NDE and Weld Surface Prep
NDE/NDT surface preparation needs:
One of the most critical steps in NDE/NDT inspections is the cleaning of the surface prior to the inspections. All coatings, such as paints varnishes, plating and heavy oxides must be removed to ensure that the defects are open to the surface of the part.
Coatings, paint as an example, are much more elastic than metal and will not fracture even though a large defect may be present just below the coating. Also contaminates can also lead to higher background noises.
Common coatings and contaminates that must be removed prior to inspection include the following: paint, dirt, scale, oil, grease, wax, oxide, decals, rust, flux. A good cleaning procedure will remove all contamination and not leave a residue so a proper inspection can be performed.
When using conventional cleaning methods, such as alkaline cleaners can be detrimental to the inspection process It has also be found that domestic soaps and commercial detergents can clog flaw cavities allowing these cavities to go unnoticed leading to catastrophic failure in the future. Media blasting and grinding have led to media entrapment in addition to metal smearing. It is very important that material being inspected has not been smeared across its own surface during machining or cleaning. It is well known that the following methods can cause some materials to smear; hand sanding, hand scrapping, grit blasting, tumble deburring, honing and peening operations.
Welding surfaces preparation needs:
The best welds come from pure clean metal to metal contact, any foreign materials in the welding area can cause welding imperfections. Even brand-new metal must be prepped before it can be welded because there is usually a coating put on new metal so it does not rust or oxidize during the shipping process. This is a factor that is often overlooked and will always result in a weak and ugly weld. Be mindful, once you remove this coating the metal is exposed to the elements, if left out unprotected steel will begin to rust, even indoors.
To start, the type of welding you are doing will determine how you prep the metal. Inherently MIG welding steel does not need the metal to be perfectly clean. On the other extreme, TIG welding aluminum requires contaminant free metal to create a strong clean weld.
The use of a LASer provides cleaner results in a fraction of the time with no cleanup or addition fire watches required with grinding away the surface. Also when the inspection and welding is complete the surface can be cleaned immediately without the use of harsh chemicals or additional grinding to prepare the surface for painting or coating.
Everything Changes with a LASer!!!!!
Unlike adequate, average and barely acceptable conventional cleaning methods, cleaning with LASers is making the perfect surfaces for inspecting and welding more of a reality without having to repeat cleanings.