Pallet Testing
Pallet designs need to be confirmed as safe whether by software, working to a specific design supplied by a competent authority, or by load testing. European and ISO pallet standards define load testing of pallets as the single method of doing this which is because load testing is as close to real life loading as it is possible to get. This is since load testing does not have to make generalised mathematical assumptions about quality of nails or timber which are often not available to the person inputting data to software. Closer to real life also means that compared with pallet design software, testing usually specifies less timber is required and therefore a more commercial result follows.
ISO block compression test
Good pallet design software can be very close to testing results although nailing is the weak point with some software which does not handle joint strength in a manner that reflects its structural significance. Even the sophisticated building and construction industry with design engineers involved in projects, still places great confidence in testing of 3-dimensional structures. An example is the Thames Flood Barrier where a one-fifth scale model underwent tests to be sure of the strength of the sheet metal steel clad laminated timber pierhead superstructures.
When basic data is required on a new design or an existing packaging product, load testing is invaluable. It can form the basis for a manufacturer’s confidence in marketing or making subsequent deviations to optimise materials, yet still be confident of overall safety. Selected major packaging products need this, anything less and the company may risk a product failure in their product range. There is also no doubt that testing gives sales staff confidence in a product. Some customers require testing evidence, they want a certificate or report, nothing less. If you use load testing be sure of the organisation undertaking it and if you use software be certain of the quality of your inputs.
Turning to the protocols, the most popular in Europe is the well tried pallet load testing standard ISO 8611: 1991: General purpose flat pallets for through transit of goods - Test methods which remains the best analytical tool for users or manufacturers to know exactly how pallets perform under realistic conditions. Full size specimen pallets are required, plus nails of each size used in the pallet. The test acceptance levels are set by ISO TR 10233: 1989: General purpose flat pallets for through transit of goods - Performance requirements.
PalletLink can provide a service offering advice on design change if a product on test proves to be not up to the standard required. We are not in the habit of just producing a ‘pass’ or ‘fail’ report. Testing can be halted while we discuss improvements with the client until the product meets test requirements.
Some labs favour the system of pallet loading using an airbag. This protocol is given in the new draft of ISO 8611 and places a more uniform load on a pallet deck than the current ISO and some feel is more realistic than the steel applicator bar ISO method. However it has been shown to need careful control of several additional variables to maintain a constant result between commercial testing laboratories and this complexity means it is not the better method of the two. Some designs such as the Europallet have their own long established tests such as those operated by EPAL who are responsible for maintaining the quality and maker registration of the Europallet. EPAL also emphasise the importance of fastenings and accredit nail makers.
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21L International Voting - ISO DIS 8611 Parts 1, 2 & 3 - 2007 (PDF 20kb)
21a Pallet load testing to ISO 8611 (PDF 50kb)
21f Every pallet has more than one level of safe working load (PDF 28kb)
21k History of ISO 8611 - Pallet Testing Standard up to 2007 (PDF 24kb)
25b Variables to be provided to assess the SWL of a given design of pallet (PDF 19kb)
52m Mibant, Rockhi, Verus - Wood packaging nail test methods (PDF 56kb)
92a Safety factors (SF) in wood pallets and packaging (PDF 20kb)
94b Marking of pallets with their safe load is not recommended (PDF 18kb)