The Process in China

Page 1: Historical Overview
Page 2: Latest Process Developments
Page 3: The Process in China
Page 4: Pros and Cons of the Process
Page 5: Types of Products Made

Despite it relative short global history, the aluminium extrusion process in China is extremely well established, receiving government interest and support. In 2001, a reported output of 2,817,000MT per year, placed it behind Russia and the USA on a global scale. By 2009 212 717 tonnes were being exported to the USA on a yearly basis, and by 2012, China was second only in its production to the USA.

Back in 2001 the growth of the Chinese aluminum extrusion process was of such interest that the US Government analysed the threat value of the Chinese market to their own aluminum extrusion industry.

This report showed that around 20% of aluminium extrusions are ‘standard’ shapes (such as extruded aluminum channels), the rest being custom to that of the client and the end applications. From 2001, the Chinese industry itself grew by 25% annually for a number of years, and growth of exports to USA also continued.

In 2009 a US report showed that the Chinese industry for alumnium extrusion employed largely the same equipment, and indeed, the equipment being basically the same as those used in other countries, allowing for the easy transfer of work from other countries into China.

Though China has a massive capacity and huge domestic demand for extrusions, the industry is characterised by a large number of small producers instead of small number of large organisations. Because it is a relatively simple process, smaller manufacturers are also able to enter into the industry.

The extrusion process used in China is the same as that used in the rest of the world and can be summarised as follows:

  1. First the production of a suitable die is required. When producing the die, the shape of the extrusion along with allowances are needed in order to ensure that the product has the correct dimensions and desired finish.
  2. The die is then installed in the barrel of the hydraulic extrusion machine.
  3. Now the billet of aluminium is pre-heated.
  4. The pre-heated billet is placed in the chamber of the extrusion machine.
  5. The aluminium is then pressed through the die using the hydraulic ram of the the extrusion machine.
  6. The press is then emptied and the process is repeated for the further production of extrusions.

In many cases, the extrusion process is followed by heat treatments to homogenise the grain structure of the product and develop the full properties of the material used.

China is able to offer a complete range of post extrusion processes, usually conducted by the operator of the extrusion equipment. A notable process here, is straightening.

Straightening involves a long length of material taken from the press, clamped at its ends and stretched (typically by up to 5%), thereby straightening the extrusion (which may have minor misalignments caused by variances in the material itself and the extrusion process applied).

This straightening causes a minor shrinkage of the cross section and must thus be taken into consideration when the die is designed at the beginning of the extrusion process.

The aluminum extrusion processes used in China is the same as those used in the rest of the world. China is also capable of delivering a wide range of post extrusion services, allowing for the end product to be tailored to the exact needs and specifications of the client.

Aluminum Extrusion Manufacturers

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