Additive manufacturing (AM) has grown far beyond its origins in rapid prototyping and is now used to produce a range of high-performance products and components.
As well as offering material and energy efficiencies beyond traditional methods, AM enables the creation of multi-material objects with complex internal geometries.
Computed tomography (CT) plays a key role in the development of AM processes by enabling the complete 3D visualisation of additively manufactured parts.
Understanding Additive Manufacturing
Most ‘traditional’ machining techniques can be considered subtractive. Milling, turning, drilling – all involve the removal of material from bulk solid in order to leave behind useful products (and, wasted material in the form of offcuts and shavings).
Rather than taking material away to carve out products from a larger piece, AM methodologies instead build up products through the controlled deposition of material.
As technology continues to evolve, additive manufacturing becomes increasingly versatile. As well as reducing material waste and the weight of components, AM techniques enable the construction of complex geometric shapes that would require multiple distinct processing steps and/or highly specialised production methods.
The combination of precision, speed, affordability, and freedom of design means that AM is increasingly being used for the production of high-performance components; especially in aerospace applications where it can be used to produce porous or hollow-chambered components with drastically reduced weight.
Developing New Additive Manufacturing Processes with Computed Tomography
Any defects in additively manufactured components must be reliably identified and accurately characterised to develop new AM processes and applications.
AM has special metrology requirements compared to other manufacturing techniques, as it involves the fabrication of 3D components either ‘from the ground up’ or ‘from the inside out.’ This means that any metrology technique for additively manufactured parts must consider the interior of objects as well as the surfaces.
CT scanning has emerged as the best non-destructive method for doing so. Computed tomography is a method of forming 3D representations of objects by taking many 2D X-ray images of an object around an axis of rotation. These 2D ‘slices’ can then be assembled into a 3D model using software.
Such visualisations enable a much clearer interpretation of internal structures than other techniques, which typically cannot provide data of internal structures.
CT scans of AM parts are enabling the refinement of existing AM processes as well as the development of new ones. For example, performing a CT scan of a particular component and comparing it to the original design enables manufacturers to determine the precise correlation between the schematic and the finished product. Manufacturing artefacts or flaws can be easily identified and then corrected by making design or process adjustments.
See full Azom article here.