Round knife master experience sharing: factors affecting the quality of die cutting

There are many factors that affect the quality of die cutting. This article answers some common sense on the selection, use and maintenance of magnetic roller and flexible cutter cover.

1. Why choose electromagnetic roller?

A: The magnetic roller uses high-strength permanent magnetic block, high-quality steel and high-performance adhesive to ensure the stability of its long-term magnetic function.

The magnetic roller composed of permanent magnetic block is safe and reliable when die-cutting the rotary connecting line, and there is no need to worry about the accident at high speed caused by the sudden disappearance of the electromagnetic force, and the electromagnetic device is more complex.

2. How strong is the magnetic force of the magnetic roller?

A: After the selection of a high-strength permanent magnetic block that meets the standard, the normal magnetic roller and the flexible cutter can withstand the rotation speed of up to 300 meters per minute.

Magnetic roller on the surface of the roll body is partially placed with a super strength permanent magnetic block, so that the edge of the flexible cutter is more firm and withstand more high-speed rotary die cutting, but the domestic cutter because there is no coating technology, can only find a way in the material, more and more rigid to enhance the wear resistance, but the adsorption force of magnetic roller on the cutter is getting worse and worse. The good imported blade is more wear-resistant because the coating makes it more wear-resistant. The properties of the iron itself have not changed, so the adsorption force is stronger.

3. Will the magnetism of the magnetic roller weaken?

A: If maintained and placed properly, there is generally no significant weakening of magnetism within 10 years.

Some users of the magnetic roller needs to be repaired after a few years, the reason is often not because of the magnetic roller weakened, but because of the wear of the pillow shoulder and the magnetic roller body, or due to the improper placement of pressure during use caused by the bending of the roller shaft.

4. Does the magnetic force of the magnetic roller affect other components on the die cutting seat?

A: The magnetic force of the magnetic roll only extends to the surface of the magnetic roll body about 10mm, so it will not affect the other parts on the die cutting seat.

Of course, try not to let the magnetic roller body contact with other components, such as bearing sleeve, bottom roller, etc.

5. Does the magnetic force of the magnetic roller become smaller with the smaller the diameter of the roller?

A: In the case that the diameter of the magnetic roll is not less than the minimum recommended number of teeth, the magnetic force will not become smaller with the smaller the diameter of the roller.

However, it should be noted that the diameter of the magnetic roller cannot be less than the minimum size recommended by the manufacturer.

6. Is there a limit to the minimum size of the magnetic roller?

A: The minimum and safest size recommended by the manufacturer of magnetic rollers is: the circumference of the roller is not less than the width of the machine. However, if a smaller size must be used for various reasons, it is recommended to comply with the 4:1 rule: the roller diameter is not less than 1/4 of the width of the machine.

Although the manufacturer can make a roller smaller than 4:1, in order to smooth and uniform die cutting, avoid the beat or even bending of the mold, following the above rules will extend the service life of the magnetic roller as much as possible.

7. Does high temperature affect the magnetic roller?

A: The permanent magnetic block of the normal die-cut magnetic roller can withstand temperatures up to 150 degrees Celsius. However, it is recommended not to place it in a high temperature environment of more than 80 degrees Celsius for a long time to avoid surface roughness due to the expansion of the adhesive.

It should be noted that the normal die-cut magnetic roller cannot be used for hot stamping holder. Hot stamping magnetic rollers need to withstand high temperatures to reach at least 240 degrees Celsius.

8. What is the difference between split type and connected type magnetic roller?

A: The split design finger shoulder is removable, heat treatment to 60 to 62 Rockwell hardness has ensured the wear resistance of the shoulder, the shoulder can be removed and replaced after a few years, as far as possible without wasting the original flexible cutter skin.

The combined design refers to the pillow shoulder and the roller as one material, the advantage is that the production cost is slightly cheaper, the production time is relatively short, but the disadvantage is that the hardness of the pillow shoulder is poor and not wear-resistant, resulting in a shorter life of the whole roller.

9. Can the magnetic roller be repaired?

A: Yes, but it must be inspected by the manufacturer first. Depending on the wear and damage, the most common repair is to replace the pillow shoulder, repair the roller body, and correct the concentricity of the shaft.

10. Can the user order the magnetic roller and flexible cutter in different manufacturers?

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

Even without its exact QC data, in the case that the user can not measure, the flexible blade manufacturer can infer its pillow shoulder diameter and roll body diameter, and then manufacture flexible blade matching.

