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ZT400 Series Printer - Resolving Print Quality Issues

Article ID: 29367945

Issue / Question

Resolving print quality issues for ZT400 series printers.

Applicable To

ZT400 Series

Resolution / Answer

This article has 5 sections:
 

 

Symptoms
 

  • Light print or faded image
  • Partial missing print or image cut-off
  • Broken bars or lines in a barcode
  • Poor or low barcode ANSI grade
  • White lines appearing in the print
  • Streaks appearing in the print

 

Causes
 

Media 

Print quality is a product of proper printer setup and use of compatible media for the application. When ribbon is used for Thermal Transfer printing, it must be compatible with the labels to ensure the printer meets the requirements expected by the users. 

Proper matching of the labels or ribbon assures the pressure and darkness settings do not have to be at the extremes to print correctly. Direct Thermal (no ribbon) labels must be approved for thermal printing applications since it does come in direct contact with the printhead.


Configuration 
Printer setup includes adjusting the printhead pressure properly, setting the appropriate darkness level, and optimizing the print speed. In addition, regular maintenance assures the printer is operating at an optimal level. 

 

IMPORTANT! All printer settings can be impacted by commands from a mismatched or misconfigured driver or software application. A printer that is functioning well after setup but fails or indicates an error after label requests are received are most likely affected by the host side misconfiguration of the driver or printer software settings. The host device that generates the printer commands for printing, typically have setup configuration that send these as commands to the printer. Ensure all settings match with the printer settings to avoid intermittent issues.


 

Problems and Resolutions
 

NOTE Use the printer Pause Test Label when performing initial print quality adjustments. This will eliminate any issues introduced by the application or driver configurations. Refer to: PAUSE KEY SELF TEST.

 

Problem

 Example

Resolution

The print is faded or too light when printing self-test
 

NOTE If the problem occurs after printing from your application, verify your driver or  software configurations.

 

NOTE If there is a flood coating or preprint on the label surface where the print issue is occurring, check with your supplier for  corrective action.

Click to Enlarge
  • Clean the Printhead
Contamination can cover the elements preventing heat transfer. 
  • Try increasing the Burn Temp.       
  • Try increasing the printhead pressure by adjusting the ZT400 Printhead Pressure. 
Refer to this article: Adjust ZT Series Printhead Pressure.
 
  • The media must be matched (if the ribbon is used). If no ribbon is used, verify the quality of the Direct Thermal stock. Check with your media supplier if you have exhausted all suggestions provided. 
 
  • Reduce the print speed. 
Refer to this article: Setting the Print Speed on a Zebra Printer.  
 
  • Verify the ribbon is not slipping due to improper loading.

The print is faded or too light on the left or right side of the label


Refer to Label Properties to view the left or right side of the label.

Click to Enlarge
 
  • Ensure the printhead pressure is balanced.
Balancing the Printhead Pressure Detail. 
Refer to: Printhead Pressure Adjustments.
 
ZT400 Printhead Pressure. 
Refer to this article: Adjust ZT Series Printhead Pressure.

Barcode ANSI grade is low or won't scan

 

NOTE It is common to have the darkness
set too high, resulting in bar spreading. This may look visually better but it causes the barcode spaces to reduce lowering the barcode grade.

 

  

  

  • Darkness is set as too high or low. Try changing the darkness on the LCD Display. Check the driver or application darkness settings. 
  • Print the Feed Self-test Labels and note the barcode quality as the darkness changes.
  • Verify your quiet zone is 10x the narrow bar width. Barcodes too close to the edge may not scan properly.
 
  • Check for printhead element problems printing the Pause test. Missing elements can create problems with the bars in the barcode. Refer to: PAUSE KEY SELF TEST.
The print is smearing or rubbing off

Click to Enlarge
 
  • Media and ribbon mismatch
The ribbon ink will rub off the label if it is not matched for the media. Verify your ribbon and media are properly matched for your application.
The ribbon is wrinkling

Click to Enlarge
 
  • Resolving ribbon wrinkle issues
Refer to this article for ribbon wrinkle resolution: Video: Loading Ribbon and Resolving Ribbon Issues on ZT400.

 

 
White lines in the print

Click to Enlarge
 
  • Clean the printhead elements.
Build-up can cause lines in the print. Aggressive cleaning with cleaning film is sometimes needed if there is baked on residue that fails to be removed by swabs. 
Refer to this article:  Video: Zebra Tabletop and Print Engine Printhead Cleaning Procedure​​​​​.​​
 
  • The printhead element(s) may have failed and the printer requires servicing.

Image is cut off on the right 

Refer to Label Properties to view the left or right side of the label.

 

Click to Enlarge
 
  • Verify the PRINT WIDTH is set correctly in the LCD Display and in the driver or application configurations. 
 
  • If using ribbon, ensure the ribbon is wider  than the labels.
     
  • Verify there is no  debris or label stuck to the printhead covering the print elements.

 

Helpful Information:
 



Watch this video and learn how to clean the printhead and platen:



 

How the ZT400 Series Printers work
 

There are 2 thermal printing methods: 

  • Direct Thermal 

  • Thermal Transfer 

Each method uses a thermal printhead that applies heat to the surface being marked. 

Differences:
 

 

Direct Thermal 

Thermal Transfer 

Heated ribbon 

Uses a heated ribbon to produce a durable, long-lasting images on a wide variety of materials. 

No ribbon is used, creating the image directly on the printed material. 

Sensitivity to light, heat and abrasion 

More sensitive. 

Reduce the life of the printed materials 

Less sensitive compared to Direct Thermal media. 


The printer uses a single row of heating elements in a printhead assembly that is pressed against a rubber roller called a platen. The printhead elements are heated as the ribbon (if used) and labels pass as they are pressed together to produce the image.  Any factors that affect the transfer of heat being applied by the elements will result in print image problems (assuming the labels and ribbon are properly matched for the application). 
 

  • Printhead Maintenance – Failure to properly clean the printhead elements can result in an insulating build-up that prevents heat transfer. This can also lead to element failure.
  • Printhead Pressure – The pressure must be sufficient to maintain a constant pressing of the printing media while the element heat is transferred. This pressure must be evenly distributed across the width of the label, so the image transfer is at the same intensity.
  • Burn Temperature – The darkness must be set high enough to meet the print darkness needed for the image transfer but not so high as to result in image spreading or burning of the ribbon carrier.  Barcodes require that the bars and spaces are of equal width and increasing the darkness beyond those required can result in space width reduction and barcode scan failures
  • Print Width - The Print Width value determines the maximum width the printer will print.  Most often it is set to the full width and the label format determines the printed area based on the image location. Applications and drivers may set a print width and reduce the printable area based label size. This is not a problem unless one attempts to print outside the previously restricted area. Check the LCD Display if this occurs to see if the PRINT WIDTH was changed.

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