Non Destructive Testing, Part 3

Fluorescent Penetrant Testing

The most commonly-used of non-destructive testing methods is the liquid penetrant testing. A dye solution that is either visible or fluorescent is used to coat the casting part being tested. Any excess is blotted from the part before a developing agent is applied.

The developer pulls out any penetrant that has seeped into the part through imperfections that reach the surface of the part. An ultraviolet light causes the seepage to glow, revealing the areas of imperfection.

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Non Destructive Testing, Part 2

Magnetic Particle Inspection

To find flaws on the surface or just below the surface, magnetic particle inspection is used. This type of inspection can only be used on iron-based, ferromagnetic metals, such as iron, steel, cobalt and nickel. Ferromagnetic alloys used in the casting must contain enough of the magnetizeable material for this type of inspection to be effective.

Flux, or magnetic lines of force, gets distorted when it attempts to pass thru a flaw. Thus this “flux leakage” follows the application of infinitesimal particles of iron to the part of the casting that is being examined. There might be some differences in the application of the magnetic field, but the principle of magnetic particle inspection is the same for all applications.

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Non-Destructive Testing, Part 1

You can have your casting project put thru a number of non-destructive tests and analyses. These include a certified chemical and physical analysis, including the following types of inspection and non-destructive testing options:

Radiography X-Ray Testing
Penetrating X-rays or gamma radiation is used to inspect castings for imperfections. This radiography testing uses an X-ray machine or radioactive isotope as the radiation source. Like a normal X-ray, the radiation passes through the casting and creates an image on the film.

When the X-ray is developed, it creates a shadowgraph that reveals the internal accuracy and compliance with the original design. Inaccuracies and problems will be revealed as more dense portions on the film. Unsoundness will show up much like a broken bone will show up on an X-ray film.



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Freedom of Design

These biopsy cubes contain several designed challenges: beveled edges, chambers that are recessed and corner with segregated areas. There was also a circular pattern on one side. The challenge was made even more difficult by the necessity of using one of the most unforgiving metals, 410 stainless steel.

Shelmet’s investment casting process provided absolute design freedom to the design engineers. If you have a design challenge, then you need to contact Shelmet. We love those kinds of challenges.

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Shelmet’s Expertise Saved the Day

Before Shelmet, this part required a multiple handling process and machining. While the part used 356 aluminum and looked simple, it was actually quite complicated due to the square interior. The extensive machining required to produce the end result was extremely costly and time consuming.

Shelmet changed all that by using investment casting. As a result of our expertise in aluminum the casting was precisely what the customer specifications required. This was accomplished at a savings of time and money due to eliminating the necessity of conventional machining.

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Investment Casting Design Assistance

Shelmet provided investment casting design assistance. The part's purpose was to hold the sole of a shoe during the shoe manufacturing process.

Shelmet Precision Casting, Inc. assisted in the design process, identifying the challenge. We were also able to recommend the proper close tolerances and alloy for the part.

Before investment casting the part, Shelmet created a prototype and test the part, to ensure that the design was correct. The process saved the customer both time and money, creating a part that was the most competitively-priced in the market.

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