Magazine Article | January 1, 1999

Printing Very Small

Source: Field Technologies Magazine

Raychem Corp. and AxiCode Technologies, Inc. combine efforts to create a bar code solution for marking wires installed in machinery.

Integrated Solutions, January-February 1999
Planes, trains and automobiles all have complex wiring systems as do tanks, space shuttles and oil refineries. And when one or more of the 10,000 wires that are installed in these intricate machines need repair, how does the correct wire get to the proper terminal and connector?

Wire markers, in the form of heat-shrinkable tubing, are commonly used to identify wires wherever complex operating systems are installed. In aerospace and defense applications, intricate and complicated wiring harnesses are at the heart of electronic systems. These harnesses must withstand harsh environments while maintaining identification markings for testing, maintenance and repair.

Working Together Toward A Solution
AxiCode Technologies, Inc., formerly AmeriCode Technologies, Inc. (Monrovia, CA, and York, PA), and Raychem Corp. (Menlo Park, CA), have combined efforts on a wire-marking project. AxiCode is an automatic identification and data collection (AIDC) solutions provider. Raychem is a $1.7 billion material science company and heat-shrinkable tubing manufacturer, which uses radiation chemistry to change the molecular structure of materials. Together they have developed a system to print directly onto pre-assembled kits of heat-shrinkable wire markers.

By applying its knowledge in bar-code verification, printing systems and data collection, Axicode developed a thermal transfer solution for printing identification data onto Raychem's wire marker products. These products, known as the Raychem TMS System Six family, are composed of pieces of flattened heat-shrinkable tubing fixed to a carrier. The carrier is then guided through an Eltron ThermaBar 260 verified thermal transfer printer, a printer capable of printing directly onto shrink tubing.

The TMS wire markers can be printed with varying data. Raychem selected the Eltron printer because it is especially suited to printing directly onto heat-shrinkable wire markers.

How It Works
The ThermaBar 260 print head heats microscopic pixels that instantly transfer the coating from the ribbon to the tubing. The result is an image with enhanced legibility and clarity compared to dot matrix or daisy wheel impact printers. The printer uses its patented print head circuitry and high-speed optics to ensure the quality of every bar code. It rejects those that do not meet specifications.

Unique to the industry, the combination of carrier guide and tubing is fed directly into the printer. The industrial-grade tubing material meets military-specified requirements of Mil-M-81531 for mark permanence and Mil-STD-202 Method 215 for resistance to solvents.

The printer can accommodate 13 fonts in 20 sizes, bit maps, graphic files and bar codes. This allows the printer to perform simple, successive printing on both sides of a marker, thus speeding the rate of production. Hands-off printing incorporates a direct, flat-feed mechanism which accepts the first marker to the label-set line and requires no further handling.

The AxiLabel software system, provided by Axicode for Raychem, recognizes customers' data bases and produces sequential or other identification numbers driven by the data base. The printer produces them on the marker which acts as a job instruction to the operator and eventually to the technician maintaining the wiring.

Customers Can Print According To Need
Raychem supplies the complete system of software and Eltron printer to end users who are then ready to print TMS marker sleeves. Installation at the customer's location enables the customer to print its own legends according to its needs and corresponding to its own data bases. In addition, another printer, the Eltron TB 2046 has the flexibility to print verified shipping labels and bar-code labels when it is not printing onto wire markers.

"The whole essence of the product is that the customer puts the image on the tubing," says Jeff Russell, vice president of Axicode. "The customer has a huge data base to print a series of complex numbers in just-in-time fashion. The straight-through pass and ease of loading material into the Eltron printer make it ideal for the application." The main task of the system is identification of complex wiring harnesses for installation, repair and maintenance.

Surviving Wear And Tear
The TMS wire markers are designed to maintain data integrity after they have been installed onto the wires. "Electrical systems on aircraft, satellites and other equipment today use very small wires, so image quality and clarity is important," says Nick Smith, product director at Raychem. "The tubing and its printed legend are designed to shrink over two or three times in diameter while still maintaining excellent readability."

Integrity is also maintained by selecting the combination of tubing and thermal transfer ribbon materials carefully. "The most important aspect of the product is the finished appearance of the mark," says Smith. "The tubing and ribbons work together to achieve performance tailored to specific applications."

Tubing Stands Up To Harsh Environments
Intensive testing and development by Raychem has produced combinations of tubing and ribbons that are resistant to dangers which might affect the markings. Among them are fuel, de-icing and hydraulic fluid, toxic chemicals, high and low temperatures and ultraviolet light. In addition, Raychem has used its materials knowledge to develop qualified marker products for mass transit industries to fulfill low fire-hazard component requirements.