What is a Good Mechanical Design?

  • The cost vs quality vs requirement dilemma should be uppermost in the minds of anybody in the world of mechanical design as this will dictate success or failure.
  • A good mechanical design may not be practical mechanical design and vice versa.
  • While many mechanical designs work in theory it is imperative that they are tested in practice using prototypes before being released into the marketplace.

good mechanical designWhen it comes to judging a good mechanical design, there is a fine line between resonating with the artistic aspect and assessing the practical one. What can start as an assessment request or a brief advice can easily escalate to a cavalcade of fancy words clashing with engineering terms.

Requirements

This is the immediate and founding argument over judging whether a mechanical design is good or not. It’s a necessary condition and without it the piece shouldn’t even be considered for assessment. Mechanical models don’t pop up to fumble for meaning, their goal should be instilled in them and easy to fulfil, already implemented and with no hindrance. The world is full of products and services which in theory sounded useful but in practice do not have a market – this is taking much need investment from viable products.

Feasibility

Next comes the feasibility issue. While a virtual model may looks fancy on screens and fulfils its requirements, if it’s not a feasible creation then it’s as relevant as a designer’s whimsical ideas cobbled together in their leisure time. Feasibility implies many aspects: manufacturing processes capable of reproducing the model as well as availability of the machinery and materials required. The cost vs quality vs requirement dilemma is also included in the first lines of the checklist. Nowadays, there is also the question of offshore manufacturing, logistics and shipping variables which can impact a final decision about whether the design is feasible or not.

Ergonomics

One of the common mistakes in the design process is creating something for use by humans which is actual difficult to use. As inferred to during the rapid prototyping process, once the model is to hand, the next move is to have the janitor try it for as long and as extensively as it takes. How many items have gone from virtual reality to a physical one only to be bashed by consumers for the lack of firm grip, the harsh contact, the annoying amount of conducted vibrations…etc. Those who design and create a product are not the best people to test it – they will likely find it difficult to be objective. Think about who the product is meant for and undertake testing within that specific environment for REAL feedback.

Checking and replacement

Whether the model is an assembly, or a component of it, the verification step and its repair or removal are often underrated in new technologies. Simple cases where a good mechanical design doesn’t display the weaknesses of bolted assembly thanks to additive manufacturing raises questions over the way inner shapes and tolerances will be assessed or how the inner settings will be monitored in preventive maintenance procedures. It is all good and well creating a must have product but if it cannot be maintained or repaired with relative ease then it will only have a limited life span. A perfect example is the simple changing of a car headlight bulb – why do they make it so difficult, why should you have to remove parts of the engine to complete a relatively simple procedure? Is this not an example of a mechanical design fault or simply a compromise between space and positioning?

Geometric appeal

While taste is a matter of personal preference, geometry resonates with most people. Beauty is in the eye of the beholder and there is a direct link between the design process and geometry. A model that displays symmetry and repetition appeals to a sense of stability – it gives us confidence in a design/product. Smooth surfaces with invisible transitions and aerodynamic lines display elegance. That said, convoluted surfaces are also an option when they answer functional splines although they may be better received if they are are subconsciously similar to constructs from nature.

The Indie side

The subjective part of a design is down to the designer’s personal style, although sometimes it can be difficult to include the designer’s “signature style” while dealing with tight timescales and budgets. However, many brands have common and particular features which set them aside from their peers and their competitors allowing instant recognition when placed in front of potential customers. These common elements instil confidence in certain products and can encourage companies to be a little more creative and daring with future prototypes.

Summary

All in all, the assessment of a design is often very critical and a topic of debate between those valuing the effort and looking for the positive qualities and those searching for the faulty aspects and inviting more improvement. The assessment process is vital and can lead to a product either being confined to the dustbin or introduced to the market with or without adjustments – it is vital that sufficient time is taken to assess feedback and comments and make changes where possible. It is equally as important to realise when even a good mechanical design is just not feasible in the real world, at which point it may be put on the back burner for the future or confined to the theoretical mechanical design bin.

As there is no such thing as a perfect mechanical design, thinking of one’s model as a gem in constant need of polishing until constraints catch up with you is healthy. Being able to quantify the assessment and speak with people equally able to do the same is precious. The point is to be open about one’s designs and able to handle criticism however harsh it can be. At the end of the day, a good mechanical design doesn’t come after six years of being cocooned in one person’s mind with no one’s insight or opinion. Only when a good mechanical design is detached from the umbilical cord of its owner will the “baby” be allowed to grow and develop.

About: Khadija Ouajjani

Since 2012. Mechanical Design Engineer in the aeronautics industry. Mainly dealing with CAD, FEA, simulation and analysis for turbo-engines. Writing for EC since 2014. Garlic, Color Pencils, Open Systems, Coffee, Herbert, Final Fantasy VII, Writing, Tolkien, Mechanics, Deutsch, Nihongo, Herbs, Aïkido, Tea, Cinnamon, Motion, Friends.

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