A Complete Guide to ISO 179 Standaard: Core Principles of Plastic Impact Strength Testing

In the entire chain of research and development, productie, and application of plastic materials, impact strength is a key indicator for measuring material toughness and fracture resistance, which directly determines whether a product can withstand sudden external impact without damage during use. As a core standard formulated by the International Organization for Standardization (ISO), ISO 179 specifically specifies the method for determining the Charpy impact properties of plastics, providing a unified and reliable testing basis for the global plastic industry, and is widely used in automotive, electronics, construction, packaging and many other fields. This article will comprehensively dissect ISO 179 from the dimensions of standard definition, core content, testing details, and application value to help you quickly grasp its core knowledge.

I. Core Definition and Development History of ISO 179 Standaard

ISO 179, fully known as “Plastics — Determination of Charpy impact properties”, is a set of international standards for testing the impact strength of rigid plastics. It is formulated and revised by ISO/TC 61 (Plastics Technical Committee), aiming to quantify the ability of plastic materials to absorb impact energy through a standardized testing process, thereby evaluating the toughness, brittleness and impact reliability of materials.
The standard has undergone several revisions, and the current latest version is ISO 179-1:2023, which replaces the second edition released in 2010 and has made a number of technical optimizations, including adding cyclic test results for unnotched specimens, referencing ISO 16012 standard, improving the clauses related to micrometers and gauges, updating the symbols used in formulas, enz., further improving the accuracy and applicability of the test. ISO 179 is not a single document but consists of multiple parts. Onder hen, the most commonly used are ISO 179-1 (non-instrumented impact strength testing) and ISO 179-2 (instrumented impact strength testing), which provide standardized methods for different testing needs respectively.

II. Scope of Application and Core Testing Principle of ISO 179

(I) Scope of Application
ISO 179 is mainly applicable to various rigid plastic materials, covering a wide range, inbegrepen:
•Rigid thermoplastic molding and extrusion materials (including unfilled, filled and reinforced types) and rigid thermoplastic sheets;
•Rigid thermosetting molding materials (including filled and reinforced types) and rigid thermosetting sheets (including laminates);
•Fiber-reinforced thermosetting and thermoplastic composites (including unidirectional or multidirectional reinforced materials, such as mats, woven fabrics, rovings, enz., and sheets made of prepregs);
•Thermotropic liquid crystal polymers.
It should be noted that notched specimens are usually not applicable to rigid foam materials, long fiber-reinforced composites or thermotropic liquid crystal polymers; unnotched specimens can be used for such materials. Tegelijkertijd, this standard is not applicable to elastomers, flexible plastics and film materials, which have special impact testing standards and specifications. In aanvulling, test specimens can be made into specified sizes by molding, processed from the central part of standard multi-purpose specimens, or processed from finished products and semi-finished products such as moldings, laminates and extruded sheets.
(II) Core Testing Principle
ISO 179 adopts the Charpy impact testing method (Charpy impact method), and its core principle is: place the qualified prepared specimen horizontally on the support of the Charpy impact testing machine to ensure stable support at both ends of the specimen, then release a pendulum with specified energy, allowing the pendulum to impact the specimen once from a specific height. When the pendulum impacts the specimen, part of the energy will be absorbed by the specimen to break it, and the remaining energy will make the pendulum rebound. By accurately measuring the energy difference before and after the pendulum impacts, the impact energy absorbed by the specimen can be obtained, and then the impact strength can be calculated — the higher the absorbed energy, the stronger the impact resistance and toughness of the material; on the contrary, the material is more brittle and the impact resistance is worse.
Compared with ISO 180 (Izod impact testing method), ISO 179 has a wider scope of application and is more suitable for testing materials with interlaminar shear fracture or surface effects affected by environmental factors. The core difference between the two methods can be quickly distinguished by the specimen placement method and stress state: ISO 179 specimens are horizontally simply supported and impacted on one side, which is suitable for evaluating the overall toughness of formed parts; ISO 180 specimens are vertically cantilevered, fixed at one end and impacted at the other end, which focuses more on the local impact resistance of materials.

