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polymers
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Quality, productivity, time to market: plastic-processing companies are facing many new challenges

From the simplest shape to the most complex one, plastic and rubber industries are more and more demanding concerning quality standards:

  • Packaging such as PET/PETE (PolyEthylene TErephthalate) containers, NYLON receptacles or PLA (PolyLactic Acid) boxes need to pass compliance tests.
  • PVC (PolyVinyl Chloride) structures and others PC (PolyCarbonate) helmets are optimized to guarantee economically function and safety.
  • Material based on rubber layers must be free from air pockets and de-bonding areas.
  • Injection moulded plastic parts get tighter and tighter manufacturing tolerances.
  • Some small plastic parts assemblies have to be checked after mechanical stress being applied.

  • Regardless of the application, caps, toothbrushes, customized shapes dashboards, yogurt containers, cups, bottles, housings, they all can benefit from X-Ray Computed Tomography (CT) advantages. Being easy to penetrate with X-Rays, plastic parts are well adapted to CT and benefits can be found in prototype development, in-line quality control, injection mould optimization…

 

X-Ray Computed Tomography: a new way to increase efficiency and reduce costs

Nowadays inspecting polymeric parts is a common task for computed tomography. Polymer consists of materials with really good penetrability to X-rays, that determines a clear image, with low artefacts due to beam hardening or scattering.  

This relatively new non-destructive testing technology provides high data density, fast acquisition time, reliable results and can be fully automated from the scan to the inspection report generation. 

For random sampling, robots can be installed directly on the production line in order to load one or several parts at the same time in the system. Data acquisition duration is reduced, parts are not damaged and can then be released in production.

Because destructive inspection is always incomplete, several iterations are often needed before having the right correction applied to a particular mould for instance. With a CMM (Coordinate-Measuring Machine) inspection, the problematic area is sometimes overlooked. On the contrary, with X-Ray CT, internal and external structures are fully reconstructed with only one scan and in-depth analyses are performed wherever it is needed and green light for production can then be given in time.

In addition, more detailed analyses can always be performed in retrospect with data generated thanks to CT systems. Warpage and shrinkage analysis can be achieved and going back on a previous scan to get a new dimension is not any longer a problem.

Multiple analyses performed thanks to powerful software

Combining X-Act acquisition/reconstruction software from RX Solutions and analysis software, Geometric Dimensioning and Tolerancing (GD&T) can be performed to obtain positions, diameters, depths, profiles, parallelism, flatness, cylindricity even on internal features.

Thanks to sub-voxel surface determination, details up to a few microns can be detected. Data generated can then be stored and analysed in order to detect a potential drift out of tolerance, watch statistics and correct directly the production.

Pre-production series samples can be scanned in order to get wall-thickness or CAD / actual comparison to adjust moulds. Comparison of the geometry of the moulded parts occurs with CAD model, among different moulders, different materials, or after a heat treatment. Full gap and flush analyses are another available option that can only be obtained with CT. It allows accurate results on the whole volume within a few seconds computation. This is an easy way to detect potential leak paths or wrong assembly.

Foreign materials and porosities are also often important to detect in plastic parts to avoid latter cracks or deformations. Through CT 3D volume reconstruction combined with void/inclusions analyses, it is easy to have a complete report of the biggest ones found in a particular sample. It is then effortless to obtain their characteristics (size, position, shape) because all the data are already stored.

Whatever your plastic application is, Computed Tomography and RX Solutions systems can play a role to help you.