Aluminium is used wherever low weight and high strength is required. For Leichtmetall Aluminium Giesserei Hannover GmbH it means manufacturing numerous high-strength aluminium alloys for the aviation and aerospace industries as well as vehicle, power plant and mould-making construction: “hard alloys” of the highest quality.
Secondary aluminium (processed scraps), aluminium ingots, and addition metals such as copper, chrome, nickel, titanium, beryllium, zirconia, manganese, zinc, tin, magnesium, silica, lead and/or bismuth and iron are smelted to form diverse wrought aluminium alloys in two tiltable 50 tonne channel induction furnaces, strictly in accordance with norms or customer requirements.
Chemically and physically, it is cleaned even during the smelting process and analysed at pre-determined stages in the process by a reliable team of qualified and experienced employees.
In a vertical equal-level aluminium continuous casting process, we cast round billets up to 6,400mm in length and seamed at both ends. The dimensions range from a diameter of 178 mm to 528 mm, also independent from the alloy and number of strands. We are highly flexible when it comes to changes in alloy and formats and respond to short-term orders.
The semi-finished products are heat-treated in two gas-heated homogenisation ovens after casting with minimal temperature variation. We can even guarantee the accurate temperatures demanded by the aviation industry. Temperature and resting time for the homogenisation are dependent on the alloy and its intended use, and according to customer requirements where applicable. The capacity of each oven is up to 70 tonnes.
In the first step, homogenised billets are cut to a length of min. 500 mm and max. 1,500 mm – according to customer preference - with a standard length tolerance of max. 5 mm. Each billet is marked automatically using needle embossing with the alloy, batch number, strand position of the casting table as well as the billet position with the casting length.
This ensures 100% traceability from the finished billet back to the input batch. Further data can be stamped upon request. After this, the billet is turned to a diameter between a minimum of 140 mm and maximum of 500 mm in a lathe.
Standard diameter tolerances are regarded as 2 mm however we can, upon request, realise lower tolerances. The surface is therefore absolutely clean and free of any cast crust.
This is also the basic prerequisite for the final automatic ultrasonic inspection under water which is required for applications in the aviation and automobile industry. This includes in particular: maximum error margin of up to max. 2 mm, potentially smaller depending on the alloy. This can be verified by certified personnel (up to Level III).
Absence of defects in volumes and surfaces
Exact marking for traceability, material samples from every billet and regular wet chemistry inspections ensure a consistently high quality for all of the batches. We analyse the composition of the scrap metals and secondary materials prior to smelting.
We store all the materials separated according to the product and alloy in a covered space.
We stock batches of our cast billets in all the usual sizes and alloys.
