Flat-press-flat vs. Round-press-round die-cutting: The selection logic and core differences of the die-cutting tooling spring pads
Flat pressing flat die-cutting and round pressing round die-cutting are currently the two most mainstream die-cutting processes in the printing and packaging industry. The former is widely used in high-end gift boxes, fine packaging, and small-batch multi-category orders, while the latter focuses on large-scale high-speed production of e-commerce cartons and label soft packaging. The operating principles, working conditions, and applicable scenarios of these two processes are vastly different. However, many printing companies, in an attempt to save time, use the same universal spring pad to handle both processes, ultimately resulting in poor die-cutting quality, short spring pad lifespan, and low production efficiency. This completely fails to leverage the full potential of the equipment. After 22 years of specializing in die-cutting consumables, Shenhua Printing Materials has dissected the core differences between these two processes and explained the selection logic of knife plate spring pads, helping you choose the right spring pad and maximizing the production efficiency of the equipment.
First, understand the core differences in working conditions between the two die-cutting processes.
To select the right spring pad, you must first clearly understand the core requirements of the spring pad for each process. These requirements are essentially determined by the operating principle of the equipment.
Flat pressing flat die-cutting machines use an intermittent opening and closing die-cutting method. Through the up-and-down reciprocating motion of the moving platform, the knife plate and the platform are pressed together for die-cutting. Its core feature is that the impact force during the pressing moment is large, and the anti-impact and anti-compression permanent deformation performance of the spring pad is extremely high; the die-cutting pressure is in face contact, and the consistency and hardness uniformity of the full-width thickness of the spring pad are strictly required; the change of the single sheet is flexible, and it can be adapted to all types of substrates from thin paper to thick corrugated board, with high requirements for the universality and adaptability of the spring pad.
Round pressing round die-cutting machines use a continuous rotating die-cutting method. Through the relative rotation of two rollers, continuous and uninterrupted die-cutting is achieved. Its core feature is that the linear speed is extremely high. The mainstream e-commerce carton linear speed can reach over 300 meters per minute, and the label rotation linear speed is even higher. The requirements for the rebound speed and response frequency of the spring pad are extremely strict; the die-cutting is in line contact, and the contact time between the knife edge and the spring pad is very short, with extremely high requirements for the wear resistance and rebound stability of the spring pad; it focuses on large-scale continuous production, with strict requirements for the long lifespan and low attenuation performance of the spring pad.
Flat pressing flat die-cutting: Core selection points for knife plate spring pads
The core of the working condition of flat pressing flat die-cutting is to cope with the frequent impact of intermittent pressing, ensuring the stability of rebound during long-term use. The selection must focus on four core points.
First, prioritize the use of high-density polyurethane. The impact force during the intermittent opening and closing of flat pressing flat die-cutting will quickly cause ordinary rubber spring pads to undergo compression permanent deformation and collapse. The anti-impact and anti-compression deformation performance of high-density polyurethane material is more than 3 times that of ordinary rubber, with a compression permanent deformation rate controlled within 3%, and it can maintain stable rebound performance after 500,000 continuous die-cutting cycles. It is the preferred material for flat pressing flat die-cutting. For short single small-batch and ordinary paper production, a more cost-effective rubber composite spring pad can be selected; for long single large-batch, thick corrugated board, and special material production, high-density polyurethane spring pads must be used.
Second, the hardness must be strictly matched with the substrate thickness. The substrate range suitable for flat pressing flat die-cutting is very wide. Selecting the wrong hardness will directly lead to line breakage and inability to cut through. For 80-250g thin paper, art paper, and self-adhesive labels, 30-40 Shore A low-hardness flexible spring pads should be selected to avoid line breakage and surface scratching; for 250-400g thick cardboard, gift box packaging, 40-50 Shore A medium-hard balanced spring pads should be selected, balancing cutting effect and paper protection; for 3-7 layers of corrugated paper, heavy industrial packaging, 50-70 Shore A high-hardness impact-resistant spring pads should be selected to provide sufficient reverse supporting force and ensure complete penetration die-cutting.
Third, the structural selection is adapted to the production scenario. For regular order production, priority is given to using spring pads with back adhesive, which are convenient to install and flexible in arrangement, and can be adapted to various irregular knife lines; for large-batch fixed orders, pre-made whole-page spring pads can be selected, with higher installation efficiency and more uniform rebound; High-end special materials, complex irregular structures, customizable gradient hardness elastic pads can be selected. Different knife line positions match different hardness levels, perfectly balancing cutting and protection.
