Choosing between Charpy and Izod testing machines

Written by

Radhika Menon

Technical Content Editor

9 Sep 20269 min read

Impact testing is used to evaluate how a material behaves when subjected to a sudden load. In a charpy izod test, the machine records the energy absorbed as a notched specimen fractures. Although Charpy and Izod testers use the same broad pendulum-impact principle, their specimen orientation, support arrangement, and reporting requirements are different.

Choosing the right impact testing machine therefore starts with the required test method, applicable standard, specimen geometry, and laboratory workflow—not simply the machine name.

Quick answer: how charpy izod test options compare

A Charpy impact tester is generally selected when specimens are supported horizontally between two anvils and struck at the centre. The notch orientation and support arrangement are defined by the applicable test method.

An Izod tester is selected when the specimen is held vertically as a cantilever and struck on the specified side of the exposed section. This configuration is commonly associated with plastics and other materials where the required method specifies vertical clamping.

The decision rule is straightforward:

• Choose a Charpy configuration when your standards, customer specifications, or production tests require supported-beam impact testing.
• Choose an Izod configuration when the required method specifies a vertically clamped cantilever specimen.
• Choose a combined or changeover arrangement only when the laboratory has a documented need to perform both methods and the machine supports the required fixtures, capacities, and reporting functions.

Before requesting quotations, review the relevant standard and confirm the specimen dimensions, notch form, impact energy range, temperature conditions, and reporting requirements.

charpy izod test compared at a glance

The table describes configuration-level differences. Exact machine capacity, fixture design, digital functions, and supported standards must be verified for the proposed model and laboratory procedure.

Compare charpy izod test by the criteria that matter

Fit and use case

The most important difference is how the specimen is positioned before impact.

In a Charpy test, the specimen is supported at both ends, with the pendulum striking the central region. The laboratory must control the support spacing, notch orientation, specimen positioning, and impact direction required by the applicable method.

In an Izod test, the specimen is clamped at one end and struck at the exposed end. The clamping arrangement is therefore central to repeatable testing. Incorrect insertion depth, reversed notch direction, or inadequate fixture alignment can make results unsuitable for comparison.

Consider a materials laboratory serving a steel producer. If its routine work involves impact toughness testing of metallic specimens according to a specified Charpy procedure, a Charpy impact tester with the correct anvils and specimen supports is the logical starting point.

By contrast, a plastics testing laboratory may receive a customer procedure requiring an Izod impact test. In that case, an Izod tester with the appropriate vertical clamp and specimen support is more relevant than a general-purpose pendulum machine.

A laboratory serving several industries should map its current test requests before choosing a configuration. List:

1. The materials tested.
2. The required test methods and standards.
3. The specimen dimensions and notch types.
4. The impact energy range required by the procedures.
5. Whether testing occurs at controlled or reduced temperatures.
6. The data and certificate format expected by customers.

This review can also help separate impact testing from other laboratory requirements. For example, tensile, compression, and flexural work may require a Universal Testing Machine, while hardness measurements require a different instrument and test workflow.

Pendulum capacity and energy range

Pendulum capacity should be matched to the test method and specimen population. A machine that is unsuitable for the expected energy range can create poor measurement resolution, unusable results, or unnecessary operating limitations.

Do not choose capacity only from the largest specimen currently in the laboratory. Review both routine and planned applications. A supplier should understand:

• The material types being tested.
• The expected impact energy.
• The specimen size and notch geometry.
• Whether several pendulum capacities or interchangeable arrangements are needed.
• The resolution and readability required for acceptance decisions.
• Any future test methods included in the laboratory’s scope.

For example, a quality-control department may test a narrow range of production specimens every day, while a central laboratory may handle research materials, incoming inspection, and customer investigations. These applications can lead to different capacity and fixture priorities.

Capacity should also be considered together with calibration and verification. Ask how the machine’s energy indication is checked, what calibration documentation is supplied, and which components require periodic inspection. A laboratory manager should evaluate the complete measurement system rather than the pendulum alone.

A broader laboratory quality system may also include hardness testing equipment and other material testing machines. Keeping the documentation approach consistent across instruments can simplify training, maintenance records, and audit preparation.

Safety enclosure, digital readout, and reporting

Impact testing releases energy suddenly, so guarding is a fundamental purchasing consideration. The enclosure should help protect operators from fractured specimens, moving components, and unintended access during the test.

When comparing quotations, ask the supplier to describe:

• The enclosure and access arrangement.
• How the pendulum is secured during specimen loading.
• How the machine is released and reset.
• Emergency stopping or safe operating provisions, where applicable.
• Routine inspection points for the guard and impact area.
• Cleaning access after specimen fracture.

A digital readout can make routine work easier, but its value depends on what it displays and records. Ask whether the proposed system provides the measurements and test information required by your reporting procedure. Useful questions include:

• Is absorbed energy displayed directly?
• Can the operator identify the selected test method?
• Are specimen identification and test conditions recorded?
• Can results be exported or printed?
• Does the system distinguish between Charpy and Izod configurations?
• Can reports include operator, date, material, specimen, and observation fields?

