design 1 dpt224 topic 3: formulating design problems

DESIGN 1DPT224

Topic 3:Formulating Design Problems

Objectives At the end of this topic, students should be

able to: Define design problems/ needs Develop an objective tree from the design’s

need Identify product anatomy

Design Problems/ Needs Starting point of design projects is the

identification of a client’s need Client’s need is often presented as a

verbal statement A gadget that will attract certain markets:

Ex: Portable MP3 player A product that will perform specific functions

Ex: Battery operated portable screw driver A product that will solve a problem through

new design Ex:

Design Problems/ NeedThere are several characteristics that

differentiate one design problem from another:

Design problems involve improvements to existing product.

Ex: Lower-cost car seat. Our customer, a leading automobile manufacturer,

has contacted our company to lower the total cost of a line passenger seats

that we make for them. What compromises will our customer be willing to make? Cost for comfort? Cost for safety?

Design Problems/ Need Development of a new product, something

that never exist.Ex: Clothes folding machine. The CEO of our company has requested the R&D department to design and manufacture a new automatic clothes folding

machine. For a trial run, only six units to be produced, what manufacturing

processes that would be economical?

Design Problems/ Needs Design problems involve relatively simple, one-piece

products.

Ex: Toothpick or hockey stick. Shaped from a single material.

Design problems involve a very complex products.Ex: Automobile, army tanks and commercial jet airplane. That include thousands of

components made with different materials or manufacturing processes.

Objectives tree Important to clarify the design problems &

objectives Procedures:

1. Prepare a list of design objectives 2. Order the list into sets of higher level and

lower level objectives 3. Draw the tree of objectives, showing the

hierarchical relationships and interconnections

Objectives Tree Objectives:

The desired attributes of a design Example: High Performance

Constraints: Limitation of a design that is acceptable

Example Design a water purifier for Gotham City Build an objective tree

Example Water purifier 1. List of design objectives:

Cost effectiveness Can detect chemical imbalance Fewer repairs Easy to repair when needed Long lasting Affordable Low or no contamination Takes up least possible space Safe for humans Safe for environment Low maintenance Cleans high volume of water Efficient …… ………

Example 2. Order the list into sets/ groups: Safety

Safe for humans Safe for environment

Cost effectiveness Few repairs Easy to repair Affordable Takes least possible space Low maintenance

Example Efficiency

Can detect chemicals Long lasting Low damage Clean high volume of water

Example

fig_03_02

Product Anatomy Product are made of one or more

fundamental components arranged in structure assemblies.

Products anatomy is like structures, (e.g.: like the parts and systems of the human body that work together.)

Product Anatomy

A product is an item that is purchased and used as a unit.

Some products are simple and others are complex depending on the number, type, and function of their components.

Example, the paper clip, canoe paddle, and toothpick are single-component products.

The penlight, bicycle, and toaster oven are somewhat more complex.

The refrigerator, automobile, and commercial jet airplane are very complex.

Table 2 lists a small portion of the many thousands of products manufactured each year.

Product Anatomy Products are composed of components that

include parts and assemblies. A part is a single piece requiring no

assembly, sometimes called piece-part. An assembly is a collection of two or more

parts or subassemblies. A subassembly is an assembly that is

incorporated into another assembly or subassembly.

Product AnatomyProduct

Sub-assembly AStandardPart

Standard part

Special purpose part

Special purposePart

Sub-assembly B 

Special purpose part

Sub-assembly B1

Standard part

Special purpose part

Product Anatomy A standard part is a common interchangeable item,

having standard features, typically mass-produced, used in various applications. Exp.: screw, bolt, nut, washer, rivet, and gasket.

A special-purpose part is a part designed and manufactured for a specific custom application. Exp.: engine housing, control link, access cover, support bracket, and washing-machine tub.

Product Anatomy A standard assembly or subassembly is one that is

commonly sold and used in various applications. Exp.: electric motors, pumps brake calipers, ball bearings, valves, and electric switches. They are sometimes referred to as modules. Companies that use standard components purchased from one or more suppliers are called original equipment manufacturers, or OEMs.

A special-purpose assembly is an assembly that is designed for a specific application. Exp.: a garden tractor transmission that incorporates a custom housing, drive shafts, standard bearings and gears.

Examples of types of components

Product Anatomy Process of categorizing the components of

a product into parts and assemblies is called product-component decomposition.

It is useful during reverse engineering process when design team want to learn about each components of an existing competitive product

Example of decomposition

Figure 1

Decomposition example Looking at the assembly drawing from left to right, we see that the

penlight is an assembly of a cap, bulb, battery, spring, button switch, and case.

The cap is special purpose part made specifically to hold the bulb. The bulb is a subassembly composed of a glass lens, filament, and base.

Since the bulb is mass-produced and made in standard sizes it is a standard subassembly. The spring is a part that is usually purchased as a standard part.

The special-purpose button part acts as a switch by pushing the battery toward the bulb to connect the circuit.

The battery is a standard subassembly including an anode, cathode, electrolyte paste, and plastic cover.

The metal case is a special-purpose part, cylindrical in shape and electrically conducting.

A product component decomposition diagram is shown in Figure 1. Note that the diagramming scheme uses an oval to represent a product and rectangle for a subassembly.

Individual parts are shown as plain text. Also note that solid lines are used to show the hierarchy of the parts and subassemblies.

Figure 6: Product component decomposition diagram of a penlight

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