Fourth, prioritize high consistency products for precision. Flat pressure flat die-cutting is a face-contact compression process. The thickness tolerance of the elastic pad directly determines the uniformity of the die-cutting pressure. Preferentially select elastic pads produced by fully CNC grinding, with a thickness tolerance of ±0.03mm and a hardness deviation of ≤±2 Shore A. This avoids uneven local pressure leading to incomplete cutting, burst lines, etc. The deephua printing material flat pressure flat dedicated knife plate elastic pad is specially designed for the impact condition of flat pressure flat die-cutting. The entire series uses high-density polyurethane substrate, with excellent impact resistance and long service life. It has become a standard product for thousands of packaging factories in China.
Round-to-round die-cutting: Core selection points for elastic pads
The core of round-to-round die-cutting is to cope with high-speed continuous rotation with extremely high frequency die-cutting, ensuring millisecond-level rebound response and long-term wear resistance. The selection must focus on three core points.
First, core performance should prioritize rebound speed and wear resistance. In round-to-round high-speed die-cutting, the contact time between the blade and the elastic pad is only a few milliseconds. Ordinary elastic pads cannot keep up with the rebound speed, directly causing problems such as incomplete cutting, sticking blades, and overflow glue. It is necessary to select elastic pads with a super-fast rebound formula, with a rebound response time ≤ 10ms. Even at a high-speed line speed of 350 meters per minute, it can achieve instantaneous reset, ensuring uniform and consistent depth of each die-cut. At the same time, the continuous rotation die-cutting method requires extremely high wear resistance of the elastic pad. Nanometer-level wear-resistant fillers must be added, with a wear resistance improvement of more than 4 times compared to ordinary elastic pads. It can withstand millions of continuous die-cutting impacts and significantly reduce the frequency of equipment shutdown for material replacement.
Second, hardness and structure should be adapted to application scenarios. For high-speed die-cutting of non-woven labels and flexible packaging films, low-hardness elastic pads of 25-35 Shore A are preferred, combined with permanent anti-stick coatings, perfectly solving problems such as sticking blades, overflow glue, and cutting through the base paper. For high-speed die-cutting of e-commerce cartons and corrugated paper, medium-high hardness elastic pads of 45-60 Shore A are selected, balancing wear resistance and support, avoiding rapid collapse and incomplete cutting. For ultra-high-speed wide-width production lines, seamless ring-shaped integrated elastic pads are preferred to avoid jitter and wear at the joint, ensuring consistent die-cutting effect across the entire width.
Third, environmental adaptability cannot be ignored. Round-to-round die-cutting is mostly used for large-scale continuous production. The equipment will run for a long time and heat up. At the same time, the e-commerce carton production workshop has a lot of dust and high humidity, and label production frequently comes into contact with adhesives and solvents. It is necessary to select a formula that is resistant to heat, oil, and aging, maintaining stable performance in high-temperature and high-humidity environments, without softening, swelling, or aging problems. The deephua printing material round-to-round dedicated knife plate elastic pad is specially developed for high-speed die-cutting conditions. The ultra-fast rebound formula is adapted to high-speed production lines with a line speed of 350 meters per minute or more. The wear resistance and impact resistance are more than 4 times that of ordinary elastic pads, with a service life more than 4 times longer. It is widely used in leading e-commerce packaging and label printing enterprises in China.
Selection pitfalls: Don't make these mistakes
Do not replace round-to-round elastic pads with flat-to-flat elastic pads. Flat-to-flat elastic pads usually have slow rebound speed and will cause problems such as insufficient rebound time, incomplete cutting, and sticking blades when used on high-speed round-to-round lines. At the same time, they have insufficient wear resistance and will quickly wear and collapse, with an extremely short service life.
Do not use round-to-round low-hardness elastic pads for thick corrugated flat-to-flat die-cutting. Low-hardness elastic pads have insufficient support force and cannot provide sufficient reverse penetration force for thick corrugated. It will cause incomplete cutting problems. At the same time, under the strong impact of flat-to-flat, it will quickly undergo permanent compression deformation and completely lose rebound performance.
Do not ignore equipment status adjustment for selection. The parallelism of the old flat die-cutting machine is poor. To address this issue, we need to select elastic pads with smaller tolerance in thickness and higher consistency to compensate for the insufficient precision of the equipment. For the old round-round die-cutting machine, the rollers have large vibration. We need to choose elastic pads with better wear resistance and slightly higher thickness to ensure stable die-cutting pressure.
In conclusion, for different die-cutting processes, specific solutions for knife plate elastic pads are required. There is no one type of elastic pad that can cover all scenarios. Shenhua Printing Materials has been deeply involved in the die-cutting consumables field for 22 years. It has developed an exclusive product matrix of knife plate elastic pads for all types of die-cutting equipment, such as flat-press flat, round-press round, and rotary label die-cutting. At the same time, it provides one-on-one selection guidance and process optimization services to help printing enterprises choose the right elastic pads, fully utilize the equipment performance, and achieve cost reduction and efficiency improvement.