Industry Standards for Passenger Transit, Rail Vehicle Specifications

Materials & Workmanship


Thermoforming Plastic

Thermoforming plastic material is commonly used in the form of a PVC-Acrylic material provided under trade names of Kydex, Royalite, etc. This material is tough, resistant to impact, but remains relatively soft (cuts or scratches with a sharp object), and is not used in areas where it is exposed to high heat.

An alternative construction of the PVC-Acrylic thermoforming material, uses a polyvinyl fluoride (PVF) (AKA Tedlar®) coating which can be printed with a variety of patterns. This material is commonly used for aircraft interiors, is quite durable and easy to clean, however, it is damaged easily with sharp instruments.

 

Standard: ASTM D792 - Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
Purpose: These test methods describe the determination of the specific gravity (relative density) and density of solid plastics in forms such as sheets, rods, tubes, or molded items.
Criteria: Specify standard name, desired specific gravity and tolerance
Usage: ASTM D792, specific gravity XX to XX - (see table below)
Standard: ASTM D785 - Standard Test Method for Rockwell Hardness of Plastics and Electrical Insulating Materials
Purpose: This test method covers two procedures for testing the indention hardness of plastics and related plastic electrical insulating materials by means of the Rockwell hardness tester.
Criteria: Specify standard name, Rockwell scale, desired hardness, and tolerance.
Usage: ASTM D785, Rockwell, R-Scale, Hardness XX to XX - (see table below)
 

Thermoplastic Materials Common Usage Table

Physical Property

Test Method

Performance Requirement Value

Specific Gravity

ASTM D792

1.20 to 1.36

Hardness, Rockwell

ASTM D785

90 to 100, R-Scale

Tensile Strength

ASTM D638

5,500 psi (38 MN/m2) minimum at 73°F (23°C)

Flexural Modulus

ASTM D790

320,000 psi (2206 MN/m2) minimum elasticity at 73°F (23°C)

Flexural Strength

ASTM D790

10,000psi (68,947.6 kPa ) minimum at 73°F (23°C)

Impact Strength

ASTM D256

6.6 foot pounds per inch of notch minimum (at 73°F notched IZOD)

Heat Shrinkage

None

1.5% maximum, 10 minutes @ 380°F (193°C)

Thickness

None

3/32 inch (2.38 mm) minimum

Note: other test procedures listed in the above table, but not shown above, are described in the FRP section.