The material properties and classification system of knife plate spring pads

The ejection rubber is an indispensable auxiliary component in the die-cutting and creasing process. Its core function is to buffer the die-cutting pressure through its own elasticity, protect the cutting edge of the knife plate, and ensure die-cutting accuracy. The material composition and structural design directly determine its applicable scenarios and service life. As a typical elastic functional accessory, the material research and development of the knife plate spring pad has always revolved around the three core demands of "high elastic recovery rate", "resistance to compression permanent deformation", and "adaptation to die-cutting environment", forming a diversified product system.

From the perspective of core materials, natural rubber elastic pads are the basic products. Their Shore hardness is usually between 30 and 50 degrees, and the elastic recovery rate can reach over 90%. They have excellent adaptability to paper substrates in a normal temperature (0-40℃) die-cutting environment and are relatively low in cost, making them suitable for batch die-cutting of ordinary cartons and boxes. Synthetic rubber elastic pads have been upgraded to meet special requirements. For instance, nitrile rubber elastic pads have outstanding oil resistance and can withstand the erosion of die-cutting oil, lubricating oil and other media. Their compression set rate is less than 5%, making them suitable for die-cutting operations in oily environments. Polyurethane elastic pads feature both high hardness (Shore 60-80 degrees) and high wear resistance, with tensile strength reaching over 20MPa. In die-cutting of thick materials such as corrugated paper and cardboard, their service life is 3 to 5 times longer than that of natural rubber elastic pads. In addition, silicone rubber pads, due to their excellent resistance to high and low temperatures (-40℃ to 200℃), are often used in die-cutting equipment in high-temperature die-cutting or low-temperature storage environments.

According to structure and application, ejection rubber can be classified into three types: general-purpose type, precision type and extreme resistant type. The cross-section of general-purpose elastic pads is mostly rectangular or circular, with a thickness of 2 to 10mm. They are suitable for conventional flatbed die-cutting machines and are used for ordinary packaging printing. The precision elastic pad adopts micro-foaming technology, with surface error controlled within 0.01mm. Its cross-section is wedge-shaped or stepped, suitable for rotary die-cutting machines, and is used in high-precision die-cutting scenarios such as labels and cigarette packs. Extreme resistant elastic pads, through material modification, such as flame-retardant elastic pads with flame retardants added having an oxygen index greater than 32, and UV-resistant elastic pads with anti-aging agents added having an outdoor service life of more than two years, are respectively suitable for special environments such as high-temperature die-cutting and outdoor operations.