What Is Izod?
The Izod impact test is a test in which the specimen is clamped vertically as a cantilever at one end, while the energy absorbed as the pendulum hammer strikes on the notch side is measured.
Purpose of Izod
The purpose is to determine notch sensitivity and impact strength, especially for thermoplastics, and to compare the effect of formulation and filler.
Which Products Is Izod Applied To?
- Thermoplastic injection-moulded parts
- Reinforced plastics
- Electrical insulating materials
- Automotive plastic components
In Which Sectors Is Izod Used?
Standards Related to Izod
- ISO 180
- ASTM D256
Izod Conditions
- Specimen mounting
- Vertical, cantilevered at one end
- Impact direction
- Directly onto the notched face
- Notch type
- Notch A, B or C in ISO 180
- Environment
- Conditioning at 23 °C ± 2 °C and 50% ± 10 relative humidity
Equipment for Izod
- Izod impact test machine
- Notch-broaching machine
- Conditioning chamber
- Pendulum capacity set
Sample Requirements for Izod
- Typical specimen for ISO 180 is 80 × 10 × 4 mm
- Notch radius and depth must be checked
- Generally at least ten specimens per set (polymers)
- Conditioning is mandatory
Duration of Izod
Testing per specimen is short; conditioning typically takes 24 hours, or the duration defined in the standard.
Izod Procedure
- 1Specimens are cut and the notch is machined.
- 2Conditioning is completed.
- 3The appropriate pendulum capacity is selected.
- 4The specimen is clamped vertically as a cantilever.
- 5The pendulum is released and the absorbed energy is read.
- 6The fracture type (complete, partial, unbroken) is recorded.
Izod Acceptance Criteria
The acceptance criterion is given in the material data sheet or specification as a minimum impact strength (kJ/m²).
Evaluation of Results
The result is given as energy per unit cross-sectional area. Specimens that do not break are noted separately and excluded from the average.
Izod Report
- Applied standard and notch type
- Specimen dimensions and conditioning
- Pendulum capacity
- Impact strength values and the average
- Distribution of fracture type
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Plastic material specifications
Plastics Testing — What Does This Testing Field Cover?
The section below describes the field that the Izod test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.
The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.
Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.
Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.
Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.
The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.
The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.
Method groups in this field
Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.
Commonly confused in this field
- A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
- A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
- HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
- The UL 94 class depends on thickness; a different wall thickness requires re-verification.
- For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
- ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.
Which decisions these results support
- Material selection and supplier approval
- Meeting the flammability and thermal requirements of the product standard
- Verifying the use of recycled content and lot control
- Moulding process control and lot consistency
- Demonstrating ageing resistance for outdoor use
Related Tests
Frequently Asked Questions About Izod
According to which standard is Izod made?
Izod is executed in scope ISO 180 and ASTM D256. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.
Which products does Izod apply to?
Mainly applied to Thermoplastic injection-moulded parts, Reinforced plastics, Electrical insulating materials and Automotive plastic components. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Izod done?
The determining parameters are: Specimen mounting — Vertical, cantilevered at one end, Impact direction — Directly onto the notched face and Notch type — Notch A, B or C in ISO 180. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.
What kind of sample is needed for Izod?
Typical specimen for ISO 180 is 80 × 10 × 4 mm, Notch radius and depth must be checked and Generally at least ten specimens per set (polymers). The number of samples is determined according to the product standard and the scope to be reported.
How long does Izod take?
Testing per specimen is short; conditioning typically takes 24 hours, or the duration defined in the standard. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.
What is the Izod result called "appropriate"?
The acceptance criterion is given in the material data sheet or specification as a minimum impact strength (kJ/m²).