What is the ASTM D256 Test?

ASTM D256 is the standard test method for determining the Izod pendulum impact resistance of plastic materials. The force it takes to initiate a fracture and continue the process until the specimen fractures is called the “Izod impact. The test measures the energy required to break a notched specimen held in a cantilevered position, using a weighted pendulum arm. The instrumentation for this test consists of a rigid frame, a swinging hammer, and a calibrated dial or digital sensor to record energy loss. Test results are expressed in J/m or ft-lb/in, which represents the energy absorbed per unit of specimen thickness. This data is important and critical for assessing plastic material toughness and notch sensitivity.

What is the Scope of ASTM D256?

ASTM D256 (Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics) is a standardized method for measuring the Izod pendulum impact resistance of plastics.

ASTM D256 is used for compliance checks to determine whether plastic materials can bounce back from abrupt impact forces without breaking.
ASTM International provides test procedures commonly used to assess the toughness and durability of plastic materials.
Test Method A is a Cantilever Beam Test, and Test Method C is a Cantilever Beam Test for materials with less than 27 J/m (0.5 ft·lbf/in.).
In Test Methods A and C, the notch creates a stress concentration that increases the likelihood of brittle rather than ductile fracture.
Results are reported as energy absorbed per unit specimen width or per unit cross-sectional area under the notch. The test results are used in quality control and materials specification.

Where to Get ASTM D256 Testing in the USA?

Matestlab offers ASTM D256 testing in the USA. We work with a network of accredited partner laboratories across the USA and Canada to fulfill the requirements. After receiving the request, we confirm the material and dimension details of the plastic sample and the required test method (A, B, or C). Once these details are clear, an in-house materials science expert (project SPOC) is assigned to handle the project, create a scope of work (SoW), and get it verified by the client. Based on the SoW, the SPOC identifies the best accredited partner lab to complete the test within the required timeline.

Checklist of what to verify first before selecting a laboratory for ASTM D256 testing

One needs to be careful while selecting a lab for ASTM D256 (Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics). This standard is sensitive to specimen preparation and test setup because it measures how a material behaves under sudden stress, and even minor deviations can lead to significant data error. ‘Notch precision’ in the prepared samples is very important, as the notch is the stress concentrator that ensures the breakage at the correct place. Specimen conditioning, clamping pressure, and alignment are other important factors.

Priority	What to Check	Why It Matters	Key Questions to Ask
1	Accreditation (ISO/IEC 17025)	Ensures the lab meets international competence standards and is experienced.	Is the lab accredited by A2LA, NVLAP, or PRI? Is the specific ASTM D256 test listed on their scope of accreditation? Can you test both methods A and C?
2	Notching Equipment & Precision	The notch is the most critical variable. Poorly cut notches lead to “scattered” and inaccurate data.	Do you use a single-tooth milling cutter? Do you verify the notch radius regularly?
3	Pendulum Capacity Range	Using a pendulum that is too heavy or too light for test samples leads to high measurement error	Does the lab have a range of hammers (e.g., 1J, 2J, 5.5J, 11J) to ensure results fall within 10–85% of the scale?
4	Specimen Conditioning and environmental control	Moisture/temp affect plastic flexural properties significantly. The testing room should be conditioned.	Are the samples prepared per ASTM D618? What are the lab conditions for ASTM D256 testing?
5	Turnaround Time (TAT)	Depending on queue times and conditioning requirements, results can take days or weeks.	What is the current lead time for sample evaluation? How long does the sample prep/conditioning process take?
6	Industry Experience	A lab familiar with your specific material (plastic) will handle it more carefully.	Do you frequently test materials similar to mine (e.g., rigid plastics, other plastics)?

Prices that Laboratories usually charge

ASTM D256 testing cost depends on the sample type, the number of specimens, sample machining and conditioning, the required method, and the report. Under standard conditions, USA laboratories usually charge 250-350 USD for sample machining and 370-500 USD for Method A testing at 23 DegC per material type. More complicated projects can raise the price to 600 USD or higher.

Rush services and further data analysis can also affect pricing. We offer reduced prices on bulk (more than 10 submitted together) submissions or long-term contracts. Requesting a detailed quotation that includes sample quantity, dimensions, and testing method helps prevent unexpected costs.

Tips for Selecting the Appropriate Laboratory

Experience, the ability to customize to your requirements, accreditation level, equipment performance, and technical expertise are crucial to producing reliable outcomes. One needs to consider these attributes when choosing a laboratory, rather than focusing only on price. Manufacturers must ensure the laboratory follows ASTM D256 procedures and provides clear, traceable reports. Effective communication and clear pricing build trust and support long-term relationships.

Why Should One Choose Matestlab for ASTM D256 Testing?

At Matestlab, we offer the ASTM D256 test on plastic samples to determine Izod impact resistance using both methods A and C. We offer reasonable prices for sample machining, if required, and for later testing. We report failure types as: Complete, Hinged, Partial, or Non-break. We can also customize the testing solution per the client’s requirements. We regularly perform this test for industry giants. We offer quick correspondence, fast query resolution, reasonable prices, and quick turnaround times for the client’s convenience.