印刷過程中，有時印刷品版面會出現一條或幾條橫向杠影，行業上習慣稱為印刷杠痕。印刷杠痕有兩種表現特征：一是印品版面出現的橫向條狀杠影部位的墨色明顯深于其他部位的墨色;二是出現條狀的杠影墨色明顯淡于其他部位的墨色。前者屬于墨杠，后者屬于水杠。它們產生的原因是多種多樣的。下面小編就來分享其產生原因及消除方法。

  一、產生墨杠的原因與消除方法

  1、膠輥因素引起的墨杠。當膠輥與印版間的接觸壓力過大時，那么機器運轉過程中，著墨輥與印版接觸滾刷時，就容易產生沖擊而引起震顫，這樣摩擦力增大造成了條痕杠影。如果幾根靠版式的著墨輥壓力都太大，杠痕的密度將更大。對此，應通過調整膠輥與印版間的接觸壓力，保持均勻、適度的接觸條件，消除過量的阻力后，墨杠才可得到較好的消除。

  2、滾筒齒輪磨損、齒輪間隙過大或是齒輪間有異物聚積。當滾筒齒輪磨損、間隙或齒間中有異物粘附情況時，機器運轉過程中，各滾筒齒輪間不能精確地嚙合，使滾筒之間的線速度不夠一致。此外，齒隙太大，滾筒也容易發生震顫抖動，形成印刷杠痕，使印品版面出現一道道與齒輪節距相近的墨杠痕跡。齒隙中有異物障礙，又容易因”頂齒”現象而引起滾筒顫抖，使印品橫向版面形成條狀墨杠。對此，應通過重新調整滾筒間的中心距，減少齒間；對磨損厲害的齒輪，應更換新齒輪;對齒間有中異物粘附，應清理干凈，方可達到消除墨杠的效果。

  3、滾筒軸承出現較大的磨損。當滾筒軸頭缺油運轉或機器長期使用產生自然磨損時，使滾筒軸頭與軸承間隙增大，配合不良，合壓時因震顫而引起墨杠痕跡。對此，宜將橡皮內襯墊叼口處搞成梯形，以減少壓印狀態時的撞擊，使墨杠痕程度減輕。另外，對滾筒軸承磨損嚴重的，應考慮采取鍍補修復或更換新軸承，以消除墨杠痕跡。

  4、印版滾筒或橡皮滾筒包襯過大。這兩種情況存在的話，將因它們表面線速度不一致而引起條狀墨杠痕，同時也因壓印時滾筒產生撞擊顫動，那么顫動時兩滾筒的接觸處容易產生摩擦而引發墨杠痕跡。此外，有時由于咬口部位印跡不明顯（壓力偏輕），墊紙條的墊得過多的話，也容易引起墨杠。對此，應準確調整好包襯厚度，盡量用小的印刷壓力，使墨層均勻轉移，以保持滾筒間表面線速度的一致為前提條件。對于咬口部位墊加紙條時，應采用逐漸加熱墊的辦法進行，切不可一下子多墊，以免產生墨杠痕跡。

  5、橡皮布松散，滾壓時容易產生滑動摩擦，于是便出現了條狀墨杠痕跡。所以，應及時采取措施進行繃緊，以防止產生印刷墨杠。

  二、產生水杠痕的原因與消除方法

  1、印版版面水分過大，使墨輥之間或墨輥與印版間存在水膜，阻礙了油墨的正常傳遞，使印刷壓力增大形成摩擦而產生條狀淡痕杠影。對此，應通過清洗水、墨輥、橡皮布和印版，把乳化油墨去除并調整合適的供水量，以消除版面水分過大引起的杠痕。

  2、潤版液酸堿度不適。當潤版液PH值控制不當，酸性不足使版面形成的無機鹽溶解，破壞了版面結構，降低了親水性能，使版面水墨失去平衡。而酸性過大的潤版液則容易腐蝕印版砂眼，加速油墨乳化，破壞圖文基礎，也會因水墨不平衡而引起水杠痕。對此，采用消除的辦法是：對印版表面結構受到破壞的，應換裝一塊新版；機上乳化的油墨應清洗干凈;高速潤版液的濃度，根據印刷實際情況，潤版液的PH值可在3.8至4.6的范圍內作適當的高速達到消除杠痕的目的。

