For better or worse, all days are interesting when it comes to UV applications and process control. We still enjoy the questions, learning and plethora of unknowns associated with a customer visit, training session, email or phone call. There are some interactions that fall into the “if we couldn’t laugh, we would all go insane” category (Credit to Changes in Latitudes, Changes in Attitudes by Jimmy Buffet). Even in my wildest imagination, we couldn’t have made up some of these “interesting” interactions.
Why Measure UV?
When we ask this question, we normally hear answers related to saving time, saving money and/or both. People measure to improve communication between their different facilities and/or their supply chain partners. Other “Why Measure” answers include establishing a process window, transferring a process from the R&D lab to production, and troubleshooting when there are issues. We also get answers related to quality – especially when our customers need to verify cure conditions or provide certificates of conformance to their customers. Outside of these standard curing industry interactions, the following certainly qualifies as “interesting.”
EIT 2.0: Why do you have a radiometer?
Customer: To show the numbers to the inspector.
EIT 2.0: Do you know how to use it?
Customer: No.
EIT 2.0: Did you read the manual?
Customer: No.
EIT 2.0: Do you use it on a regular basis?
Customer: No.
EIT 2.0: Aren’t you concerned about the numbers you get?
Customer: No.
EIT 2.0: Why not?
Customer: The inspector is more concerned with the bribe I pay during the audit than the numbers.
I was at a loss for words. Measure to save time and money, not to appease an inspector with his hand out. Process managers: Keep asking questions. Train your team so they understand the reasons and “whys” for a particular procedure or process. If the established procedure or process is not followed, what is the possible impact on their livelihoods?
“We don’t need no stinking badges.”
At the risk of dating myself, this quote is from Treasure of the Sierra Madre, a 1927 book that was made into a 1948 film. For those younger, the quote also was used in the 1974 film Blazing Saddles. We had multiple “interesting” interactions with people new to UV working with UV LED digital printers at the PRINTING United tradeshow last October. Some of the people approached us with a “We don’t need no stinking radiometers” attitude. With the show held in Las Vegas, maybe a lot of people felt it was ok to also gamble with their UV process?
I think the initial “We don’t need no stinking radiometers” attitude has three root causes.
Lack of Education: Our industry grows when new people and applications use UV. The need for training and education also grows when new people enter industry. People do not always keep up with technology.
UV LED Stability: UV LED sources tend to be long lasting and can offer more stability than broadband (mercury) sources. UV LEDs are comprised of hundreds (if not thousands) of individual light emitting diodes (LEDs). In a good LED system, the individual diodes have been carefully selected (binned) by their spectral wavelength, intensity and forward (drive) voltage. They are connected (wired) together and driven by a power supply with electronics, controls and cables. Proper cooling of the diodes and the overall array (via clean air or water) is essential for their long life. On a digital press, UV LED arrays often are attached to the print head and move quickly, stop suddenly and reverse direction by 180°. A premature failure in any of these components or one induced by mechanical stress can change the output of the LED, which could lead to changes in product cure.
Have some LED source suppliers gone too far and convinced inkjet manufacturers (and, ultimately, the end users) that UV LED systems are so stable that they do not need measuring and only minimal maintenance over the lifetime of the press?
This attitude was evident with one LED source manufacturer at the show. The manufacturer’s lab tests of an array had showed very little change over almost 10 years and, because of these tests, didn’t feel a need to use measurement equipment. I imagine the difference between running lifecycle tests in a clean, controlled R&D lab vs. running 24/7 in a production facility is like the difference between probation or “hard time” in a maximum-security prison.
Process Variables: New users want to push the “start” button and begin printing or curing. Let’s assume that the UV LED is stable. When using UV for the first time, users may not understand the other process variables and how they are interconnected to guarantee success. What happens if a variable (such as the LED brand, power level, height, wavelength or speed) is changed by an operator? What happens if the ink suppliers change? Substrate material or height? Changes in environmental conditions between summer and winter? Are facilities located in multiple geographic locations?
Using a radiometer will help to confirm that the UV output (and, sometimes, process speed) is where it needs to be and allows users to use other tools to isolate any issues. My father always said that casinos are not built by the winners, and the odds always favor the house. In UV, the long-term odds also favor something changing within the UV process.
Is 60 the New 40?
With regular exercise and a healthy diet, people claim that “60 is the new 40.” This may work for age, but it does not work for UV process numbers. At PRINTING United, we were asked for help by a formulator whose ink was not completely curing on two different brands of digital presses, with two different brands of UV LEDs. The ink was formulated based on an expected irradiance value of 8 W/cm2 on each of the two 395 nm UV LED arrays on each press.
Fortunately, I happened to have a radiometer at the show. Testing showed peak irradiance values of 3.1 W/cm2 on one press and 3.6 W/cm2 on the other – MUCH less than the formulator’s expected 8 W/cm2. Additionally, the output between the two UV LED arrays on either side of the inkjet printhead was not symmetrical. (See Figures 1 and 2.) The ink was formulated correctly, but did not cure fully because of the much lower than expected UV values. While “60 may be the new 40,” 3.1 to 3.6 W/cm2 is not the new 8 W/cm2.
Buyer Beware
Having successful and recognized products leads to imitation or, in some cases, outright counterfeiting. Our company continues to educate buyers that a genuine unit and counterfeit unit do not perform the same. A customer in Europe purchased a radiometer second-hand on eBay from China. When the radiometer arrived and its readings were significantly different than a genuine EIT radiometer, the buyer contacted us for support. The serial number and unit type did not match our records, and the buyer was upset that we were not able to support the counterfeit unit.
The buyer contacted the counterfeit seller and was falsely told, “The products sold can be ensured to be original and authentic. The instrument has been certified by domestic manufacturers in China, which is the reason why EIT does not recognize it, but this does not affect its use.” It was at this point the buyer realized the statement seemed suspicious.
Be suspicious of any sellers not associated with the original, genuine manufacturer of any product.
Summary
Customer interactions always are interesting, with the majority being a good two-way exchange of information. Some days, customer interactions go beyond interesting and genuinely surprise us. We all need to maintain an “If we couldn’t laugh, we would all go insane” attitude when these interactions happen. Use these interactions to learn.
Parting Thought
While people claim “60 is the New 40,” I firmly believe “9:00 pm is the new midnight.” I end this column with another Jimmy Buffett pearl of wisdom from his song Coast of Carolina: “These days I get up about the time I used to go to bed.”
Jim Raymont
Director of Sales
EIT 2.0 LLC
jraymont@eit20.com
