Acetek engineering expertise extends to leading edge technology in a number of fields.
Electron Beam Curing
Electron Beam (E-beam) curing is a non-thermal, non-autoclave curing process that produces high performance composite aerospace parts. It makes it possible to build composite structures without the need for slow, high-temperature, high-pressure curing cycles with associated expensive fabrication tools.
|This process uses a beam of high-energy electrons from a device called an accelerator to initiate resin cure in place of the usual autoclave that applies heat and pressure. E-beam curing is suitable for composite parts as thick as 5 cm. Parts are cured by spraying these electrons onto the composite part. The cure is controlled through the application rate of the electrons and the total number of electrons or dose applied to the part. The process is fast and easy to control. Most significantly, it is conducted at room temperature so that the normal thermal stresses associated with heat curing are minimized.
As E-beam curing of composite materials becomes established as an industrial process, there will be far reaching benefits to the entire composites industry, primarily because of reduction in manufacturing costs. Independent economic studies of the E-beam curing process in aerospace manufacturing applications have concluded that cost savings of 25% to 65% are possible depending upon part configuration. These impressive savings result from the following characteristics of the E-beam process:
- Curing time is reduced.
- Tooling costs are reduced.
- Resin stability at ambient temperatures is improved.
- The production of volatiles is minimized.
- The use of chemical crosslinking agents for thermosetting resins is eliminated.
- The curing energy‑absorption profile can be controlled to allow greater product design flexibility.
Type Trial Electron Beam Repair
Airbus A320 aircraft contain composite parts in more than 20 sections. Traditional thermal-cure repair techniques are costly because of the time the aircraft is out of service due to hand lay-up and curing process flow times. Acetek has collaborated with Air Canada to repair composite secondary structures on their Airbus fleet using E-beam techniques in order to validate the several E-beam process advantages, particularly with respect to rapid cure cycles, ambient temperature curing, and the possibility of on-aircraft curing repaired parts without loss of material properties.
In our first type trial a fairing, located at the lower rear of the aircraft fuselage, was repaired using E-beam curing. This fairing was in service on the aircraft for 900 landing/take off cycles over 16 months. This was the first commercial airline application using this technology in the world. The type of damage normally encountered on this component is primarily from baggage loading equipment and objects being thrown up by the aircraft’s wheels. In addition, the component is also exposed to considerable amounts of various fluids, such as oils, hydraulic fluid and water.
Preliminary testing showed a marked difference in properties between the thermal and E-beam repaired panels. Most notable was a retention of properties at higher temperatures for the E-beam cured panels. Better hot/wet properties were also observed since E-beam cured resin systems tend to have higher crosslink densities compared to thermal systems. The higher crosslink densities prevent water and other liquids from intruding into the resin system and causing a loss of physical properties.
Subsequent testing and development work led to the certification of E-beam repair under a Repair Design Certificate (RDC) granted by Transport Canada.
Acetek can also provide comprehensive, state-of-the-art material-testing services. Corporate laboratories are equipped to perform dynamic mechanical analysis, gas chromatography, mass spectroscopy, scanning electron microscopy, radiography and a complete range of mechanical tests:
- Gas Chromatography Mass Spectrometry (GC/MS)
- High Performance Liquid Chromatography (HPLC)
- Fluorescence Spectroscopy
- UV-Visible Spectroscopy (UV-VIS)
- Differential Scanning Calorimetry (DSC)
- Dynamic Mechanical Analysis (DMA)
- 20 KN and 100 KN Automated Universal Testing Systems
- Lap shear strength, tensile, flexural and compression modulus and strength
- Sample conditioning over a wide range of environments (dry, moisture,
temperatures from ambient to 120oC)
- Mercury Intrusion Porosimitry (MIP)
Research and Development
To date, in-house research efforts, mainly through a Department of Energy - Defense programs Cooperative Research and Development Agreement (CRADA, 1994) for the project entitled “Electron Beam Curing of Polymer Matrix Composites”, have been devoted to the development and optimization of resin systems and composites.
Ongoing R&D projects include further investigation into alternate composites processing techniques such as UV curing and improved moisture, impact and abrasion resistant coatings.