NDT Services
At Aerotech, we offer a full range of in-house and site-based Non-destructive Testing capabilities. Due to our extensive experience and technical knowledge in the field of NDT, we are able to tailor our services to meet the exacting needs of our customers.
Dye Penetrant Inspection is a relatively simple process used to detect the presence of open to the surface discontinuities in components of all non-porous materials. The dye is coated onto the surface to be inspected and after a dwell time dependent on specification, during which the dye penetrates cracks etc, the excess is removed, the component, dried, developed and inspected. The dye penetrant systems used are of the Fluorescent and Visible red dye systems. The fluorescent is sub divided into water washable and post emulsifiable dependant upon sensitivity required and is generally used mainly on Aerospace and more critical components. The visible dye system is standard red dye used with relevant solvents for removal and developing, and is used for more local and less stringent testing of components
Magnetic Particle examination is carried out on ferritic steels to reveal surface and slight sub-surface discontinuities. A magnetic field is induced into the part under test and the area to be examined is covered by magnetic ink. Any discontinuity in the part will cause a break in the magnetic field resulting in a leakage path which attracts the magnetic particle in the ink giving rise to an indications and this is evaluated as to the acceptability of the part. Magnetic particle at Aerotech is carried out using bench units, electromagnetic yokes and permanent magnets with both fluorescent and visible black inks.
Radiography is used as an inspection method to find mainly internal volumetric discontinuities in a variety of components, although surface indications are also revealed. These components may be in the form of castings or welds in varying metals ranging from light alloys such as aluminium and magnesium through to more dense metals such as steel and bronze and other specialised alloys. Composites and lead cladding may also be inspected by radiography. Aerotech undertakes radiographic examination of many components. Inspection is carried out using conventional methods, i.e., x-ray and gamma rays from Iridium and Cobalt sources. Specialised sources such as Ytterbium and Selenium may also be used is requested. All components for radiography are inspected to approved techniques and procedures on a single part basis or on multi-batch jobs.
The x-ray film is supplied by GE Inspection, which is approved by all major prime contractors. The radiography is carried out in purpose built rooms with controlled access for safe operation or is carried out on site as requested where greater safety is controlled by our Radiation Protection Supervisors.
Ultrasonic examination is a method of determining the internal and surface integrity of components in all metals using high frequency ultrasound. This is achieved using probes that generate various types of sound wave depending on the probe used and results in different planes of defect detection. Several types of sound wave are usually used to give the optimum results. The image is produced on oscilloscopes or in digital form.
Nital Etch Inspection is a non-destructive testing technique used to evaluate the effects of poorly controlled manufacturing processes such as machining, grinding and heat treatment on metallic components. Using a Nitric acid solution, machined components are etched revealing grinding and machining abuse. The nital acid etchants work by forming a coloured surface film on the steel and attacking its surface to form pits. Under certain circumstances machining and grinding can introduce sufficient heat in a component to heat-treat its surface, this is generally local over-heating and can produce undesirable changes in material properties. An example occurred in the late 1960’s when a helicopter of the Queen’s flight crashed killing 4 crew. The aircraft lost a rotor blade due to the effects of grinding abuse on the main rotor shaft. Shortly afterwards the society of British Aerospace companies recommended the use of surface acid etch inspection. This inspection method is now widely used throughout the aerospace industry to detect this type of abuse.
Aerotech carry out etch inspection on many components for the Aerospace industry using our specifically designed etch inspection unit and viewing area.
