The ISO 2039-1 Plastics - Hardness determination - Part 1: Ball indentation method, published by the International Organization for Standardization (ISO), describes a method for determining the hardness of plastics and ebonite using a loaded ball indentation tool. The ball indentation hardness determined by this method can provide data for research and development, quality control, and acceptance or rejection according to specifications.
For the purposes of this standard, ball impression hardness is defined as the ratio of the load on the ball impression to the surface area of the impression formed by the ball impression after a specified period of load application. It is expressed in Newtons per square millimeter.
The method consists of forcing a ball onto the surface of a test specimen under a specific load. The depth of the indentation is measured under load. The surface area of the indentation is calculated from its depth. The ball indentation hardness is then calculated from the following relationship: Ball indentation hardness = Applied load / Indentation surface area.
The hardness testing device used in the tests essentially consists of a frame with an adjustable platform equipped with a plate to support the test specimen, an indenter with associated fittings, and a non-impact load application device. This device must also be equipped with a device that measures the penetration depth of the indenter in the range of 0,4 mm with an accuracy of plus/minus 0,005 mm. The frame should not deform by more than 0,05 mm under maximum load; the deformation should be measured along the main axis of the applied force. The indenter should be a hardened and polished steel ball. The ball should show no deformation or damage after the test. The diameter of the ball should be 5,0 mm plus/minus 0,05 mm. A timing device is also used in the tests (with an accuracy of plus/minus 0,1 seconds).
Each test specimen should be a smooth, flat plate or block of sufficient size to minimize edge effects in the test result, e.g., 20 mm x 20 mm. The surfaces of the test specimen should be parallel. A thickness of 4 mm is recommended. The supported surface of the test specimen should not show any deformation after testing.
If testing specimens with a thickness of less than 4 mm, it is possible to stack several specimens on top of each other. However, the hardness values obtained from stacked specimens and from single specimens of the same thickness may differ.
Test samples must be conditioned in one of the standard atmospheres specified in ISO 291 prior to testing.
In short, ISO 2039-1 is an international standard that defines a test method for determining the hardness of plastics and ebonite by measuring the depth of the indentation created by a steel ball under a specific load and duration. This is commonly known as ball indentation hardness (or Rockwell hardness for plastics in some regions). This test is widely used in quality control and material comparison for thermoplastics, thermosets, and hard rubber (ebonite).
This standard is generally applied in the following areas:
Common materials tested include:
The advantages of this method are as follows:
However, the method has some limitations:
The method described in the ISO 2039-1 standard is widely used in evaluating the mechanical properties of plastic materials under load and makes significant contributions to material selection, quality control, and product design processes in various industries.
The primary objective of this standard is to provide a consistent and reliable test technique for measuring the indentation hardness of thermoplastic and thermoset materials using a force applied through a spherical indentation. This hardness measurement reflects a material's resistance to deformation under stress. This method is widely used because plastic hardness is a critical property affecting:
The ISO 2039-1 standard plays a significant role in industry in the following areas:
In conclusion, the ISO 2039-1 standard is a critical standard for characterizing the hardness of plastics using the ball indentation method. By offering a reliable and repeatable approach, it supports material selection, product design, and quality assurance in various sectors, including automotive, aerospace, consumer goods, and electronics. Understanding and implementing this standard contributes to improving product performance, reliability, and safety.
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