  3、著水輥與串水輥的壓力太大。著水輥與串水輥之間若接觸壓力過大的話，不僅對輥表面的潤版水形成擠壓狀況，使潤版液傳遞不均或傳水阻礙，同時還容易使著水輥產生徑向滑移跳動，形成水杠痕。對此，應適當調輕著水水輥與串水輥間的接觸壓力，以消除水輥引起的杠痕。

  4、著水輥與印版的壓力太大。當著水輥與印版間的壓力太大時，印機轉動過程中，水輥經過印版滾筒無版包裹的空段部位時，容易在印版起步的叼口部位產生碰撞，使印品叼口附近產生水杠痕。對此，應適當調輕著水輥與印版式的接觸壓力，以消除水輥對印版的壓力過大引起杠痕。

  5、水輥軸頭和輪承磨損、松動產生跳動。當水輥使用時間久了，或因潤滑不良使水輥軸頭、軸承發生磨損情況時，由于水輥轉動過程中，在版面產生跳動或滑動弊病，那么，就將因表面滑擦而引起條狀水輥杠影痕跡。對此，應檢查看是水輥軸頭磨損或是軸承磨損，采取相應的措施進行修復，以消除間隙松動現象，消除水輥杠痕。平時還應注意對軸承的潤滑，防止使用磨損情況發生。

  6、水絨套墨跡附著、老化變硬。對此，平時應注意勤清洗水螺，減少墨跡滲透附著發生的機會。對使用老化的水套，應及時予以更換新套，以防止發生水杠痕的機會。

  總的情況來說，日常膠印工藝中發生印刷杠痕的原因，是多種多樣的，情況有時是錯綜復雜的。有一種原因造成的，也有多種不浪花情況并存構成的;有設備零部件磨損引起的，亦有操作方法不當、凋整不適之故。只有在日常生產中注重加強設備的維護和保養，科學合理地使用和調整好機器，才能較好地防止和避免杠痕發生的機會。若生產過程中已發生印刷杠痕，應認真進行分析和觀察，才能準確地排除杠痕故障。

