Finding the best solution: Pre-engineering for beginners
Preliminary research using morphological analysis and Pugh Matrix
For larger and/or more complex projects that we do, we look at various solutions and possibilities during the pre-engineering phase. We want to make sure that we find and implement the best possible solution for our customer. Setting up a morphological analysis and Pugh Matrix can be part of this phase.
These methods allow us to explain and compare various solutions. The methods are applicable at all scales. Not only complete production lines but also individual parts and functionalities can be developed this way.
We are happy to share with you how we go about this with our tutorial for beginners. Try it yourself!
Generating ideas with a morphological analysis
A morphological analysis is a method to capture and elaborate different solutions to a problem. It takes the following steps:
- Describe the problem
Sum up what the current situation is, what it is not (what is missing) and what the desired situation is. This helps to gain an overview of the required functions of the solution.
- Determine the dimension or functions of the solution
You now determine the different dimensions of the solution based on the described situation. In mechanical engineering, this often concerns functions of a possible solution. Think of the various process steps that the solution must be able to carry out, also including issues such safety and control. You put functions in the first column of the overview, take a new row for each function.
- Set up the morphological analysis
List all possible solutions for each functions in the column next to it. Creativity and open-mindedness are key here. The following applies to a morphological analysis: the output is only as good as the input! Taking earlier, or later, functions into account is not necessary yet and has a restrictive effect.
Preferably you have 2 to 8 solutions per function to keep the evaluation of the solutions manageable. Are there more possible solutions? Perhaps the concerning function can be divided into multiple functions or steps.
- Review the possible solutions
Lines are now drawn from the first function possibilities to each underlying possibility IF this combination is consistent and effective. This creates different end solutions. Choose the most obvious and/or diverse solutions. These solutions are then weighted in a Pugh Matrix.
In the example below, a morphological analysis has been done for automating the loading and unloading of a machine. The products are supplied on trays and must disposed in the same trays again. In addition, there is a need for an internal quality control of the process.
Scoring solutions in a Pugh Matrix
In a Pugh Matrix, different scenarios and solutions are compared and assessed on different criteria.
This method was developed and named after Stuart Pugh (1929-1993). As a professor of engineering he developed the Total Design principle of which the Pugh Matrix is part.
At first glance, a completed Pugh Matrix can appear impressive. Our engineers like to use images in their matrices to visualise and clarify the solution. The rows are assigned to the different criteria the solution must meet. The different solutions are then listed in the columns.
This is how a Pugh Matrix is set up:
- Fill in the possible solutions that emerged from the morphological analysis
Assign each column to a solution, the criteria they have to meet will appear in the rows later.
- Determine the criteria the solution has to meet
The various criteria on which a solution in machine building projects is assessed can (often) roughly be divided into the following categories:
- Product / function quality
- Required resources (money, sustainability, square metres, maintenance, FTE’s, et cetera)
- Complexity of the process
When developing the criteria, it is important to determine how detailed the comparison should be. With more detailed criteria, more time and money will have to go into the preliminary investigation. Often, it is sufficient to list 10-20 criteria. But matrices with 50-100+ criteria are also not uncommon. Depending on the number of criteria, the following two steps have to be specified more precisely as well.
3. Give a weighting factor to each criterion
You can use the Kesselring method to determine the weighting factors. Within this method you compare each criterion with every other criterion and decide which of the two has more weight. The most important criterion get a 1, the other a 0. Ultimately, this creates a score for each criterion. This can be used as the weighting factor.
4. Score each solution on the criteria
We usually take a scale of 1-5 for this, in which everything is compared to a baseline (=3). Score 1 = much worse, and 5 = much better. The results are therefore not an absolute science but indicate a trend. For an experienced engineer, assigning the scores is mainly based on their gut feeling and logical thinking.
The baseline can be either the current situation or one of the possible solutions. This can be decided per project.
- Bekijk welke oplossingen het hoogste scoort aan de hand van de totaalscore
Door de deelscores (score*wegingsfactor) bij elkaar op te tellen kom je tot een totaalscore per oplossingsmogelijkheid. De oplossing met de hoogste score komt als beste uit de bus.
You finished pre-engineering, now what?
Now that it is clear what the best solution is on paper, you can further develop this concept. The advantage of pre-engineering is that you can justify to others what the choice for a solution was based on. Moreover, it is easier to turn to other alternative solutions if the solution turns out not to be feasible in the end.
Do you have a technical challenge or automation issue? We at STT Products are happy to look into it and think along with you. We have been helping manufacturing companies with smart technical solutions for over 35 years. You can also come to us for stand-alone pre-engineering projects. Contact us for the possibilities.