Teaching publicationsMTT 655 Polymer Processing : Calendering: Design and product control Presentation contents Principle of calendering Materials Processing of calendering Products Advantages of calendering process Estimation of output rates and pressure MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala 2 1/2552 Asst.Calendering MTT 655 Polymer Processing. Prof. Ekachai Wimolmala 3 3 . table cloths. internal mixers and extruders) Product: shower curtaining. L/D ratio between 2 to 3. rainwear.5-2. Continuous process Minimum thickness of 0. length (L) and diameter (D) (Rollers speeds 10-200 m/min . Sheet or film form Simple process. Ekachai Wimolmala 4 . tarpaulins. Prof. diameter 0. tyre.5m. floorcovering. 1/2552 Asst.05mm.9m) Adjusted by heating and cooling systems Usually the compound mixture of the polymer and filler and/or additive using other mixers (two roll mill. conveyor belt. waterproofing MTT 655 Polymer Processing. wall covering. length 0. credit cards.Principle of calendering Consists rollers.4-0. 1/2552 Asst.Materials Poly (vinyl chloride). Ekachai Wimolmala 5 . PE. PVC (reason lies on degradation calendering processing has a relatively shorter residence time) Polyethylene. Polypropylene. PP (more used in the sheet and film extrusion) PU Rubber (carcass coating) MTT 655 Polymer Processing. Prof. Prof. 1/2552 Asst.Calendering Machines MTT 655 Polymer Processing. Ekachai Wimolmala 6 . http://tpe-u. Ekachai Wimolmala 7 . Prof.html MTT 655 Polymer Processing.com/tpu/emea/en/processing/special_processes/calendering/Calendering. 1/2552 Asst. 1/2552 Asst.Calendering process I-shape •ชุดลูกรีดไมตองทําหนาที่หลอมเหลวพลาสติก •ทําหนาที่ปรับขนาดความหนาของผลิตภัณฑ •นิยมใชในอุตสาหกรรมพลาสติกในปจจุบัน MTT 655 Polymer Processing. Ekachai Wimolmala 8 8 . Prof. Ekachai Wimolmala 9 9 . Prof. 1/2552 Asst.Calendering process Vertical L-shape •ผลิตภัณฑแผน PVC แบบแข็ง •โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว พลาสติก MTT 655 Polymer Processing. Prof.Calendering process F-shape •ผลิตภัณฑ PVC แบบออน •โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว พลาสติก MTT 655 Polymer Processing. Ekachai Wimolmala 10 10 . 1/2552 Asst. Calendering process Z-shape • ใชในการเคลือบพลาสติกลงบน แผนผาหรือเสนดาย MTT 655 Polymer Processing. 1/2552 Asst. Ekachai Wimolmala 11 11 . Prof. 1/2552 Asst. Polymer Processing. Ekachai Wimolmala 12 .H.PVC Calendering plant D. Morton –Jones. CHAPMAN AND HALL MTT 655 Polymer Processing. Prof. Prof.Factors processing Roller temperature Pressure of roller Gap size Rotating speed of the rollers Viscosity of the polymer MTT 655 Polymer Processing. 1/2552 Asst. Ekachai Wimolmala 13 . Prof.Products MTT 655 Polymer Processing. Ekachai Wimolmala 14 14 . 1/2552 Asst. Prof. Ekachai Wimolmala 15 . 1/2552 Asst.The advantages of calendering Higher output rates Less chance of thermal degradation Much easies to operate Lower machine and maintenance costs MTT 655 Polymer Processing. The disadvantages of calendering Difficult of control thickness Limited only to materials in the rubbery state No other product (pattern sheet and film) Difficult to control processing temperature Premixing and compounding are required MTT 655 Polymer Processing. 1/2552 Asst. Prof. Ekachai Wimolmala 16 . Ekachai Wimolmala 17 . 1/2552 Asst. Prof.Estimation of output rates and Pressure in calendering Control properties of the product Behavior of flow Assumptions - The melt is incompressible The flow between the rollers is isothermal and laminar There is no slip between the rollers and the polymer The size of the rollers is the same The rotating speed of the rollers is the same MTT 655 Polymer Processing. The schematic of flow along the nip in a calender MTT 655 Polymer Processing. 1/2552 Asst. Ekachai Wimolmala 18 . Prof. V = 2πRN Q = HWV Pmax = 16ηvd3 RH0 V = velocity of the sheet Q = total output rate P = maximum pressure R = radius of the rollers (m) N = rotating speed of the roller (rpm) H0 = size of the nip gap H = thickness of the sheet W = width of the sheet (m) d = distance nip gap to sheet (m) MTT 655 Polymer Processing. Prof. Ekachai Wimolmala 19 . 1/2552 Asst. estimate the thickness of the sheet and the maximum pressure developed on the nip of rollers.4 m. The PVC compound has a viscosity of 104 Ns.min-1 Therefore the thickness is: H = Q = 0.25X0.25X20=31.70x31.4 And the maximum pressure is : Pmax = 16ηVd3 = 16x104x(31.001 m WV 0. Roller diameter 50 cm and width 700 cm.m-2 RH0 0.45x10-3 m.Example In PVC sheet manufacture by calendering.-1 The nip gap is 0.45X10-3X60 = 0.m-2 is 0.2 mm.s. Ekachai Wimolmala 20 . The d value is 30 mm. The rotating speed of the rollers is 20 rpm. 1/2552 Asst.0002 MTT 655 Polymer Processing.m-2 . The feed rate of the PVC compound having a viscosity of 104 Ns. Prof.03)3 = 1. Sol The velocity of the sheet is determined by V = 2πRN =2X3.4x60)x(0.63x108 N.14X0. Ekachai Wimolmala 21 . 1/2552 Asst.Thank you MTT 655 Polymer Processing. Prof.