Anodisation without treating the crucial areas

In the past, it was only possible to produce anodised components with an earthing point by elaborately reworking them, making the process uneconomical in most cases. Creating the potential equalisation point economically at the anodisation stage only used to be possible for rotationally symmetrical components, for example by blocking. When processing not rotationally symmetrical shapes, it was necessary to  elaborately, mechanically rework the component or use laser processing to remove the oxidised layer in order to create earthing points. If anodised components subsequently fitted with an earthing point needed to be glued, it was often necessary to additionally clean the component before it could be adhesively bonded. However, if the non-anodised sections of an anodised component can be generated at the same time, the problem of the additional processing stages can be avoided.

In June 2013, we therefore started a ZIM (central innovation programme for SMEs, promoted by the Federal Ministry for Economic Affairs and Energy on account of a resolution taken by the German Parliament) development project. The result:
Anodised Partial Plus (HT-C60), a solution for processing partially anodised aluminium workpieces. The aim was to generate a value stream-optimised and simultaneously bondable and corrosion-protecting anodised surface with an integrated potential equalisation point. The Holzapfel Group managed to achieve this aim by means of a specially designed contacting system using a particular combination of materials. The potential equalisation point is thus created during anodisation and the components do not require separate reworking.

Promoted by: the Federal Ministry for Economic Affairs and Energy on account of a resolution taken by the German Parliament.

Creating non-anodised points during anodisation
Using our newly developed partial anodisation process, we can create non-anodised points during the anodisation process. This is achieved with the help of a specially developed sealing element, which ensures that selected points on the component remain non-anodised with the help of a specially designed rack and covering technique. This innovation has a significant number of advantages. Firstly, the process is far more efficient as the subsequent processing steps otherwise necessary are no longer needed. Secondly, there is less risk of producing rejects, as one working step no longer needs to be carried out, resulting in greater process reliability.

Process attractive for manufacturing automotive parts and electrical household appliances
Anodised Partial Plus (HT-C60), provides precise non-anodised points – and therefore reproducible results, making the process an interesting proposition for mass production. For example, in the automotive industry, components often need to be anodised with a protective coating and are subsequently fitted with an earthing point – which is no longer necessary in future, due to partial anodisation. Other mass-production sectors also benefit from making components with non-anodised points: consumers, ballasts in aluminium casings, manufacturers of casings for electrical assemblies, camera casings, technical medical devices or outdoor equipment that uses electricity, such as torches, etc. as the non-anodised points guarantee a protective circuit or very good electrical conductivity without reworking. Anodised Partial Plus (HT-C60) is the solution of choice when optically aesthetic surfaces and protective anodisation, but also the conductivity of an earthing point, are called for. The partial anodic oxidation of aluminium workpieces combines all of these advantages – in one single step. Read more about the process and its technical details here...

A summary of the benefits:


  • Non-anodised points are created during the anodisation process. Previously, a separate process was required to create a non-anodised point (either as an earthing point or a potential equalisation point).
  • The process saves one complete step, as reworking is no longer necessary.
  • Also helps to reduce transportation costs.
  • Less risk of rejects as reworking is no longer required.
  • One working step less in the process means fewer current inventories, as additional components no longer need to be stocked.
  • Not only are reworking processes such as turning, drilling, grinding or lasering no longer required, other related work such as subsequently cleaning or deburring the workpiece is also rendered needless.
  • Any possible scratching of the newly applied surface when fixing the workpiece also becomes a thing of the past.
  • Non-anodised points guarantee good electrical conductivity without reworking. Sophisticated surface optics are supplemented to include an earthing point with outstanding electrical conductivity in one single process.
  • The process innovation came about as the result of a specific requirement from an automotive industry customer to produce casings for electronic components that regulate and control electrical consumers.

Anodised Partial flyer as a PDF

For more information visit the process page Partial Anodised

Anodised Partial makes it possible to partially anodise workpieces that require an integrated earthing or potential equalisation point that must not be anodised.

Anodised Partial Plus saves a complete process step by integrating the earthing point right at the anodising stage.