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2025
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Want to produce high-quality sheets? These 5 key parameter adjustments are crucial!
Author:
Once the sheeting machine is turned on, will gold naturally flow in? Yet many business owners find that even after purchasing high-quality equipment, the sheets they produce continue to be plagued with problems: surface streaks, uneven thickness, frequent material breaks... In fact, to a large extent, these issues aren't due to the machine itself but rather to “parameters that haven’t been properly adjusted.”
A high-quality sheeting machine is like a superb musical instrument—whether it can play a perfect melody depends entirely on the operator’s precise tuning. Today, we’re going to reveal the five key parameter adjustment secrets that master craftsmen never readily share, helping you stabilize product quality, reduce waste, and turn your equipment into a true money-making asset!
Chapter 1: Temperature—The “Lifeline” of Sheet Molding
- Adjust what? It is typically divided into: temperatures of various sections of the machine body (from the feeding section to the homogenizing section) and the die temperature.
- How to judge?
1. Too low a temperature: The material is poorly plasticized, resulting in high melt strength, which overloads the motor and causes crystal spots and rigid lumps on the sheet surface, or even prevents proper forming altogether.
2. Excessive temperature: Material degradation may lead to bubbles, burnt particles, and yellow streaks, and the sheet material will become brittle and prone to cracking after cooling.
- Adjustment mnemonic: “High at both ends, low in the middle.” The temperatures for the feeding section and the die head can be set slightly higher (to ensure smooth feeding and stable extrusion), while the temperature in the compression section should be set at its peak (to guarantee thorough plasticization). The temperature in the metering section can be slightly lowered (to prevent overheating and degradation). The key is to ensure that the melt reaches the die head with a uniform and stable temperature.
Chapter 2: Screw Speed—The “Throttle” for Controlling Production Output
The screw speed directly determines the extrusion rate and output, but it must work in coordination with other parameters.
- Adjust what? The rotational speed of the main motor.
- How to judge?
1. Excessive rotational speed: The material spends a short time inside the barrel, which may result in insufficient plasticization. At the same time, this can lead to excessively high melt pressure, placing undue stress on the equipment.
2. Too low rotational speed: This results in low output, and the material may degrade due to excessive heating time.
- Adjustment mnemonic: “Pursue stability, not extremes.” The rotational speed should be matched to the set temperature and the desired thickness. When adjusting the thickness, it’s generally advisable to follow the principle of “slightly increase the speed to fine-tune the temperature, and slightly decrease the speed to fine-tune the cooling,” in order to maintain stable material output.
The first Chapter 3: Lip Opening—The “Gate” for Thickness Control
- The die lip is the most critical component in determining the thickness of the sheet, and fine-tuning its opening is essential.
- Adjust what? The gap size of the slit at the die end.
- How to judge?
1. Excessive opening: The discharge is too large, resulting in excessively thick sheets. Moreover, due to the “die swell effect,” the transverse thickness becomes uneven—thicker at the edges and thinner in the middle.
2. Too small an opening: Difficult discharge, low output, and the sheet material is prone to stretching marks with poor surface gloss.
- Adjustment mnemonic: “Fine-tune slowly and observe patiently.” The adjustment range for the lip gap is typically very small—on the order of millimeters—and after each adjustment, you need to wait a while before the sheet thickness stabilizes and changes. The goal is to find the “golden opening” that ensures stable extrusion and uniform sheet thickness.
Chapter 4: Three-Roll Speed and Gap—The “Magic Hands” of Shaping and Glossiness
The three-roll calender is the final stage for shaping sheets and achieving a smooth surface.
- Adjust what? The linear speed of each of the three rollers and the gap between the rollers.
- How to judge?
1. Too Fast or Too Slow Speed: If the speed is too fast compared to the extrusion speed, the sheet will be stretched, leading to increased internal stress and making subsequent thermoforming prone to deformation. If the speed is too slow, it will result in material buildup and wrinkling. Improper Gap: If the gap is too large, the sheet cannot be properly compacted, resulting in poor surface gloss and inaccurate thickness control.
2. If the gap is too small, it may cause the sheet material to be crushed or increase the equipment load.
- Adjustment mnemonic “Slightly faster speed, with gap matching.” Typically, the linear speed of the three-roll system should be slightly higher than the extrusion speed (about 1.05 to 1.10 times faster) to provide adequate traction. The gap, meanwhile, should be precisely adjusted to be slightly smaller than the target sheet thickness.
Chapter 5: Tension Control—The “Invisible Hand” Ensuring Smooth Winding
For sheet materials that require rewinding, the tension control during unwinding and rewinding determines whether the roll is neatly wound and has an appropriate tightness.
- Adjust what? The torque or tension setpoint for the winding motor.
- How to judge?
1. Excessive Tension: If the sheet material is stretched too tightly and wound too firmly, it may not only lead to stretching and deformation of the sheet but also make it difficult—or even impossible—to unwind in subsequent processing steps.
2. Insufficient tension: The winding is loose, the rolled material is uneven, and “chrysanthemum patterns” are prone to appear, affecting transportation and storage; the roll is also likely to collapse when unwound.
- Adjustment mnemonic: “Tapering decreases, flattening comes first.” Advanced winding machines should employ “tapered tension” control—meaning that as the roll diameter increases, the tension gradually decreases, ensuring consistent tightness across both inner and outer layers. The core standard is neat winding with smooth, even edges.
Parameter adjustment is not a rigid, fixed formula—it’s an art of dynamic balance. It requires flexible responses based on variations in raw material batches, ambient temperature and humidity, and product specifications.
The best approach is to keep meticulous records! After each successful production run, document the optimal parameter combination and compile it into a standardized “Process Parameter Card.” This will significantly reduce the time required for future material changes and adjustments, turning high-quality production into a replicable, standard procedure.
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