Windows and doors: A quick production tour


Do you know how windows and doors are created?


Probably not! In fact, if you are a builder your main concern is probably to have the right size window fitting comfortably into the space. Or if you are an architect your commitment is to the aesthetic, pushing window boundaries to the limit on occasion!


So how does the not so humble window begin?


It begins as raw mined ore — bauxite — and is refined into alumina (aluminium oxide). Alumina is shipped as a white powder to the Tiwai smelter at Bluff. Here it is smelted into molten aluminium.


The next step is extrusion. Aluminium logs 7 metres long arrive at extrusion plants such as INEX in Hamilton. There, everything is done on a large scale, with enormous presses extruding 50 metre lengths of aluminium.


Here the logs are cut into billet lengths, and sized according to the sections being extruded. The aluminium is heated to 564°C and shaped by forcing through small shapes in steel dies in the extrusion press.


Dies are designed by companies such as Aluminium Systems who specialise in the design and distribution of aluminium extrusion for the window and door market.


They draw up plans for the aluminium profiles and have their own dies cut, and extrude aluminium on a contract basis and, as such, are a “prime die holder”.


The major “prime die holders” all have design departments working on new ideas and designs for residential and commercial aluminium joinery. These are the inventors, creating the latest and greatest windows and doors.


A new suite recently developed for Aluminium Systems is the Evolution suite. This suite has a full range of windows and doors available. During its creation, 30 dies were cut, each one costing up to $4500.


Once extruded, mill finish metal is distributed. Arriving at Aluminium Systems, it is then powdercoated or anodised according to builder or architect specifications for a specific building.
The powdercoated metal and components arrive for fabrication at a local Fairview and Elite fabrication factory.


Here the windows and doors are manufactured and are delivered to site for installation, where the builder hopes the window will fit the space.