III. Key Detailed Requirements for ISO 179 Testing

ISO 179 has strict specifications for every link of the test. Any deviation in details may affect the accuracy and comparability of test results. The core detailed requirements are as follows:
(I) Specimen Requirements
Specimens are the basis of the test. ISO 179 has clear regulations on the type, size and preparation process of specimens, and the core requirements are as follows:
1.Specimen type: There are two types: Type A (notched) and Type B (unnotched). Type A notched specimens are mainly used to determine the notched impact strength of materials, which can better reflect the ability of materials to resist notch sensitivity in actual use (actual products often have notches, edges and other weak parts); Type B unnotched specimens are used to determine the unnotched impact strength of materials, which can reflect the overall toughness level of materials.
2.Standard size: The standard size of conventional standard specimens is 80mm×10mm×4mm (length × width × thickness). The thickness can also be 2mm, 3mm and other specifications according to the actual situation of the material, but it must be clearly marked in the test report. Onder hen, the notches of Type A notched specimens are divided into V-type and U-type: the radius of the bottom of the V-type notch is 0.25mm±0.025mm, and the depth of the notch is 2mm±0.1mm; the radius of the bottom of the U-type notch is 1mm±0.1mm, and the depth of the notch is 2mm±0.1mm. The notch size must be calibrated by special instruments to ensure accuracy.
3.Preparation requirements: Specimens shall be processed from representative parts of the material to avoid cracks, scratches or damage to the internal structure of the material during processing; for injection-molded specimens, the demolding and cooling conditions shall be strictly controlled; for sheet cutting specimens, appropriate cutting methods (such as stamping, sawing) shall be selected to avoid the impact of the cutting process on material performance; notches shall be processed by special notch making machines to ensure that the dimensional accuracy, shape and surface roughness of the notches meet the standard requirements.
(II) Test Equipment Requirements
The core test equipment is the Charpy impact testing machine, and its performance must meet the following requirements:
•Pendulum: Pendulums with different energy specifications (such as 1J, 2J, 4J, 5J, enz.) shall be equipped. The pendulum with appropriate energy can be selected according to the expected impact performance of the specimen to ensure that the impact energy of the pendulum can not only break the specimen but also not cause test errors due to excessive energy.
•Measuring device: It shall be equipped with accurate angle measurement and energy measurement systems, which can accurately record the energy change before and after the pendulum impacts. The energy measurement accuracy shall meet the standard requirements to avoid the impact of measurement errors on the test results.
•Support: Used to place specimens. The size and shape of the support shall meet the standard requirements to ensure that the position of the specimen is stable and the support conditions are consistent during the impact, avoiding uneven stress on the specimen due to support deviation.
(III) Test Environment and Procedure Requirements
1. Test Environment
The conventional test environment conditions are: temperature 23℃±2℃, relative humidity 50%±10%; specimens shall be placed in this environment for at least 16 hours to reach environmental equilibrium before testing, ensuring that environmental factors do not affect the impact performance of materials. If there are special requirements, other environmental conditions can be agreed upon by the relevant parties, but the environmental parameters must be clearly stated in the test report.
2. Test Procedure
De ISO 179 test process is standardized and rigorous, and the core steps are as follows:
1.Specimen preparation: Select qualified specimens, check that there are no cracks, scratches, damages and other defects on the surface of the specimens, measure the actual size of the specimens (lengte, breedte, dikte, notch size), and record the relevant data.
2.Environmental equilibrium: Place the specimens in the specified environment for a sufficient time to ensure that the specimens reach equilibrium with the ambient temperature and humidity.
3.Equipment debugging: Adjust the Charpy impact testing machine, select a pendulum with appropriate energy, calibrate the zero point of the testing machine to make the initial position energy of the pendulum zero, and debug the data acquisition system to ensure the normal operation of the equipment.
4.Specimen installation: Correctly place the specimen on the support to ensure stable support at both ends of the specimen. The notch of the notched specimen shall face away from the impact direction of the pendulum to avoid direct force on the notch leading to deviation of test results.
5.Impact test: Release the pendulum, let the pendulum impact the specimen, record the rebound angle or residual energy of the pendulum, and observe the failure form of the specimen (such as complete fracture, partial fracture, crack propagation, enz.).
6.Data processing: Calculate the absorbed energy and impact strength of the specimen according to the energy difference before and after the pendulum impact; test at least 5 specimens in the same group, take the average value as the final test result, and record the abnormal conditions during the test.
(IV) Test Report Requirements
The test report shall be complete and accurate, covering all key information affecting the test results, so as to facilitate subsequent traceability and comparison. The core content includes:
•Standard number and version (zoals ISO 179-1:2023);
•Specimen information (material name, specification, bereidingswijze, specimen type, size, notch type and size);
•Test environment (temperatuur, relatieve vochtigheid, specimen equilibrium time);
•Test equipment information (testing machine model, pendulum energy specification);
•Test data (absorbed energy, impact strength of individual specimens, as well as group average value and standard deviation);
•Description of specimen failure form;
•Test date, tester and relevant remarks (such as abnormal conditions during the test).

