Why Printing on iPhone 14 Cases Is Difficult — UV Printer Products (Part 4) ARTJET 2026

1. The Gap Between Head and Substrate — Stand-Off

• The distance between the substrate and the print head is called the “stand-off,” and its optimal value is 1.2 mm.
• Up to 1.5 mm, there is minimal change — but as the stand-off increases, ink increasingly fails to land in the intended position.
• Due to the iPhone 14’s protruding camera bump height, the stand-off must be set much higher to print with a UV printer.

2. However, When the Stand-Off Is Too High:

• Ink begins to spread sideways — especially White ink, which has heavier pigment and higher deposition volume, scatters more severely.
• Since neither White nor Color lands in the correct position, White may show visible lines, and Color images appear rough.
• When the stand-off exceeds the print head’s maximum tolerance, air turbulence causes ink droplets to land in completely unintended locations.
• Prolonged printing at high stand-off can cause partial clogging of print head nozzles.
• Depending on the print head being used, some level of production may still be possible,
• but print quality drops noticeably and the defect rate increases significantly.
• Repeated identical jobs over long periods can partially block print head nozzles.

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1. When the Stand-Off Is Too High

1_1. Why Ink Fails to Land in the Correct Position

• The photo below shows the optimal jetting conditions found using a dropwatcher.
• When the droplet maintains a round shape, its straightness is also good.
• However, no matter how optimal the jetting conditions are, the greater the stand-off, the more ink fails to land accurately.

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• The ink jetting speed is typically 7 m/s — meaning the ink travels 7 meters per second. It jets extremely fast.
• However, 7 m/s is the speed at the moment the ink is fired (jetted) through the nozzle.
• The low-mass ink droplet’s speed decreases from the initial 7 m/s as the distance increases,
• and the offset alignment calibrated for each color and White — based on the ink drop speed of 7 m/s and the print head carriage travel speed of 0.8 m/s — also becomes misaligned.
• Ultimately, ink droplets miss their intended landing positions, making the print rough and causing colors to deviate from the intended output.

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1_2. And When the Drop Distance Increases Even Further:

• The ink jetting speed of 7 m/s drops sharply, and the ink that was falling as a single unified droplet breaks apart into smaller satellite droplets.
• With reduced speed and fragmented low-mass droplets, the ink becomes susceptible to air turbulence generated by the print head carriage speed (0.8 m/s).
• In particular, these small fragmented droplets ride the air turbulence and drift along with the head carriage — eventually landing together in completely unintended locations.
• Click the video below to understand this explanation more easily.
• Why Ink Lands in Different Positions Depending on Head Height

2. The Danger of Airborne Ink Mist

• The tiny airborne ink droplets don’t just fall on the substrate surface — they also adhere to the print head nozzle surface.
• Small ink droplets gradually accumulate on the nozzle surface, growing into larger droplets that partially block nozzle openings — preventing ink from jetting straight.
• Ink from partially blocked nozzles jets at an angle instead of straight, causing visible banding (lines) in the actual print output.
• The bigger problem is: if this ink accumulated on the nozzle surface is not properly wiped clean,
• the ink around the nozzles will be cured by the UV lamp, making it impossible to recover even with cleaning.
• Initially, angled jetting affects print quality — but if more ink accumulates and cures in this state, it eventually blocks the nozzle completely.
• Refer to the photos below for partial and complete nozzle blockage.

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• If you print a nozzle check pattern in this state, the result will look like the messy output shown below.

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3. Users Who Actually Print on iPhone 14 Cases

• Despite these risks, some customers do occasionally print iPhone 14 cases using our printer.
• Initially, they used jigs to print multiple cases at once, but air turbulence caused the starting point on each case to shift slightly — so they now print one at a time.
• Whenever we speak with this customer, we always advise: “If possible, please look for other items instead of iPhone 14 cases.”
• We’ve also heard of one business owner who purchases cases with detachable camera modules — removing the camera bump section before printing and reassembling afterward.
• From conversations with various shop owners, we’ve heard that Mimaki printers can handle iPhone 14 printing to some extent — though print quality still suffers.