THEMOFORMING

Submitted to:Prof. M P Gururajan

Submitted by:

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

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.

Importance of forming temperature

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 kand 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