How to avoid flat crush in the process of die-cutting

First of all, let me state the fact: If pressure added by any step in the cardboard processing beyond the range that glue adhesive force or fiber can bear, the cardboard will be crushed. This often causes the inner linerboard fiber damaged or the adhesive force between inner linerboard and linerboard is not effect.This will cause a series of problems, such as equipment congestion, product scrap, poor printing quality, cardboard compression strength reduction. From the point of view of the carton factory, there are four key factors affecting the flat crush, namely laminated cardboard, processing tools, die-cutter status and cardboard feeding.1.Laminated cardboardIn general, corrugated density: the larger the number of flute per inch, the better the printing performance of cardboard, and the stronger the ability to resist flat crush. This is because the flute tip or flute waist is relatively close to the linerboard to provide more support. For example: compared flute B or flute C, flute E has more excellent printing performance and resistance to flat crush, but its edge compression resistance is poor.There are so many factors contributing to the flat crush resistance that it is almost impossible to find a single crushing factor for any given flute type. For example, if flute B crushed under the pressure of 40 pounds per square inch, we can see that the maximum pressure that flute C can withstand will be about 18% lower than that of flute B, that is 33 pounds per square inch, flute A will be about 35% lower than that of flute B. This is then greatly affected by the paper quality, gram weight, moisture content, the amount of glue used in the paperboard processing and the initial pressure applied to the corrugator processing.2.Die-cutting formsAlthough they are respectively used for specific die -cutting process, flatted and rotary steel die-cutting moulding are both used in the three main parts: Steel band( whether used for cutting or scoring ), veneer board, rubber. If any part is not used or improperly set, a flat crush may occur.Most of the flatted die-cutting is processing on the impression device, there is a steel cutting board under the cardboard when doing die-cutting. In the process of die-cutting, corrugated board sandwiched between the cutting board and the steel band, by both of the extrusion, cutting and scoring are both finished at the same time. This requires great pressure and a high degree of accuracy.Because the steel tools are used to cut each other, it is crucial that the distance between the surface of the veneer board and the tip of the steel band, as well as the depth of the impression. If the distance is too all, extra pressure is needed and may cause effluent. In some extreme cases, it drains off the veneer board and crushes the cardboard. If the distance is too large, then the cardboard and paper scraps are difficult to discharge.Even the slightest over impression may cause the steel band over contacting the steel cutting board, causing steel band premature wear. In this way, not only the steel band is not sharp, but may cause short distance above mentioned. In addition, blunt steel band cannot cut off cardboard sharply, and the cardboard may be mashed, which causes the cardboard crushed around the section of cutting line.Most of the rotary die-cutter is cutting on the surface of polyurethane with sawtooth cutting tools. Sawtooth shape and cutting bevel taper putting pressure at different angles in the die-cutting process. Cutting occurs only in the cutting position between the die drum and the anvil pad drum.Therefore, only a all part of the mold is cutting at each moment. Although this process requires much less pressure, the height of the steel band is still an important factor in controlling crush.One of the most unique points of the rotary steel band is the number of saw teeth per inch of the straight-line distance. In general, the less number of saw teeth means less force required to penetrate, however, at the cost of a greater depth of impression. The greater the impression depth, the faster the polyurethane anvil pad wear, resulting in uneven cutting surface, and flat crush.3.RubberThe proper use of exhaust rubber plays an important role in controlling the crush in the die-cutting process. There are various types of exhaust rubber available in the market, each type according to the formula has a specific advantage. Rubber is the least requirements among the die-cutting tools, but it has certain stimulation in controlling the crush.There are three basic types of rubber in die-cutting process, namely, open cell porous rubber, close cell porous rubber and pore rubber. It is worth noting that these rubbers or their use may have a great deal of difference in the rotary or flatted die-cutting process . And among these three types of rubber, hundreds of different specifications and formulas can be divided into different products.