Problem solving in product design and manufacturing

We often think of designing a new product is a straightforward activity.

When you design something new, from scratch you will find yourself with a bunch of parts that have been manufactured and designed to fit together. You would think because they fit perfectly on the CAD screen they will fit together in reality.

One could not be more wrong.

When designing a new product you have to apply caution as manufacturing processes are not 100% perfect, you will have to take in account different factors that will affect your components fit, form and function:

• Fit
  •  the way the component interacts with each other to fit as an assembly.
• Function
  •  The way the components fit together and function in a way to create a movement or be still but work as intended by the designer.
• Form
  • The shape of each component that is affected by manufacturing processes

Each component will have dimensions to define a shape or a feature, for example a hole, a thread, a groove, each dimension will have a tolerance. A tolerance is a permissible variation in measurement deriving for the nominal dimension.

If we take a very basic example of a tenon and mortise. Where we want to assemble the tenon inside the mortise:

The tenon will have a width and height dimension to which we have to apply a tolerance. For example 10mm±0.2mm which mean the tenon can be 9.8mm or 10.2mm and everything in between.

The same applies to the mortise and if we apply the same dimension as we want them to fit tightly together to remove movement in all direction then you will find an issue where your tenon could be 10.2mm or oversized but still within tolerance and the mortise is 9.8mm or undersize. The result is that neither can fit together due to the interference between the two features.

When this happen on a new product it is an easy problem to solve as the issue is there in front of you. A bigger issue is when a problem occurs even though all the component fitted together but do not function as intended. Quite often the issue lies somewhere within an assembly and finding out how to fix the problem, especially in a complex assembly then you have to apply some basic rules for problem solving.

One way of doing it is using the “5 why”. This technique was invented by the Toyota Motor Company in the 1950’s in Japan. It is easy as it sounds by asking “Why” until you can find the root cause of the issue.

Let’s take a simple example scenario of a car which stop working:

1. Why did the car stop?
   1. The engine overheated causing it to lock.
2. Why did the engine overheat?
   1. There was insufficient lubrication. 
3. Why were there insufficient lubrication?
   1. The oil pump is not circulating enough oil.
4. Why is the pump not circulating enough oil?
   1. Because some debris and dirt block the oil strainer?
5. Why is the oil strainer clogged?
   1. Because the car was not serviced properly, and the filter never been changed.

You get my gist.

Today this method is used in a wide variety of production and manufacturing environment especially in the automotive industry.

The best way to counter act problem solving is to pre-empt at the design stage the possible failure mode that could occur in a product. The Design Failure Mode and Effect Analysis (DFMEA) is the perfect tool and is widely used in automotive, but we do apply it for every component we design be it a oil and gas Pipeline flow measuring device up to simple coffee maker machine.

To find out how we can help you convert your concept to reality, get in touch with our team.