PVC board is also widely used in daily life. Today, Qingdao Sainuo polyethylene wax manufacturer takes you to know some common problems of PVC board.

1. The longitudinal thickness deviation of PVC board is large
(1) The temperature control of the barrel is unstable, which makes the melt flow rate unstable. The temperature of the barrel shall be adjusted to stabilize it.
(2) The instability of screw speed leads to the instability of extrusion quantity. The process parameters of extruder should be adjusted to make extrusion stable.
(3) The rotation speed of three roller calender is unstable, so the rotation speed of three roller calender should be adjusted.
(4)The traction speed is not stable, fast and slow. The traction speed should be adjusted to make it run smoothly.
2. Uneven transverse thickness of PVC board
(1) The mold design is unreasonable and the cross-sectional fabric flow is not uniform, so the mold should be modified to make the die discharge uniform.
(2) The gap adjustment of die lip is unreasonable and uneven. The gap between the two sides should be slightly smaller than that between the two sides.
(3) The three roller gap deviation of three roller calender is large, so the gap between the three rollers should be uniform.
(4) The height selection and processing of three roller are unreasonable. The middle height of roll surface should be changed appropriately.
3. The surface of PVC board is rough and lusterless
(1) The three roller working surface is rough or has sticky material. The three roll working surface shall be cleaned and polished to make the surface meet the smooth requirements.
(2) The roller temperature of calender is low, so the temperature of three rollers should be increased properly.
(3) If the surface of die lip is not smooth, the die lip should be cleaned.
(4) If the filter is broken, a new filter should be replaced.
4. There are transverse lines on the surface of the plate
(1) The uneven mixing of materials results in the fluctuation of extrusion quantity. In order to make the material plasticized well and the extrusion quantity uniform, the mixing material should be changed and the process parameters of extruder should be adjusted.
(2) The barrel temperature fluctuates greatly. Check and adjust the barrel temperature control system to ensure the accuracy of temperature control.
(3) The rotation speed of three rollers is not stable or the roller surface is scratched. The speed of three rollers should be adjusted to make it run smoothly; Replace the injured roller or repair the roller surface.
(4) Traction speed is not stable or traction roller pressure is insufficient. The traction speed and the tension of traction roller should be adjusted to make the plate traction stable.
5. Longitudinal pattern on the surface of plate
(1) The gap opening of die lip is too small. It should be increased appropriately. The opening of die lip is generally equal to or slightly less than the thickness of sheet metal, which is expanded after extrusion and stretched to the required thickness.
(2) The extrusion temperature is low and the melt plasticization is poor. The temperature of fuselage and nose should be increased appropriately.
(3) The towing speed is too fast. It should be slowed down appropriately. The pulling speed should be a little faster than the extrusion speed.
6. Warpage
(1) Calender roller temperature control is improper, especially in the middle and lower roller temperature is too low. The roller temperature should be controlled in a suitable range.
(2) The contact surface between the two ends of the plate and the air is too large, the cooling speed is too fast, and the cooling speed of the thin part of the plate is also fast. When forming, the plate bends to the first cooling part, resulting in internal stress. In order to reduce the internal stress of forming, it should be cooled as evenly as possible to reduce the draft.
7. Bubbles
(1) The raw material is wet and the moisture content exceeds the standard. Materials should be kept low moisture.
(2) The temperature of the fuselage and nose is too high, resulting in material decomposition. The processing temperature should be reduced appropriately.
8. Black or discolored stripes and spots on the surface
(1) The head temperature is too high and the material is overheated and decomposed. The head temperature should be reduced properly.
(2) There is dead angle in the head, and the stagnant material is decomposed. The machine head should be cleaned to eliminate dead angle.
(3) There are impurities blocking in the head, resulting in the decomposition of stagnant material. The machine head should be cleaned to remove impurities.
(4) There are precipitates on the surface of three roller calender. The roller surface should be cleaned to remove volatiles.
9. Surface spot
(1) The temperature of the lower roll of the three roller calender is too high, and the plate adheres to the surface of the roller. The temperature of lower roll should be reduced properly.
(2) The precipitates of liquid additives on the surface of three roller calender make the sheet adhere to the surface of the roller, so the roller surface should be cleaned.
10. Cold spot on the surface
(1) The roller temperature of three roller calender is too low. The roller temperature should be increased appropriately.
(2) There are wax precipitates on the surface of three roller calender. The roll surface should be cleaned.
Qingdao Sainuo Chemical Co.,Ltd. We are manufacturer for PE wax, PP wax, OPE wax, EVA wax, PEMA, EBS,Zinc/Calcium Stearate…. Our products have passed the REACH, ROHS, PAHS, FDA testing.
Sainuo rest assured wax, welcome your inquiry!
Website：https://www.sanowax.com
E-mail：sales@qdsainuo.com
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Adress：Room 2702,Block B, Suning Building, Jingkou Road, Licang District, Qingdao, China