●Open cell porous rubber:Appearing in red hue, it is rubber of medium density. The surface is uneven and spongy. Such materials are sensitive to ultraviolet light and can suck dust into exposed cells. Rubber will become brittle and hard over a period of time. There is no doubt that this has changed the characteristics of common rubber, however, excessive impression on this type of rubber has little effect.●Close cell porous rubber:Appearing in grey or black hue, it is widely used in rotary and flatted die-cutting process. Compared with the open-cell rubber, this type maintains longer original physical properties under general factory conditions. However, excessive impression can cause tiny seal cell ruptured. When this happens, the rubber bounces much slower and no longer s properly.●Pore rubber:Pore rubber is the strongest among the three, and is in fact a type of close cell porous rubber. The compact pore structure creates a tremendous amount of rebound force, removing waste from the narrow area. Although this type of rubber can withstand greater pressure, excessive compression can cause the same problem that the same as close cell rubber.Each rubber material is supplied in a number of different height specifications and tolerates considerable error. In addition, over period of time, these rubbers have decreased in height and rebound speed due to recycling use. This is especially common in close cell rubber.Rubber firmness in cardboard crush plays a very important role. At present the industry mainly uses two kinds of hardness test standards: Shore”00” and Shore “A”, which is similar to the Fahrenheit and Celsius scales. Please determine which standard to use for testing rubber.There are two important points worth noting about rubber. First of all, soft materials can usually withstand greater pressure and produce less crush. But it often limits the speed of production. Harder rubber can achieve faster market speed, but more likely to crush carton.Rubber is a porous material, not a solid material. When rubber is compressed, it tends to be solid. The force and energy of the compression is discharged by the rebound force. The tricky part is to decide the degree of how compressible the rubber is and how hard it needs to get waste or product out of the mould. Then we have to find appropriately joint of the two factors, both reduce cardboard crush and extend rubber’s service life.●Veneer boardThere are basically two kinds of thickness of veneer board used to make die - cutting tools:1/2 inch and 5/8 inch. The height of the steel band is always the same regardless of the thickness of the board, but the distance from the tip of the band to the veneer board is variable. To compensate for the distance, a suitable rubber height must be selected .For 5/8 inch veneer board, a thinner rubber is recommended, To 1/2 inch, a thicker rubber is adopted, other than cardboard crush and discharge will happen.4.Die cutter statusIn general, pressing a cardboard on a die cutter will always be more accurate than embedding the anvil pad into the machine. Therefore, in the use of flat die - cutter, irregular cutting surface will not have a great impact. Be careful, however, the adhesive tapes and other materials that is sticky on the pressing plate. These materials may temporarily help cut, but it will also create excess pressure on the board.The condition of the soft anvil pad has a great influence on this part. The alignment between the die drum and anvil pad surface, normal wear of anvil pad and poor rotation can cause excessive pressure, resulting in cardboard crush.5. Cardboard feedingMost of the flatted die cutter feeding cardboard with a gripper bar, which is only contact the front waste. This is an excellent feeding way that will not crush the cardboard.The suction paper feeder with a vacuum device lifted from the top is also excellent and does not crush the board. On the other hand, rotary die cutter with a soft anvil pad usually adopts more than one feeding roller, so that mesh point formed between the polyurethane wheel and the lower steel cylinder. Basically, these die cutter are processing the cardboard in the center position. Liner paper is rough that is easy to wear polyurethane anvil pad, resulting in uneven force, and cardboard crush.Guide wheel of rotary die cutter will also cause cardboard crush. If you use a guide wheel, it is possible to trimming as well as die cutting. If so, remember to minor adjust the mesh point every time you pulling it, so as to better control the cardboard. If not trimming, then moving the paper guide wheel horizontally, at this point, not increase the meshing pressure, to reduce the compressive force.If the compressive force during the cardboard transfer minimized, the corrugated material may be slightly deformed. But this will almost not affect the cardboard strength, simply because the inner linerboard glued by starch glue has good elastic force. If the compressive force is greater than the elastic force, it will damage the fiber material, and this damage is permanent, giving rise to a permanent structural performance problem.

