Business & Finance Productions and Operations Assignment

GoodsandServiceDesignPart2TaguchiLossFunctionandReliability.pdf

Home >Business & Finance homework help >Business & Finance Productions and Operations Assignment

Goods and Service Design

Part Two

Prof. Fiyinfoluwa Abioye

Bowie State University

©2023 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

Content

• Designing Manufacturing Goods

Designing Manufactured Goods

For a manufactured good such as an automobile, computer, or textbook, design involves determining technical specifications such as dimensions, tolerances, materials, and purchased components; or choice of fonts and page layout for a textbook. This step also requires coordination with operation managers to ensure that manufacturing processes can produce the design (step 4b). Many different tools and techniques are used to support product design activities.

Tolerance Design and the Taguchi Loss Function

For most manufactured goods, design blueprints specify a target dimension (called the nominal), along with a range of permissible variation (called the tolerance); for example, 0.500 ± 0.020 cm. The nominal dimension is 0.500 cm but may vary anywhere in the range from 0.480 to 0.520 cm. This is sometimes called the goal-post model (shown in Fig. 1).

Fig. 1. Traditional Goal-Post View of Conforming to Specifications.

Tolerance design involves determining the acceptable tolerance. Narrow tolerances improve product functionality and performance, but tend to raise manufacturing costs because they usually require higher precision technology. Wide tolerances, on the other hand, reduce costs, but may have a negative impact on product performance. Thus, designers must consider these trade-offs and should use sound scientific and engineering approaches to optimizing tolerances rather than simply setting them judgmentally.

Genichi Taguchi, a Japanese engineer, maintained that the traditional practice of setting design specifications is inherently flawed. The goal-post model assumes that any value within the tolerance range is acceptable, but those outside are not.

Taguchi argues that the smaller the variation from the nominal specification, the better the quality. Taguchi measured quality as the variation from the target value of a design variation and then translated that variation into an economic “loss function” that expresses the cost of variation in monetary terms. This approach can be applied to both goods and services.

Taguchi proposed measuring the loss resulting from the deviation from the target by a quadratic function so that larger deviations cause increasingly larger losses. The loss function is

𝐿 𝑥 = 𝑘 𝑥 − 𝑇 2

Where

𝐿 𝑥 is the monetary value of the loss associated with deviating from the target, T

x is the actual value of the dimension

k is a constant that translates the deviation into dollars. A graphical illustration of the Taguchi loss function is shown in Fig. 2.

Fig. 1. Taguchi Loss Function.

Design for Reliability

Reliability is the probability that a manufactured good, piece of equipment, or system performs its intended function for a stated period of time under specified operating conditions. Reliability applies to services as well as manufacturing; a system could be a service process where each stage (work activity or station) is analogous to a component part in a manufactured good. Reliability can be improved by using better components or by adding redundant components. In either case, costs increase; thus, trade-offs must be made.

Reliability of a Serial System

Many manufactured goods consist of several components that are arranged in series but are assumed to be independent of one another, as illustrated in Fig. 3. If one component or process step fails, the entire system fails. If we know the individual reliability, 𝒑𝑗 , for each component, 𝑗, we

can compute the total reliability of a n-component series system, 𝑹𝒔 .

If the individual reliabilities are denoted by 𝒑1 , 𝒑2 , … 𝒑𝑛 , then the reliability of the system 𝑹𝒔 can be computed as:

𝑅𝑠 = 𝑝1 𝑝2 𝑝3 ⋯ 𝑝𝑛

Fig. 3. Structure of a Serial System

Reliability of a Parallel System

Other designs consist of several parallel components that function independently of each other, as illustrated in Fig. 4. The entire system will fail only if all components fail; this is an example of redundancy. The system reliability of a n- component parallel system is computed as

𝑅𝑝 = 1 − 1 − 𝑝1 1 − 𝑝2 1 − 𝑝3 ⋯ 1 − 𝑝𝑛

Fig. 4. Structure of a Parallel System.

Example:

The following system is a series system with parallel redundancy for component B. What is the reliability of this system?

Design for Manufacturability

Design for manufacturability is the process of designing a product for efficient production at the highest level of quality. One way of doing this is through product simplification. Product simplification is the process of trying to simplify designs to reduce complexity and costs and thus improve productivity, quality, and flexibility, and customer satisfaction. The simpler the design, the fewer opportunities for error, the faster the flow time, the better the chance of high process efficiency, and the more reliable the manufactured good or service process.

Design for Sustainability

Environmental concerns are placing increased pressure on design. Pressures from environmental groups clamoring for “socially responsible” designs, states and municipalities that are running out of space for landfills and consumers who want the most for their money have cause designers and managers to look carefully at the concept of Design for Environment.

Design for Environment (DfE) is the explicit consideration of environmental concerns during the design of goods, services, and processes, and includes such practices as designing for recycling and disassembly.

Slide 1: Goods and Service Design Part Two
Slide 2: Content
Slide 3: Designing Manufactured Goods
Slide 4
Slide 5: Tolerance Design and the Taguchi Loss Function
Slide 6
Slide 7
Slide 8
Slide 9
Slide 10
Slide 11: Design for Reliability
Slide 12: Reliability of a Serial System
Slide 13
Slide 14: Reliability of a Parallel System
Slide 15
Slide 16
Slide 17
Slide 18: Design for Manufacturability
Slide 19: Design for Sustainability
Slide 20