However, for other magnetic roll manufacturers that have no rules to follow, in addition to providing QC data or users' own measurements, flexible cutter manufacturers use speculative methods to design and manufacture flexible cutter skins with accuracy requirements in the range of a few microns, and the risk and possibility of error are great.

In order to ensure a close fit between the two, the user generally uses a magnetic roller and a flexible cutter from the same supplier.

11. Does the flexible cutter cover need to be positioned on the magnetic roll with a pin?

A: Dowel positioning is generally not recommended and is not required.

However, some special processes, such as label manufacturers using a rather small diameter of the magnetic roller, the shape of the die cutting is particularly complex and multi-line, in addition to the magnetic roller itself should be equipped with a super-strong magnetic block, pin positioning can completely avoid the flexible cutter skin on the surface of the magnetic roller body, due to the possibility of sliding caused by die cutting resistance.

12. How to accurately place the flexible cutter cover on the magnetic roller?

A: Under normal circumstances, the operator can first attach the flexible cutter cover to the magnetic roller next to the machine. The roll body of the magnetic roller has a horizontal side line for alignment, and the horizontal and circumferential alignment lines are also provided on the flexible cutter skin to facilitate alignment between the two.

Then the flexible cutter cover and magnetic roller are covered with the bearing sleeve, and the die cutting seat is installed like the fixed round cutter. Sometimes for the convenience of the operator, the magnetic roller is first installed on the die cutting seat, and then the flexible cutter cover or change the position of the machine.

There is nothing wrong with this mode of operation, but special care is needed to avoid the blade touching the other parts of the die cutting seat to wear the blade.

13. Can the flexible cutter cover save the cost of not using the magnetic roller?

A: This is generally not recommended. If you do not use a magnetic roll and try to use a general metal roll, whether it is using double-sided tape to stick to the back of the flexible knife, or using tape to stick the edge of the flexible knife to the metal roll, it is impossible to make the flexible knife tightly attached to the roll.

The result is a flexible cutter with a height error of only a few microns, and an uneven die cutting depth due to the gap between the back of the cutter and the roller when pasting, which is an unacceptable die cutting quality and accuracy in today's increasing application of automatic labeling.

14. What is the difference between coated blade and uncoated blade?

A: The blade without wear-resistant coating can only increase the hardness of the blade itself by quenching and hardening (it is also said that laser hardening), the hardest can be hardened to 58°-65°, if it continues to harden, the blade will crack when bending.

A good coating hardness can reach 75°, the coating is a molecular structure attached to the knife skin essence, can bend with the knife plate, and the life is longer and more wear-resistant.

15. What is the difference between back grinding or back grinding of flexible knife skin?

A: The flexible cutter cover was not accompanied by the application of back grinding technology when it was first promoted. Later, manufacturers who began to use back grinding technology found that back grinding can better control the total height of the flexible cutter skin, and the back grinding as the highlight of their marketing.

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

The quality of the flexible blade after back grinding is not much different from that of a successfully formed blade without back grinding.

16. What is the difference between the life of the flexible blade and that of the round blade?

A: Under normal circumstances, the life of a flexible knife will be less than that of a fully hardened round knife, but because there are too many factors that wear the blade, customers use a flexible knife to make a die cutting revolution close to the circular knife, and the life exceeds the example of the circular knife (thick-coated imported knife).

Depending on whether the wear is natural wear or collision wear, such as the wear condition is not large, the cutting face paper is easy to cut, the flexibility of the flexible blade will be reflected: the user can add a layer of thin paper at the bottom of the blade, film or coated with a layer of ink, the original place can be temporarily cut, so that the batch goods to be rushed can be completed first.

If the engraving round knife is in the same situation, it can only be returned to the mold manufacturer for repair, which will produce time and repair costs.

17. What should we pay attention to when designing the knife line?

A: The layout design of the flexible cutter is the same in principle as that of the circular cutter. However, because the blade height of the flexible blade is shorter than that of the engraving round knife, the knife line spacing can be made smaller, and the rounded corners can also be made smaller. Typesetting should also follow the principle of the minimum diameter of the drum, as far as possible to avoid a lot of horizontal lines at the same time cutting.

18. Can the flexible cutter cover be made into double or multi-layer cutter height?

A: Yes. For example, the labels are cut in half, and the dotted lines between the labels are cut in all. Or multiple layers of label paper where some blades cut the first layer and some blades cut the first and second layers of material.

In order to avoid the jitter problem of the tool die during high-speed operation, the distance between the cutting line and the knife line is best left at 3mm.

