How to make your product finish friendly

Choose the right alloy.
The grade of alloy will affect:

The machining properties

The colour of the base metal (e.g. silvery or greyish)

The brightening capability

The colouring capability

The achievable thickness of the coating

The etching (pre-treatment) reaction and hence the appearance after stripping.

Choose the right stock
for the fabrication of your components i.e.

Engineering plate

Casting

Sheet

Extrusion

We will test a sample of your stock for anodising suitability

Ensure that your product has good jigging/contact points.

All components must be jigged securely, to prevent them falling off the jig / frame during processing. Where the jig pins contact the work there will be no anodic coating and a small mark will result. Naturally, jig marks are kept to an absolute minimum and contact points are usually situated where they are not easily visible in service and where the lack of anodic film has minimum detrimental effect. The selection of the position of contact points is therefore important and non-significant areas should be marked on drawings. The size of the contact points will vary with the type of component, and the amount of anodising current required.

Very firm jigging and contact points capable of carrying high current densities are essential in hard anodising.

When designing a component that is to be anodised, it is imperative to consider how it can be jigged. It may very well be cheaper overall to introduce a 'surplus' hole that has no functional purpose except to aid jigging.

Unless specified by drawing, or by written instructions on order, contact points will be chosen at our discretion to suit the availability of our standard jigs.

! Forming or fabrication must be done prior to anodising.

The anodic film is hard and brittle, and will craze if badly deformed.

! Welds should be carried out prior to anodising and should be restricted to non-significant areas if appearance is important.

! It is not possible to develop the full depth of anodic oxide coatings on sharp edges and corners, particularly in hard anodising.

If possible edges should be gently broken or radiussed, and a general rule of thumb is about 0.030" radius per 25 microns of coating thickness.

! Attention must be paid to critical dimensions.

Should holes be made under/oversize to allow for growth of film? Do fine threads or toleranced holes require masking?

! Ensure that your raw component is adequately packed and protected.

Unprotected surfaces can be scratched and bruised in transit. Swarf and cutting compounds should be removed. Minute pieces of swarf can blemish the surface of the component and compounds left in holes and crevices can leech out during the process causing unsightly 'runs' in the cosmetic finish...

...but...

...don't allow adhesive tape or labels to get on to the workpiece. Adhesives are difficult to remove and being transparent, are not always visible on the component. Areas affected by residual adhesive will not anodise properly and may require removal by mechanical means to get back to the bare metal. Please wrap your components in paper, and then the tape and labels which are so useful in making tidy and well identified parcels.

! If you need to make some indication on the component, it is acceptable to write on the workpiece with a WATER BASED FELT TIP marker, as this is readily removed in processing.

! Please ensure that all work is accompanied by appropriate drawings and written purchase order.

Ask the experts at the design stage -Remember

FINISHING COMES FIRST

Thought put into the finishing of your product at the start of the project can save time and money at the final finishing stage!