© M. Reber04/19/23

Functional Descriptions

Documenting Product Specifications

Definition of a Functional Description

An overall description of the function and appearance of the entire mechanism

A description of the function and appearance of each major part of the mechanism

An explanation of how the mechanism operates and how each part contributes to the functioning of the whole

Functional Descriptions focus on physical, quantifiable details

They are often also called a mechanism description or a product specification 2

What Functional Descriptions are NOT

Not typical user instructions or documentation Not comprised of steps or “how to“ instructions

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Uses of Functional Descriptions

To instruct the assembler/repairperson To market a product to prospective buyers To explain a product to an owner

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Functional Descriptions are Organized:

By location (spatially) If you are describing a car for new owners, you might

organize according to location so that your reader will learn about the comforts and conveniences available to them when sitting in the passenger compartment

According to function If you are describing a car for mechanics, you might

organize according to function so the reader can effectively diagnose and correct problems

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Parts of a Functional Description

Title Introduction

Names the object Explains origin of the name Explains its function or behavior Describes its overall appearance Lists its individual parts

Sections for the various parts Drawings and other graphics Conclusion

Explains how it works (NOT how to operate it!)

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Extended Descriptions May Also Include:

A scope statement: Indicates what you will and will not specify and who will have which roles and responsibilities

A definitions section: Establishes the meaning of any specialized terms (both the scope statement and definitions section can be incorporated into the Introduction if they are short enough

A materials section: Specified required materials to be used

An operating characteristics section: Lists operational requirements (such as how much load the product can bear) for design and construction purposes

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To Write a Functional Description:

1. Choose a product requiring description2. Define the purpose, audience, and situation3. Research the mechanism as appropriate 4. Identify the parts and subparts5. Plan the overall description6. Sketch the headings you’ll use7. Select the sources of description8. Plan an introduction9. Consider the format10. Review and revise your draft

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Document All “Sources of Description”

Purpose: How is the item used? What are the applications?

Size: How big or small is it? Can you compare its size to something familiar?

Shape: How is it shaped? Can you compare its shape to something familiar?

Color: What are its colors? Texture, finish: How does it feel to the touch?

How does it look (shiny, dark, etc.)? Dimensions: What are its length, height, width,

depth? 9

“Sources of Description” (cont.)

Weight: How much does it weigh? Materials of construction: What materials were

used to create it—wood, steel, cardboard? Ingredients: If it is something that is mixed,

what are the ingredients? Methods of attachment: How are the different

parts attached—glued, welded, bolted, screwed, nailed?

Location, orientation of parts: What’s the orientation of the parts to each other—above, below, to the left or right, within?

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“Sources of Description” (cont.)

Age: How old is it? Temperature: Is temperature an important

descriptive detail? Moisture content: What’s the percentage of

water content? Amounts: How many are there? Capacity: How much can it hold? Volume: What are the various measurements of

volume related to it?

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“Sources of Description” (cont.)

Smell, odor: What does it smell like? Pattern, design: Does it have a certain pattern

or design associated with it?

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Tips for Writing Functional Descriptions

Be accurate!! (a small discrepancy in measurement might mean an object won’t fit where your reader needs it)

Be specific and concrete (give parts a name, etc.)

Use simple language and analogies to help readers visualize

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Questions to Ask Myself

1. What is my purpose?2. Who is my primary reader and what are his/her

needs?3. How can I learn about the object and its

function? (experimentation, literature)4. What major headings do you plan to use?5. What should my overview contain?

A definition, a purpose statement, general appearance, illustration, a list of components?

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Questions to Ask Myself (cont.)

6. How is the breakdown and description of parts organized? Is the organization logical?

7. Have I thoroughly described each part and broken it into components if necessary?

8. What pictures and graphics effectively explain the object? (Cite your sources.)

9. Do I need a conclusion?

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Your Assignment

Choose an object or simple machine you are already familiar with and have at your disposal. For example: Blender Air popcorn popper Blow dryer Electric razor

Write a description of three to five pages (model specific if possible)

At a minimum, you should have three parts: An overview or introduction section A breakdown into parts with descriptions Conclusion (explains how the object works)

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Tips for Completing Your Assignment

Understand the purpose and the audience Be model-specific Do not do any outside research!!

(graphics excepted) Learn about the object through experimentation Be sure to provide citations for any graphics you

did not create

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