Particulate Contamination – Extruded polyurethane tubing contained white particles at a low, but unacceptable, frequency. Tubing samples were provided for analysis. Micro-infrared spectroscopy and scanning electron microscopy/energy dispersive x-ray spectroscopy showed the particles were agglomerates of two compounds present in the starting formulation. The compounding process was changed to provide a more thorough mixing of the starting ingredients.
Adhesion Variation – A purchased part was not adhering as well as it had in the past. Contact angle measurements showed that new parts have a lower surface energy than the older parts. X-ray photoelectron spectroscopy and thermal desorption gas chromatography mass spectrometry confirmed a low surface energy substance present on the new parts that could be traced to a manufacturing process change.
Problems with Smeared Printing – Print on a plastic product was found to smear at some locations but not others. Microscopic analysis showed smearing was associated with much higher ink film thickness. The problem was subsequently traced to ink build-up on certain print pads in the process and was eliminated by establishing a pad cleaning and replacement protocol.
Optical Device Failure– An optical device which incorporated a diffraction grating was performing inconsistently. Optical and electron microscopy revealed large localized inconsistencies in the period and amplitude of the grating. Once this was understood the manufacturer was able to address process variations.
Wrong Resin – A prototype part was machined from a block of acetal homopolymer. Performance in trial service runs was far below expectations and the R&D team was considering redesign and/or alternate resins. A sample of the material was submitted for identification. Differential scanning calorimetry and infrared spectroscopy showed the prototype resin was high density polyethylene not acetal.
Alumina Particle Distribution Uniformity – For optimum operation of an optical device, a uniform distribution of small alumina particles was required near the surface of an aluminum sheet. Analysis showed the particles could not be detected by optical microscopy, scanning electron microscopy or Auger electron microscopy; however, they could be monitored by Raman spectroscopy. With this knowledge, IMS and the company worked together to optimize the distribution of the alumina particles.
Customer Return – A company’s customer complained of incomplete hardening of a two part epoxy resin. Thermal desorption Gas Chromatography Mass Spectroscopy analysis of the failed parts showed that the hardener had been omitted. Proper product usage was subsequently reviewed with the customer so that their process could be adjusted.
Welding of a Stainless Steel Tube – An electronic device was housed within a stainless steel tube through which it needed to sense the outside world. Tubing welds were inconsistent and often leaked. With the advice and guidance of IMS faculty, the company was able to produce a more consistent and leak-proof weld which improved device response time by 10x.
Sticky Seal – A freely moving polycarbonate part was found to stick to the adjacent polyvinylchloride seal once pressure was removed. Thermal desorption Gas Chromatography Mass Spectroscopy showed the seal was highly plasticized with a compound known to be compatible with polycarbonate. The compound was somewhat incompatible with polyvinylchloride thus it squeezed out of the seal upon compression and diffused into the polycarbonate thus causing a “sticky” surface.
Fatigue Life of a Flexible Metal Part – A metal part used in a product where continual flexing was required was fracturing prematurely for unknown reasons. Investigation revealed that under existing loads and cycling, the part should have had a lifetime at least two orders of magnitude longer. Examination of the part and process revealed an inadequate preparation of the surface leading to high localized stress levels. Modification of the surface processing produced greatly improved life.