Plastics : Performance Testing and Quality Control

Why is plastic performance testing important:

• Proves product is safe
• Shows product will last
• Reduces customer complaints
• Saves money long term
• Required by customers

Main Test methods used:

• Strength testing (pulling)
• Drop testing (impact)
• Heat testing (melting point)
• Bend testing (flexibility)
• Chemical resistance (exposure)

Tensile Test Explained:

• Pulls plastic until it breaks
• Measures material strength
• Uses dog-bone shaped samples
• Standard: ISO 527-2 measures how plastic specimens behave when pulled until they break.
• Equipment: Universal Testing Machine
• Result: MPa (megapascals) unit of pressure or stress that measures force applied over an area
• Good result: Depends on plastic type

Impact Test Explained:

• Hits sample with weighted pendulum
• Measures impact resistance
• Uses notched specimens : 

           - Impact strength testing (Izod, Charpy tests)
           - Fracture toughness evaluation, 
           - fatigue performance assessment, 
           - Stress concentration studies

• Standard: ISO 179 (Charpy)measures how much energy it takes to break a plastic specimen with a swinging hammer
• Equipment: Impact Testing Machine
• Result: kJ/m² : standard unit for impact strength in plastic testing (energy absorbed per unit area)
• Shows material toughness

Izod is a standardized impact test that measures a material's resistance to impact by striking a notched sample with a pendulum hammer.
Think of it like hitting a partially cut piece of material with a swinging hammer to see how much energy it takes to break it (the notch acts like a controlled weak point)

Melt Flow Test:

• Measures plastic flow rate
• Standard weight and temperature
• Standard: ISO 1133 (explained below)
• Equipment: Melt Flow Indexer (Measure how much melted plastic flows through a die in 10 minutes)
• Result: g/10min
• Shows processing ease
• Key for quality control

ISO 1133 is a standard test method for measuring the Melt Flow Rate (MFR) or Melt Volume Rate (MVR) of plastics, essentially how easily melted plastic flows under standardized conditions.

Heat Deflection Test:

• Bends plastic under heat
• Shows temperature resistance
• Standard: ISO 75 (test method that determines the temperature at which a plastic starts to soften/bend under load).
• Equipment: HDT tester standard is method for Heat Deflection Temperature (HDT) that measures when a plastic specimen bends under load as temperature increases
• Result: Temperature in °C
• Important for hot products
• Tests shape stability

Hardness Test:

• Measures surface hardness
• Uses durometer
• Scale: Shore A or D
• Standard: ISO 868 is method for measuring the hardness of plastics using a durometer
• Equipment: Durometer (hardness tester)
• Simple, fast test
• Numbers 0-100 (higher = harder)

Shore A and Shore D are two scales used to measure the hardness of materials (Scale from 0-100 - softest to hardest -), particularly plastics and rubbers, using a durometer (hardness tester). Shore A is used for softer materials while Shore D is used for harder materials

Durometer is a device used to measure the hardness of materials (especially plastics and rubbers) by testing how resistant they are to indentation.

Think of it like a fancy thumb-pressure tester which has a spring-loaded pin that is pressed into material
and measures how much the material resists the pin. It  gives reading on Shore scale (A or D)

Testing Rules:

• Follow standard methods
• Control room conditions
• Calibrate equipment
• Use proper sample size
• Record all data
• Regular equipment checks
• Train operators well