When comparing slitting methods it is important to consider:
- A strict quality comparison based on the actual situation when multiple strips (4 or more) are being cut.
- Ability to adapt to extremely difficult situations by eliminating both cutting burrs and delamination.
- Even with solid-state batteries and LFP, cutting burrs and delamination can lead to performance degradation and cell safety issues over lifetime.
Goebel Type
This is a cutting method in which the upper knife is fixed in the cutting position in advance, and the entire shaft is moved sideways by a specified amount of air pressure to bring it into contact with the lower knife.
The thickness of the upper knife is about 0.70-1.00 mm.
| Contact Pressure | Toe-in | Knife Depth |
| Under the assumption that the contact pressure of the upper and lower knives are directly equal to the air pressure value, that moves the entire shaft fixing the upper knife sideways. However, there are considerable error due to individual differences in each air cylinder. (good) | Because it is a single-axis method, it is impossible to change for adjustment the toe-in. (poor) | Managed by the upper knife outer diameter value. As long as the diameter is the same, the depth of all upper knives is the same. (average) |
Even with high-precision air pressure equipment, differences in component assembly can lead to errors between the set air pressure value and contact pressure, which are essentially proportional. During pre-production quality checks, the upper knife must be made elastic to correct the contact relationship with the lower knife. This requires the upper knife to be elastic and less than 1mm thick.
Advantages
- The upper knife cutting position can be freely adjusted, and the cutting quality can be finely adjusted by the elasticity of the knife itself.
- The structure is simple, and the integrated upper and lower knife set is cartridge-type, so it is easy to replace when changing the cutting width.
Disadvantages
- Instability in cutting quality due to elastic upper knives.
- The upper knife is less than 1 mm thick to finely adjust the contact pressure. Conversely, the elasticity of the upper knife, which makes this possible, can cause unstable contact pressure during operation, which in turn leads to unstable cutting quality. In the case of multiple cuts, setting the cutting quality each upper knife before operation and correcting and adjusting each knife in the event of a sudden deterioration in quality during operation can be extremely labour intensive. Furthermore, removing the resulting burrs with a forced cleaner can damage the cut area, posing a risk to the battery and causing performance problems.
- There is no indicator that shows the contact state of the upper and lower knives, so even if a cutting failure occurs during operation, the cause is unknown and it cannot be recurred.
- Even if only one of the upper knives needs re-sharpening, all upper knives must be re-sharpened to avoid quality changes due to changes in outer diameter.
Costs
- Capital: The single-axis type is almost the same for both the Goebel and the Goebel-Gang, and is almost the same even if the number of knives is increased. Due to the structure, burrs and other defects are inevitable, so a cleaner is required. High-performance ultrasonic cleaners are more expensive than the slitter itself.
- Operating: Because it is thin less than 1mm, it wears out and breaks easily, so it has to be re-sharpened or replaced frequently. When sharpening, all knives must be the same depth, so even if only one knife needs to be resharpened, all upper knives must be sharpened.
- Service: Basically left to the customer’s discretion and implementation. Since there is no reproducibility of cutting conditions, even if a slit test is performed, the results of testing on a test machine cannot be reflected in the production machine, so in the case of poor cutting, if minor adjustments are not sufficient to repair the problem, the cleaner strength is simply increased to remove the cut. However, this practice has recently been linked to fire accidents and malfunctions.
Gang Type
This simple structure clamps the upper and lower knives with spacers depending on the cutting width. It provides stable rigidly a thickness of 5mm or more, but does not allow for any fine adjustments.
| Contact Pressure | Toe-in | Knife Depth |
| The upper and lower knives are fixed in position, and contact pressure is also fixed and un-adjustable. (good) | Due to the single-axis design, toe-in cannot be adjusted. (poor) | All upper and lower knives maintain a constant depth. (average) |
This simple, integrated upper and lower knife set uses a cartridge system, making it easy to replace for changes in cutting width.
Advantages
- Cartridge system makes it easy to replace a whole unit.
Disadvantages
- Spare upper and lower knife sets are expensive, so increasing the number of cutting widths significantly increases costs.
- Changing the contact condition due to changes in the material condition requires disassembly, adjustment, and reassembly of the upper and lower knives, rather than a cartridge replacement system. This is extremely labour-intensive and generally impossible.
Costs
- Capital: Due to the manufacturer’s sales strategy, the initial unit itself is inexpensive.
- Operating: spare upper and lower knife sets can be expensive, so be careful if you plan to add more widths in the future.
- Service: After delivery, cutting quality issues are left to the customer; the manufacturer only provides consultation regarding the unit’s operating conditions.
Goebel-Gang Type
In addition, an adjustable leaf spring is attached to the upper knife relative to the gang, allowing for some fine adjustments of contact pressure.
The upper knife is approximately 1.0mm thick.
| Contact Pressure | Toe-in | Knife Depth |
| The upper and lower knives are fixed in position, but contact pressure can be very slightly adjusted using the included leaf spring. (good) | Due to the single-axis design, toe-in cannot be adjusted. (poor) | All upper knives have the same outer diameter, and all knife depths are constant. (average) |
The basic structure is the same as the gang, but the contact pressure can be adjusted slightly for each upper knife depending on the cutting quality. However, this can lead to instability in the cutting quality during operation.
Advantages
- Cartridge system makes it easy to replace a whole unit.
Disadvantages
- Difficult to adjust.
- Changing the contact condition due to changes in the material condition requires disassembly, adjustment, and reassembly of the upper and lower knives, rather than a cartridge replacement system. This is extremely labour-intensive and generally impossible.
- Instability in the cartridge system can lead to quality issues.
- Spare upper and lower knife sets are expensive, so increasing the number of cutting widths significantly increases costs.
Costs
- Capital / Operating: The unit and upper knife resharpening costs are roughly the same as those for the Goebel type.
- Service: same as Gang Type
Separate Upper Knife
Separating the upper knife and then adding a control system solves a number of the design flaws in the Gang and Goebel type slitting approaches.
Air Pressure Operated
Assuming that the contact pressure between the knives is directly proportional to the air pressure supplied to the upper knife holder, the supplied air pressure is used as the contact pressure between the knives.
The contact pressure is managed by the air pressure supplied to the separate upper knife holder.
With this being air operated it is possible to control the cutters, but not to the degree that the servo operated system can.
Contact Pressure Operated
Operated by direct contact pressure detection and hence can adapt during operation to all of the control parameters.
The direct contact pressure between the upper and lower knives and knife depth, which determines the cutting quality, is detected by a sensor and displayed digitally. By utilizing this, the three cutting factors of contact pressure, toe-in, and knife depth can be digitally reproduced with high precision.
The fully controlled servo based system allows each knife to be controlled, react to changes in the material and to be optimised offline and parameters uploaded to the production system.
Maysun Corporation was established based on a Paper-making company in 1967. So we see from perspective of Paper-making manufacturers and have developed technology which they require truly. We are pioneers in the introduction of numerical control to Paper-making machine, and rated highly by our customers.
And other than paper-making, orders of NC Slitters and Non-contact thickness gauges for optical films for Flat Panel Display and electrode materials of lithium-ion battery are increasing in number. Our products rated highly by trendsetter material manufacturers.
Contact Hiroshi Yamada (h.yamada@maytech-corp.jp) for more information (LinkedIn)
See also: Slitting