These are probably the smallest parts we make in-house, but they’re critical to the proper function of about half of the instruments we support. These little bushings support the impeller of the water flow sensor in many Siemens and some Bruker XRF and XRD machines. They last for several years in most cases, but we replace them during most PM service visits because they’re easy to keep on-hand and very inexpensive.
This is a great example of a part that would force any machine into obsolescence if it were not available. Having the ability to rebuild these sensors gives them a lifespan measured in decades and while they are prone to sticking during periods of downtime, they can almost always be cleaned up and put back into service.