How to use flexographic press well

Date:2023-02-23 10:17:50 click:737

First, prepare before starting

1. Establish safety awareness and do a good job of safety protection.

All flexographic operators should develop the habit of working safely. A safe operating environment is also emphasized.

You are not allowed to wear slippers while working in the workshop. The hem of the shirt must not be exposed, the buttons of the overalls must be buttoned, and the cuffs should be buttoned to prevent the printing press from being involved in the moving parts. The cover should not be opened during mechanical operation of the printing press. Wipe the machine cloth and handy tools should be placed in a fixed container or position. At all times be very aware of possible dangerous things and related situations. Practice safety at all times.

2. Start-up preparation (including equipment maintenance) :

Compared with other printing methods, flexographic printing mainly has the following characteristics: simple equipment structure, easy operation and maintenance. The equipment occupies less area, the plant utilization rate is high. Widely used materials, strong adaptability to various materials. Plate - making speed, low cost. Improved working conditions, no environmental pollution. Line processing ability is strong, short production cycle, high efficiency. Suitable for medium and short printing (50,000 ~ 100,000), reliable product quality, long print live, stable quality, consistent tone.

Flexo printing machine operation is simple and easy to master, but to print good quality products, any link can not be taken lightly. The following preparations should be made before starting the machine:

① Before starting the machine, check whether the indicating part of the power supply is normal; Whether the air source reaches above 6MP; Add 40# oil in rotation, reciprocating parts; Printing station between the printing roller, plate cylinder, roller, mutual gear lubrication. (Add ultra-high viscosity gear oil (grease) on the small adjusting gear, so that the machine can be transferred to other gears after operation, and does not affect the surface of the roller, plate cylinder is appropriate); The lubrication of the power part should be checked regularly, and the clearance of the power side bevel gear bearing should be checked and adjusted at the same time. Discharge water in the triplet (preferably add an air filter at the air source); Before and after startup, attention should be paid to the operation of each part of the abnormal.

(2) The humidity of the printing workshop is relatively large. In addition to the normal lubrication of each shift, the surface of all parts (except paint) should be coated with oil (including breaking knife) on the surface when the machine is shut down; Wipe off with a cloth when turning on.

(3) Equipment maintenance: two hours before work each weekend is the statutory weekly guarantee time. The machine personnel must conduct a comprehensive inspection of the equipment, repair (or replace parts), lubrication, debugging and wiping. After the workshop is inspected and qualified, the production can be started next time.

Two, (cited) substrate (paper) : (tension, correction part) :

The uncoiling mechanism is mainly to complete the unrolling of web under certain speed and tension conditions, and maintain the corresponding stable state, and complete the automatic or manual stitching of web. The uncoiling mechanism is a driven mechanism without power. It adjusts the supply of paper by itself mainly according to the needs of the paper feed of the printing unit (the rotation speed of the paper pulling the web). The rotation speed of the web is controlled by the magnetic powder brake and the reel.

The press has strict requirements for web tension, surface smoothness and evenness of thickness. According to the requirements of different products, the whiteness and glossiness of paper also have a choice.

Drum substrate (paper) must be installed in the middle of the unspool, the left and right deviation shall not exceed 5mm, (can be delimited on the unspool line), to facilitate the operation. When ordering web paper, you must pay attention to the core size and the outside diameter range of the paper roll. If it exceeds the limit, it cannot be installed and used. When the reel is quickly raised in place, the paper roll should be rotated circumferential by hand to ensure that the gear is engaged correctly, and then open (push) the anti-drop support rod; The paper path must be followed by the machine process, and according to the paper thickness and printing conditions, set up the empirical tension value. Uncoiling tension (230g paper, ∮1200mm, 20 volts; 80g, ∮1200mm, 14 volts); The second tension is generally 5~6 volts. In order to ensure that the printing material before entering the printing unit, the transverse position is stable, the photoelectric head of the automatic correcting device can check the deviation of the transverse position of a certain edge of the printing material, and adjust the transverse position of the paper according to the printing plate pattern position, to ensure that the edge of the material roll is always in a constant position of the printing machine (transverse position); (The so-called transverse adjustment is to adjust the position of the paper along the axial axis of the machine roller; Sometimes the printing plate pattern to one side, must adjust the horizontal position of the whole roll of paper, generally a one-time manual adjustment). After the printing material enters the printing unit, the stability of the transverse position will be ensured by the installation precision of the machine itself and the parallelism between the rollers.

