ISO/TS 19278:2019

Plastics - Instrumented micro-indentation test for hardness measurement

This document specifies a hardness test method for plastics using instrumented indentation in the micro scale with one clearly defined test condition to ensure reproducibility and comparability of test results. The test method is selectively suitable for use with the following materials: - moulding, extrusion and cast thermoplastic materials; rigid and semi-rigid thermoplastics sheets; - rigid and semi-rigid thermosetting moulding materials; thermosetting sheets. This test method could also be utilized for nanometric filled system, considering the fillers are distributed uniformly in the polymer matrix. This test method allows dumbbell type specimen, strip type specimen, platens and specimen cut from any finished parts or products. This test method is useful for quality control, material selection, and screening of new formulations. NOTE This document does not aim to describe all scientific or technical aspects of microhardness testing on plastics in general.

Plastiques — Essai instrumenté de micro-indentation pour le mesurage de la dureté

General Information

• Status: Published
• Publication Date: 31-Mar-2019
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 2 - Mechanical behavior
• Drafting Committee: ISO/TC 61/SC 2/WG 2 - Hardness and surface properties
• Current Stage: 9093 - International Standard confirmed
• Start Date: 27-Sep-2023
• Completion Date: 13-Dec-2025

Overview

ISO/TS 19278:2019 - Plastics: Instrumented micro‑indentation test for hardness measurement defines a single, reproducible instrumented micro‑indentation method for measuring the hardness of selected plastics. The specification standardizes test conditions (indenter, force, timing, specimen preparation and environment) so results are comparable across laboratories. It is aimed at moulding, extrusion and cast thermoplastics, rigid/semi‑rigid thermosetting materials and sheets, and can be applied to uniformly nanofilled polymer systems.

Key topics and technical requirements

• Test principle: A calibrated Berkovich indenter is forced into the plastic; indentation depth is measured under load and hardness is calculated from the applied force and the contact area derived from indentation depth (see clause 10.1).
• Apparatus:
  • Original Berkovich indenter per ISO 14577‑1 (calibration per ISO 14577‑2).
  • Instrument must record force, displacement and time, compensate for machine compliance and apply the correct indenter area function.
• Loading and timing:
  • Maximum test force: 500 mN.
  • Force application and removal times: 30 s each.
  • Hold at maximum force: 40 s.
  • Force repeatability: ±1.5%; force application time tolerance ±10%.
• Displacement accuracy: Maximum permissible error ±1% of indentation depth when depth > 6 μm.
• Specimen requirements:
  • Thickness: at least 40 × h_max (to avoid substrate effects).
  • Surface roughness Ra ≤ h_max / 20.
  • Parallel, untwisted surfaces; minimum spacing between indentations and from free edges ≥ 4 × indentation diameter (cut edges ≥ 10 mm away).
• Environment & conditioning: Preferred atmospheric conditions 23 ± 2 °C, 50 ± 10% RH (ISO 291).
• Quality assurance: Periodic apparatus checks using control charts and suitable reference materials.

Applications and who uses it

• Quality control in manufacturing of plastic parts and sheets.
• Material selection and specification for product design (comparing formulations and grades).
• R&D and formulation screening, including evaluation of uniformly nanofilled polymers.
• Typical users: materials laboratories, plastics manufacturers, testing labs, R&D teams, and third‑party certification bodies.

Related standards

• ISO 14577‑1 / ISO 14577‑2 (instrumented indentation for materials)
• ISO 291 (conditioning and testing atmospheres)
• ISO 4287 (surface texture)
• ISO 2602, ISO 294 series, ISO 6507 and ISO 2039 (context and complementary hardness methods)

ISO/TS 19278:2019 helps ensure reproducible, comparable microhardness data for plastics - useful for reliable quality assessment, benchmarking and material development.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 19278
First edition
2019-04
Plastics — Instrumented micro-
indentation test for hardness
measurement
Plastiques — Essai instrumenté de micro-indentation pour le
mesurage de la dureté
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 General . 2
5.2 Indenter . . 2
5.3 Displacement measurement device . 3
5.4 Loading unit and force measuring device . 3
5.5 Periodic checks of test apparatus . 3
6 Test specimen . 3
7 Conditioning . 3
8 Procedure. 4
9 Number of test specimens . 5
10 Expression of results . 5
11 Test report . 6
Annex A (informative) Precision statement . 8
Bibliography . 9
Foreword
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2,
Mechanical behaviour.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

