X-Ray equipment in which the focal spot size is less than 100 µm is referred to as microfocus unit. Advanced micro-focus units have a focal spot size as low as 5 µm which is achieved by focussing the electron beam on the target in combination with sufficient cooling to avoid overheating.
Micro-focus radiography facilitates to observe the minute details of the object through production of magnified X-ray images, which in turn enhances the flaw detection capability which improves reliability in comparison to conventional radiography. Micro-focus X-ray systems having focal spots that approach a point source are useful in obtaining very high resolution images due to the negligible penumbra effect.
The X-ray source generates a continuous beam of X-rays from the very small focal point. The beam passes through the sample placed on the manipulator turntable, and casts an X-ray projection onto the detector sensor. The sensor converts the transmitted X-ray projection into a visible greyscale image, which is displayed on a monitor. The magnification of the sample depends on its position between the X-ray source and detector. Moving the sample towards the X-ray source increases the magnification and improves the spatial resolution by increasing the number of pixels over which the X-ray image is projected. Even when operating at maximum magnification, the micro-focus X-ray spot ensures the image is always sharp. The associated software enables contrast enhancement and image integration.
TWI Resources
X-Tek HMX225 micro-focus advanced X-ray system
Features:
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5-10 µm Focal Spot Reflection Target X-ray Source
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25 to 225 kV, 0 - 2000 µA, 225 Watt
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5 axis fully programmable manipulator
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Maximum scan area 480 x 450mm
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Geometric Magnification up to: 160x
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System Magnification up to: 400x
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Feature recognition: down to 5µm
Benefits
Applications
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Inspection of integrated circuits and PCBs
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Inspection of high quality castings and weld material
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Tube to tube sheet weld inspection
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Inspection of composites and ceramics for micro-voids and structural inhomogeneity
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Inspection of inaccessible areas
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Inspection of turbine blades of aero engine to detect hair line cracks
For more information about TWI's NDT services, please email contactus@twi.co.uk.