HELLO EVERYONE, Dr Bokana is back after his disappearance. It has been a couple of weeks since my last blog and I hope y'all find this blog as interesting as the previous ones. So basically in the previous blog we had completed the sketch of design and everyone was able to see my marvelous UPPER JET. ✈✈ .
Today's blog is basically going to be about Materials for Design (MFD) and Design for Materials (DFM). To be frank, don't these 2 phrases seem like they just jumbled the words around until they made sense? Literally they just swapped the positions of the words and called it a day. However, despite the similarity in the naming they both are effective methods used to aid us in the improvement of our product.
Materials for Design
Lets start off with Materials for Design (MFD), okay lets have a flash back. I was an innocent year one student in Chemical Engineering. I had just completed my Intro to Chemical Engineering (ICHE) module, barely scraping through. In secondary school I was a pure biology student and this lack of even basic physics made me suffer a lot not only did I not know simple formulas I also had no idea what the unit conversion rates were. I was utterly clueless on the topics taught in class. Luckily, the next module was Materials for Design (MFD), from the name itself I assumed that it was easy and being honest with myself it was relatively easy. Like Materials for Design, just choose the material for your design lah aiyo. SO hard meh , need to make it so complicated meh!!! BUT that's not the case obviously. HAISSSS
Basically all we had to do is choose a few suitable materials and compare the characteristics of the materials, after that we chose the material with the best compatibility for our product. It can be broken down to 3 key steps.
- Define the material Requirement (Material Specifications required)
- Selecting possible Candidates (C.O.W.S matrix)
- Choosing the most cost effective option (Cheapest out of the best)
So how do we choose the best product within our limits? We use C.O.W.S matrix as a guideline when choosing, this ensures that there is not biasness when choosing the product. As we all know C.O.W.S stands for
- Criteria
- Options
- Weightage
- Score
For criteria, we just have to note down what are the required characteristics for the product is. For example, cost , density , machinability ( how easy it is to shape ) and melting temperature are important material properties to take note of when choosing our material. We also have to find the accurate values for these criteria from credible sources or even online shops which sell these materials. When choosing a material, it is always important for the cost to be a low as possible while still producing a good product or when when the material is supposed to deal with high temperature, something with a high melting point would be preferred. Writing these criteria down and comparing between options also gives us a clear view of which material fits all our checklist and out of all that fit which material is the best.
Here are some examples of material properties you can take note of when doing your C.O.W.S matrix.
Next, we have the options. When designing the product, we can't only have one option for the choice of material. This restrict any possible improvements for our product. We need to ensure that we have multiple choices to choose from and that there are always other substitute materials we can use for our design. Try to at least list out 3 - 5 materials down to ensure that you get a more broader perspective when choosing your material.
Thirdly we have weightage (usually labelled using percentage), this is the hardest part of the C.O.W.S matrix. You need to reason out why different criteria each have a different level of importance. Sometime, certain criteria are not as important as the rest as the requirements for your products do not require them. For example, the density of the material have to be 1.5 g/ml and 2 of the material that you chose have densities lower than the requirement, we could place the percentage of the weightage to be lower compared to the others. Or if the most important part of the material is that it requires a high melting temperature for our design, the percentage would be higher.
Lastly, we have the score. This part is fairly simple, we just have to rate the products from 1 to 3. 1 being the being the material which least likely meets the requirements and 3 being the most suitable. After that we just have to multiple the score by the weightage of the criteria and add up all these values for the criteria, this product with the highest score is the most desirable material for the product. FYI the score for the materials is up to the person doing the matrix, so it does not have to be from 1 to 3 it can even be from 1 to 5.
Here's an Example of the finalized C.O.W.S Matrix
And as you can tell Aluminum is the clear winner with 360% but we can also see that Copper and Stainless Steel are also suitable substitutes. While Cast Iron is not even close to the scores of the rest.
Next we just have to compare the cost of the products and the production cost by giving he product cost and the manufacturing cost a weightage can comparing between the better options.
In this case stainless steel has both the best product cost and manufacturing cost making it the best options out of all the 4 that we initially compared even though it is not the best scoring one in the C.O.W.S matrix.
Class Activity
I know I have been talking about MFD and C.O.W.S matrix this whole time but time to show you all what my group's matrix looks like. For this MFD, Mr Chua had assigned different products for the groups to do a C.O.W.S matrix. We also told to find our own materials for this matrix and selective the most suitable one.
The product we were given was:
How innovative am I right? ( I'm being sarcastic ) especially during this Covid period. As you can see our product is a face shield and it has 2 main components, clear plastic as the shield and the foam that comes in contact with the face of the user aka a forehead support.
We did the transparent plastic as the first material as it was easier to find, where we compared 4 different materials
- Lexan (Polycarbonate)
- Polypropylene
- Acrylic
- PETG (Glycol - modified polyethylene terephthalate)
The picture above is the data that we collected for us to compare the values between each product, this provides us a summarized table for us to refer to when choosing an appropriate score for each of the criteria for every material.
In the picture above, you can see the 4 different materials we chose to compare. Here are the product specifications we took into consideration before choosing which materials to compare together with the percentages for their weightage and the reasoning behind them. The 5 specifications we used were:
- Transparency
- Low density
- High Flexibility
- Low Cost
Even though the main purpose of this material is to be transparent, as all the material have a have a high light transmittance rate meaning that they are all close to being fully transparent. Causing us to only put 10% as the weightage. While the objective is also to have something light and water proof, therefore we put more importance on density and waterproof by giving them a higher weightage.
Lastly, this the final product after compiling all the information together and give appropriate scores. And the most compatible one was Polypropylene.
