Characteristics of water jet cutting machine used for processing rubber and plastic of knife die cushion and various soft materials

Water-jet cutting takes high-pressure water jet as the processing medium, which is increasingly widely used in the processing field of soft rubber and plastic materials such as die pad, rubber, foam, silica gel, etc. Different from the traditional die cutting, laser cutting and blade cutting processes, it adapts to the processing difficulties of soft materials that are easy to stretch, melt and deform by virtue of the cold-state non-contact cutting characteristics, and has outstanding advantages in the processing scene of die pad, but also has certain application limitations.

First of all, water jet cutting is a cold working process, and there is no heat affected zone, which perfectly avoids the heat damage of soft rubber and plastic materials. When laser cutting and processing rubber and plastic materials, high temperature will cause the incision to melt, carbonize and yellow, foam and sponge materials will also undergo edge melting and hardening, and rubber and silica gel will easily produce scorch and deformation. After the processed die spring pad is assembled on the steel die, the hardened incision will affect the resilience, resulting in uneven indentation of die-cutting products. However, the water jet relies on high-pressure water flow to peel off the material, which does not generate heat in the whole process, and the incision will not be burned or coked. The original physical characteristics of rubber, EVA, PU foam and silica gel spring pads remain unchanged, and the elasticity and compression resilience of the materials are not damaged. The finished spring pad is compressed evenly, which is suitable for high-speed die cutting operation of the knife die, and there will be no problems such as early wear and rebound failure due to the hardening of the incision.

Secondly, the quality of the incision cut by water jet is stable, the cross section is neat, and there is no burr and extrusion deformation, which is suitable for high-precision shape processing of the die pad. When the traditional blade is used to cut soft materials, the rubber and plastic materials will be squeezed and pulled when the blade advances, and the thin rubber elastic pad is easy to stretch and deform, and there are tears and burrs at the corners. The punching process is limited by the precision of the cutter die, and the processing cost of small-sized special-shaped holes and complex contours is high, and even small-sized inner holes cannot be formed. Water-jet cutting belongs to non-contact processing, and the lateral force of water flow on the material is very small, so it can stably process complex structures such as irregular contours, sharp corners, narrow grooves and small holes. The dimensions of the inner and outer contours of the spring pad are consistent, and the cross section is vertical, so there is no flattening and stretching phenomenon. The processed die spring pad is closely attached to the steel knife, and the stress is even in die-cutting production, which effectively improves the dimensional stability of die-cutting products and reduces the defects of flash and material shortage, and is especially suitable for processing multi-layer composite rubber and plastic soft materials and spring pad blanks with different thicknesses.

Thirdly, the processing flexibility is strong, there is no need to make a special knife die, and the production economy of small batch and multi-style spring pads is higher. In the traditional punching process, each spring pad needs to make a separate punching knife. When new products are made and a small number of customized orders are made, the molding cycle is long and the cost is high, and frequent replacement will greatly increase the production cost. The water jet cutting machine adopts numerical control programming, and the drawings can be directly cut without making a tool mold. Facing the frequent modification of spring pads, new samples and customization of non-standard special-shaped spring pads in the tool mold factory, the proofing can be completed quickly and the delivery cycle can be shortened. The same equipment can be compatible with rubber, EVA foam, CR foam, silica gel, felt, non-woven fabric and other soft materials, and materials can be switched only by fine-tuning cutting speed and water pressure parameters, which is suitable for multi-category and small-batch production modes in knife and die supporting industries.

Fourthly, the material has wide adaptability, and can be used to process single-layer or multi-layer composite soft materials, with a large thickness adaptation range. From 1mm thin rubber elastic cushion to tens of mm thick high-density foam pad, water jet can realize one-time molding and cutting. For composite sandwich materials, such as foam and rubber double-sided composite elastic cushion, there will be no delamination and peeling during processing, and there will be no interlayer sliding dislocation like blade cutting. At the same time, there is no dust in the processing process. When the rubber and plastic soft materials are cut and polished by blades, a large amount of debris dust is easily generated, which pollutes the workshop environment and endangers the health of operators. When the water knife is cut, the debris is taken away with the water flow, and the working environment is clean, which is convenient for the on-site management of the knife mold processing workshop and reduces the investment of dust removal equipment.

At the same time, there are some shortcomings in water jet machining. Soft materials are soft, and the high-pressure water flow is easy to cause the material to shake slightly. When cutting extremely thin materials, it needs to be supported by the stage, otherwise the contour accuracy will decrease. The cutting speed is slower than that of blade cutting, and the production efficiency is not as good as that of continuous blade cutting when mass standardized spring pads are produced. The cutting process needs continuous water supply, water treatment and sand (in some working conditions), and the equipment operation and maintenance cost is higher than that of ordinary cutting machines. In addition, when processing soft low-density foam, high-speed water flow may slightly scour the edge, so it is necessary to optimize cutting parameters and pad scheme to improve it.

On the whole, in the field of processing rubber-plastic spring pads and all kinds of soft materials, the core value of water-jet cutting machine focuses on no thermal damage, high contour accuracy, no need for mold opening, and multi-material compatibility, which is very suitable for proofing and production of irregular, high-precision and small-batch spring pads. In the knife die manufacturing industry, the water knife complements the cutting and punching process of the blade, which solves the pain points of easy burning, easy deformation and difficult processing of complex contours in the traditional processing of rubber and plastic spring pads, and is an important processing means for non-standard customization of the knife die spring pads.