Printing ink under the extrusion of scraping blade through the silk screen version of the graphic part of the mesh on the printing to the substrate to form printing graphic, and to a large extent by the amount of ink is influenced by the scraping blade used.Therefore, a thorough knowledge of the performance and characteristics of scraping blade, choosing appropriate scraping blade to get the ideal printing effect is particularly important.
Scraping blade are generally made of flexible polyester plastic, when the production of raw materials is liquid, after processing after slicing, slitting machine, grinding smooth finished product.For bulk purchase of scraping blade is commonly roll, when printing according to the actual need to be carried out in accordance with the specific size cutting.Scraping blade in printing with four functions:
A. scraping, press ink through the screen plate.
B. make the silk screen printing contact with substrates.
C. make the silk screen version of the corresponding to the surface of the substrates.
D. scrape off the screen plate on the rest of the ink.
All in all, is the main purpose of scraping blade will ink extrusion through the silk screen version and make the transfer to the substrate, the performance of the scraping blade has a direct effect on final printing effect, therefore understanding the performance parameters of scraping blade can provide the basis for our right to choose scraping blade.
A, the performance parameters of the scraping blade
When other factors in the printing process (such as ink, substrates, etc.) to determine, after scraping blade plays an decisive role in the final printing effect.In order to get good printing quality, must choose the most suitable scraping blade, when the choice to comprehensively consider the following performance parameters.
1, scraping blade hardness.
Scraping blade hardness affecting scraping blade adaptability to substrates, it decides the imposed on substrates and silk screen printing pressure plate.Scraping blade hardness, common shore hardness said, according to the hardness of scraping blade can be divided into soft, neutral and rigid scraping blade.The soft scraping blade adaptability is best, transfer printing pressure to a minimum.

2, namely the scraping blade cross section shape of the mouth, this parameter also affects the scraping blade of the adaptability of substrates and to the printing surface pressure.Scraping blade shape also affects the actual scraping blade Angle and the relationship between the set scraping blade Angle.We know that the real scraping blade Angle between is really scraping blade when printing and silk screen version of the Angle, due to the stress along the direction of the printing press, scraping cutter will happen slight deformation and deviates from the set of scraping blade Angle, through the silk screen version of the ink quantity will be more at this moment.So as to choose the scraping blade shape is different, through the silk screen version of the ink quantity is not the same.Common scraping blade shape has the following 3 kinds:
A. pointed scraping blade.Pointed scraping blade can change its sharp degree (parts can have 45 °, 60 °, 70 °, etc.) and get the biggest printing adaptability and the smallest printing pressure.Use the scraping blade, the actual scraping blade Angle is always less than set scraping blade Angle, in the scraping blade length less than 36 cm and the surface printing was very applicable.
B. rectangular scraping blade.Rectangular scraping blade can provide moderate printing adaptability and the largest printing pressure, the actual scraping blade Angle and set the basic equal scraping blade Angle, rectangular scraping blade is also used in screen printing one of the most frequently.
C. circular scraping blade.Worst round scraping blade printing adaptability, printing pressure is the smallest, apply this shape (there are large and small round head 2) scraping blade, the actual scraping blade Angle is very small, and almost nothing to do with set scraping blade Angle.
Although determine appropriate scraping blade and silk screen version of the Angle of A difficult, but people are still in production practice, summarizes some experience: when A print it is advisable to take 20 ° to 70 °, and the surface printing was best take 30 ° to 65 °.
3, scraping blade height
Note that don't put scraping blade sharpness and scraping blade shape and confuse, scraping blade sharpness characterization is scraping blade mouth edge sharpness, such as the same are pointed scraping blade can have different scraping blade sharpness.Scraping blade sharpness depends on the final transfer amount of ink on the substrate, the higher the acute Angle, the smaller the amount of ink transfer, more suitable for high resolution image printing;Acute low scraping blade can significantly increase the amount of ink through the screen plate, therefore more suitable for large area printing.

4, scraping blade wear resistance and chemical resistance properties
In addition to the performance parameters of the front told, scraping blade abrasion resistance and chemical corrosion resistance is also very important.We, scraping knife to contact in the process of using ink and solvent, such as ethanol, gasoline, scraping blade after contact with the ink and solvent will have different degrees of change, thus affecting the scraping blade wear resistance and chemical resistance properties.However, the two hard to quantitative performance, still no testing standard in this field.So we must pay attention to the accumulation in the production, used for scraping blade material performance record filing and evaluation, so that you can build a database, to help decide on a calendar to choose what kind of scraping blade material performance is best.Also some scraping blade can be determined for a specific service life of ink, and then replaced periodically.
Second, the maintenance and storage of scraping blade
To be the most effective use of the scraping blade performance, also need to effectively maintain and store scraping blade.Note the following:
A. the scraping blade flat and not to roll into a save.
B. the assembled scraping blade (i.e., not from the scraping blade on the fixture will be unloaded) should make scraping blade toward placing, scraping blade shall not come into contact with anything in the process of storage.
C. use the scraping blade should immediately after the serious cleaning, prevent ink dry solid on it.
D. the scraping blade has solvent resistance, but had better not put scraping blade solvent soak, because it will cause a slight expansion of the scraping blade, long term will lose flexibility.
E. no assembly support pad after scraping knife in the use of 4 to 6 h should be unloaded, and replace the support direction, to prevent scraping blade permanent deformation.
F. use increases with time, scraping DaoHui aging, hard, therefore, recommended not to use than the factory when the hardness by 10 degrees of scraping knife.The scraping blade in the process of using performance is not very stable, elastic, small friction resistance is poor.
In order to obtain satisfactory printing quality, screen printing workers must pay attention to the many variable factors.Through carefully choose scraping blade and effectively maintain scraping blade, is likely to get good repeatability, high quality print.