Automated fiber placement (AFP) is a process used to manufacture composite materials in which continuous fibers are placed onto a substrate using a specialized machine. The process has been around for decades and has undergone numerous developments to improve efficiency and quality. Today, AFP is widely used in various industries for the production of composite parts with improved mechanical properties, fatigue life, and fracture toughness.
In this chapter, we will discuss the history and development of automated fiber placement systems, as well as their benefits and limitations. We will also cover the role of automation and robotics in the AFP process, and how to program and operate these systems. Additionally, we will explore the composites' design lifecycle and the potential applications of automated fiber placement systems. Overall, this chapter aims to provide a comprehensive overview of the automated fiber placement process, including its history, benefits, and potential applications.
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AFP Process Description
In an automated fiber placement process, an AFP head is attached at the end of an industrial robotic arm that is simulated and programmed using digital twin software like AddPath. As the AFP process is running, the head moves and places multiple strips of composite material tapes, or tows onto a tool surface. It is crucially important for the tape/tows to adhere with minimal defects. To ensure adhesion between incoming tows and substrate the fiber placement head utilizes heating and compaction. Tow tension plays a key role in ensuring the accurate placement of the tow. Each row of tows forms a course. Put together in a surface slice the course forms a ply, and all plies stacked together in a precise sequence form a laminate.
Role of automation and robotics in the AFP process
The use of robotics allows for precise and repeatable placement of the tows onto the substrate, with a level of accuracy and precision that may not be possible with manual techniques. Automation also allows for a faster production process, as a single robotic arm can lay up to 10kg of material in one hour, resulting in significant time and cost savings compared to manual labor.
In addition to improving accuracy and efficiency, the use of robotics and automation in the AFP process also helps to reduce the risk of human error and improve the overall quality of the composite parts being produced. This is especially important in industries such as aerospace, where the performance and reliability of composite parts are critical.
Overall, the use of robotics and automation in the AFP process is essential for improving efficiency, accuracy, and quality in composite manufacturing.
How to program and operate automated Automated Fiber Placement systems
To program and operate AFP systems, operators typically need a basic knowledge of composites processing and operational knowledge of CNC machine operation. The specific steps involved in programming and operating an AFP system may vary depending on the specific equipment and software being used. However, the general process typically includes the following steps:
Planning and simulating the part production using software such as AddPath. This involves creating a digital model of the part to be produced and simulating the AFP process to ensure that the tows will be placed in the desired pattern.
Generating the NC (numerical control) code from the simulated part. The NC code is a set of instructions that tells the robotic arm how to move and place the tows during the AFP process.
Uploading the NC code to the robot and setting up the AFP tool by loading the material. This may involve preparing the tool surface and attaching the AFP head to the robotic arm.
Starting the part layup with a slower speed, typically around 15-30% of the programmed speed or less than 100 mm/sec. This allows the operator to ensure that the AFP process is running smoothly before increasing the speed.
Gradually increasing the speed to 100%. Quality monitoring software may be used to alert the operator in case of any defects and pause the operation for correction.
Checking the production data for any anomalies or unplanned interruptions after the program is completed. This can help the operator identify any issues and make adjustments as needed.
Overall, programming and operating an automated AFP system requires a combination of technical knowledge and careful attention to detail to ensure that the composite parts being produced are of high quality.
History of ATL/AFP Developments
The automated fiber placement (AFP) process has a long history of development, with the first AFP machines becoming commercially available in the 1980s. These machines were a combination of the differential payout capability of filament winding and the compaction and cut-restart capabilities of automated tape laying and had the ability to vary layup speed, pressure, temperature, and tow tension. In the 1990s, research focused on improving the productivity of the AFP process, including the development of a system that could deliver up to 24 tows at once and the use of thermoplastic composites for aerospace structural applications.
Starting in the 2000s, a significant portion of the research was focused on continuing to improve process reliability and productivity, including the development of automated defect detection systems and high-speed AFP machines. More recent research has focused on high throughput AFP, minimal defect layups, and in-situ thermoplastic layups, with the goal of improving the overall quality and efficiency of AFP-manufactured structures.
Composites Design Lifecycle and AFP
The integration of digital technologies into the composites manufacturing process is essential for overall success. This integration should be intelligent, connected, and involve communication between the four fundamental pillars of composites design and production:
An Industry 4.0 automated fiber placement (AFP) workflow would involve seamless connections between all of these pillars, ensuring that design is not just a starting point but rather a continuous improvement cycle that integrates with the other pillars.
At the design and process planning stage, data sharing can help to eliminate the common issue of designers failing to account for manufacturing limitations and streamline the process of getting the part from the designer to the manufacturing floor.
The next stage of the workflow involves connecting process planning and manufacturing, with the use of a digital twin allowing the machine to draw on operation data and propose changes to th