What is ASTM D790 Testing?
The ASTM D790 test method determines the flexural properties of plastics and electrical insulating materials using a universal testing machine (UTM) and a three-point bend fixture. A rectangular bar specimen is kept horizontally across two supporting pins and loaded vertically by a loading nose. The testing machine then pushes down on the central part of the specimen till it breaks or reaches a maximum strain of 5%. The standard lists two procedures: Procedure A uses a rate of 1% per minute (slower), and Procedure B uses 10% per minute (faster). Flexural properties include Flexural Stress (σf), Flexural Stress for Beams Tested at Large Support Spans (σf), Flexural Strength (σfM), Flexural Offset Yield Strength, Flexural Stress at Break (σfB), Stress at a Given Strain and Flexural Strain (ɛf), Modulus of Elasticity, and Chord Modulus (Ef). These flexural properties are useful for quality control and specification purposes.
What is the Scope of ASTM D790 Testing?
The ASTM D790 (Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials) test method utilizes a universal testing machine (UTM) and a three-point bend fixture (a three-point loading system) to apply a load to the plastic specimen, causing it to bend. The specimen is a simply supported beam. The specimen rests on two supports and is loaded using a loading nose midway between the supports. ASTM D790 test parameters, based on sample thickness, are support span, loading speed, and max deflection. The specimen is first placed on the UTM span, and the loading nose is set at the center, causing three-point bending. The test stops when the sample reaches 5% deflection or breaks before reaching 5%.
- Flexural strength is the maximum stress a material can withstand under a bending load before it breaks.
- Flexural or tangent modulus) is a measure of the material’s stiffness or resistance to bending deformation in the initial linear elastic region.
- Secant and chord modulus are slopes calculated between specific points on the stress-strain curve.
Where to Get ASTM D790 Testing in the USA?
Matestlab offers ASTM D790 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 or B). 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 D790 testing
The ASTM D790 (Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials) standard applies to materials that can undergo three-point bend testing. Test specimens of rectangular cross-section are injection molded or cut from molded or extruded sheets, plates, or other shapes. Specimens must be solid and uniformly rectangular. The specimen rests on two supports and is loaded by means of a loading nose midway between the supports. Equipment precision and technician expertise are critical and non-negotiable.
| 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 D790 test listed on their scope of accreditation? |
| 2 | Fixture Compliance (3-point / 4-point bending) | Incorrect fixtures lead to invalid modulus/strength values | Do you use ASTM D790-compliant flexural fixtures (span-to-depth ratio control)? |
| 3 | Universal Testing Machine (UTM) Capability | Flexural testing requires precise load control and deflection measurement | What is the load capacity, accuracy class, and calibration frequency of your UTM? |
| 4 | Specimen Conditioning | Moisture/temp affect polymer flexural properties significantly | Do you condition samples per ASTM D790 (e.g., 23°C / 50% RH)? |
| 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, film, coated fabric, etc.) will handle it more carefully. | Do you frequently test materials similar to mine (e.g., rigid plastics, elastomers, coated substrates)? |
Prices that Laboratories usually charge
ASTM D790 testing cost depends on the type of sample to be tested, the number of specimens to be tested, sample conditioning, number of frequency and the report. In standard conditions, USA laboratories usually cost 200-400 USD per type of material. More complicated projects can raise the price to 500 USD or higher.
Pricing can also be impacted by rush services and further analysis of data. Other laboratories are also offering reduced prices on large sample submissions or long-term contracts. A request for a detailed quotation, which includes sample quantity, dimensions, and testing method, is useful to prevent any 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 D790 procedures and provides clear, traceable reports. Effective communication and clear pricing build trust and support long-term relationships.
Why You Should Choose Matestlabs for ASTM D790 Testing
We at Matestlab can perform the ASTM D790 test on suitable plastic samples to determine flexural modulus, strength, and other properties. 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.
