Troubleshooting (5) - Solving Problems

The image problems listed below are caused by uncertainties in the equipment, materials, or printing process. The forty-one variables listed below cover all the causes (about 200) that cause problems in the screen printing process. They are very representative. The 41 variables that can cause problems can be divided into 6 categories: Wire mesh and screen making process (12 kinds) 2. Equipment and printing/drying process (13 species) 3. Ink (4 kinds) 4. Originals (4 kinds) Environment (4 kinds) 6. Substrates (4 types) If you use the Pareto analysis method to analyze each of the causes (Pareto analysis can find out which factor is the most important factor among various factors), you will find the correlation of the following reasons. 33% of the image problems are related to the screen, of which 30% is related to stretch tension and 14% is problem of cleaning and screen recycling. (Remaining for Other reasons) 26% of image problems are related to equipment, of which 25% are due to off-gaps/stripping too much, and 16% are due to bad settings for blade pressure and speed. 13% of problems were related to manuscripts, of which 43% were caused by incomplete/bad manuscripts and 36% were related to dirt on film and tools. The 12% problem is related to the ink, of which 38% is due to the viscosity of the ink being lower than the required viscosity and 23% is higher than the required viscosity. The 9% problem is related to the environment, of which 45% is caused by dust impurities and 38% is caused by changes in temperature and humidity. The 7% problem is related to the substrate, of which 37% is caused by the surface properties of the substrate and 25% is caused by the ink absorption of the substrate. As described in the previous sections, identifying major and minor causes is an important step in solving the problem. Analytical methods allow you to quickly find the right way to solve the problem. The analysis steps are as follows: After removing all the uncommon reasons, the most likely reason as indicated in Table 2 remains. The number of optional factors has been reduced from 41 to 13, and each item may be the real cause of the problem. Problem flow chart: Screen tension cleanliness equipment is not off-gauge/stripping pressure Originals are not image quality Not high Dust inks are not sticky Sticky environments are not particles Temperature/humidity substrates are not silk Absorption rate Other variables are not of course if these are the most None of the possible choices is the real reason. There is no doubt that we must begin with what we want to say. Sometimes you may find that the real reason is not listed in the table. The point is that if you start looking for the most probable cause, instead of chaos, you are more likely to succeed. Conclusion: 1. The attached manual describes 41 types of equipment, materials, and process factors related to image problems. 2. Some factors are more important than Others, because they can cause many problems. 3. With statistics, two-thirds of the causes of image defects are caused by screen and device related factors. Among them, the tension is not enough, the screen is contaminated, the porosity is too large, and the cable is not parallel. 4. Checking from the most probable factors, checking secondary factors can find the cause quickly and efficiently. Of course, there are exceptions (see section 5). However, this is usually the most reliable method, especially for unskilled workers.