The sub-committee SC59D “Performance of household and similar electrical laundry appliances” of IEC is in charge for preparing global standards for measuring performance on laundry appliances. The major standard describing the measurement of primary performance measures is IEC 60456 ‘Clothes washing machines for household use – Methods for measuring the performance’. The 5th
ed. published in 2010 has considerable changes compared to the 4th edition from 2003.
This edition includes the following significant technical changes from the previous edition:
Modified test load mass requirement for cases where rated capacity of test machine is not declared. Test load mass determination in case rated capacity is not declared was changed, to remove ambiguity and to encourage declaration.
Introduction of soft water option.
Improved method of loading and folding test load items to better suit vertical axis, horizontal axis and twin tub systems.
Revised and amended reference machine specification reflecting full qualification of new Electrolux Wascator CLS.
New reference programmes for lower temperatures and vertical axis systems. New informative annex comparing reference programmes to typical household programmes. Refined rinsing efficiency method.
Introduction of low power modes “Off” and “Left On” (for assessment of energy consumption).
New annex about uncertainty of measurements.
Additional work was invested to define an alternative rinsing performance measurement which should have a better reproducibility than the present alkalinity method. Work is also under way to define a load calibration procedure which may eliminate, to some extent, the change of the properties of cotton load items during each washing process in which the load is used in testing of a washing machine.
Mechanical action – gentleness of action
Mechanical action is a main parameter in a washing process. This parameter improves, on the positive side, the washing performance, but can cause, on the other side, damage to the textiles. Mechanical action has not been determined as a single parameter in washing processes in today’s IEC 60456 measurement standard.
Mechanical action has a high relevance for consumers and manufacturers of washing machines and, therefore, a comparison of this parameter (especially in relation to the washing performance achieved as measured in IEC 60456) in different washing machines is very important.
“Gentleness of action” defines the mechanical action influence of washing machine parameters on irreversible changes of the textile properties. These changes can be visible or invisible.
Examples of these irreversible changes are: Loss of tensile tear strengths, Surface friction (abrasion, pilling),
Dimensional changes (shrinkage or elongation), Creasing, or
“Structural disorientation”.
Due to the fact that washing programmes cover a wide range of mechanical action (gentle cycles to heavy-duty cotton programmes, single cycles to multiple cycles), three methods for different ranges of mechanical action are described to measure and quantify the influences of the machine parameters by measuring one or several of these irreversible changes:
Thread Removal Method (TRM – preferable for low to medium mechanical action), Dot Removal Method (DRM – preferable for high mechanical action) and
Fraying Method (FM – preferable for medium to high mechanical action).
All three methods are described in document IEC/PAS 62473:2007 “Clothes washing machines for household use - Methods for measuring the mechanical action in household washing machines.” Meanwhile, this document has expired, as, in the IEC, any PAS document may exist only for a
maximum of six years. Nevertheless, it was decided by the IEC 59D committee to include parts of it in the 6th ed. of the IEC 60456 measurement standard.
There is not much experience and no information on measurement uncertainty regarding “gentleness of action”. Nevertheless, it is a complementary measure to the washing performance, as a very long washing time, which is positive to get a better washing performance, may cause increased damage to the textiles.
Hygiene assessment
IEC59D decided to limit its standardisation activities for washing machines to the measurement of the microbial contamination reduction on textiles. SC 59D decided to develop a globally acceptable Publicly Available Specification (PAS) to respond to the increase in consumer complaints regarding odour from washed laundry caused by the presence of microorganisms. This IEC/PAS 62958 Ed.1: “Clothes washing machines for household use – Method for measuring the microbial contamination reduction” was published in 2015.
There is not much experience and no information on measurement uncertainty on the use of PAS 62958. Nevertheless, this measure may be seen as a complementary measure to the washing performance.
Uncertainty reporting
In order to encourage the efficient use of energy and other resources, national governments and regional authorities have issued regulations which mandate the provision of information to consumers regarding the energy and water consumption of household appliances and associated performance characteristics. This information is usually conveyed by labels attached to appliances at the point of sale and also by brochures provided by manufacturers.
Methods for measuring declared values for energy and water consumption and performance characteristics must be of sufficient accuracy to provide confidence to governments, consumers and manufacturers. The accuracy of a test method is expressed in terms of bias and precision. Precision, when evaluating test methods, is expressed in terms of two measurement concepts: repeatability and reproducibility. Therefore, standard procedures are required to determine the repeatability and the reproducibility of test methods developed by the Technical Committee 59 and its subcommittees. Repeatability and reproducibility of a test method must be sufficiently accurate for the determination of values which are declared and for verifying and comparing these values. Uncertainty reporting is essential to ensure measured data are interpreted in a correct way. It is necessary to know the uncertainty with which data can be measured especially when data of measurements are to be compared between laboratories or when normative requirements are set up. Details of this are described in IEC TR 62617 “Home laundry appliances – uncertainty reporting of measurements”.
IEC TR 62617 publishes expanded uncertainty of measured values of IEC 60456 4th Edition for
horizontal drum washing machines (see Table 1.10). Values for IEC 60456 5th Edition have not yet
been published. No round-robin test for EN 60456:2011 was carried out. The values may not be the same as the testing procedure is somehow different from the procedure defined in IEC 60456.
Table 1.10: Expanded uncertainty of measured values of IEC 60456 4th Edition for
horizontal drum washing machines (from IEC TR 62617)
Relative expanded uncertainty of measured value
(k = 2) Wash performance ratio q 4%
Relative expanded uncertainty of measured value (k = 2)
Total energy Wtotal (in kWh) 10% Total water Vtotal (in l) 5% Remaining moisture RM (in %) 5% Programme time (in min)5 6%
Future standardisation activities
In preparation for the 6th edition of IEC 60456, the Technical Sub-Committee IEC SC59D is actually working on many additional issues which may improve the measurement standard, e.g. in terms of consumer relevance (change of cotton load to mixed polyester-cotton load, liquid detergent), coverage and ease of testing. Usually any new IEC standard will be taken over in Europe as a new EN standard. So these modifications may be relevant for Europe as well. However, no new version of IEC60456 is expected to come before 2020.