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Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter

     In the packaging and printing industry, offset printing is the main printing mode of printing enterprises. Due to the failure of the output system, offset lithography is the main reason for the incorrect printing of printed materials, uneven ink color, unable printing and delayed delivery. This is one of the most common thorny problems for printing workers.Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter

1、 Two or more sheet feeding faults.

      The paper is uneven and the edge is warped. When the air flow from the loose paper blowing port contacts the paper edge, the paper edge warps into an arc angle, and the air flow is divided into two parts. Solutions To the Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

     One part of the air flow makes the paper lift up, while the other part of the air flow makes the paper press down, so that the paper can not be separated, and the paper blocking brush also loses its function, resulting in double or multiple sheets, or even large stacks for paperboard conveying. The general processing method is to unload the paper for anti knock processing to make the paper flat and conducive to separation.Solutions To the Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

     The height of the installation paper exceeds the allowable height of the teeth of the paper. According to previous printing experience, generally, the height of paper loading should be about 5mm lower than the paper retaining teeth. If the adjustment is improper and exceeds its allowable range, two or more sheets will be generated into the conveyor board. The general treatment method is to control with a wooden wedge to keep the paper on the same plane. If there is a model with a regulator, it can be solved by reducing the paper feeding height through the regulator.Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter

      The blowing presser foot and paper retaining brush extend too little into the paper edge. According to the previous operation experience, the general paper retaining brush extends into the paper edge by about 8mm, and the blowing presser foot extends into the paper edge by about 10-15mm. Solutions To the Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

      If the adjustment is improper or the paper cutting is uneven, double or multiple sheets will appear. Generally, the whole paper conveyor is adjusted closer, so that the paper separation suction nozzle is about 5mm away from the edge of the paper. It is solved by adjusting the paper retaining brush and blowing presser foot.Solutions To the Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

   When the paper is too thin, the air volume is not adjusted properly. When printing 70g / m2 tissue paper, the air volume is not adjusted properly, and double or multiple sheets are easy to occur. The general treatment methods are as follows: 

(1) adjust the blowing foot downward and increase the distance between the paper stack and the paper suction nozzle; 

(2) appropriately adjust the small air volume;

 (3) reduce the rubber ring and transparent glue on the paper suction nozzle and reduce the wind force; 

(4) press the paper retaining brush downward and increase the pressure control.Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.Solutions To the Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter

     The paper is not loose or bonded. Generally speaking, when cutting paper, the incision is bonded, or when printing the full version of semi-finished products, water stains and ink stains will bond to form more than two sheets. Therefore, before printing, that is, when the paper is loaded into the machine, it must be trembled and overlapped with force, and the semi-finished products must be overlapped slightly. Do not install it easily when on the machine to avoid heavy pressure and bonding.Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.

     The blowing presser foot is worn. The blowing foot will wear after being used for a period of time. When the paper is pressed down, the paper will become an oblique angle, the force will change the direction, the paper will move forward, the paper retaining brush will lose its function, and the paper separation suction nozzle will suck to the edge of the paper to form more than two sheets. Generally speaking, it is handled by replacing a new blowing presser foot. If the wear is not too serious, it can be welded with copper sheet and then leveled with file.Solutions To The Problems Of Inaccurate Overprint And Uneven Ink Color Of Printed Matter.