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Rotary Die Cutting vs. Flatbed Die Cutting--How to Choice?

Now the world corrugated packaging industry USES the most two die –Rotary die cutting and flatbed die cutting Many companies are confused, so how to make a choice?Now it’s time to take a closer look at the two die cutting methods available - rotary die cutting and flatbed die cutting. Which one is right for you? The BoxMaker corrugated plant has both available in-house, and each method is used regularly in different situations. The working Speed between Rotary and FlatbedThe Rotary Die CuttingIt is usually one of the units of flexo printing machine,it’s called Die-cut unit. Speed often depends on the type of carton produced and die cutting type.The normal production speed is 150-250 piece/min,some machine can reach 350 piece/min. Flatbed Die Cutting To be exact, there are 3 types in the market, one is manual, Semi-automatic and full automatic. The speed of the device in type 3 is completely different.the Manual speed around 30 piece/min, semi-automatic is around 60 piece/min.Full automatic die cutting max speed can reach 100-120 piece/minCutting Dies Cutting dies are long lasting, quality structures and present a one-time charge for your company. The maintenance, storage, and cleaning of all dies is covered in the initial price you pay.Rotary steel dies are more expensive than flatbed dies because the wood for a rotary die is circular in shape, and the method for making these is more extensive. Yet, looking at the price of the steel die alone is not enough information to make an informed decision.There are many factors to consider when choosing the best method for your packaging needs. Our estimating team will take into account the following factors to determine the right direction for you and your organization:How many will you be ordering? Rotary steel dies can be 30-100% more expensive than a flatbed die, but the rotary machinery can run more pieces at once due to a larger blank size and faster speed. So, while the initial steel die may cost more, a lower per-each price can offset the die cost quickly.Will you be buying multiple orders on a regular basis, or is it a one-time purchase? If you are purchasing a specific product for a one-time promotion or a single distribution, then a less expensive flatbed die may be the best way to go. But, if you have regular usage of a specific product and plan on purchasing multiple orders of a particular package, the rotary machine will offer a lower piece price and will quickly offset the higher die cost.Example:Flatbed die charge: $800, .25 cents per box for a 5,000-piece orderTotal investment after 1 order: $2050Total investment after 3 orders: $4550Total investment after 10 orders: $13,300Rotary die charge: $1400, .19 cents per box for a 5,000-piece orderTotal investment after 1 order: $2350Total investment after 3 orders: $4250Total investment after 10 orders: $10,900As you can see, rotary die might be more expensive, but you actually start saving money after just 3 orders!How large is your product? The rotary machine may be fast, but it doesn’t handle all pieces well. If your blank size (piece of corrugated product laid flat, before folding or gluing) is less than 15” in width or length, we will need to cut it on the flatbed die cutter. On the opposite spectrum, the capabilities for die cutting large blanks are limited on the flatbed machine. With a maximum blank size of 66” x 85” on the rotary die cutter, it can handle a lot of larger format pieces, and can cut out more at one time. The flatbed machine has a maximum blank size of 41” x 55”.How intricate is the design? The rotary can handle big designs, but not necessarily intricate ones with tiny cut-outs, tight radius on corners, and slit scores. Since the rotary is a giant wheel rolling over the corrugated, the cutting isn’t quite as precise as the flatbed die cutter. Our structural designers have the expertise to know ahead of time which machine will be best suited for your product.Is your corrugated packaging printed? The rotary press can print up to 3 colors AND die cut at the same time. This means that if your product needs to be die cut on the flatbed, it will need to get printed on another machine first. This adds to labor costs, and ultimately can lead to a higher price for you. Whenever possible, it makes sense to pay more upfront for the rotary die so you will see the savings from this investment down the road.As you can see, selecting the correct die cutting method is not a “cut” and dry decision! We take great care in guiding you to the best solution for your specific needs.--If there is Copyright Dispute about the content, please Contact us to Delete.

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