Due to wide-spread materials non-conformance in China, Star-Prototype takes positive metal identification (PMI) very seriously in China. Recently we purchased yet another PMI analyser called an XRF Gun.
X-Ray Fluorescence (XRF) analysis is a non-destructive-testing (NDT) process by which materials such as metals, clothes, plastics, ceramics etc. are exposed to low level short-wave-X-rays or gamma radiation. Each different element reflects the emission with a different wavelength and a specially calibrated spectrometer can detect what elements are present and in what relative concentrations. http://en.wikipedia.org/wiki/X-ray_fluorescence
XRF analysis is particularly useful for fast on-site positive material identification (PMI) and RoHS testing.
As you can read on another page, Star Prototype purchased a USD 70,000 Oxford Instruments Optical Emissions Spectrometer (OES) specifically for the PMI of incoming metals. Metals fraud in China is rife and soon after we commissioned the machine we realised that up to two-thirds of certain materials were out of specification. The OES is a very accurate ‘spark testing’ analyser that leaves a very small spark site on the test piece with a depth of about 100 to 300 microns.
Our USD 35,000 Oxford Instruments X-Met 7000 XRF analyser gun is completely non-destructive and leaves no mark on the surface of the test piece. The analysis is not as accurate as the OES, but it is sufficiently accurate to find non-conforming material. If a measurement is just outside of specification we will check it again on the OES for a more accurate analysis.
Being completely portable we can take the XRF Gun to suppliers and test materials in-situ. If can also detect banned materials under the REACH and RoHS legislation. See our video here.
EXAMPLE: One of the biggest materials non-conformances in China is the use of 201/202 stainless steel as a substitute for 303/304. http://en.wikipedia.org/wiki/SAE_steel_grades Many western engineers have never heard of 200 series stainless; it is known in China as furniture stainless. One of the reasons it causes so much trouble is that like 300 series stainless steel it is non-magnetic (or only very slightly magnetic when magnetised) when tested with a regular magnet – but it rusts very easily. In China many Chinese will use a 2 part chemical testing kit to detect 201 stainless – but often the testing kits are fake or non-conforming. In a recent case an engineer in Zhongshan approached STAR to test 18 samples of 303/304 stainless steel after some of his product started rusting. 15 of the samples tested as 201 stainless. It turned out that the stainless supplier had supplied a fake chemical testing kit with the stainless and deliberately defrauded that engineer.