregnated unidirectional fiber.
Although the material is oftentimes the same fiber and resin as used in ATL and AFP, wider material directly affects manufacturing capabilities. Wider material is more prone to process failure when deposited on non-flat surfaces, such as the fiber folding during layup. As a result, almost all ATL applications feature a large, flat surface. Too much curvature on a form can render ATL incapable of being used without producing significant defects. Therefore, prime applications of ATL include aircraft stringer charges and other flat parts that can be easily kitted together for gains in manufacturing efficiency. AFP on the other hand can perform complex shapes while having fewer defects on the complex shape. Additionally, the material savings significantly increases, while maintaining high production rates.
Automated Fiber Placement Manufacturing Process
AFP systems consist of the following components:
AFP tool mounted onto a robot
Automation control system
Planning and Simulation software
AFP tool mounted onto a robot
The AFP toolhead handles either one tape or multiple narrow tapes and lays them down on a predefined mold surface in a specific manner.
The material can either be mounted directly on the toolhead or separate from the system entirely, and then routed through various mechanisms to reach the head. Each material has it's handling challenges, i.e. thermoset materials require additional cooled passage while thermoplastic tapes require a lot of heat at the endpoint of the tool.
Automation Control System
The automation control system ensures the communication between the robot and the tool, including its sensors and actuators. The AFP tool can be connected to multiple robot brands such as KUKA, ABB, Fanuc, etc., so it is very critical to ensure seamless communication with the robot. The automation system uses the fastest available protocols to communicate with the robot controller, ensuring instant signal sending/receiving.
Planning and Simulation
Over recent years there have been great advances in the optimization of AFP layups using simulation software such as AddPath. As a consequence, it is now possible to design a part and simulate its manufacturing via AFP offline. Composite design software tools take into account AFP manufacturing requirements at an early stage in the product development cycle allowing all the benefits of close-knitted design transfer to the final manufacturing process.
User interaction data suggests the difficulty no longer lies with validating the concepts, but instead with figuring out how to maximize the potential of automation. Money fades whenever this equipment performs non-value-added tasks. Consequently, AFP owners want to eliminate unnecessary operations so the machines can focus on production. Through the use of advanced simulation tools, composites programmers can optimize their programs before they ever run, thus increasing up-time and freeing the system to manufacture valuable products. The key value such simulation software brings are:
Simulation to eliminate costly “dry runs.”
Compiled data to improve cycle-time estimates and help with process planning.
Detect robot singularities and range of motion issues, enabling virtual modification.
Identify and avoid inconsistent heating during layup.
Designing parts for AFP
We talk about this subject here. Things to consider when Designing for ATL/AFP Manufacturing
Pros and Cons of Automated Fiber Placement
Compared to other composite fabrication methods there are a number of key advantages and disadvantages of using AFP. These include:
Automation benefits - lower labor cost and higher production rates
Repeatable production with high traceability
High quality and accuracy of placement
Low material wastage
Monthly rental of AFP (read more here)
Reinforce 3D printed parts
3D print and finish the mold, then a layup and post-process the part all with the same robot cell
Layups with Thermoset, Thermoplastics, and Dry fiber.
Create preforms and final part shapes
Restrictions of part shape
The Future of AFP
The ongoing push for faster deposition rates, the development of new material combinations, and the increased pressure on cost reduction mean that AFP will continue to evolve in the coming years. It is expected that thermoplastics will continue to replace thermosets as the preferred polymer matrix. In addition to making better and cheaper AFP tools, they will also decrease in size, enabling a greater diversity of products to be made, and Addcomposites is at the forefront of these innovations.
The article is inspired by a similar title published by Coventive explains. The original article can be read here!