IV. Core Application Scenarios and Value of ISO 179

(I) Core Application Scenarios
As the core standard for plastic impact performance testing, ISO 179 has application scenarios throughout the entire process of plastic material R&D, productie, quality control and application selection, mainly including the following aspects:
1.Material R&D stage: It is used to evaluate the impact performance of new plastic materials, optimize material formulas (such as adjusting the proportion of fillers and reinforcing agents), and develop materials that meet specific toughness requirements to meet the application needs of different industries.
2.Production quality control: As a core item of factory delivery inspection, it is used to detect the impact strength of raw materials, semi-finished products and finished products, judge whether the products meet the production standards and quality requirements, and avoid unqualified products flowing into the market.
3.Product application selection: Provide material impact performance data for downstream enterprises (such as automotive, electronics, construction enterprises), help enterprises select appropriate plastic materials according to product use scenarios (such as whether to withstand sudden impact, whether the use environment is complex), and ensure the safety and service life of end products.
4.Quality arbitration and certification: In trade, ISO 179 test results can be used as the basis for quality arbitration between supply and demand parties; tegelijkertijd, many industry product certifications (such as automotive parts certification) also take ISO 179 test as a necessary requirement to ensure that products meet industry specifications.
5.Other scenarios: It can also be used to study the impact of environmental factors (such as temperature, vochtigheid, aging) on plastic impact performance, and carry out material fracture mechanics related tests to provide data support for material improvement.
(II) Core Value
The core value of ISO 179 lies in “unified standards, standardized testing and reliable guarantee”, which is specifically reflected in three aspects:
•Uniformity: It provides a unified testing method and evaluation standard for the global plastic industry, eliminates testing differences between different countries and enterprises, makes test results of different laboratories and batches comparable, and facilitates global trade and technological exchanges.
•Accuracy: By strictly standardizing the details such as specimen preparation, equipment requirements and test procedures, it minimizes test errors, ensures that the test results are true and reliable, and can accurately reflect the actual impact performance of materials.
•Practicality: It covers various rigid plastic materials, adapts to the testing needs of different industries, provides a scientific basis for material R&D, production and selection, promotes the standardized and high-quality development of the plastic industry, and ensures the use safety of end products.

