By Chris Grant, Sales & Marketing Co-ordinator, Mecmesin Limited, Force & Torque Test Solutions, Mecmesin Limited
SubscribeWell-designed packages, or indeed manufactured products in general, must almost inevitably be a compromise between conflicting demands. Few products illustrate this principle better than the single-trip PET beverage bottle.
While being sufficiently stiff to withstand all reasonable product lifecycle demands, no more primary resource material than necessary should be consumed. PET bottles need the ability to sustain significant axial top-load – both on the capping line and during stacking at various stages of the distribution cycle. A number of technical Standards (i.e. ASTM D2659-89 and DIN 55440-1:99) prescribe top-load testing procedures which enable the 'downgauging' of these containers to be optimised.
For a number of years Mecmesin have been configuring their proven range of force measurement equipment to provide a cost-effective and easy-to-use system for this particular application. Our 'Top-Load Tester', based upon a VersaTest motorised test stand, a 1000N Advanced Force Gauge and a specially-designed vented compression plate, has the load capacity and speed range to meet the requirements of the relevant Standards. Data for the load required to initiate container collapse can be downloaded either to a PC or a mini-printer.
However, following the recent launch of two new ranges of force gauges the top-load tester is now based upon Mecmesin's pace-setting new 'AFG-Mark 3' (see illustration).
This is typical of a Mecmesin test system configured from our standard range of products and accessories to meet one particular quality control testing requirement of the packaging industry. Such systems are however sufficiently flexible to be modified to carry out a range of packaging testing applications. Simply by fitting a larger compression plate and adjusting the speed of the test stand, a system for crush testing two-piece aluminium bevcans is available.
Mecmesin force gauges are suitable for tension or compression testing, therefore with another suitable change of fixturing, a tensile system for peel adhesion testing of labels, aluminium foil, clear film or perforated board would in principle be available – although a 1000 newton force gauge might not be considered sufficiently sensitive for some of these applications.
No problem, it is not necessary to buy another force gauge, the Advanced Load Cartridge, could be removed (as illustrated) and replaced with a more sensitive unit, and this AFG used for appropriate tests,
(note that in this illustration the lower fixturing has been removed to show the product.)
With a lower capacity loadcell fitted, further testing applications such as measuring 'press-out' forces of blister packs, and determinining the characteristic open/re-seal/re-use forces of 'snap-cap' closures could be carried out - simply by acquiring a few relatively inexpensive appropriate extra items of fixturing.
However having started with soft drinks, or possibly beer, it might be appropriate to finish up by considering that most demanding of fluids, which has been inspiring innovative packaging design for centuries – wine!
It is, of course, almost impossible for today's consumer to get at a single drop of the stuff without first applying force to a package: pushing a bag-in-box button, tearing or peeling a lined board carton, pulling the ring on a bevcan, twisting a roll-on aluminium cap, perhaps even (perish the thought) piercing a foil seal with a straw – but most people still anticipate gaining access to this product by removing a cylindrical friction closure without needing to apply an unacceptable degree of tensile load …
… a cue, after switching back to a larger capacity loadcell, to illustrate just one more tension testing system.