Aluminium cylinder blocks

Hard anodising certainly does require grinding.

I don't think so.

My experience of using it is that it is so thin as to make grinding nearly impossible without removing it completely.

If using 'O' ring seals, which would be a good idea, there is no need to grind the bore for either hard chrome or anodizing as the fits are not that close.

Very light lapping of either finish, with a very fine abrasive, is the most that may be required.

I have used hard anodising in tooling for plastic injection tooling and on disc breaks on racing motorcycles to reduce weight. You can get it done local to where I live and they also do PTFE coating on hard Anodising. There is no need to grind after treatment but there is a build up and that should be taken into account they will tell you the amount but it would be between 0.002 " and 0.005 ". Mansfield Anodisers Ltd. There may be other anodisers local to you.

David

1. My experiance of hard anodising is only with aircraft components which are produced to higher specifications than usual. My firm used to make uplocks for Airbus landing gear which had hydraulic actuator cylinders with a bore of about 3/8". The anodising was about 0.002" thick and was ground in house to a mirror finish, the unground ends of the cylinder were smooth, but not as good a finish as the bores. These pictures are of a hard anodised and ground tube which the swashplate spherical bearing slides up and down on for a helicopter. Possibly, a Bell Jet Ranger. The grinding may be visible in the photos. The diameter is about 4".

Edited By old mart on 23/06/2019 12:06:09

It is most unlikely that the bore was ground post anodizing more likely it was honed to achieve the surface finish required.

Lapping is an option for the model engineer 's work shop.