Of late CAD software developers have started looking at providing tools and technologies to assist designers in developing sustainable designs. This is definitely a positive development as a Corporate Social Responsibility initiative that could have far reaching consequences for the evolving globally connected societies. If the issues relating to waste generation, energy conservation and efficient resource utilization are addressed at the design stage, downstream issues involving environmental, social and economic considerations are more effectively manageable. But will this lead to profitability?
Before we get into the aspects of mechanical engineering design for sustainable development, let us look at what the implications of small actions towards sustainability mean to this planet. Setting the computer to sleep mode instead of the screen saver mode would
significantly reduce electricity consumption for every user. Imagine the implication when there are millions of users on this planet having their computers go into sleep mode, after say 5 minutes of inactivity! The savings when computed would be astronomical. A default setting of ‘sleep mode in 5 minutes’ by the Operating System designer would save more trees, fossil fuel among other resources in one stroke. The implications are larger than what the mind can perceive.
Returning to our subject of discussion, let us take a look at a simple toggle lever design as shown in the figure. If the design intent is to provide for location and path traversal alone with not much load coming on it, then the designer would be driven in terms of cost
focusing on material selected. If the designer chose Carbon Steel Sheet, for example, a simple analysis of sustainability in terms of environmental impact would be as shown. The component would weight around 1.9 kilograms. If stamping process for sheet metal is employed in manufacturing, the environmental impact assessment (using SustainabilityXpress inside SolidWorks) would be as shown in the figure.
Based on design considerations, if the designer chose alternate material, say plastics, what would the environmental impact be? Now the situation becomes more interesting since cost and sustainability are getting attention at the design stage.
Finding Alternate Plastics for Injection Moulding process
We find that in terms of Environmental impact, Energy Consumption, Product Manufacturing, Water Eutrophication, the indicators are definitely better for the chosen plastic material except for End of Life Considerations under Water Eutrophication. A few more iterations, and we would have all the sustainability considerations addressed and a green design is bound to emerge. Now where does this stand vis-a-vis profitability.
If we look closer at the toggle mechanism its mass has been reduced. Hence its inertia is lesser, pointing to a smaller energy required to move it – a smaller motor required for actuation. Now, that is going to lead to a lower initial cost as well as a lower running cost. That again, is sustainability and profitability without any ambiguity.
Sustainability checklist as given below could be incorporated in the design process:
Raw Materials – Sustainable, Damage Free, Eco- Friendly?
Manufacturing – Energy Intensive, Polluting, Un-healthy?
Packaging – Uses Minimum Materials, Re-cyclable, Eco-friendly ?
Transport – Energy or Resource Intensive?
Use – Uses less water, electricity, consumables and is safe?
Disposal – Re-processible, Recyclable, Bio-degradable, non-polluting?
Finally,let us look at the Goals of Sustainability and its benefits as follows:
|Least amount of material used||Reduced Cost|
|Least amount of energy consumed
(in manufacturing and in use)
|Least amount of resources used to
produce the design
|Eco-friendly||Increased Value / USP|
|Smallest Carbon Footprint||Incalculable Value|
The benefits overwhelmingly point to increased market share and increased profitability, while addressing Corporate Social Responsibility. Consciousness about Sustainability, with focus on design, could not have come a day sooner.