Three, installation roller, plate roller and printing:

Printing unit is the main part of the machine, complete the main process of printing: including ink supply, printing, drying and so on.

① on the cartridge:

Ink cartridge positioning, first hand support, to power side hole positioning after the adjustment of the operating side positioning pin, then, eye, hand push, check the accuracy and stability of the ink cartridge, to ensure that it does not affect the mesh roller and cylinder work, printing to add ink at any time, ink should pay attention to the outside of the drip, leakage on the printing.

② In the case of ink leveling switch off, install the roller. The roller in the machine positioning, first adjust the rotation of the groove and the groove in the sliding block repeated alignment (perpendicular to the horizontal plane or parallel); Secondly, hand support, mesh roller machine, equipped with auxiliary tools; Pay attention to the adjustment, the roller boss on the vertical horizontal groove position, placed positioning, and then rotate the roller by hand, check the accuracy of its position, remove the protective layer; At the same time, pay attention to all the roller, plate cylinder, printing roller gear, into the rough meshing state, the three are not rotated. Loading and unloading should pay special attention to the surface and metal surface collision, (due to material reasons, the surface of the roller collision, it is easy to cause permanent damage). In the process of use, the position and equipment of the roller, according to the confirmation of the printing quality. (Professional personnel should strictly check the sample, with 50 times magnifying glass, to determine whether the plate is correct or not; What is the network condition; Whether the color and content are consistent with the sample; It can be put into production after inspection). Color order determines the roller position, so it should be changed often, pay attention to safety.

(3) Adjust the position of the sliding block on both sides of the frame according to the plate diameter, so that the hole is basically level with the printing roller; Then hand (can not have oil) to help the version, protect the page; The cartridge shaft of the cartridge version can be normally inserted by pressing the pin setting key when inserting; After insertion, move the cylinder along the lateral so that the two enter the state of mutual pin. Rough check and rough adjustment of horizontal printing position, and check whether it is reasonable and safe; Adjust the relative position between the mesh roller and the cylinder, the cylinder and the printing roller (at this time, should be connected in the air source, under the state of pressure), and ensure that the left and right, the upper and lower parallel, with a gauge (feeler) check. (The thickness of the current version of the machine is 1.7mm, the thickness of the paste plate is 0.38mm, pay attention to the thickness of the two, adjust the thickness of the format).

(4) Before adding ink, the application of wet non-fiber cloth, the net roller all roll surface, gently wipe again, in order to clean; Before adding the scraper, rub the edge lightly with the same damp cloth.

Before rotating the roller, add ink (must be viscosity and PH value to ensure) micro rotation of the net roller with ink, carefully installed scraper, transverse movement several times (do not dry grinding on the net roller or in the rotation of the scraping knife), scraping knife pressure should be appropriate, not too large, not too small. It is recommended to adjust the pressure to the surface of the mesh without ink (i.e. clean scraping), then reduce the pressure so that ink appears on the roll surface, and slightly increase the pressure so that no ink appears on the roll surface. At this time, it is considered appropriate to adjust the pressure and ensure that the straight line of the knife edge is completely parallel to the line of the roller of the mesh roll (wear gloves when installing and removing the old scraper to prevent the sharp edge from cutting). Too much pressure affects the life of the mesh roll; Too small can not achieve the due role, scrape off the excess ink, reduce the printing color difference, improve the clarity of the dot. The thinner the ink, the more you can control the printing effect of the highlight dot. Rotate the net roller and observe the vertical ink bar caused by the knife edge. If the ink layer is not smooth and uniform, you can check the blade of the ink scraper to see whether there is physical damage or rust, or it may be loose screws on the fixed ink scraper, resulting in the blade and the mesh roller shaft line is not parallel; In addition, the screw on the scraper frame should be carefully adjusted to change the contact pressure between the local scraper and the surface of the roller.

