Welcome to the World of Design Viability!

Ever wondered why most paperclips are made of galvanized steel and not solid gold? Or why a prototype might use cardboard instead of high-grade carbon fiber? In this chapter, we are exploring the "business side" of design. We’ll look at how cost and availability are the secret bosses that decide which materials actually make it into a finished product. Don't worry if this seems a bit "maths-heavy" at first—we’ll break it down step-by-step!

1. What is Commercial Viability?

When designers talk about commercial viability, they are basically asking: "Can we make this product, sell it for a profit, and will people actually buy it?"

If a designer chooses a material that is too expensive, the final price of the product will be too high. If the price is too high, customers (stakeholders) won't buy it. If no one buys it, the company goes out of business. This balance is key to a successful design.

The Stakeholder Balance:
• The User: Wants the best quality for the lowest price.
• The Manufacturer: Wants materials that are cheap to buy and easy to process.
• The Environment: Needs materials that are sustainable (which can sometimes cost more!).

Quick Review: Commercial viability means the product makes financial sense to produce and sell.

2. The "A-List": Availability and Stock Forms

You can't build a product if you can't get the materials! Availability refers to how easy it is to buy a material and how quickly it can be delivered (this is called lead time).

Designers usually prefer stock forms. These are standard sizes and shapes that materials are sold in (like 2440mm x 1220mm plywood sheets or standard length metal rods).

Why use stock forms?
• Cheaper: They are mass-produced, so they cost less than custom sizes.
• Easy to get: You can order them from almost any supplier.
• Consistency: You know exactly what size you are getting every time.

Did you know? If a designer chooses a very rare "exotic" hardwood that only grows in one forest, the product's availability is low. If there’s a storm or a trade issue, production stops completely!

Key Takeaway: Choosing materials that are "off-the-shelf" (standard stock forms) keeps costs down and availability high.

3. Calculating Quantities and Costs

As a designer, you need to be a bit of a detective with numbers. You must calculate exactly how much material you need so you don't waste money.

The Math of Making:
To find the cost of your materials, you usually use this simple logic:
\( \text{Total Cost} = \text{Quantity Required} \times \text{Unit Price} \)

Working with Waste:
Rarely can you use 100% of a material. When you cut a circle out of a square piece of sheet metal, the corners are waste. You still had to pay for those corners! Designers use tessellation (fitting shapes together like a puzzle) to reduce waste and save money.

Common Formula Alert!
To calculate the percentage of waste material:
\( \text{Percentage Waste} = \left( \frac{\text{Waste Material}}{\text{Total Material Purchased}} \right) \times 100 \)

Memory Trick: Think of C.A.V.E. to remember why we select materials:
C - Cost (Is it affordable?)
A - Availability (Can I buy it now?)
V - Viability (Will the product succeed?)
E - Environment (Is it sustainable?)

4. How Selection Affects Marketability

Marketability is how "attractive" a product is to a specific market. The materials you choose directly affect this.

Example: A luxury watch made of stainless steel is marketable because it feels heavy and expensive. If you made the same watch out of polypropylene (plastic) to save money, it might lose its "luxury" appeal, even if it tells the time just as well!

Common Mistake to Avoid: Don't just pick the cheapest material! If the material is too cheap, it might break (low durability), which ruins the brand's reputation and costs more in repairs later.

5. Step-by-Step: Selecting a Component

If you are choosing a system component (like a microcontroller or a hinge), follow these steps:
1. Identify the Function: What does it need to do? (e.g., hold a door open).
2. Check Stock Forms: Is there a standard component that fits? (e.g., a standard 50mm butt hinge).
3. Compare Costs: Is the bulk price cheaper if we buy 1,000 instead of 10?
4. Check Lead Times: If we order it today, will it arrive before we start manufacturing?

Key Takeaway: Designers often choose standard components because they have been tested for quality and are much cheaper than making something from scratch.

Final Quick Review Box

• Cost: Includes the price of the material, transport, and the cost of any waste produced.
• Stock Forms: Standard sizes that help keep costs low and ensure availability.
• Tessellation: Arranging shapes to minimize waste and save money.
• Commercial Viability: The ability of a product to be manufactured profitably.
• Lead Time: The time it takes between ordering a material and it arriving at the factory.