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How to further improve the precision of slitting tools installation in actual production?

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Author : Yuan Feng
Update time : 2021-01-20 11:34:00
  The more precise slitting tools are, the better strips quality is. Thus there is the task of better precision in order to better serve the improvement of product quality. Here are several methods:
  1. For tools with poor tolerance, their actual thickness can be measured and matched. The low precision of cutting tools is a fait accompli, and users cannot change it, but through matching, we can improve their precision. Of course, it will cause lots of trouble for us. It is better no to choose this way, unless we have no choices. 
  a. First prepare some precision measuring tools, including: digital display micrometer, a set of 38 block gauges manufactured, and a marble plate.
  b. Ask an experienced and responsible operator to measure the parallelism (at least four points) and thickness of all slitter blades, rubber ring cores, and spacers, and record the measured data on the surface of the tool. Then through manual collocation to eliminate errors and improve precision.
  2. For tools with better tolerance, their actual thickness can be measured and grouped together. The thickness tolerance of high-precision knives is ± 1μm, which is already very precise. However, professional manufacturers have to divide them into three groups of "+", "-", and "0". Matching "+" and "-" improves the precision. If our tools cannot reach the precision of ± 1μm, this grouping method can still be learned.
  3. The method to solve the problem of knife radial runout caused by big knife ID. If knife ID is big, there must be a large gap between the knife ID and shafts (refer to figure 1). This gap will cause uneven overlap between the upper and lower circular knives, and uneven pressure on the strip from male and female bonded stripper rings. To solve this problem, we can consciously place the knife on the regrinding shaft in a special direction. If there is a keyway, the keyway shall prevail, if there is no keyway, the knife brand shall prevail. After the knife or bonded stripper ring is placed on the regrinding shaft, tighten the nut lightly, and then tap one side of the outer circle with a rubber hammer to make the inner circle surface of the tools close to the regrinding shaft. If there is a keyway, use a rubber hammer to hit the outer circle on the side of the non-keyway. After that, tighten the nut again and grind it on a grinder. After grinding in this way, we artificially created a small eccentricity on the slitting knife and bonded stripper ring. But this small eccentricity will offset the eccentricity caused by the original gap after the knife and the stripper bonded ring are put into the shaft in the same direction and sequence.
  Figure 2 shows Radial Runout of Slitting Tools can Be Repaired by Regrinding. 
  4. The method to clean the cutting tool:
  a. Never use dirty tissue to clean the surface of the tool.
  b. If you feel that the tools are not clean enough, you can wash them with clean gasoline, especially the dirt groove, but apply clean anti-rust oil immediately after washing.
  c. For contaminant and rust spots which cannot be removed, use a polishing machine to clean up, but be sure to control the polishing time.

Fig. 1 Gap between ID of Knife and OD of Arbor Causes Radial Runout
Fig. 2 Radial Runout of Slitting Tools to Be Repaired by Regrinding