How does an aluminum tube offset printing machine print patterns onto aluminum tubes?

Printing patterns onto aluminum tubes (commonly used for packaging ointments, cosmetics, pigments, etc.) is a typical application of aluminum tube offset printing. This process is highly precise and combines the principles of offset and relief printing.

The following is a detailed step by step explanation of how an aluminum tube offset printing machine transfers patterns onto aluminum tubes:

   Core Principle: Indirect Printing

Unlike printing on flat paper, aluminum tubes are cylindrical. Therefore, the core challenge lies in accurately transferring the flat image from the printing plate onto the curved surface. This is achieved through "indirect printing," where the printing plate does not directly contact the aluminum tube but instead uses a   blanket cylinder   as an intermediate transfer medium.

   Detailed Step by Step Breakdown:

  Step 1: Preparation and Feeding    

  Pre manufactured plain aluminum tubes are automatically fed into the printing machine's conveyor track or chain. 

  Each aluminum tube is secured and rotated by a   mandrel  , which provides support and drives the rotation. 

  Step 2: Inking and Plate Making    

  Similar to traditional offset printing, a   PS plate (pre sensitized plate)   is used. This is a lithographic plate where the image areas are oleophilic (ink receptive) and hydrophobic, while the non image areas are hydrophilic (water receptive) and ink repellent. 

  The printing machine's inking system transfers ink to the   plate cylinder  . 

  The dampening system ensures the non image areas remain moist and free of ink. 

  Step 3: First Image Transfer (Plate → Blanket)    

  The plate cylinder transfers the inked image areas as a   mirror image   onto the blanket cylinder. 

  This step is identical to traditional sheet fed offset printing. 

  Step 4: Second Image Transfer (Blanket → Aluminum Tube) – The Most Critical Step    

  The aluminum tube, fixed on the mandrel, rotates and approaches the blanket cylinder. 

  The   mirror image   on the blanket cylinder is precisely pressed onto the curved surface of the aluminum tube, forming a   right reading image  . 

    Precision Synchronization System  : To ensure the pattern is accurately applied without misalignment, overlapping, or distortion, the rotational speed of the mandrel driven aluminum tube must be   perfectly synchronized   with the circumferential linear speed of the blanket cylinder. This is the core technology of curved surface printing machines. 

Step 5: Drying and Curing    

  The ink on the aluminum tube is wet and requires immediate curing to prevent smudging. 

  Aluminum tube printing commonly uses   UV (ultraviolet) curing ink  . 

  The printed aluminum tube immediately passes through a   UV drying unit  , where high power UV lamps instantaneously irradiate the ink, transforming it from liquid to solid in a fraction of a second. This ensures the ink firmly adheres to the aluminum tube surface. UV ink not only dries quickly but also offers abrasion resistance and high gloss. 

  Step 6: Unloading and Subsequent Processing    

  The cured aluminum tubes are automatically removed from the mandrels and collected into bins. 

  The printed aluminum tubes typically undergo further processing, such as: 

      Capping  : Attaching plastic caps. 

      Filling  : Loading the contents (e.g., ointment, cream) from the tube's end. 

      Tail Sealing  : Flattening and sealing the tube's end. 

   Why Choose Curved Surface Offset Printing for Aluminum Tubes?

1. High Precision and Clarity  : Inheriting the advantages of offset printing, it can reproduce fine dots and complex multi layer patterns with extremely high color accuracy. 

2. High Efficiency  : Modern curved surface offset printing machines are fully automated, capable of printing thousands of aluminum tubes per hour. 

3. Strong Adhesion  : Combined with UV ink, the图案 firmly adheres to the smooth aluminum surface, resisting scratches and abrasion, ensuring durability during transportation and use. 

4. Versatility for Complex Shapes  : This method can be applied to any cylindrical container (tubes or bottles of varying diameters) that can be uniformly rotated by a mandrel. 

   Summary Process Flowchart:

  Plate Cylinder (Inking) → Transfer to → Blanket Cylinder (Forms Mirror Image) → Impressed onto → Rotating Aluminum Tube (Forms Right Reading Image) → UV Curing → Finished Product 

In summary, aluminum tube offset printing machine utilize a precision synchronized rotating system to cleverly employ the blanket cylinder as an intermediate transfer medium. This seamlessly "wraps" the flat image onto the cylindrical aluminum tube, achieving high quality, high efficiency packaging printing through instant UV ink curing technology.