QUALITY FUNCTION DEPLOYMENT (QFD)
QFD ELEMENTS
PRELIMINARY CUSTOMER REQUIREMENTS LIST
Ease of use
Can’t require too much physical strength
Must be durable
Not break after dropping
Not break after drilling
Drill must last long time
Usable in variety of situations
Multiple tool bits
Multiple gear ratios
Drill different materials
Do stuff other than drilling
Aesthetics
Ergonomics-comfortable to touch
Comfortable to use
Completes work quickly
Doesn’t damage workpiece
Allows better control than power drill
Portable
Safe
Cheap
Easy maintenance
Reliable
10 MOST IMPORTANT CUSTOMER REQUIREMENTS
Easy to use
Easy to maintain
Affordable
Durable
Reliable
Portable
Safe
Drills a variety of materials
Fits a variety of tool bits
Aesthetics
QUANTIFIABLE DESIGN REQUIREMENTS
Time to change tool bit (s)
Points of contact with user’s body
Disassembly time (s)
Price of a set of replacement gears ($)
Retail price ($)
Ability to sustain 30 lbf applied to crank
Weight (lb)
Volume (in^3)
Surface area (in^2)
Handle length (in)
Number of gear ratios
Number of different colors
Ability to sustain fall from 7 ft
Angle of wrist (degrees)
Roughness of handle material (microinches)
Handle diameter (in)
MOST SIGNIFICANT DESIGN REQUIREMENTS
The ability to sustain 30 lbf applied to the crank.
Weight
Volume
​
This implies that, above all, customers value durability in hand tools, followed closely by portability. It is sensible for prospective consumers to desire a long-lasting product. Fragile tools require frequent replacement, which requires frequent expenditure of time and money.
In addition, hand tools are, by definition, supposed to be hand-portable. Customers often purchase hand tools primarily for lightweight alternatives to stationary machines.
FOCUSED DESIGN EFFORT ANALYSIS
Considering the most heavily-weighted design requirements, the first priority in the design of the new drill is durability. Likely sources of damage are unexpected, user-inflicted damage (such as drops), and wear and tear from repeated use. Parts must therefore be made of material strong enough to sustain rough use and corrosion over time, especially the gears. However, strong customer desire for portability means the drill must be compact and light.
Polyethylene is lightweight, durable, and common. Commonly-used materials are easy and cheap to obtain. They also have a large variety of methods used to process them into finished parts, increasing manufacturing options.
PRODUCT DESIGN SPECIFICATIONS ("THE SPEC")
DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA) ANALYSIS
UPDATED BILL OF MATERIALS (B.O.M.) AFTER DFMA ANALYSIS
OPTIMIZED NUMBER OF PARTS IN ASSEMBLY PREDICTIONS
CONCEPT DESIGN SKETCHES
Recognizing the limitations of the original drill which we purchased from Schröder we decided to focus our design efforts on functionality and quality
CONCEPT DESIGN SKETCH 1
CONCEPT DESIGN SKETCH 2
CONCEPT DESIGN SKETCH 3
PUGH DESIGN MATRIX
Using the Pugh Design Matrix we analyzed and ranked each of the three design sketches in comparison to the original product to help narrow down an idea for our final prototype
ANALYSIS OF PUGH MATRIX
Based on a careful analysis of our Pugh Matrix we decided on a design that is somewhat of a mix between all of the concept designs with a focused design structure around the first concept design. In general, most of the concept designs we came up more or less were illustrations of different possible iterations of useful improvements to the original product. As a result of each of these designs having some useful components, we took a little inspiration for our final design from each of the different concept designs. As seen in almost all of the concept designs, we decided to replace almost all of the forms of fasteners from the original part with snap fits to increase the manufacturability of the product. As well, we decided we would attempt to increase the possible number of gear ratios that are available for the crank action hand-drill through the use of snap fits and planetary and bevel gears. Even though we took the base shape of the final product design from the first conceptual design, we also enveloped small elements from the other designs to maximize the amount of improvements that could be made. Considering the trade-offs between function, quality, and cost that is an inherent element in designing for manufacturability, we chose a design that could possibly significantly improve the function and the quality of the product for a trade-off of a potentially higher overall price.