Slitting Imperfections Description & Causes

KNIFE SURFACE FINISHES and WEB CUT QUALITY

Based on Juyou’s 20 years slitting and rewinding experiences, we hereby summarize a list of the frequently inquired problems of a slitter rewinder.

The surface finish of a knife will affect the surface finish of your cut material. Rougher surface finishes act as “sanding” agents against the web you are slitting, causing frayed, rough, or jagged edges. Critical surfaces should be polished if optimum edge quality is expected.

SURFACE IMPERFECTIONS

TRIM DYNAMICS： Sometimes in cut quality questions, the machine and/or the blades are not he culprit. Sometimes the trim system needs to be scrutinized.

1. The trim must be supported, under tension, and horizontal during exit. 2. Trim must be drawn away straight ahead and in line with the web path. 3. Trim must not be permitted to flutter at the slit point.

4. Trim must not be pulled directly off the slit point.

5. Trim must not be forced into abrupt changes of direction.

6. Trim suction speed should match web speed.

7. Fluttering trim will aggravate break-off tendency.

8. Avoid abrupt corners on trim pickup systems.

OPERATORS CHECKLIST AND SLITING SETUP

1. Are your cutting blades in acceptable condition?

A. Top Knife

1. Is it flat within .002?

2. Is the cutting edge concentric with the ID to within .002?

3. 3. Are the cutting edges nick- and burr-free for installation? 4. Is the surface finish what engineering specifies to achieve the cut quality your customer desires? 5. Is the blade sharp? 6. Does the blade have the correct angle on it to achieve the desired cut?

2. Top Knife Holders

A. Are seats for both holder mounting to the machine and blade

mounting to the holder burr-free to allow for accurate setting?

B. Does the bearing in the holder show excessive radial or axial run-out? (should not exceed .0003/.0005)

3. Is the cant angle set to the proper degree?

A. Use the minimum amount necessary to achieve the quality cut desired.

4. Is side pressure set correctly?

A. Use the minimum amount necessary to achieve the quality cut desired.

5. Is your trim being removed in such a fashion that causes stress on your cut points? If so - correct it.

6. Is your machine capable of cutting material you are slitting? (check with the manufacturer) 

7. Do you have the proper hand tools to safely and correctly change and/or adjust the knives?

Other problems