Bulge Forming



  • Bulge formed inconel exhaust ducts 30" diameter


Bulge Forming is a process that involves expanding fluid in a rubber bladder, or bung, within a cavity die tool containing a sheet metal blank (cone or tube) to create a pre-determined shape reflected by the inner contour of the cavity die tool. It is an axial loading,cold forming process and is typically used to form cylindrical and spherical components from super alloy materials. The advantages of this process are that it is capable of producing complex shapes, with non-symmetrical features if required, and with uniform wall thickness.

It is a much more efficient and reliable method than spinning or stretch forming in the fact that it is much easier to control, involves higher forming forces and is therefore more consistent.  It is a much smoother forming method and so is less stressful on the material, and is more cost effective without the need to do any post forming work to remove scratches and surface irregularities. This guarantees the final component to be more consistently accurate, of better quality and more cost effective. In the aerospace industry Bulge forming is typically used to produce products such as aircraft exhausts, intake lip skins, nacelle doors and fairings.

Using a combination of our expertise on hydroforming and our extensive press shop facilities, MSM aero has developed the Bulge forming technique to a fine art with a capability of forming parts up to 1 metre diameter and 1 metre long from Titanium, nickel alloys and aluminium. Typical examples of aircraft components are bleed air duct reducers, venturis, ozone converter shells, exhaust cones and after-burner cones. Note that sized tube is not required to make the sheet metal blank as MSM has the ability to roll the cylinder (or cone) from flat sheet and then fusion weld the joint; this enables parts to be made of any diameter and any length and from any sheet material making the process very cost effective.

Components can be supplied as finished parts or can be further worked and/or assembled within MSM aero’s 25,000 sq ft facility containing their other NADCAP approved specialist capabilities.

MSM aerospace fabricators is a leading SME manufacturer specialising in complex forming and welding of high temperature metals such as inconel 625 and inconel 718 and titanium.  Our engineers are more than happy to be involved in the design stage of components of this type and can add a positive contribution in finding the optimum solution.