The tube hydroforming (THF) process is a metal forming process that uses a pressurized fluid as the forming mechanism. Recently, this process has increased in popularity in the automotive industry as a method to reduce the number of required components and consolidate parts which can substantially reduce the overall automobile weight. This reduction in weight is a currently pursued method for improving the vehicles fuel economy.
At the micro scale, hydroformed tubes have the potential to offer additional benefits with possible uses in medical and MEMS (Microelectromechanical systems) applications. However, this can be a challenge when the forming materials have small mating features. In many macro scale tube hydroforming processes the forming fluid is supplied to the tubes by a tapered filling nozzle inserted inside the inner diameter of the tubes. When considering forming tubes with sub-millimeter features, this poses a significant challenge.
This paper explores the design of a new method for creating the required high pressure seal. Specifically, this seal is made on the outside surface of the tube by using a flexible encompassing rubber gasket and two proprietary designed seal cavities. In this study, stainless steel 304 micro tubes of varying outer diameters (1.0 mm and 2.1 mm) and thickness were tested.