(Do not scrap the ink scraper with small defects easily. It can be randomly run in other spare printing units, and then used after the defects are ground away). A scraper can be used over its life even if it has shaved off a few millimeters of width. Can also be adjusted according to the pattern position.

The thickness of the blade can be selected according to the number of lines of the mesh roller. When color overprinting, the mesh roller with high network cable should be used, and the thinner blade should be selected. And printing field, generally use the number of thick line roller, rough surface generated by large friction, so should choose thicker blade.

After the blade is cleaned, it should be coated with alcohol to take away moisture and keep the blade from rusting and forming a notch.

For the printing device of ink roller scraping ink, the amount of ink is determined by the following aspects: the tighter the press between the ink roller and the mesh ink transfer roller, the less the amount of ink; The higher the hardness of the ink roller, the less ink. If the ink roller is too soft, even if the ink roller and the mesh ink transfer roller are pressed tightly, the ink can not be scraped off, resulting in excessive ink; The faster the printing speed, the more ink; The lower the ink viscosity, the less ink.

Printing speed and ink viscosity. When the ink roller scraping device is used, if the printing speed is fast, the ink pushes the mesh roller and the ink roller to strengthen the force, the higher the viscosity of the ink, the stronger the tendency, so that the amount of ink is difficult to limit. Therefore, when printing speed is fast, the viscosity of ink should be reduced, and vice versa, the viscosity of ink should be increased.

In actual production, when the printing press with a scraper is used, the relative humidity of the workshop is 60%~70%, and the temperature is about 25℃. (The workshop should be constant temperature and humidity, because the paper road of flexographic printing machine is very long, if you cannot ensure constant temperature, humidity, quality is difficult to master). When the temperature and viscosity of ink change, the printing quality is different. To maintain the consistency of printing quality, it is necessary to maintain the consistency of ink viscosity.

Four, drying, slitting, die-cutting:

1. Drying

Adjust the hot air volume correctly according to the thickness and dryness of the ink layer. By printing ink is transferred to the substrate, the liquid ink on the substrate loses fluidity and becomes solid, so that in the follow-up various kinds of work does not rub dirty, friction resistance to prevent the first color ink by the second color ink wet or the second color, the first color ink color mixing. This change from liquid to solid process for ink drying. Unit flexo printing machine is equipped with a dryer behind each unit, using infrared electric heat pipe to heat the air, and the hot air is blown to the printed substrate material at a high speed, forming an impact air curtain, breaking through the air layer attached to the running paper, in order to achieve the best drying effect. When using thicker ink layers for field printing, the type of substrate material and its absorption capacity should be fully taken into account, because most of the ink used in flexo printing is water-based ink, volatile drying is the main, sometimes due to drying problems affect the speed of flexo printing machine. In this case, try to increase the impact velocity of the airflow and try to make the transverse flow uniform; Because for ink painting, the impact speed of drying air flow on the drying effect is larger than heating, and the heat of the printing material is too large to cause excessive deformation of the material, resulting in inaccurate overprinting.

2. Cutting: crosscutting

There are two kinds of waste edge materials for unit flexo printing machine cutting (die cutting), one is scrap paper, the other is connected together waste edge materials. For the waste edge material that can continue to move paper after die cutting or slitting, rewinding can be used for rewinding recovery. In addition, the transverse position of the printing material relative to the die cutter should be centered to avoid the fracture of the waste material on the narrow side of the width, causing the shutdown. Vacuum under the substrate to remove it. Knife pressure, need to balance, the pressure can not be too large, just cut the paper is appropriate.