The 'inclusive engineering' approach: an optimum diameter for ease of opening

Social equality demands a shift in attitude, away from treating older people and people with disabilities as special cases requiring special design solutions, and towards enabling them to have equal access to any product or service through a more inclusive approach to the design of buildings, public spaces and, more recently, products and services. This is not just important for social equality but also for business growth through new products and services and through creating wider potential markets. It is a sad fact of life that as people get older there is a massive decline in their strength and dexterity. Due to the fact that we handle and manipulate so many things throughout our life time, from the tiniest and most dexterous of tasks to heavy manual labour, this decline is very noticeable in our hands. In nearly all the actions that we use our hands for there is some form of grip used in order to hold onto an object before manipulating it. The natural decrease in strength combined with debilitating illness such as arthritis, means that hand grip strength or finger grip strength are very seriously affected. This has a knock on affect of making it much harder to twist things or pinch and pull things. Therefore there is often a measured decrease in torque strength with age caused not so much by a decrease in wrist strength but more often than not by a decrease in grip strength. Consumer packaging is a field in which many people, including young able bodied people, often struggle in relation to openability. Yet it is present in even the most mundane and neccessary of every day tasks such as eating, cleaning teeth, even drinking. Human interation with consumer packaging requires a wide range of hand dexterity and strength and a variety of differing hand actions. This paper looks at just one such set of actions; that used to open bottles and jars. It outlines all the arguments for inclusive design, stressing the importance for both consumers and business. This paper also outlines an engineering design approach for inclusive design that uses real human factors as design limits, resulting in packaging that will be easily opened by all it’s end users without the expensive trial and error approach that has been used up to this point in time. This paper examines the affect of grip strength on the required trorque to open closures and concludes that there is an optimum diameter for ease of opening that will decrease the required strength to open such closures