Author: Yeh-Liang Hsu(2000-08-01);
Last updated: Yeh-Liang Hsu(2003-06-25);
recommended: Yeh-Liang Hsu(2000-08-01).
Note: This article is the lecture note of “ME4410 Automated Machine
Design” Yuan Ze University. It is used strictly for teaching purposes.
Measuring a design
“It’s a bad
design.” You must have said this very often. But why is it a bad design? How do
you know it’s a bad design? Can a design be measured?
Price and quality
From the consumer’s point of view, a design (a product)
could be measured by its price and quality.
Actually, the price of a product may change consumers’ expectation to the
The price of a
product depends heavily on the cost of producing the product. Manufacturers do
whatever they can to reduce the cost of producing the product. However, the
fact that is often overlooked is that, the decisions made during the design process have a great
effect on the cost of a product but cost very little. According to the data from Ford Motor Company, the cost of a
vehicle consists of 50% material, 15% labor, 30% overhead, and only 5% design.
But design can change the cost of manufacturing a product by 50%!
On the other
hand, good design can also add value to the product. People are willing to pay more for
good quality designs, even though the actual “cost” is much lower than the
price. Note that here we are talking about the
“quality of a design”, not manufacturing quality that we often talk about.
So what is a
good quality design, anyway?
Here is the
result of a consumer survey on what determines quality: works as it should:
98%; lasts a long time: 95%; is easy to maintain: 93%; looks attractive: 58%;
incorporates latest technology: 57%; has many features: 48%.
think there is one intangible quality that is missing, “being cool”.
Kano’s model of
According to the
Kano’s model of
customer satisfaction, there are three different types of product quality that give
customer satisfaction: basic quality, performance, and excitement quality, as shown in the figure below.
Figure 1. Kano’s
model of customer satisfaction
Basic quality is
the customers’ requirements that are not verbalized as they specify assumed
functions of the device.
quality refers to customer’s requirements that are verbalized in the form that
the better the performance, the better the product.
that include excitement quality will be popular and delighted. However, these
customers’ requirements are often unspoken because customers do not expect them
to be met in the products. Therefore, an engineering designer has a responsibility to find the
excitement qualities of the products that customers may not even realize.
interesting fact is, over time, excitement level requirements become performance
level requirements and, ultimately, basic requirements.
The only way to
learn about design is to do design.
Just do it.