Transcript THEMOFORMING

THEMOFORMING
Submitted to:
Submitted by:
Prof. M P Gururajan
Dinesh Kumar Verma
(2008AMD2931)
Department of Applied Mechanics
IIT Delhi
Contents:
•Introduction
•Processes
•Advantage
•Types of material
•Applications
•References
“Thermoforming is the process of heating a thermoplastic sheet to its
softening temperature, then force the rubbery sheet against mold by
vacuum or pressure. The sheet is then allow to cool so that it take the mold
shape.”
Infrared heating elements are used for heating sheets.
Infrared pyrometer is used to measure the temperature.
A vacuum of 4.6 KPa is developed.
Vacuum Forming
Pressure Forming
Mechanical Forming
Importance of forming temperature
Advantages
 Large surface area parts can be formed at low temperature and
pressure.
 Easy formation of thin walled parts that are difficult in other methods.
 For thin walled parts high rate of production at low capital investments.
Heat requirement calculation:
Heat Requirement= length X Width X Thickness X Density X ( specific heat
X Temp. Difference + Heat of fusion)
Heat required for 0.0254cm thick polyethylene sheet (specific heat of 2.3 kJ/kg k
and heat of fusion 76.75kJ/kg) having width of 106.68 cm and sheet speed of
0.508 m/sec from 210C to 1760C will be
Heat Requirement= 55 kW
Type of material for which Thermoforming is used
ABS
Polyvinylchloride (PVC)
Polycarbonate (PC)
Polyethylene (PE)
Low Density Polyethylene (LDPE)
High Density Polyethylene (HDPE)
Polypropylene (PP)
Polystyrene (PS)
Polyphenylene Oxide (PPO)
Polyphenylene Ether (PPE)
Polymethyl-Methacrylate (PPMA)
Acrylic
Closed Cell Foam
Polyester (PBT, PET)
Polyester Copelymer (PETG)
Thermoplastic Olefin (TPO)
Thermoplastic Elastomer (TPE)
Thermoplastic Rubber (TPR)
Industrial applications:
Aerospace : Interior trim panels, covers, cowlings.
Medical:
Radiotherapy masks, pressure masks, medical devices.
Computer: Transparent keyboard cover, enclosures.
Automotive: Wheel covers, storage racks, door interior, housings.
Packaging: Trays, cosmetic cases, food containers.
References:
• www.stat-rite.com/Guides/stat-tfg.pdf
•www.Nationmaster.com/encyclopedia/thermoforming
•www.custompartnet.com/wu/thermoforming
•http://en.wikipedia.org/wiki/Thermoforming
•http://books.google.co.in/books?id=ESuVudu6h_YC&printsec=
frontcover&dq=thermoforming#PPA2,M1
THANK YOU