Problems and solutions when using flexible cutting dies on magnetic cylinder

1. What is the difference between split and one-piece magnetic rollers?

 

    The split design means that the pillow shoulder is detachable. Heat treatment to 60 to 62 Rockwell hardness ensures the wear resistance of the pillow shoulder. The pillow shoulder can be disassembled and replaced after a few years. It can be restored to its original state as much as possible without wasting the original flexibility. Knife skin.

    The one-piece design means that the pillow shoulder and the roller body are made of one piece. The advantage is that the production cost is slightly cheaper and the production time is relatively short. However, the disadvantage is that the pillow shoulder has poor hardness and is not wear-resistant, resulting in a shorter life of the entire roller.

 

2. Can users order magnetic rollers and flexible blades from different manufacturers?

 

    Yes but there are conditions. If the user's rotary machine is already equipped with a magnetic roller, but wants to switch to a flexible knife blade from another manufacturer, the flexible knife blade manufacturer must know the shoulder diameter and roller body diameter of the original magnetic roller. Some foreign magnetic roller suppliers often have rules and error ranges that they have followed for many years.

    Even if there is no exact QC data, and the user cannot measure it, the flexible knife skin manufacturer can estimate the shoulder diameter and roller body diameter, and then manufacture the flexible knife skin to match.

    But for other magnetic roller manufacturers who have no rules to follow, in addition to requiring them to provide QC data or users' own measurements, flexible blade manufacturers use guesswork to design and manufacture flexible blades with accuracy requirements within a few microns. The risks and potential for errors are high.

    To ensure a close fit between the two, users generally order magnetic rollers and flexible blades from the same supplier.

 

3. Does the flexible blade need to be pinned to the magnetic cylinder?

 

    It is generally not recommended or necessary to use pins for positioning.

    However, there are some special processes. For example, label manufacturers use magnetic rollers with a very small diameter, and the die-cut shapes are particularly complex and multi-line. In addition to the magnetic roller itself, super strong magnets should be installed, and the pin positioning can completely avoid flexibility. The knife skin may slide on the surface of the magnetic roller body due to die-cutting resistance.

 

4. How to accurately place the flexible knife blade on the magnetic cylinder?

 

    Under normal circumstances, the operator can first stick the flexible knife skin to the magnetic roller next to the machine. There is a horizontal edge line on the roller body of the magnetic roller for alignment, and there are also horizontal and circumferential alignment lines on the flexible knife skin to facilitate alignment between the two.

    Then put the attached flexible knife skin and magnetic roller on the bearing sleeve, and install the die-cutting seat like a fixed circular knife. Sometimes, for the sake of convenience, the operator first installs the magnetic roller on the die-cutting seat, and then attaches the flexible knife skin to the machine or changes its position.

    There is nothing wrong with this method of operation, but special care must be taken to prevent the blade from hitting other parts of the die-cutting seat and wearing out the blade.

 

5. Can flexible knife blades save costs by not using magnetic rollers?

 

    This is generally not recommended. If you do not use a magnetic roller and try to use a general metal roller, whether you use double-sided tape to stick to the back of the flexible knife skin, or use tape to attach the edge of the flexible knife skin to the metal roller, you will not be able to make the flexible knife skin better. Stick tightly to the roller.

    The result is a flexible blade with a height error of only a few microns. Due to the gap between the back of the blade and the roller when attaching the plate, the die-cutting depth is uneven. This is an issue that is increasingly used in automatic labeling today. Cases of unacceptable die cutting quality and accuracy.

 

6. What is the difference between coated and uncoated knife blades?

 

    The knife skin without wear-resistant coating can only increase the hardness of the knife skin itself. It needs to be quenched and hardened (also said to be laser hardened). The hardest can be hardened to 58°-65°. If it is continued to be hardened, the blade will be weakened. Cracking when bent.

    The hardness of a good coating can reach 75°. The coating has a molecular structure attached to the essence of the blade. It can bend with the blade and has a longer life and more wear resistance.

 

7. What is the difference between a flexible knife blade and a back grind?

 

    When the flexible knife blade was first promoted and used, it was not accompanied by the application of back grinding technology. Later, manufacturers that began to adopt back grinding technology found that back grinding could better control the total height of the flexible blade, and regarded back grinding as the highlight of their marketing.

    In fact, at that time, CNC could not control the height of the knife blade at one time, and had to use a back grinder to adjust it. Advanced CNC machining equipment can process the once-formed blade in most cases without back grinding adjustment. However, due to the uneven thickness of the die-cut material, especially the backing paper, back grinding cannot be avoided in some cases.

    The quality of the flexible knife blade after back grinding is not much different from that of the knife blade that was successfully formed in one go without back grinding.

 

8. What is the difference in life between flexible knife blade and engraving round knife?

 

    Under normal circumstances, the life of a flexible knife blade will be shorter than that of a fully hardened round knife. However, because there are too many factors that wear the blade, customers use a flexible blade to make a knife that is close to the round knife. There are many examples of die-cutting revolutions and service life exceeding those of round knives (imported knife blades with thick coating).

    It depends on whether the wear is natural wear or collision wear. If the wear is not serious and the tissue paper is easy to cut, the flexibility of the flexible knife skin will be reflected: the user can add a layer of tissue paper or film to the bottom of the knife skin. Or apply a layer of ink, and the areas that were not originally cut can be temporarily cut, so that the bulk goods to be rushed can be completed first.

    For example, in the same situation, the engraving round knife can only be returned to the mold manufacturer for repair, which will incur time and repair costs.

 

9. What should you pay attention to when designing the knife line?

 

    The layout design of the flexible knife blade is the same in principle as that of the engraving round knife. However, because the blade height of the flexible knife blade is shorter than that of the engraving round knife, the distance between the knife lines can be made smaller and the fillet can also be made smaller. When typesetting, you should also follow the principle of the minimum diameter of the roller and avoid cutting many horizontal lines at the same time as much as possible.

 

10. Can the flexible cutting dies be made into a double-layer or multi-layer die height?

 

    Yes. For example, cut the label halfway through, and cut the dotted line between the labels fully through. Or on multi-layer label paper, some blades cut the first layer, and some blades cut the first and second layers of material.

    In order to avoid the beating problem of the knife mold during high-speed operation, it is best to leave 3mm between the knife line and the knife line when cutting through.