What is Automated Fibre Placement (AFP)?
- 19th January 2021
- Gary Foster
- Reading time: about 7 minutes
What is Automated Fibre Placement?
Automated Fibre Placement (AFP) is part of a family of manufacturing techniques, which refer to the precise laying of continuous fibre tapes to manufacture multi-layered composite products, typically with significant strength.
These techniques include:
- Filament winding (FW) – the manufacture of products using a single narrow tape (usually between 3 to 13 mm). Typically used for the manufacture of pipes, tanks and shafts
- Automated Tape Laying (ATL) – manufacture of products typically using a single wide tape (up to 300 mm). Typically used for the manufacture of large parts, such as the skins of aircraft wings
- Automated fibre placement (AFP) – manufacture of products using multiple narrow tapes (usually between 3 to 13 mm). The use of multiple tapes allows for more complex layup geometries than ATL.
Automated Fibre Placement (AFP) vs. Automated Tape Layup (ATL)
The terms AFP and ATL are commonly used to describe similar manufacturing processes. Both terms fundamentally refer to the process of applying fibre reinforced tapes using a loaded roller system to create a part.
ATL typically refers to the application of a single wide tape to create a product, while AFP systems have greater control of how and where to lay multiple narrow tapes. As ATP uses multiple tapes, they are more easily “steerable” and can be added or removed individually. An AFP machine can cover a surface containing a higher degree of curvature than ATL. However, modern ATL systems now have improved control of tape start, cut and orientation. Therefore, the distinctions between the AFP and ATL techniques are not as clear as they once were.
History of automated fibre placement
Over the last 20 years both the processing equipment and the materials they use have advanced significantly. In particular, the demand for increased manufacturing rates and tighter tolerances on the final products have led to major design changes to the equipment and corresponding refinements to the materials.
As AFP moves towards the greater use of thermoplastic tapes changes to the equipment over recent years have seen the emergence of improved technologies such as in situ heating and the consolidation of the tape via laser or infrared technology.
As the materials used by AFP offer lighter weight with equivalent or greater strength than metals, they are being increasingly used in the aerospace sector and specialised industrial sectors such as oil and gas.
Thermoset and Thermoplastic Tape Materials
Originally, thermosets (typically epoxies) were used exclusively as the polymer matrix in order to bind the fibres together during the manufacturing process. There are many advantages to using thermosets, which include:
- Easier to impregnate fibres (liquid)
- Less compatibility problems between polymer & fibre
- Superior adhesion to fibres (especially true of epoxies), paint & other materials
- Higher thermal resistance
- Already approved for many applications
However, over recent years thermosets are being replaced by thermoplastic (typically PA6, PP, etc..) for the following reasons:
- Cost effectiveness
- Enhanced impact toughness
- Better Corrosion resistance
- Flexibility of design
- Typically faster cycle times
- Safer raw material handling
- Long term raw material storage
- Improved control of the chemistry
- Better recyclability
Although carbon fibre is still widely used as the preferred continuous reinforcement, other fibres such as glass and natural materials are starting to appear in the market.
Automated Fibre Placement Manufacturing Process
Although AFP systems are usually bespoke for the particular application, they all consist of the following components:
- Head with compaction roller
- Tape feeding system
- Robotic mechanism holding the head
- Human Machine Interface.
AFP machines lay down a strip consisting of several individually narrow tapes (typically 3mm to 13mm in width) via a tape laying head in order to build-up the product. The tapes are fed into the head via the tape feeding system, which holds multiple bobbins or spools containing the tape. These spools typically hold around 1000m of tape per bobbin.
These tapes are precisely laid by AFP machines according to a computer program, which has been defined to give the final product the optimum alignment of the fibres based on the expected operational loads of the part being manufactured. The tape laying head is connected to a robot, which guides the head into the correct position during the process.
Optimisation of AFP layups
Over recent years there have been great advances in the optimisation of AFP layups using simulation software such as CGTech’s Vericut package. This type of simulation package has begun to replace the more basic programming software supplied by the machine builders. As a consequence this has allowed end-users to select the best machine for their product, while being able to have one software package to simulate and create suitable layups.
As per computer numerical control (CNC) of machining tools (such as drills, lathes, mills, etc.) it is now possible with AFP to design a part and simulate its manufacture offline. Composite design software tools take into account AFP manufacturing requirements early in the product development cycle allowing the direct transfer to the final manufacturing process.
Advantages and Disadvantages of Automated Fibre Placement
Compared to other composite fabrication methods there are a number of key advantages and disadvantages of using AFP. These include:
- Advantages
- Automation
- Repeatability of manufacture
- Low material wastage
- Disadvantages
- Relatively slow build rate
- Restrictions of part size and shape
- Cost of processing equipment
Suppliers of ATP equipment
There are a number of suppliers around the world who make equipment for applying fibre reinforced tapes to create a part. The apparatus they sell varies in size, complexity, as well as cost and the requirement for a particular application means that most machines are bespoke for a particular job.
Suppliers of AFP machines include:
- Automated Dynamics (USA)
- Coriolis Composites SAS (France)
- Electroimpact (USA)
The Future for AFP
The ongoing push for faster deposition rates, the development of new material combinations as well as the downward pressure on cost means 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. Also the size of the heads with the compaction rollers will get smaller allowing a greater diversity of products to be made.
How can Coventive Composites help with AFP?
Coventive Composites has significant experience in the development and use of fibre reinforced tapes for AFP. We can manufacture pilot-scale quantities of a variety of tapes for initial evaluation, and can provide technical support to assist with application development..
Please feel free to contact us to discuss your requirements.
Share this article
Found this article useful? We have a full range of services to help you...
Materials & Process Development
Whether it's thermosetting or thermoplastic composites, biocomposites or nanocomposites, we can help you develop a material or process that meets your requirements.
Developing composites...
Pilot-Scale Manufacturing & Prototyping
Our suite of pilot-scale manufacturing facilities are at your disposal - prepregging, compression moulding, resin transfer moulding, injection moulding, and many more.
Making composites...About the author
