Back in my shop days, most workpieces were marked by using hardened steel stamps and a 2-lb. hammer. WHAM!
That heavy-handed approach didn’t cut it when the shop began supplying thin-walled aluminum brake sleeves to Boeing. We ordered a bunch of rubber stamps and gently rolled the part number in permanent ink around the sleeve’s circumference. Quite often the ink would smear and we’d have to clean it with alcohol before trying again.
Later, we got an order from Sundstrand for tight-tolerance 4140 steel bearing housings. The print called for electrochemical etching of the contract and part number. We invested $500 in a benchtop machine, a supply of electrodes and some weird-smelling chemicals. Using a typewriter to generate the characters on a sheet of transfer paper, we’d then cut out the stencil with scissors, fit it to the electrode and apply DC current, one workpiece at a time. What a hassle.
Manual electrochemical etching and rubber and steel stamps are still in use. These tried and true part-marking methods are simple and affordable, and, except for steel stamps, gentle enough for even flimsy workpieces. The problem is those manual processes are slow. The good news is there are better ways to mark parts, especially ones with thin walls or other delicate features.
Perhaps the most flexible is laser marking, used to mark everything from saw blades to circuit boards, and pacemaker housings to bearing races. Best of all, laser marking, contrary to what some might think, is simple to perform: Set up the workpiece in the machine, load the program and press cycle start. A few seconds or minutes later, the part’s been marked with the required number, phrase, bar code or graphic design. Laser marking is noncontact, so clamps are typically unnecessary, although in some cases a multipart fixture might be used if production volumes warrant.
Read the rest: www.ctemag.com/aa_pages/2014/141207-PartMarking.html