For Reliable Marking, Consider Valvejet Technology

What makes valvejet printers the reliability champions?

For marking applications involving harsh conditions, valvejet excels where all other inkjet technologies falter. Why? Let’s take a look.

Marking industrial products – everything from metal pipes to large stacks of lumber– with codes and brand marks has been a necessity for decades. Before the advent of digital inkjet print technologies, marks were applied by physically stenciling products with rollers or engraving devices. We’re talking slow, messy and inflexible.

That all changed with the invention of inkjet printers in the late 1970s that could create whatever mark you wanted at high speed. Continuous inkjet (CIJ) and drop-on-demand (DOD) inkjet printers could both precisely place marks at the click of a button, but only one inkjet printer technology was up to the task for the most demanding industrial applications.

Valvejet technology wins when the going gets tough

While CIJ technology found broad acceptance for creating the small date codes found on consumer-packaged goods like bottles and cans, it has struggled to gain much traction in the industrial segment. CIJ printers are susceptible to failure due to contamination or temperature extremes, and can only create small characters, limiting their usefulness for many industrial applications that require large marks. Sierra Aluminum, for example, found that CIJ printers required extensive maintenance under the harsh conditions in the company’s plant that drove up costs resulting from downtime.

Valvejet printer technology, on the other hand, has proven to be the perfect fit for harsh industrial marking and coding applications, and continues to this day to be the runaway leader in virtually all industrial segments. The past 20+ years have seen the emergence of other DOD-style technologies such as thermal inkjet (TIJ) and piezo inkjet (PIJ) that are suitable for many marking applications such as carton/case coding. Yet, for most industrial applications, there’s simply no better or more reliable choice than valvejet – and that’s likely to be the case for the foreseeable future.

The reasons for valvejet print technology’s success for industrial (and other marking applications) are numerous:

  • Outstanding reliability, supporting many years of operation with little to no maintenance.
  • Able to withstand harsh environments, including dust and extreme temperatures.
  • One of the most economical methods of printing available today with the ability to precisely tune ink consumption to match requirements.
  • Versatility to make a wide range of marks, from less than ¼” to several feet high by stitching printheads together.
  • Adaptable to production requirements, not the other way around. Valvejet printheads can be mounted over, under or beside a production line. They can also be mounted on robotic arms.
  • Long throw distances (the distance between the printhead and the item to be marked) to accommodate uneven or bumpy production lines.
  • Support for a broad range of porous and non-porous substrates and ability to work flawlessly with virtually any type of industrial grade ink. After decades of development, valvejet printers benefit from an unmatched — and still expanding — catalog of inks.
  • More than enough speed to handle fast-moving production lines.
  • Bulk ink supply systems that boost usability and help meet production runtime needs.
  • Simple cleaning with automated built-in valve flushing systems.

Valvejet printers work by propelling ink droplets through precisely engineered nozzles toward substrates. The jets are controlled by valves that open just long enough to release a droplet and close, hence the name drop on demand. The ink is supplied by a pressurized supply system that provides a constant flow, with no loss of ink. As a result of this design, valvejet printers are very efficient and minimize the exposure of solvents and other chemicals used in inks to the external environment. In contrast, with CIJ printers ink flows continuously and only a few droplets are re-directed electrically to create marks, exposing ink to the environment throughout the printing process.

Compared to other DOD technologies including TIJ and Piezo, valvejet printers generally support higher line speeds, longer throw distances, overall lower cost of ownership, and greater durability under harsh conditions. Where TIJ and PIJ stand out is for applications that require higher-resolution marks, such as logos or very small barcodes.

Over 9 billion firings – at least

Valvejet printers are designed for reliable, low-maintenance, 24/7 operation in harsh industrial environments. They can mark porous and non-porous substrates with high-quality and lasting codes. In the case of Matthews V-Series DOD inkjet printers, the printheads can withstand 9 billion firings before maintenance is required, and anecdotal evidence from production sites indicates the printheads can print high quality marks far longer than that before they need tuning.

To understand what makes valvejet technology so reliable, it’s helpful to look under the covers. First, the nozzles themselves need to be durable enough to withstand the abrasive effects of inks and solvents constantly flowing past. To that end, Matthews uses some of the hardest industrial materials on the planet such as Zirconium and synthetic Sapphire to form its nozzles. The exact composition used by manufacturers is typically proprietary since it’s so critical to get nozzles right to ensure mark consistency over time.

Looking inside a 16-valve V-Series printhead.

Looking inside a 16-valve V-Series printhead.

The other vital element in valvejet technology is the valve itself. Drop on demand technology was originally invented in Sweden in the late 1970s by Swedot AB, which is now part of Matthews Marking Systems. The technology has steadily moved forward thanks to decades of continued refinement and updates to improve quality and durability.

The way the valve works is simple in concept, but as with many electro-mechanical devices, the details matter. Each valve consists of a plunger with a rubber tip that seals off the nozzle and is held in place with a spring. A solenoid coil at the opposite end overcomes the spring tension and pulls back the plunger just far enough and long enough to release an ink droplet through the nozzle and fire it out to the substrate. The distance the plunger pulls back is factory tunable to ensure optimum droplet size.

Patented design, continuous innovation

The specific design for the Matthews V-Series printheads, as shown below, is protected by United States patent US 9,108,424 BS titled Valve Jet Printer with Inert Plunger tip. This patent outlines key improvements to the plunger design that allows for the use of any ink type and ensures the plunger and rubber tip perform reliably over billions of cycles. Among the innovations are an improved plunger and seal design that is not available elsewhere across the industry.

Inside of a valvejet.

It’s also important to note that valvejet printers achieve the greatest reliability when they are part of a complete system, including a fully integrated print controller, application-specific ink supply systems, and the right type of ink for the application. Ink variables that need to be accurately tuned include viscosity, drying time, and surface tension.

Valvejet technology has slightly larger dot sizes than other inkjet technologies, adding to the reliability equation. These larger drops are better able to absorb small dust particles or debris that may accumulate in front of the nozzles (remember these printers are often used in dust-filled conditions like sawmills or cement factories) and remove it from the printhead. As a result, the “line of fire” remains clear from build-up that otherwise would clog most printheads.

Keep the lines running – get a free sample mark

If you’re tired of dealing with marking and coding technology that takes a beating and then stops ticking, it may be time to take a closer look at valvejet for your most demanding applications. Crisp clear marks are a requirement to deliver products to customers. When the printers go down, your line goes down. When marking reliability is paramount – and when is it not? – valvejet is the clear choice. Matthews invented valvejet technology and is still the industry leader. Contact us at 800.775.7775 or email at [email protected] to learn more about the V-Series and to obtain free sample marks.