Corrugated carton Flexo printing slotting machine Maintenance tips and common problems

Nowadays the most suitable models on the market are mostly printing and slotting machine. This machine has four major functions including paper feeding, printing, creasing, and corner cutting and slotting. Printing and slotting machines are generally two-color, three-color and four-color. The more advanced printing and slotting machines adopt a full computer control system.

Usually the whole printing slotting machine is installed on two parallel tracks, which is more convenient for plate loading and adjustment. The first and second printing parts can be driven by a motor with a gear reducer, Move along the track to separate it from the slotted part. Some models machine adopts the design of printing and slotting parts separated by a certain interval, each part is connected by conveyor belt.

1. Feeding part

   Corrugated cardboard has a certain degree of stiffness, thus the printing machine feeding part system adopt the single-sheet feeding system. Its feeding part pushes the end of the cardboard into a pair of paper feeding roller， thereby the cardboard is fed to printing part. During the entire feeding and printing part, the cardboard passes through the printing press on a horizental plane.

2. Printing part

   There's so many specifications of printing machine, The small one can print 610*1620mm carboard, the large one can reach 2030*4830mm. The arrangement of the rollers of the flexographic printing for the most corrugated cardboard printing machine is that the impression roller is the on the top and the printing roller is on the bottom, that is, the bottom of cardboard is printed. This will allow the dust and waste on the printing surface to fall off naturally.

3. Pressing Line part

   The cardboard is fed to pressing line device through the traction roller for longitudinal creasing. (In the same direction as the corrugated lines). The longitudinal limits the width and length of the carton.

4. Coner cut and grooving part

   The operation of cutting the connection between the box cover and the box body tongue is called coner cutting and grooving.

   
   

The operation procedures for printing slotting machine

(PS: the operation procedures for printing slotting machine vary slightly depending on machine model, but principles is same)

• Check the lubrication system and Air compressor system before starting. Fill in enough lubricating oil and drain the condensed water in the air compressor.

• Set the host speed switch to the 'OFF' position and turn the speed the knob the lowest speed position before turning on the power.

• Start the gear motor to separate the feeding paper part, printing part, second printing part and cutting slotting part, so as to adjust the size of each part and install the printing plate.

• Install the printing plate according to the production requirement, adjust the slitting knife, slotting knife, slotting and coner cutting knife and creasing wheel.

• Adjust the front, left and right limit baffles according to the thickness and length of the cardboard.

• Reset and lock the separated parts.

• Start the suction fan and ink pump, remove all the tools and debris from the machine.

• Test printing, check the printed graphics, ink color, slotting cut quality, size specifications of each part, color accuracy etc, until comfirmed to be correct.

• Start-up to accelerate continuous production.

• When the machine is runnung, the operation should pay attention to observation and inspection, find problems early and make adjustments at any time. After work is completed or before leaving get off work, the ink roller should be cleaned, the replace printing plate must be cleaned and hung to storage, routine maintenance work must be done, and the power must be cutted off.

Abnormal situation	Analyze the causes	Treatment
Block plate	Ink Drying	Add a slow-evaporating solvent to the ink. Check whether there is solid sediment in the ink and filter it if necessary Check the ink circulation system and eliminate any obstacles
The ink tank surface is full of foam	Ink viscosity	Add a small amount of quantity to the surface of the ink tank.(Do not stir) Add a small amount of defoamer Switch to low viscosity ink
Ink accumulates on the plate, resulting in poor printing quality	Insufficient roller pressure Ink layer is too thick Ink viscosity is too high	Increase the pressure between the rollers appropriately Thinning the ink layer Dilute the ink appropriately
The printing ink is powdered, easy to fall off after friction, and the ink color is turbid	Ink overweight Ink deterioration	Reduce dilution solvent and increase ink concentration Increase the amount of resin to enhance ink viscosity and adhesive adhesion Replace deteriorated ink
Mottled marks on the printed surface	There is old ink accumulation on the printing plate Ink concentration is too low The paper surface has uneven absorption capacity for ink solvents	Wash the printing plate carefully to keep it clean and flat Add high-viscosity ink to increase ink concentration; avoid leaving ink unused for too long. Avoid using poor quality paper for box printing
Dark spots appear at the edge of the print	Excessive pressure on the stamping Ink is too thin	Reduce the pressure of the stamping Add high concentration ink
The print has smudges	The ink dries too slowly Ink is over-diluted	Adjust the ratio of water and alcohol in the ink solvent to improve the evaporation and quick drying performance of the ink Increase the amount of resin, improve the ink concentration, and enhance the wear resistance of the printing ink
Blank spots appear on the printed surface	Insufficient printing pressure The printing plate has dirt or dents The ink is too little or too thin The paper surface is uneven or has poor affinity with ink.	Adjusting the roller pressure Check the printing plate and eliminate layout problems Adjust to increase the ink volume or increase the ink concentration Avoid using paper with poor surface condition
There are stripes of ink on the printed surface, uneven shades, or blank spaces without ink.	Insufficient printing pressure The rubbing phenomenon of cardboard is serious	Increase the printing pressure appropriately, but not excessively, so as not to seriously damage the strength of the corrugated paper. After increasing the printing pressure, if the print has sunk into the cardboard and the uneven print cannot be eliminated, the printing of this batch of cardboard should be stopped and handled separately.
The whole printing is misaligned or one of the above defects occurs in part of the printing surface	Improper mechanical adjustment Running too fast, exceeding normal capacity Cardboard warping is serious	Check the parallelism, clearance and pressure strength of each component of the printing system. If there is any imbalance, adjust and correct it in time; adjust the speed Differentiate the different states and severity of paper warping and handle them separately, such as reverse lamination, reverse bending, selection and removal, or batch processing before printing.