Blog Entry 5 (Week 11 + Week 12)

Hey guys its me Eshvin, its been so long since i wrote a blog 😩 and yes i know my blog for the 3D printing and the egg drop challenge is not up yet but all i can say its in progress and it will be up after this week's blog 🤩.

For this week's blog, i will be talking about MATERIALS 👀.

The main aim is to select the best material for a design in terms of different factors which i will be discussing about it.

Materials For Design

Selection of Materials 📝

The aim of the material selection process is to identify one or more materials with properties that satisfy the functional requirements of a product. Even better materials that can optimise performance objectives The “most suitable” material is a trade-off between requirement and numerous constraints.

The following factors are too be accounted for when selecting a material;

Material Properties

The expected level of performance from the material

Material Cost and Availability

Material must be priced appropriately (not cheap but right)

Material must be available (better to have multiple sources)

Processing

Must consider how to make the part, for example: Casting, Machining, Welding

Environment

The effect that the service environment has on the part

The effect the part has on the environment

The effect that processing has on the environment

Now clearly these issues are inter-linked in some fashion. For example, cost is a direct result of how difficult a material is to obtain and to machine and the effect of the environment on the material is clearly related to the material properties.

Two things we should ask ourselves

(What kind of materials can I use?)

Kinds of Materials 1. Metals: Iron; Aluminium; Copper; Magnesium 2. Composites 3. Ceramics: Glass; Semi-conductors; Structural ceramics (SiN, SiC); Refractory Composites 4. Polymers: Rubber; Plastics

(What characteristics does the material possess)

Material Properties

Mechanical Properties

Strength: Yield Strength; Ultimate Tensile Strength; Shear Strength

Ductility

Young’s Modulus

Poisson’s ratio

Hardness

Creep

High or low temperature behaviour

Density

Anisotropy

Fatigue strength

Fracture Toughness

Thermal Properties

Thermal expansion coefficient

Thermal conductivity

Specific heat capacity

Fabrication Properties

Ease of machining

Ease of welding casting

Hardening ability

Formability

Availability

Joining techniques

Environmental Properties

Corrosion properties

Toxic effects

Stages in Material Selection Process

STEP1 Define Material Requirement for the Design

STEP2 Select and evaluate candidate materials (COWS)

STEP3 Choose the most economical material

CA2 Report Part 1

my group was tasked to select suitable materials for the teat and cover of a polycarbonate baby milk bottle.

Function	It is typically used by infants and young children, or if someone cannot (without difficulty) drink from a cup, for feeding oneself or being fed.
Constraints	- wear and tear - lightweight - strong - corrosion resistant
Objectives	Convenient

Cow matrix for Teat

		Option 1	Option 2	Option 3
Criteria	Weightage	Silicone	Latex	Neoprene FDA Nitrile
Safe for consumptious	50%	Excellent Score: 5 5(50%)=250%	Excellent Score: 5 5(50%)=250%	Excellent Score: 5 5(50%)=250%
Flexibility	​30%	Excellent Score: 5 5(30%)=150%	Good Score: 4 4(30%)=120%	Good Score: 4 4(30%)=120%
Wear and Tear	20%	Poor Score: 1 1(20%)=20%	Good Score: 4 4(20%)=80%	Excellent Score: 5 5(20%)=100%
Total	100%	420%	​450%	​ 470%

Choosing the Most Economical Material

		Option 1	Option 2
Criteria	Weightage	Latex	​Neoprene FDA Nitrile
Cost of Material	60%	Cheap Score: 5 5(60%) =300%	Cheap Score: 5 5(60%) =300%
Ease of Fabrication	40%	​Good Score: 4 4(30%) = 120%	Medium Score: 3 3 (30%) = 90%
Total	100%	420%	390%

Based on this, the selected material for the teat is Latex.

Cow matrix for Bottle

		Option 1	Option 2	Option 3
Criteria	Weightage	Borosilicate Glass	Polyethersulfone (PES)	Stainless Steel
Lightweight	35%	​Heavy Score:1 1(35%) = 35%	​Light Score: 5 5(35%) = 175%	​Medium Score: 3 3(30%) = 90%
Strength	30%	​Weak Score: 1 1(30%) = 30%	​Very Strong Score: 5 5(30%) = 150%	​Very Strong Score: 5 5(30%) = 150%
​​Non reactive to milk	35%	​​Non-Toxic Score: 5 5(35%) = 175%	A Little Toxic Score: 4 4(30%) = 120%	​​Non-Toxic Score: 5 5(35%) = 175%
Total	100%	240%	​445%	415%

Choosing the Most Economical Material

		Option 1	Option 2
Criteria	Weightage	​Polyethersulfone (PES)	Stainless Steel
Cost of Material	60%	Expensive Score: 3 3(60%) =180%	Cheap Score: 5 5(60%) =300%
Ease of Fabrication	40%	Medium Score: 3 3 (30%) = 90%	Excellent Score: 5 5(30%) = 150%
Total	100%	270%	450%

Based on this, the selected material for the bottle is stainless steel.

Design of Materials

In many instance, we want to use a certain material for a certain reason and because of that, we make changes and even compromises to the product design to accommodate the materials. These reasons can be cost, aesthetics and environmental sustainability.

For example ,

The blade for knives are usually made of metal. However, ceramic can also be used as the blade of the knives.

Pros of using ceramic knives are;

• very lightweight

• extremely thin, which allows for very thin slices of food

• stays sharp for very long (10 times longer than a similar steel blade.

• The blades are non-porous, preventing bacterial growth.

• The knives will not stain.

• Ceramic knives will not transfer ions from the blade surface; steel knives leave ions (which can result in faster oxidation of some sliced fruits).

Cons of using ceramic knives;

• brittle

• chipping of the blade is common

So should the metal blade of the knife

simply be replaced with ceramic or not?

In summary, there is many factors that we have to take note of such as cost and environmental sustainability before finalising which is the suitable material.

CA2 Report Part 2

for this section of the CA2 report, my group had to choose one material that appeals to us and discuss how this material can be used as a replacement to a material in an existing product without any significant changes in the design and how to enhance the functionality of an existing product through some changes in the design.

Sustainable Design

is the approach to creating products and services that have considered the environmental, social, and economic impacts from the initial phase through to the end of life.

some design considerations are;

• Use non-toxic, sustainably produced, or recycled materials.

• Use energy efficient processes.

• Make product last longer.

• Design for reuse and recycling. (e.g. easy to disassemble)

• Consider product life cycle.

• Shift from personal ownership to shared ownership.

CA2 Report Part 3 What change can be made to my group's design to make it more environmentally sustainable?

That is it for my blog! Really hope that you enjoy reading it and gain some interesting knowledge🤗

Don't you worry, my upcoming blog will be about my journey in 3D printing and the egg drop challenge🤩🤩. STAY TUNEE FOR IT AND HAVE A GREAT ONE!!!!!