Factory and process conditions aren’t always ideal for printing quality images on wire and cable at higher speeds due to the wide variety of outer jacket materials. The pressure is on front line personnel to manage changeovers, maintenance, and consumables to reduce cost and minimize production delays.
A poor image or code on a high-speed production line can result in scrap and reruns, wasting time and money.
Evolving needs for variable coding and other information that is required to be printed on wire and cable surfaces calls for reliable wire and cable marking printers and a strong understanding of ink chemistry.
Overall operational effectiveness, or OEE, is becoming a key metric in wiring process design and equipment selection for coding and labeling. According to Assembly Magazine, OEE is defined as the product of availability factor, performance factor, and quality factor all multiplied together. Improving the performance and efficiencies of the coding portion of the process lowers manufacturing costs and yields higher-quality output.
What are the Key Variables Affecting Printing Quality?
1. How Do the Covering Materials Impact Printing?
Substrates on modern wire and cable are common variables for wire marking printers and ink. Appropriate ink formulation requires an understanding of the types of materials used in the process. The ink must be able to adhere to substrates and provide contrast on different colors of cable.
Materials used for covering and protecting wire and cable continue to evolve and are becoming more complex. Driven by competition, the manufacturers are creating coverings that are:
Heat- and fire-resistant
There are also more types of specialty cable for military, automotive, aerospace, commercial, and home use. Many of the new types of cable have unique extruded protective coverings to meet the new applications of the Industrial Internet of Things (IIoT).
2. Are Different Surface Contours of the Cable an Issue?
Surface contours vary with diameter, bundling, and outer wraps of cable bundles. Wire printing machines must be able to adjust to these differences without major changeover.
For smaller diameter wires, printing directly on the wire requires that the printing mechanism print around the curvature of the wire, or it may need to print in smaller fonts. This is often accomplished with a CIJ (continuous inkjet printer), such as InkJet’s DuraCode CIJ printer.
A larger cable may need larger fonts for the coding to be printed clearly and distinguishable from a distance without rotating or turning the cable. This can be accomplished by using a large character valvejet printer or a high-resolution piezo head printer.
As the wire is bundled, the outer wrap surface may be very inconsistent while requiring clearly printed codes across the varying surface contours. Mesh or armor jackets create more difficult printing surfaces. Some cables are getting smaller - down to 26 AWG in the auto industry - requiring the ability to print smaller fonts on smaller diameters.
3. Will Temperature Affect Printing Quality?
Extrusion processes used for coating the metal wire introduce a temperature variable. Is the cable being coded before or after the quench tank? Prior to the quench tank, where temperatures approach the melting point of the surface, the material is not the ideal spot for coding.
Locating the printer after the quench tank allows for reasonable surface temperature, resulting in better adhesion and quality of the marking.
Factory ambient temperatures and humidity can also impact cable marking quality when HVAC is not present. It is not unusual for the wire drawing and extrusion process to be in open-air facilities.
Even in climate-controlled environments, the processes introduce higher temperatures to the surrounding processes. The variable temperatures in and around the process need to be taken into consideration when specifying the right ink for the surface of the cable.
4. Do High-Speed Wire Process Lines Make it More Difficult to Code?
The speed of the process does introduce a variable that impacts the cost of production. If the wire manufacturing line must slow down for wire printing, the costs of production will increase dramatically.
The faster the line speed, the lower the cost of the cable being produced (in most cases). The wire printing equipment and inks need to be able to match the line speed. The speed also impacts any requirements for variable coding, graphic printing of logos, or other branding information. InkJet, Inc.’s continuous inkjet (CIJ) printers are perfect for high-speed, high-quality cable and wire printing.
If the materials and wire can be changed over quickly, so must the printing equipment and ink. Process line efficiency should not be limited by cable and wire coding.
5. What About Dirt & Grime on the Surface of the Cable?
Manufacturing extrusion and process lines can introduce dust, solvents, and other grime into the air and onto the surface of materials being processed. After the quench tank, the surface could still be wet or contain solvents. Friction in the process can introduce dirt, rubber, or metal dust. Lubricants can also be introduced from wheels, conveyors, or other surfaces.
Despite the best efforts of production personnel in modern facilities to keep the coding surface clean, surface contamination will exist in some form. The ink and printing process needs to maintain print quality in spite of these issues.
If you have a process introducing contamination that may impact the printing ink quality, you may need a custom ink solution.
6. Are There Standards for Printing Codes?
International and national standards exist for every type of wire and cable produced throughout the world. There are local codes, customer requirements, and specific industry requirements. The recommended coding is grouped by industry and purpose.
Depending on the application and industry, the codes include basic information about the size, type of wire and covering, current, voltage, and signal parameters. Some are more specific to the application or industry like aerospace, deep-sea cable, housing, commercial buildings, military, and automotive. There could be a requirement for length markings and another coding to simplify installation and maintenance.
Some of the markings are driven by the standards and others by manufacturers or customers. It is becoming common to include logos and other branding information not contained in standards. NEC, NEMA, UL, ANSI, IEEE, IEC, NFPA, SAE, TIA, CFR, NAVSEA, and local building codes influence the need for surface coding on wire and cable during manufacture.
Contact InkJet, Inc. for More Information About Cable-Marking Printers
As you can see, many variables can impact the cable marking process. But we’re here to answer any questions you may have about the process or necessary equipment!
We specialize in inkjet printers for wire & cable as well as all the inks you’ll need to keep your production line running smoothly. Contact us or call us at (936) 856-6600 today for more information.