Introduction
This document was developed in response to a demand to define an instrumented indentation hardness
test method in the micro scale for quality control of plastics materials and material selection. The test
conditions are defined to ensure reproducibility and comparability of test results.
The Rockwell hardness method (ISO 2039-2) and the ball indentation method (ISO 2039-1) have been
formulated for determining the indentation hardness of plastics. These test methods use different
scales depending on the hardness of the material and it is difficult to compare hardness values of
materials when they are measured on different scales.
The Vickers hardness test method (ISO 6507-1), used for metallic materials, is a method that does not
use different scales. The Vickers hardness is calculated as the ratio of indentation load and the residual
area of contact of the indenter. However, when this method is applied to plastics materials, it is difficult
to measure the residual area of contact of the indenter because the edge of the indentation cannot be
specified.
The instrumented indentation hardness test method (ISO 14577-1) is intended for hardness
measurement in the range from nano-indentation to macro-indentation. In this method, since the
contact area of the indenter is directly determined from the indentation depth, the above-mentioned
problem is solved. It is therefore possible to determine the indentation hardness of the plastic materials.
In this document, in order to avoid errors due to detection of initial contact, a test force that can result in
sufficient indentation depth within the range of micro-indentation is specified. For example, the range
of indentation depth under this condition, which is from 10 μm to 50 μm in the case of the four types of
materials described in this document, also corresponds to the dimension (scale) of the diagonal length
range of 0,020 mm to 1,400 mm specified by the Vickers hardness test method (ISO 6507-1). In this
document, the measurement time of a single condition is specified similarly to the Rockwell hardness
method (ISO 2039-2).
TECHNICAL SPECIFICATION ISO/TS 19278:2019(E)
Plastics — Instrumented micro-indentation test for
hardness measurement
1 Scope
This document specifies a hardness test method for plastics using instrumented indentation in the
micro scale with one clearly defined test condition to ensure reproducibility and comparability of test
results.
The test method is selectively suitable for use with the following materials:
— moulding, extrusion and cast thermoplastic materials; rigid and semi-rigid thermoplastics sheets;
— rigid and semi-rigid thermosetting moulding materials; thermosetting sheets.
This test method could also be utilized for nanometric filled system, considering the fillers are
distributed uniformly in the polymer matrix.
This test method allows dumbbell type specimen, strip type specimen, platens and specimen cut from
any finished parts or products.
This test method is useful for quality control, material selection, and screening of new formulations.
NOTE This document does not aim to describe all scientific or technical aspects of microhardness testing on
plastics in general.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 2602, Statistical interpretation of test results — Estimation of the mean — Confidence interval
ISO 4287, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions
and surface texture parameters
ISO 14577-1, Metallic materials — Instrumented indentation test for hardness and materials parameters —
Part 1: Test method
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Principle
The original Berkovich indenter is forced under a specified load into the surface of the test specimen.
The depth of indentation is measured under load. Indentation hardness H is calculated from F and
IT max
A (see 10.1).
p
5 Apparatus
5.1 General
The testing apparatus comprises of a rigid frame, a stage, a test specimen holder, an indenter, a loading
unit, and a displacement measuring device. The apparatus is required to measure and record the applied
force, the indentation depth, and the time throughout the testing cycle. The apparatus shall have the
capability of compensating for the machine compliance and of utilizing the appropriate indenter area
function in accordance with ISO 14577-1. The general design is as shown in Figure 1.
Key
1 machine frame 5 stage
2 indenter 6 test specimen holder
3 loading unit 7 test specimen
4 displacement measuring device
F test force
Figure 1 — Example of testing apparatus
5.2 Indenter
The testing apparatus shall be equipped with an original Berkovich indenter in accordance with
ISO 14577-1. The indenter should be calibrated according to ISO 14577-2.
2 © ISO 2019 – All rights reserved

ISO/TS 19278
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