      During the printing process, sometimes one or several horizontal stripes appear on the printed product layout, which is customarily called printing stripes in the industry. There are two characteristics of printing bar marks: one is that the ink color of the horizontal stripe shadow on the printed product layout is obviously darker than that of other parts; the second is that the ink color of the stripe shadow is obviously lighter than the ink color of other parts. The former belongs to the ink bar, and the latter belongs to the water bar. The reasons for them are many and varied. The following editor will share its causes and elimination methods.
  1. Causes and elimination of ink streaks
  1. Ink bars caused by rubber roller factors. When the contact pressure between the rubber roller and the printing plate is too large, when the inking roller is in contact with the printing plate during the operation of the machine, it is easy to produce impact and cause tremor, so that the increase in friction will cause streaks and shadows. If the pressure of several ink rollers relying on the format is too large, the density of the bar marks will be greater. In this regard, the contact pressure between the rubber roller and the printing plate should be adjusted to maintain a uniform and appropriate contact condition. After the excessive resistance is eliminated, the ink stick can be better eliminated.
  2, the roller gear is worn, the gear gap is too large, or there is foreign matter accumulation between the gears. When roller gears are worn, gaps or foreign matter adhesion between the teeth, the roller gears cannot be accurately meshed during the operation of the machine, so that the linear speeds between the rollers are not consistent enough. In addition, if the tooth gap is too large, the cylinder is also prone to tremor and jitter, forming a printing bar mark, causing the printed product layout to have a line of ink bar marks close to the pitch of the gear. There are foreign body obstacles in the tooth gap, and it is easy to cause the cylinder to tremble due to the phenomenon of "top teeth", so that the horizontal layout of the printed product forms a striped ink bar. In this regard, the center distance between the rollers should be re-adjusted to reduce the teeth; for gears that are severely worn, new gears should be replaced; for foreign matter between the teeth, they should be cleaned up to achieve the effect of eliminating ink bars.
  3. The roller bearing has a lot of wear. When the roller shaft head runs out of oil or the machine is used for a long time, the gap between the roller shaft head and the bearing will increase, and the match will be poor. The ink bar marks will be caused by vibration during the press. In this regard, it is advisable to make the grip of the rubber inner liner into a trapezoid to reduce the impact in the embossing state and reduce the degree of ink stick marks. In addition, if the roller bearing is seriously worn, it should be considered to repair or replace the new bearing to eliminate the ink stick marks.
  4. The printing plate cylinder or blanket cylinder lining is too large. If these two conditions exist, the inconsistency of their surface linear speeds will cause striped ink stick marks. At the same time, due to the impact and vibration of the cylinder during imprinting, friction will easily occur at the contact between the two cylinders and cause ink stick marks during vibration. In addition, sometimes due to the inconspicuous imprinting of the bite area (light pressure), if the paper strip is too much, it is easy to cause ink streaks. In this regard, the thickness of the lining should be adjusted accurately, and the printing pressure should be used as small as possible to make the ink layer transfer evenly, and to maintain the uniformity of the surface line speed between the cylinders as a prerequisite. When adding paper strips to the bite area, it should be done by gradually heating the pad. Do not pad more at once to avoid ink stick marks.
  5. The blanket is loose and easy to produce sliding friction when rolling, so there are strip ink stick marks. Therefore, measures should be taken to tighten in time to prevent printing ink streaks.
  2. Causes and elimination of water mark
  1. Excessive moisture on the surface of the printing plate causes a water film between the ink rollers or between the ink roller and the printing plate, which hinders the normal transfer of ink, and increases the printing pressure to form friction and produce striped light marks. In this regard, the emulsified ink should be removed by cleaning water, ink rollers, blankets and printing plates and the appropriate water supply should be adjusted to eliminate the mark caused by excessive moisture on the plate.
  2, the pH of the fountain solution is not suitable. When the pH value of the fountain solution is improperly controlled, insufficient acidity will dissolve the inorganic salt formed on the plate surface, destroy the structure of the plate surface, reduce the hydrophilic performance, and make the ink on the plate out of balance. The excessively acidic fountain solution will easily corrode the blisters of the printing plate, accelerate the emulsification of the ink, destroy the basis of graphics and text, and also cause water mark due to the imbalance of ink and water. In this regard, the elimination method is: if the surface structure of the printing plate is damaged, a new plate should be installed; the emulsified ink on the machine should be cleaned; the concentration of the high-speed fountain solution depends on the actual printing situation, and the pH value of the fountain solution It can achieve the purpose of eliminating bump marks at an appropriate high speed in the range of 3.8 to 4.6.
  3. The pressure of the dampening roller and the stringing roller is too high. If the contact pressure between the dampening roller and the stringing roller is too large, it will not only squeeze the dampening water on the surface of the roller, make the dampening solution transfer unevenly or hinder the water transfer, but also easily cause the dampening roller to produce diameters. Jump to the slip, forming a water mark. In this regard, the contact pressure between the water roller and the string water roller should be appropriately adjusted to eliminate the mark caused by the water roller.
  4. The pressure between the immersion roller and the printing plate is too large. When the pressure between the landing roller and the printing plate is too large, when the printing press is rotating, when the water roller passes through the empty section of the printing plate cylinder without a plate wrap, it is easy to collide at the gripping part of the printing plate, which will cause the printed product to collide. Water bump marks are produced near the mouth. In this regard, the contact pressure between the water roller and the printing plate should be appropriately adjusted to eliminate the excessive pressure caused by the excessive pressure of the water roller on the printing plate.
  5, the water roller shaft head and wheel bearing are worn and loosened to cause bounce. When the water roller has been used for a long time, or the shaft head and bearings of the water roller are worn out due to poor lubrication, due to the bounce or slippage of the plate during the rotation of the water roller, then the surface will be slippery and cause streaks. Shadow marks on the water roller. In this regard, it should be checked whether the shaft head of the water roller is worn or the bearing is worn, and corresponding measures should be taken to repair it to eliminate the phenomenon of loose clearance and eliminate the mark of the water roller. Pay attention to the lubrication of the bearings in normal times to prevent wear and tear.
  6. Ink stains on the water velvet cover are attached, aging and hardening. In this regard, it is necessary to clean the water snails frequently to reduce the chance of ink penetration and adhesion. For aging water jackets, new ones should be replaced in time to prevent the occurrence of water bump marks.
  Generally speaking, there are many reasons for printing bumps in the daily offset printing process, and the situation is sometimes complicated. It is caused by one reason, and there are also multiple non-spraying conditions coexisting; it is caused by the wear of equipment parts, and there are also improper operation methods and discomfort. Only by paying attention to strengthening the maintenance and maintenance of equipment in daily production, and using and adjusting the machine scientifically and rationally, can the chance of occurrence of bar marks be better prevented and avoided. If the printing mark has occurred during the production process, it should be carefully analyzed and observed to accurately troubleshoot the mark.