A Hawera Engineering Company now produces dome ends up to 13mm thick in mild steel for tanks and vessels.
Global Stainless first started manufacturing 2mm and 3mm thick stainless steel domes for tank fabricators throughout New Zealand on a purpose built 3.5 metre diameter dome spinning machine but have recently acquired a hydraulic bumping press and a Swedish made hydraulic knuckling/flanging machine capable of forming dome ends or dished and flanged heads in most materials.
The manager Mr. Lincoln Raikes explains the method of "bumping" in a press or technically known as "power peen forming" is performed by multiple pressing action until the desired dish curve and contour is achieved. This is much like the Chinese have made their cooking woks for thousands of years but of course by hand.
The bumping press is best suited for heavier thicknesses of plate.
Mr. Raikes says the spinning method they first set up is most economical for production runs on thinner materials whereas the hydro-forming method also provided by Global Stainless is more suited to smaller quantities and where ultra high surface uniformity and minimal work hardening is required.
Some typical applications for domes made by Global Stainless are tank ends, pressure or vacuum vessel heads, air receivers, marine buoys, plastic tank dome moulds, manure spreader tanks concrete mixer bowl ends, petrochemical and dairy powder plant vessels.
Global Stainless fabricate mirror polished globes/spheres for architectural applications which they export globally and also fabricate large diameter long radius stainless steel bends.