Product category:
Materials testing equipment
News Release from: Lloyd Instruments | Subject: LFPlus
Edited by the Engineeringtalk Editorial
Team on 01 September 2005
Universal tester turns to packaging
assessment
The 1kN LFPlus single column universal testing machine from Lloyd Instruments can be used to test a wide range of properties of packets for potato crisps to optimise production processes.
The 1kN LFPlus single column universal testing machine from Lloyd Instruments can be used to test a wide range of properties of packets for potato crisps to optimise production processes and to ensure that the product is kept in perfect condition for the consumer Burst strength, opening strength, seam strength, tear and peel are all parameters that can be measured using the LFPlus
This article was originally published on Engineeringtalk on 24 Aug 2001 at 8.00am (UK)
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The instrument can also be used to measure the coefficient of friction on the plastic film used for the crisp packet.
The packet must be strong enough to prevent accidental tearing or bursting and to ensure that there is no ingress of air or moisture, which will adversely affect shelf life.
Peel tests determine how easy it is to open the packet.
Crisp packets must be durable to prevent accidental opening, yet not too difficult to open when required.
The packet must also not tear suddenly on opening.
Seam testing can be carried out on the LFPlus.
Industry standard tests are available for measuring opening strength, seam strength and peel strength, but individual manufacturers often set their own pass and fail tolerances.
The majority of crisp packets are manufactured from polypropylene.
A "pull-to break" test measures the tensile strength of the plastic film, and elongation tests measure the percentage extension of the film, which indicates how much it will stretch before it will break.
Static and kinetic friction measurements can be made on the plastic film using the LFPlus tester fitted with a coefficient of sliding friction fixture.
The coefficient of friction determines how easily the plastic passes over the rollers in the high speed, high volume packaging machines used in the production process.
If the film does not move at the correct speed, the process can get out of synchronisation, leading to slowed production and possible damage and wastage.
The plastic film can be tested to ASTM D1894 (2001), ISO8295 (2004) and TAPPI T549 (2001) standards by holding it on the horizontal bed and exerting a known force using a sled to which is attached a further sample of the same material.
The sled is pulled across the bed either at rates defined by the required standards or at user-selectable speeds.
Friction can be tested both on as-manufactured films and on printed films, since the amount of ink on the film influences the coefficient of friction.
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