Serial Number Removal

Why is the removal of laser applied serial numbers so effective?

Impression is not as deep & has a lower deformation level

Grinding

an operating that removed material by rotating an abrasive wheel or belt against the work piece

Overstamping

to add characters to an existing number to cover up or obliterate the original number

Peening

a series of manually applied impact depressions administered repetitively w/ a hammer or similar tool over & around the SN causing a flattening of the surrounding metal to render the number unreadable

True or False: peening changes the crystalline structure of the workpiece

True

Gouging

a thermal or mechanical process designed to obliterate unwanted metal

When is gouging most commonly used?

To remove large amounts of material to create grooves, cavities to remove defective parts

Can recovery of a serial number that has been obliterated via gouging being restored?

No

Why can’t gouging be restored?

the metal composure is changed

Heating

normalizing or annealing metal, destroying the disturbed metal evidence

What does heating the workpiece do to the serial number?

reconfigure the crystalline structure

Puddling

metallurgical process of stirring molten pig iron in a furnace to burn off carbon & impurities, transforming it into malleable wrought iron

Welding

a joining operation involving the melting of the joined metals

Scratching/Filing

a broad tip or pointed tool is used to repeatedly scratch the stamped or engraved depression of the SN & the surrounding area until the number is unreadable

Which is easier to obliterate via scratching/filing, engraving or stamping?

engraving

Drilling

uses a drill to bore out the serial number

True or False: drilling likely affects the subsurface at a deep enough level to change the structure

True