The thermoforming process involves the following steps:

Extrusion of sheet 

Place the sheet on a mould

Draw the sheet into the shape of the mould by heat and negative force (vacuum).

Raw Materials
Most thermoplastics are usable. Must be in sheet form.

Tooling
Generally, machined aluminum is used, although poured composites and even wood can be used for short runs.

Cost
Tooling costs are generally low and piece prices are strictly dependent upon the speed of the machinery.

Examples of Application
Covers, displays, blister packaging, trays, drinking cups & food packaging. 

Some of the possible advantages of thermoforming over injection molding include

Large surface-area parts formed on inexpensive molds andmachines, due to low pressure and temperature requirements

Easy formation of very thin-walled parts that are difficult to make by other techniques.

Very high rates of production of thin-walled parts atrelatively low capital investment.

Advantages

Extremely adaptive to customer design needs

Rapid prototyping development

Material and process is optimized for cost effectiveness

High-speed production allows for just-in-time shipments

Flexible tooling design offers a competitive advantage

On-the-fly product enhancements with low additional costs

Visually pleasing appearance

Weight savings for consumer and manufacturer

Wider design scope

Lower tooling costs

No anticorrosion spray necessary

Paintable and colored plastic availability

Fully integrated process with limitless flexibility for small to large product designs

Disadvantages

High initial equipment investment

High startup and running costs possible

Part must be designed for effective molding

Accurate cost prediction for molding job is difficult v