V. Common Misunderstandings and Notes on ISO 179

(I) Common Misunderstandings
1.Misunderstanding 1: Confusing ISO 179 with ISO 180. Both are plastic impact testing standards, but their testing methods and application scenarios are different — ISO 179 is Charpy impact, which is suitable for evaluating the overall toughness of materials; ISO 180 is Izod impact, which is suitable for evaluating the local impact resistance of materials and cannot be used interchangeably at will.
2.Misunderstanding 2: Ignoring the details of specimen preparation. It is considered that as long as the size roughly meets the requirements, but in fact, notch accuracy, specimen surface flatness, processing damage, enz., will seriously affect the test results, leading to failure to accurately reflect material performance.
3.Misunderstanding 3: Not controlling the test environment. Failure to balance the specimen with the environment, or deviation of test temperature and humidity from standard requirements, will lead to changes in material performance, thereby affecting the accuracy of impact strength test results.
4.Misunderstanding 4: Concluding with a single test data. Only testing 1-2 specimens to draw a conclusion on the impact performance of the material ignores the inhomogeneity of the material. The correct approach is to test at least 5 specimens and take the average value as the final result to reduce data deviation.
5.Misunderstanding 5: Considering that ISO 179 is applicable to all plastic materials. In fact, this standard is only applicable to rigid plastics; elastomers, flexible plastics, films and other materials need to adopt other special standards.
(II) Notes
•Calibrate equipment before testing: Regularly calibrate the pendulum energy, angle measurement system and support size of the Charpy impact testing machine to ensure that the equipment meets the standard requirements and avoid the impact of equipment errors on the test results.
•Specimens shall be representative: The selected specimens shall be able to reflect the overall performance of the material, avoid sampling from the edge and defect parts of the material, and ensure that the number of specimens is sufficient to meet the test group requirements specified in the standard.
•Strictly record test conditions: During the test, detailedly record environmental parameters, equipment parameters, specimen information, enz., to facilitate subsequent traceability and data comparison. If the test conditions deviate from the standard, it shall be clearly stated in the report and the impact on the test results shall be analyzed.
•Distinguish the significance of notched and unnotched tests: According to the actual application scenario of the material, select the appropriate specimen type — if there are notches and edges in the product use, notched specimens shall be used for testing; if the product is integrally formed without obvious weak parts, unnotched specimens can be used for testing to ensure that the test results match the actual application scenario.

VI. Samenvatting

As the core international standard for testing the Charpy impact properties of plastics, ISO 179 provides a unified and reliable basis for the evaluation of the impact performance of plastic materials by standardizing testing methods, specimen requirements, equipment requirements, enz., and is an important support for the standardized development of the plastic industry. Its core value lies in helping enterprises accurately grasp material toughness, optimize product quality, and provide scientific reference for downstream application selection, ensuring the use safety of end products.
Whether it is material R&D personnel, production quality inspection personnel, or selection personnel of downstream application enterprises, mastering the core knowledge of ISO 179 can better carry out testing work, avoid common misunderstandings, and ensure the accuracy and practicality of test results. With the increasing application of plastic materials, de ISO 179 standard will continue to be optimized and improved, continuously adapt to the development needs of the industry, and promote the global plastic industry to move towards a higher quality and more standardized direction.

Our product GA-1043 Impact Tester meets this standard.

GA-1043 Impacttester

Test standard
ISO 179、ISO 180、GB/T 1043、GB/T 1843、JB 8761、JB 8762、GB 18743、ISO 9854、ASTM D256

Overzicht
Used to measure the impact strength of hard plastic, reinforced nylon, fiberglass, ceramic, cast stone, plastic electric appliance, insulating material and other non-metallic materials (simple supported beam, cantilever beam).There are two kinds of electronic type and dial type for each type of specification.Electronic type impact testing machine using circular grating Angle measuring technology, in addition to have all the advantages of the pointer dial, can also be digital measurement show that thrust power, impact strength, elevation, Angle, a group of average;It has the function of automatic energy loss correction and can store 10 sets of historical data information.This series of testing machines can be used for pendulum impact test in scientific research institutions, colleges and universities, production inspection offices at all levels and material manufacturers.

Technische specificatie
1.Impact velocity (m/s) :Cantilever beam is 3.5
2.Impact energy (J) : simply supported beam (0.5, 1, 2, 4, 5J 7.5, 15, 25, En (50);
Cantilever beams 1J, 2.75J, 5.5, 11, 22
3, pendulum Angle: 160 °
4.Impact blade radius: R=2mm + 0.5mm
5.Clamping radius: R=1mm + / 0.1mm
6.impact Angle of blade: ° to 30 ° + 1
7.Clamping span of simply supported beam: 40mm, 60mm, 70mm, 95mm
8.Cantilever beam clamp mouth support span: 22mm
9.Weergavemodus: dial indicator or LCD medium/English display (with automatic energy loss correction function and historical data storage)
10.Test type, size, support span (eenheid: mm) :