Causes and solutions of burrs in foam die-cutting processing

First, the cause of the burr problem

Tool factor

Tool wear: the cutting edge of the tool will gradually wear during the long-term die cutting process. When the cutting edge becomes blunt, the material can't be cut cleanly when cutting the foam, but it will tear the foam, which will lead to the appearance of burrs. For example, after a large number of foam products are continuously die-cut, the cutting edge of the tool may appear tiny gaps or become not sharp enough.

Insufficient tool precision: If the manufacturing precision of the tool is not high, the cutting edge may be uneven. When cutting foam, the uneven cutting edge will make the cutting surface of foam uneven, and some places may be over-cut, while some places may not be cut in place, resulting in burrs.

material characteristics

Foam is soft: Foam itself is soft and has certain elasticity. In the process of die-cutting, the material is easy to deform when the cutter cuts, which makes the cutting edge irregular. For example, some low-density foam, its structure is loose, and it is easier to have burrs when cutting.

Uneven internal structure of materials: Some foams may have uneven internal structure due to process and other reasons during production. When die-cutting, the cutting effect will be different when the tool passes through different density areas, and it is easy to produce burrs in areas with structural changes.

Unreasonable processing parameters

Cutting speed is too fast: when the cutting speed of the die-cutting machine is set too fast, the contact time between the cutter and the foam material is too short, and there may not be enough time to completely cut off the foam. This will cause the foam to tear and burr at the cutting edge.

Improper pressure: too much or too little pressure will lead to burrs. If the pressure is too high, the foam will be over-extruded and deformed, and the material will easily overflow after cutting, forming burrs; If the pressure is too small, the foam can not be completely cut off, and burrs will also occur.

Mold design defect

Improper shape of die cutting edge: If the die cutting edge is designed unreasonably, for example, the angle of the cutting edge is too large or too small, it will affect the cutting effect. When the angle is too large, the lateral pressure of the cutter on the foam is too large, which is easy to deform the foam edge and produce burrs; If the angle is too small, the cutting ability of the tool will be insufficient, which will also lead to incomplete cutting and burrs.

The adaptability between the mold and the foam is poor: if the size of the mold does not match the thickness and hardness of the foam, the foam can not be positioned and cut well in the die-cutting process. For example, the gap between the cutting edge of the mold and the foam is too large, and the foam will be extruded and deformed at the gap during cutting, resulting in burrs.

Second, the solution to the problem of burrs

Cutter aspect

Change tools regularly: according to the workload of die cutting and the wear of tools, make a reasonable tool replacement plan. Generally speaking, when it is found that the cutting edge of the tool shows obvious signs of wear, such as dull cutting edge and notch, the tool should be replaced in time to ensure the sharpness of the cutting edge.

Choose high-precision tools: when purchasing tools, choose tools with good quality and high precision. The cutting edge of the high-precision tool is flatter, which can make the foam evenly stressed in the cutting process and reduce the generation of burrs. At the same time, we can also consider using tools with special coatings, such as cemented carbide coated tools, which have better wear resistance and cutting performance.

material processing

Select the appropriate foam material: according to the requirements of die-cutting processing, select the foam material with uniform texture, moderate hardness and elasticity. For products prone to burrs, foam with slightly higher density and compact structure can be preferred, so that the deformation of the material is relatively small during cutting, which is conducive to obtaining a neat cutting edge.

Pretreatment of materials: Before die-cutting, foam materials can be properly pretreated, such as freezing. By reducing the temperature of foam, the hardness can be increased, and the deformation during cutting can be reduced to some extent, thus reducing the possibility of burr generation. However, this method needs to be tested according to the material and actual processing of foam to determine the appropriate freezing temperature and time.

Adjusting processing parameters

Optimize the cutting speed: through experiments and experience accumulation, find the best cutting speed suitable for foam materials and tools. Generally speaking, for thicker and softer foam, the cutting speed should be slowed down appropriately to ensure that the cutter can completely cut off the foam. When adjusting the speed, you can gradually reduce the speed and observe the change of the burr until you find a suitable speed that can ensure the production efficiency and reduce the burr.

Adjust pressure parameters: according to the thickness and hardness of foam, adjust the pressure of die cutting machine reasonably. You can try cutting first, observe the edge of the foam, and gradually adjust the pressure. If the burr is caused by excessive pressure, the pressure can be appropriately reduced; If the pressure is too small to cause incomplete cutting, it is necessary to increase the pressure. At the same time, we can also consider using segmented pressure control, that is, using different pressures when the tool cuts in and out to obtain better cutting effect.

Mold improvement

Optimize the design of die cutting edge: redesign the shape and angle of die cutting edge according to the characteristics of foam material. For soft foam, generally, a smaller cutting edge angle can be used to reduce the lateral pressure and make the cutter cut into the foam more smoothly. At the same time, some special structures can be designed at the cutting edge, such as the micro-serrated design of the cutting edge, which can increase the cutting force of the cutter on the foam and reduce the generation of burrs.

Improve the adaptability of mold and foam: when designing the mold, we should fully consider the size and characteristics of foam. Adjust the gap between the cutting edge of the mold and the foam reasonably. Generally speaking, the gap should be as small as possible, but ensure that the foam can enter the mold smoothly for cutting. By making high-precision molds or adopting some auxiliary positioning devices, such as positioning pins and positioning grooves, the adaptability between molds and foam can be improved and the generation of burrs can be reduced.