Date post: | 30-Mar-2015 |
Category: |
Documents |
Upload: | nileshdere19 |
View: | 935 times |
Download: | 25 times |
Teaching publicationsTeaching publications
MTT 655 Polymer ProcessingMTT 655 Polymer Processing
: : Calendering: Design and product controlCalendering: Design and product control
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
2
Presentation contents
Principle of calenderingMaterialsProcessing of calenderingProductsAdvantages of calendering process Estimation of output rates and pressure
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
3
CalenderingCalendering
3
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
4
Principle of calendering
Consists rollers, Sheet or film formSimple process, Continuous processMinimum thickness of 0.05mm.L/D ratio between 2 to 3; length (L) and diameter (D)(Rollers speeds 10-200 m/min , length 0.5-2.5m, diameter 0.4-0.9m)
Adjusted by heating and cooling systemsUsually the compound mixture of the polymer and filler and/or additive using other mixers (two roll mill, internal mixers and extruders)
Product: shower curtaining, tarpaulins, table cloths, wall covering, rainwear, credit cards, conveyor belt, floorcovering, tyre, waterproofing
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
5
Materials
Poly (vinyl chloride); PVC(reason lies on degradation calendering processing has a relatively shorter residence time)
Polyethylene; PE, Polypropylene; PP(more used in the sheet and film extrusion)
PURubber (carcass coating)
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
6
Calendering MachinesCalendering Machines
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
7
http://tpe-u.com/tpu/emea/en/processing/special_processes/calendering/Calendering.html
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
8
CalenderingCalendering processprocess
I-shape
•ชุดลูกรีดไมตองทําหนาที่หลอมเหลวพลาสติก
•ทําหนาที่ปรบัขนาดความหนาของผลิตภัณฑ
•นิยมใชในอุตสาหกรรมพลาสติกในปจจุบัน
8
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
9
CalenderingCalendering processprocess
Vertical L-shape
•ผลิตภัณฑแผน PVC แบบแข็ง
•โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว
พลาสติก
9
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
10
Calendering processCalendering process
F-shape
•ผลิตภัณฑ PVC แบบออน
•โดยใชลูกรีด 2 ลูกแรกเปนตัวหลอมเหลว
พลาสติก
10
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
11
Calendering processCalendering process
Z-shape
• ใชในการเคลอืบพลาสติกลงบน แผนผาหรอืเสนดาย
11
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
12
PVC Calendering plant
D.H. Morton –Jones, Polymer Processing, CHAPMAN AND HALL
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
13
Factors processing
Roller temperaturePressure of rollerGap sizeRotating speed of the rollersViscosity of the polymer
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
14
ProductsProducts
14
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
15
The advantages of calendering
Higher output ratesLess chance of thermal degradationMuch easies to operateLower machine and maintenance costs
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
16
The disadvantages of calendering
Difficult of control thicknessLimited only to materials in the rubbery stateNo other product (pattern sheet and film) Difficult to control processing temperaturePremixing and compounding are required
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
17
Estimation of output rates and Pressure in calendering
Control properties of the productBehavior 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; 1/2552 Asst. Prof. Ekachai Wimolmala
18
The schematic of flow along the nip in a calender
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
19
V = 2πRN
Q = HWV
Pmax = 16ηvd3
RH0
V = velocity of the sheetQ = total output rate P = maximum pressureR = radius of the rollers (m)N = rotating speed of the roller (rpm) H0 = size of the nip gapH = thickness of the sheetW = width of the sheet (m)d = distance nip gap to sheet (m)
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
20
ExampleIn PVC sheet manufacture by calendering, estimate the thickness of the sheet and the maximum pressure developed on the nip of rollers. Roller diameter 50 cm and width 700 cm. The rotating speed of the rollers is 20 rpm. The feed rate of the PVC compound having a viscosity of 104 Ns.m-2
is 0.45x10-3 m.s.-1 The nip gap is 0.2 mm. The PVC compound has a viscosity of 104 Ns.m-2 . The d value is 30 mm.
SolThe velocity of the sheet is determined byV = 2πRN =2X3.14X0.25X20=31.4 m.min-1
Therefore the thickness is:H = Q = 0.45X10-3X60 = 0.001 m
WV 0.70x31.4And the maximum pressure is :Pmax = 16ηVd3 = 16x104x(31.4x60)x(0.03)3 = 1.63x108 N.m-2
RH0 0.25X0.0002
MTT 655 Polymer Processing; 1/2552 Asst. Prof. Ekachai Wimolmala
21
Thank youThank you