For the forehead support we compared 3 different materials
- Polyurethane foam
- Polyethylene foam
- Polyether Foam
I know they sound the same but trust me when I say this, when you see the values below you can tell the difference.
Here is the data for the forehead support.
Our main concern wan the material being light for the user and the it being waterproof. The material has to be waterproof as the user may sweat while using this face shield. And we want to ensure the least amount of discomfort for the user while being light to prevent any strain when wearing the shield.
Lastly we have the final scoring for the forehead support.
As you can tell Polyethylene foam is obviously the clear winner compared to the rest. However, you can see we did not do a comparison on the best cost effective material as there were not statistic on the manufacturing cost for both the transparent material and the forehead support. To make it as accurate as possible we still added the cost of the raw material itself.
Design for Material
From the name itself, what is Design for Material (DFM) ?? Hearing the phrase made me think that my group mate had incorrectly said it but damn not only must we do MFD we must do DFM also meh. Walao eh😠😠.
Moving on, DFM is basically changing the design of the product to suit the material. while MFD is choosing the appropriate material for our product. Confusing RIGHT but this kind hearted Dr. Bokana shall go through an example Mr. Chua went through in class.
Okay so the first thing I noticed when I saw this was, Holy cow what is the world is attached to that lady's hair. END up its just a hair dryer, who would have know that a handheld device in the modern age evolved from that contraption. At that point of time, it genuinely looks like it would be better to just dry your hair using a towel.
This is where we use design for material, we have an amazing idea but the solution that we create is too bonkers. We need to change the design so that it would work better with a different material. The next picture is the second evolution to the hair dryer. (Pokémon reference LOL)
From this adaptation you can see that they made it significantly smaller, and worst part is that they used a metal casing. Imagine the idiocy, the user is asking to get burnt at this point. However, to be frank it is truly a marvelous feat, from that monstrosity to a handheld device. At that point of time, it must have been a miracle. Sadly not only was the airflow slow it was not save to use.
With a few more years passing by, they made a hair dyer with a plastic coating. At least not people wont electrocute themself while tryna dry their hair. But what changes did they make ? Firstly they would have to reduce the temperature of the air flowing and they would have to increase air flow to ensure that the drying is fast. Who would have thought the first version of the air dryer was completely different from this?? From this example it may seem simple, but the fact that they even had an idea like this is astonishing. One thing is for sure, there is no way I would have thought of this.
Class Activity pt.2
This activity was a little bit of both MFD and DFM. We were told to choose a random object and change the material and compare it to the original material used. Next we had to change the design of the product to adapt to the material.
So what product should we start with? My groupmates and I were shooting out ideas after ideas but none of them were even plausible. Then I said, you know what let's just use a random object generator. Might have been the best idea to come out of my mouth. We press the generator 5 times and the object we got was handcuffs. At first we were like OH HELL NO
Then I thought of using wood to substitute metals, it seemed possible but after reading the second part of the activity we changed it to plastic. The concept we used was a zip tie.
Think about it, its literally impossible to break on when your hands are tied right?? Why don't we just make a handcuff out of its material. Zip ties are typically made of the plastic called Nylon 6 - 6.
Nylon 6 - 6 meets all the requirements and the best is that it can be produced very easily and it cheap. It is also extreme light compared to the aluminum used in a conventional handcuff preventing any strain on the hands of the criminals wearing them.
The picture above explains the benefits of using nylon 6 - 6. It is literally so much better and it has a low melting point meaning that molding the shape would not be that difficult as well. The
For the DFM part, why not just use a modified zip tie to enhance the usage of this handcuff right??
And you know what, I just found the perfect example. Not to mention that it is significantly smaller than a regular handcuff and lighter too. Meaning that officers can carry multiple around just incase. However, due to its light frame bigger criminals may be able to break away so this is meant for smaller criminals or for petty crimes. The light weight also means that it can be worn around for longer periods with causing any discomfort. Y'all have to admit this was a genius and simple idea from yours truly
Sustainable Design
Sustainable design, sounds like some environment nonsense right? WOW so smart, why you so smart dei. SYKE of course its about the environment what else would it be about. I know you have heard of the typical the world is dying we need to save it and all that stuff. But I can't deny it, the statistics show that the earth's resources are depleting. Even just a few days ago, the weather was so hot I thot this was the last day. Could you believe it ?, it was 33 degrees at night NIGHT LEH HOW TO SLEEP DEI
Sustainable design it just basically using materials that reduce the damage to the earth, like using waste items as one of the material of your product.
Trying to reduce the impacts on the environment could help us from being extinguished (NOT AN EXARGGERATION). Few principles to consider are:
- Non toxic material
- Longer lasting products
- Can be dismantled easily to be recycled
- Using Energy efficient processes
An example of a sustainable design taught in class by Mr Chua would be a water bottle made using a special polymer
It is safe for the biological cycles, humans, animals & most importantly the environment. This small effort to use a better material prevent extra waste in this world. This is our only home, at least try not to make it into a complete wasteland AM I RIGHT FOLKS??
My group and I actually incorporated this Sustainable Design into our Initial Air Filter model. We already tried to reduce waste by using coconut fiber as our filter but we totally forgot about the casing. Conventionally, the casing of air filters are PLASTIC, but we used the idea from one of our previous practicals by changing the casing to cardboard.
Cardboard is mainly a waste product in the industries, most of the packaging material used are cardboard. Substituting cardboard as our main material could also be good for the environment as it is biodegradable and will decompose. BEST part is that, cardboard is not as flimsy as you think it is. It is fairly stable and strong and yet easy to shape meaning that manufacturing costs would reduce as well.
Thank you for reading my blog my beloved bokanas. Stay tuned for the next one which will be about the weirdest practical I will ever do.
Yours Sincerely,
Dr.Bokana XOXO MUAH
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