Flow Down Issues

A significant problem throughout the aerospace industry is poor flow down of information. We see this all too regularly and it is the cause or a significant contributor to many non-conformances. We cannot achieve your requirements if we are not told about them. Nadcap's surveys regularly highlight the serious scale of the flow down problem in the industry.

Required Information and Defaults

Below are the items of information we need to successfully process your jobs. However, we find that these details are provided infrequently enough that we have instituted some defaults. Some specifications have their own defaults and these are honoured. The details below apply when a specification does not cover the area in question and it is not specified on its purchase order.


Requirement Default/Assumption
Alloy 6082 or similar
Thickness Chromic: N/A
Sulphuric: > 5µm Hard: > 20µm
Seal Cold sealing
Dye None
Colour matching Not required
Light fastness No requirement

No requirement

Please note, it is essentially impossible to reliably control the thickness of anodising without knowing the alloy of the part. The anodising efficiencies of alloys varies significantly - a process that is expected to apply 30µm of anodising on 6082 may apply in the region of 125µm on some other alloys (1000 series, some 5000 and some 7000 series). For this reason, our default is only a minimum. If you require a range, you should specify both the range you require and the alloy used.

We have produced a guide about which alloys are most suitable for anodising.

Chromate Conversion Coatings

Requirement Default/Assumption
Colour Alocrom 1200: Yellow to deep yellow (for corrosion resistance)

Zinc Plating

Requirement Default/Assumption
Thickness of coating 5µm and up
Tensile strength Less than 1000 MPa
Passivate option Clear (trivalent)
De-embrittlement Not required
Stress relief Not required
Internal anode Not required and not used

Refer to our guidance on zinc plating thickness if you are unsure what thickness is appropriate for your service condition.