Methods to produce a permanent mark on parts are: • Indenting • Embossing •
Coining •
Abrasive blasting • Adhesive dispensing •
Cast,
forge or
mold •
Dot peen •
Scribe •
Electro-chemical etching •
Embroidery •
Engraving/milling •
Laser marking • LaserShot peening • Liquid metal jet •
Stencil (mechanical cut, photo process, laser cut) Other methods like manual metal stamp, vibro-etch and embossing were not suitable to successfully apply micro size (1/32- to 15/64-inch square), high density machine-readable symbols.
Marking method selection factors The marking method depends on a number of different factors: • Part functionNon-intrusive marking methods are recommended for parts used in safety critical applications like aircraft engines or high pressure and high stress systems. • Part geometryIt is more difficult to place a Data Matrix on a curved surface than it is on a flat surface. • SurfaceHighly polished metal surfaces should be textured to reduce glare prior to marking. The textured area should extend one symbol width beyond the borders of marking. • Part SizeWhen a 2D Symbol is used, the size of the part is not a relevant factor as the available marking area is reduced to below 1/4 inch square. • Operating environment / age lifeIt should be controlled, if the used marking method can survive in its intended environment and remain readable for the life cycle of the part. •
Surface roughness / FinishA rough surface is more challenging for a 2D barcode as the data elements can be recognized appropriately. The surface roughness levels should be limited to 8 micro-inches for dot-peen marking, laser and scribe systems can make a readable mark in rougher surfaces. The laser systems burn a "quiet zone" first and then the 2D code. The scribe method provides a high resolution 2D mark that makes the part readily readable in most cast surfaces. • Surface thicknessSurface thickness must be taken into account when applying intrusive markings to prevent deformation or excessive weakening of the part. In most applications the marking depth should not exceed 1/10 the thickness of the part. ==Standards and regulations==