General information on crack diagnosis of aluminum parts - AH60.00-P-0014-01N

All models

It is necessary to check whether any cracks, inclusions or other weld faults are present before and after performing repair work on aluminum components.

A suitable method of testing is the simple dye penetration test, which accentuates faults starting at the surface or in immediate connection with it which cannot be seen with the naked eye, through color contrast. This method utilizes the capillary effect of fine surface openings. Liquids containing dyes with low surface tension penetrate into these openings and can be verified there with suitable contrasting agents.

Usually luminous red or yellow-green fluorescent dyes are used a penetration agents, which can be washed off with water. The penetration agent can be sprayed on or applied with a brush.

During the penetration time, the penetration agent should never be allowed to dry out. The smaller the surface faults, the longer the penetration time (approx. 5 to 30 minutes).

The developer used subsequently requires a high absorption capacity, to suck the penetration agent out of the damaged spot. This makes the fault visible by contrast in the developer layer. The development time is analog to the penetration time. As a matter of principle, however, faults can only be verified on the material surface.

Always observe the specific Safety instructions  of the individual manufacturers before using the cleaner, contrast agent, and developer. 

All three diagnostic agents are highly inflammable. The contrast agent also poses a health hazard.

Detection process: 

1. Crack after cleaning.
2. Crack after application of contrast agent.
3. After removal of quantity which has not penetrated into the damaged point
4. After application of the developer, damaged point is indicated.

Typical damage indications with dye penetration method 

1. Cold fissures
2. Hot fissures
3. Ground fissures
4. Fissures with strong blistering
5. Pores of various sizes
6. Nests of pores
7. Spongy structure
8. Pores with strong blistering
9. Stress