Digital reporting does not replace correct specimen preparation or fixture alignment. A clear report generated from an incorrectly mounted specimen is still an invalid result.

For laboratories that also perform verification, calibration, or repair work, it may be useful to review laboratory equipment support services alongside the initial machine proposal. Serviceability, documentation, and access to technical assistance can influence the machine’s long-term practicality.

Value and tradeoffs

The lowest purchase price is not necessarily the lowest cost of ownership. A laboratory should compare the time needed for setup, operator training, fixture changes, inspection, calibration, and report preparation.

A single-method Charpy or Izod machine may be the clearest choice when the laboratory performs one procedure repeatedly. It can reduce configuration decisions and simplify operator training.

A combined setup may offer greater flexibility when the laboratory genuinely performs both methods. However, it may involve additional fixtures, changeover procedures, training requirements, and configuration checks. The quotation should state exactly what is included rather than assuming that a machine described as “Charpy and Izod” automatically covers every required method.

For procurement teams, a useful comparison includes:

• Base machine configuration.
• Included pendulum and fixtures.
• Additional arrangements required for the second method.
• Digital display and reporting functions.
• Installation and operator training.
• Calibration documentation.
• Spare and consumable parts.
• Warranty and service coverage.
• Availability of technical support.
• Space, power, and environmental requirements.

If the laboratory expects to expand into temperature-conditioned impact testing or additional materials, state this during the enquiry. It is better to assess future compatibility before purchase than to discover later that a required fixture or procedure is unavailable.

Limitations and deal-breakers

A Charpy configuration is a poor fit when the laboratory’s approved procedure requires a vertically clamped specimen and the machine cannot accept the necessary Izod fixture. Similarly, an Izod tester is unsuitable for a Charpy procedure if it cannot provide the specified supports, orientation, and impact arrangement.

Other deal-breakers include:

• The machine cannot accommodate the required specimen dimensions.
• The available energy range does not suit the test programme.
• The enclosure does not meet the laboratory’s safety expectations.
• The display does not provide the required result information.
• Reports cannot capture essential specimen or test-condition details.
• The supplier cannot clarify calibration and verification arrangements.
• Operators would need to make undocumented fixture modifications.
• The proposed setup does not match the applicable standard.

Do not rely on a catalogue label alone. Send the supplier the actual method, specimen drawing, and reporting template whenever possible. This gives the technical team enough context to recommend a suitable configuration without guessing.

Decision rule for charpy izod test

Use this decision sequence when selecting an impact testing machine:

1. Identify the mandatory test method.
2. Confirm whether the specimen is supported horizontally or clamped vertically.
3. Verify specimen dimensions, notch details, and impact direction.
4. Establish the expected impact energy range.
5. Decide whether the laboratory needs Charpy, Izod, or both.
6. Review enclosure and operator-safety requirements.
7. Confirm digital readout, data storage, and reporting needs.
8. Check calibration, maintenance, and service arrangements.
9. Compare the complete quotation, including fixtures and documentation.
10. Approve the configuration only after the supplier confirms method compatibility.

For a single-method laboratory, select the configuration that directly matches the required procedure. For a multi-purpose laboratory, consider a combined setup only when both methods are part of a realistic testing workload.

When researching suppliers, technical directories such as Vixxar may also help laboratories identify equipment-related resources, but the final machine selection should be based on documented method compatibility and supplier technical confirmation.

Recommended next steps

Before requesting quotations for a Charpy impact tester, Izod tester, or combined impact testing machine, prepare a short technical brief containing:

• Material types and applications.
• Required Charpy or Izod method.
• Applicable standard or customer specification.
• Specimen dimensions and notch details.
• Expected energy range.
• Testing temperature requirements, if applicable.
• Required number of tests per day or week.
• Safety and installation constraints.
• Digital reporting and data-export expectations.
• Calibration, training, and service requirements.

A clear brief allows suppliers to compare the correct configuration rather than making assumptions from the phrase “charpy izod test.” It also gives procurement and laboratory teams a consistent basis for evaluating quotations from Akuracy and other equipment providers.

About the author

Radhika Menon

Technical Content Editor

Radhika writes about material testing and laboratory equipment from a practical quality-control perspective, with experience reviewing specifications, calibration requirements, and application notes for Indian manufacturers. Her work covers universal testing machines, hardness testers, impact testing, balancing equipment, and related support services. She focuses on rated capacity, applicable standards such as IS 1608 Grade 1, genuine load cells and grips, repair response, and operator training. Her articles are structured for procurement and laboratory teams that need clear technical evidence before selecting or maintaining equipment.

Material testing equipmentHardness testing standardsCalibration and complianceLaboratory equipment procurementMachine maintenance and repair