Squeezability. Part 1: A pressing issue

Abstract

Within the UK it is estimated that by 2020 over half the adult population will be over 50. A society in which the majority are aged poses some interesting questions, not least how that society will use and access goods and services, when the majority are likely to experience some loss of strength and dexterity. One such issue, the openability or accessibility of packaging, is becoming a major issue for brand owners, manufacturers, designers, and engineers due to the rapid ageing of much of the developed world. The authors have previously undertaken a significant amount of work on understanding the openability of vacuum lug closures (jam or sauce jars). This work looked at the forces to keep the system closed, the forces a human could apply and used experimental, numerical, and analytical analysis to understand these systems. Packaging, however, comes in many varied and differing forms and little or no previous work has been undertaken in this field on other forms of packaging such as thin film packets or bottles. The work in this article applies the principles used in the earlier studies to the squeezable bottle pack format. The article describes initial experimental and analytical work undertaken from first principals to establish the factors that contribute to the ease of use along with various laboratory tests carried out in order to determine the design rules for developing bottle styles and nozzle designs, for specific fluid contents. The work suggested several things that may be important for designers and manufacturers of squeezable bottles. Fundamental analysis shows that bottle material and shape generally dominate the squeezeability of and access to bottle contents. Bottle shape was seen to affect performance with the conditioner bottle having the best volume—deflection performance. Work also showed that hole size and Borda length can be calculated to determine specific flow characteristics with a relatively simple set of equations.