BUMPY BAR CODES Zero Contrast Reading
Direct Parts Marking Overview
There are many ways to permanently embed a Bumpy Bar Code into a part, including molding, casting, indent marking, laser engraving, machine engraving, investment casting and newly emerging techniques. Directly marking the part with the bar code has several advantages, including.
- The label cannot fall off
- The Bumpy Bar Code can be painted, blasted and subjected to chemical baths
- Unless the part surface is physically disfigured, the Bumpy Bar Code will remain intact.
- Mold and Cast Inserts
- Mold inserts are used to generate Bumpy Bar Codes directly in molded rubber and plastic parts. The inserts generate Bumpy Bar codes with adequate draft for mold release. The insert is placed in the mold, preferably in a cut-out, and the rubber or plastic flows into the openings in the insert. the inserts can generate both Bumpy Bar Codes and human readable information. Mold tools can also be marked directly.
Heavy duty stainless steel inserts, generated using a computer numerical control (CNC), are used for marking static information such as part numbers and manufacturer ID. These inserts are held in the mold using standard machine screws. For creating a serialized Bumpy Bar Code, a disposable Teflon or embossed tag insert is used. Traditional casting uses the same basic approach except that Bumpy Bar Codes can also be formed in sand core; once the liquid metal poured into the cores cools, Bumpy Bar Codes are formed. Casting of serial numbers has also been successfully achieved using serial cast inserts.
- Indent Markers
- Indent markers (also known as dot peen markers) can embed Bumpy Bar Codes and human-readable codes directly into a metal part. The Bumpy Bar Code mark is created by pneumatically driven "chisel" stylus impacting the metal to create bars. A "dot" chisel is used to generate the human readable characters. The stylus is accurately moved incrementally in each successive impact to the series of bars in the Bumpy Bar Code.
Indent markers can mark flat metal as well as pipes and other curved surfaces. Table-top models are used for small parts, while models that mount directly over an assembly line are used for "large" parts. The machines are controlled interactively using a computer controlled software program which allows serial bar code generation or direct control from an MRP/ERP system.
- Laser engravers can embed Bumpy Bar Codes, human readable characters and graphics directly into rubber, plastic, glass and metal parts. The mark is obtained by vaporizing away the material using a laser beam which is optically steered to create the desired pattern.
There are two types of laser engravers, CO2 and YAG. CO2 lasers are used for "organic" materials--rubber, plastic, glass, etc., while YAG lasers are used for marking metal.
Material handling systems for lasers can be designed and built to handle a large variety of parts including flat surfaces, curved surfaces, round objects such as pipes and tires, and much more. Laser engravers are not portable, but can be integrated into an automated manufacturing line or operate as a stand-along workstation. The lasers are controlled interactively using a Windows™ based software program which allows serial bar code generation or direct control from an MRP/ERP system.
- Machine Engravers
- Machine engravers are industrialized versions of the machines used to engrave trophies and plaques. The mark is obtained by moving a cutting bit spinning at a very high rate. This method appears to have promise for engraving Bumpy Bar Codes, human-readable characters and graphics in plastics and metals. In the case of plastics this method will work best with materials which have higher melting points as the friction generated by the engraving bit tends to head the material, causing it to flow.
- Investment Casting
- Investment casting is a very popular method of creating cast aircraft parts with intricate detail, hence eliminating expensive machining and complicated welding. The parts are created by first injecting hot wax into a mold pattern. The cooled wax pattern is assembled with all other wax patterns that form the total part and then dipped or invested into a ceramic pool, creating a ceramic coating over the wax. Next, the wax is melted out of the ceramic shell, and the shell is fired. The molten metal is then ported into the ceramic shell and cooled. Finally, the ceramic shell is shaken off leaving a machined quality part. As we have had success with traditional casting, and investment is capable of additional detail, we are working to create Bumpy Bar Coded parts by engraving the cooled wax pattern with a machine engraver. These machines are commonly used now to engrave human readable in the wax pattern.