19. How does the Angle of the blade of the flexible blade affect the cutting product?

A: The Angle design of the blade of the flexible cutter is determined by the combination of the face paper, glue and backing paper to be cut. The blade has 75°, 60°, 55°, 50°, etc. Experienced mold makers will determine the appropriate blade Angle according to the cutting material details provided by the customer, combined with past experience.

Choosing the wrong blade Angle in the design will affect the cutting effect and life of the die. Generally speaking, the blade Angle is larger, the life of the mold is longer; However, if the Angle of the blade is small, the cutting effect will be better, and the possibility of raw edges around the label is small. Generally, 75° is selected for the coated paper, and the cutting Angle of the film class is below 60° to ensure that the surface material is cut off rather than the pressure section material.

20. Can flexible knife cover be used to cut all breaks?

A: Yes, the flexible blade can not only be made to cut fully worn dotted lines, cutters, and fully worn in-die labels. Of course, the issue of waste should be taken into account.

The engraving round knife can be made into an air punch or air suction round knife, but if the magnetic drum itself is standard without any air punch or air suction device, the flexible blade has problems in cutting holes or small grooves (any shape less than 6mm in size).

Options to reduce the problem and increase the likelihood of success include filling the blade with thin foam to remove waste, or making the blade high so that the foam's contracting and expanding forces are more effective.

21. What is the difference between the cutting material of the flexible cutter and the engraving round knife?

A: Flexible knife cover can be used to cut most of the adhesive surface material, including paper film, can also be used to cut thin cardboard.

However, due to the problem that the blade can only be limited to (less than 2mm), there are limitations when cutting thick cardboard and foam materials. If it is used to cut hard aluminum or iron sheet materials, the life of the engraving round knife has its inherent weakness.

However, because the flexible blade is completed by CNC without any manual repair, the marks cut on the base paper have an overwhelming advantage over the hand-repaired carving knife, and the flexible blade has its absolute advantage in the application of cutting self-adhesive materials.

22. What information do I need to provide to order flexible cutter cover?

A: (1) The model of the rotary machine; (2) magnetic roller information: tooth width, roll width, pillow shoulder diameter; (3) The pattern of the cutting shape, pay attention to the tool diagram provided is the shape diagram of the finished product after die cutting, rather than the line diagram on the actual knife plate. If the circular die cutting is used on the material, the line drawing on the actual knife plate is a mirror image of the shape drawing of the finished product after the die cutting; (4) Details of the material to be cut. There are several ways to communicate material details to suppliers: (a) the material supplier's number and material specification sheet; (b) inform the type of face paper and backing paper and the thickness of face paper and backing paper; (c) Send a roll of materials to the mold supplier.

23. What should I pay attention to when I receive the ordered flexible cutter cover?

A: In order to ensure that everything runs smoothly on board, after receiving the ordered flexible cutter cover, you should first check whether the external packaging is intact. Then take out the knife cover to check whether the inside packaging is intact.

Check the supplier test results provided with the knife to see if the cut shape, die cutting effect, cut marks on the backing paper are ideal.

It is better to open the package and carefully check that each blade is in good condition as it left the factory. Check everything is correct before repacking stock, ready to go.

24. Can flexible cutter cover be repaired after wear?

A: In most cases, no. In addition to the above mentioned cases, add a layer of tissue paper, film or coated with a layer of ink at the bottom of the knife plate to make temporary adjustments.

If returned to the original factory, although the blade can be slightly repaired, but in general, it is not recommended to do so, because the flatness of the blade cannot be guaranteed, and the marks on the backing paper after cutting are difficult to ensure uniformity.

25. How to maintain and prevent rust of flexible knife cover?

A: The ink, adhesive and any other impurities on the surface of the flexible cutter should be cleaned after use. The surface of a good flexible cutter is specially treated to prevent rust and adhesive, and these coatings have been able to resist rust adhesive in most cases.

However, due to the wear and tear of the surface coating treatment during die cutting and possible back wear, it is recommended to spray a little WD40 evenly after use and cleaning, and then seal the package to achieve the purpose of thorough rust prevention.

26. How to pack and place flexible knife cover?

A: Most flexible skins require edge bending, especially those suitable for small magnetic rolls, which may require full bending.

Therefore, the packaging of flexible knife cover is mostly packaged in tubes, and the user sprays anti-rust agents on the flexible knife cover after use, seals it with a plastic bag, and puts it back into the tube packaging in a roll shape. It can also be placed in a plastic bag after sealing and hanging straight.