What is the difference between engineering plastic and speciality plastic?

Customized engineering plastic polyamide

The essential differences between engineering plastics and specialty plastics are:

1. Differences in performance indicators
Engineering plastics: Maintain mechanical properties within the 100-150°C temperature range and can replace metal in carrying structural stresses, typically in nylon gears and polyoxymethylene bearings.
Specialty plastics: Exceed the 150°C temperature limit (e.g., PEEK, which can withstand 260°C) or possess disruptive functions (e.g., self-reinforced liquid crystal plastics, polyimide, which shields against cosmic rays).

2. Different cost drivers
Engineering plastics: Reduce costs through large-scale production (>10,000 tons/year), resulting in prices comparable to metals (e.g., PA66, approximately $3/kg, only 1/10 of stainless steel).
Specialty plastics: Complex monomer synthesis processes (e.g., PEEK requires polycondensation of difluorobenzophenone), resulting in prices comparable to precious metals (>$100/kg). They are used in high-tech applications where cost is of the essence. 

3. Application Scenario Divide
Main Markets for Engineering Plastics:
Automotive oil pans (oil corrosion resistance)
Drone motor brackets (lightweight and shock absorption)
Smart meter gearboxes (2 million start-stop cycles)
Specialty Plastics Exclusive Areas:
Rocket engine nozzle seals (PBI resistant to 2000°C transients)
Artificial bone and joint substrates (PEEK biocompatible)
Chip lithography machine lenses (fluororesin with high UV transmittance)

4. Failure Cost Magnitude
Engineering Plastic Failure: Gear breakage causes production line downtime, resulting in approximately $500,000/day in losses, a commercial risk.
Specialty Plastic Failure: In-orbit aging and deformation of satellite antenna reflectors (PTFE composites) → mission failure resulting in $200 million in losses, escalating to national security concerns.

5. Material Development Orientation
Engineering Plastics: Formula adjustments address industry pain points (e.g., automotive electrification driving the development of flame-retardant PA66).
Specialty Plastics: National strategic R&D driven by national strategy (e.g., the US and Japan monopolize polyphenylene sulfide raw powder for aerospace applications). 

6. Production Control Level
Engineering Plastics: 5% recycled material blending is permitted, with a key dimensional tolerance of ±0.1mm.
Specialty Plastics: Aerospace-grade PEEK production requires a Class 100 cleanroom, with metal impurities <0.1ppm and a molecular weight distribution index ≤1.5.

Iron Rules of Industrial Selection