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:
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:
- Fracture toughness evaluation,
- fatigue performance assessment,
- Stress concentration studies
- Hits sample with weighted pendulum
- Measures impact resistance
- Uses notched specimens :
- 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)
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 Durometer is a device used to measure the hardness of materials (especially plastics and rubbers) by testing how resistant they are to indentation.
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
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