Fasteners are typically the last thing engineers consider when designing medical devices. As a result, they often specify expensive, tightly toleranced parts, when less costly fasteners would suffice.
For example, a medical device manufacturer was using seven different solid pins as free-fit axles in a surgical stapler. Made from 303 stainless steel, the pins were slip-fit and held in position by a plastic shroud that went around the outside of the device. The OD of the pins was held to a tolerance of ±0.001 inch, while the length was held to ±0.003 inch. Because 303 stainless is only available in bar stock, the parts had to be machined rather than cold-headed or roll-formed—much less expensive production methods.