Product Design Introduction

Product Design Introduction

Product design deals with the conversion of ideas into reality and aims at fulfilling the human needs.

Product design is the set of activities required to bring a new product, concept or service to a state of market readiness. This set of activities includes:

a. Initial inspiration of new product vision

b. Business and technological feasibility study

c. Engineering design of the product

d. Evaluation or validation of the product design

e. Planning or manufacturing processes of the product

f. Planning for the distribution of the product

g. Planning for the use of product by consumer

h. Planning for the retirement of the product

Product design includes design of wide range of products, concepts and services which may be of engineering type or non-engineering type. The few examples of product design are design of car, design of refrigerator, design of dress in the world of fashion, design of mobile phone etc.

Mechanical engineering design is just one of the numbers of areas of product design.

Importance of Product Design

The product design is a very important stage and has impact on the following three major areas of the product competitiveness:

1. Product cost

2. Product quality

3. Product cycle time

1. Product Cost:

The product design consumes a small fraction of the cost of product (approximately 5%) while other 95% of the cost of product is consumed by capital, material and labour.

However, the decision made in the product design stage influence about 70% to 80% of the final cost of the product. The decisions made beyond the product design stage can influence only about 20 to 30% of the final cost of the product.

In other words, the final cost of the product is almost decided in the product design stage.

2. Product Quality:

The second major impact of product design is on product quality. The old concept of achieving the product quality by inspection is no more true. The inspection can have limited influence on the product quality.

The true quality, desired by the customer in respect of features and performance, has to be designed into product.

Therefore, the product quality mainly depends upon the product design.

3. Product Cycle Time:

The third area, where the product design makes the difference, is the product cycle time. The product cycle time is the time required to bring a new product into the market.

The use of new design and development tools like computer aided engineering, rapid prototyping etc. reduces the product cycle time.

The reduced product cycle time not only increases the marketability of the product but also reduces the cost of product development.

Phases of Product Design (Philosophy of Product Design)

The product design consists of a set of activities that involves more than engineering. The complete product design process consists of twelve phases. Of the twelve phases, the first eight phases belong to the design and the remaining four phases belong to the product consumption cycle.

The different phases involved in the product design process are given in the figure below:

Figure: Phases of Product Design Process

Identification of Need or Vision of New Product:

Every product design process starts with the identification of need or the vision of new product. It is an outcome of either the requirement or discontentment with the existing products. It is highly creative act and, most of the times, comes out of innovative minds.

Many a times, it comes in the form of customer feedback about the existing products.

Definition of Problem:

The difference between the statement of need and the definition of problem is that the problem is more specific.

The definition of problem may include:

a. Required specifications

b. Input parameters

c. Functional requirement of the product

d. Constraints

Feasibility Study:

Feasibility study means checking the possibility of bringing the product into reality.

Before proceeding with the product design, it is necessary to find the answers to the following questions through scientific study, known as feasibility study.

a. Can the product be technologically feasible?

b. Can the product be economically worthy?

c. Is it possible for the organization to mobilize the resources for product development and manufacturing?

d. Can the product be acceptable to various controlling government agencies?

e. Can the product be environment friendly?

Types of feasibility study:

The feasibility study includes:

a. Technological feasibility study

b. Economical feasibility study

c. Financial feasibility study

d. Societal feasibility study

e. Environmental feasibility study

Technological feasibility study:

The technological feasibility study determines the possibility of technological success of the product with existing technology and constraints.

Consider an example of design of a solar powered car. In technological feasibility study, it is necessary to check the possibility of designing and manufacturing the car which can totally work on solar energy, with existing technology.

If the product is technologically not feasible, there is no point in initiating the project.

Economical feasibility study:

The economical feasibility study determines the economic worthwhileness of the product.

The study team needs to explore the possibility of individuals, institutions or society paying for the product which can satisfy their need, the study team has to take into account the prevailing socio-economic scene.

The product must be cost competitive, not only in terms of initial cost but also in terms of running and maintenance cost.

The solar powered car may be economically feasible, only if it is cost competitive with the petrol/diesel cars, battery operated cars and hybrid cars.

Financial feasibility study:

The financial feasibility study determines the financial capability of the company to take up the project and the expected financial returns for the company.

The project may be meritorious from the technological and economical point of view. However, it cannot be implemented if:

a. It is difficult for the company to mobilize the funds for its implementation

b. It does not assure the returns for the company for an adequate duration

For example, if a company cannot mobilize the magnitude of the financial resources required for the solar powered car project, the project cannot be initiated irrespective of its merit.

Societal feasibility study:

The societal feasibility study determines the level of acceptance of the product by the society and the various controlling government agencies.

The product must be acceptable to society. In addition, it must get approval from various controlling government agencies.

For example, before launching the project of solar powered car, it is necessary to find the acceptance of such car by society over conventional cars.

Environmental feasibility study:

The environmental feasibility study determines the extent to which the product is environment friendly.

Nowadays, the customer prefers environmental friendly products. In addition, there are strict rules and regulations in place for protection of environment. Therefore, the product must be environment friendly and non-polluting.

Preliminary Design:

In preliminary design, a number of alternative design solutions are proposed.

All alternative design solutions are critically analysed for their performance and suitability considering the factors such as reliability, safety, initial cost, running and maintenance cost, user friendliness, environmental friendliness etc.

CAD techniques are used in preliminary design.

Brainstorming:

After proposing and critically analysing the alternative design solutions, it is worthwhile to present these alternative design solutions to a group and seek the creative ideas, if any, for improvement. This is done by a technique known as brainstorming.

Brainstorming is a creative, group technique used for generating ideas in a non-threatening, uninhibiting atmosphere.

In brainstorming, the collective creativity of the group is tapped and enhanced.

The objective of brainstorming is to generate the large number of alternative ideas from the uninhibited response of the groups. The brainstorming is more effectively applied to specific problems rather than the general problem.

The problem should be defined clearly before the starting of brainstorming session. Allow 5 minutes for individuals to think on problem before starting the group process.

A brainstorming session must have a facilitator to control the group and record the ideas. The ideas coming from the members should be written by the facilitator on the board. The ideas written on the board can become seeds for further thoughts.

The facilitator should go around the group, in turn, asking for ideas. He should encourage creative, wild or apparently ridiculous ideas. There should be no questioning, discussion or criticism of ideas.

When a group has exhausted all ideas, take a break for some time and restart the session. In second session, seek clarification on idea generated. Each idea should be considered as generated by the group and not by any individual.

In second session, the ideas which deserve further consideration should be shortlisted.

Fundamental Principles of Brainstorming

There are four fundamental principles of brainstorming:

a. No criticism of ideas

b. Ideas brought forth should be picked up by other people

c. Participants should divulge all ideas entering their mind without any constraint

d. Provide as many ideas as possible within available time

No criticism of ideas:

In brainstorming, ideas should be allowed to flow freely in a supportive environment. Any attempt to analyze, criticize or reject the ideas should be postponed until the brainstorming session is over.

Ideas brought forth should be picked up by other people:

The ideas brought forth by an individual should be supported by other people. Taking clue from the idea presented by one individual, other people should add something to it so as to create the chain of ideas. The individuals should focus only on the positive aspects of ideas presented by others.

Participants should divulge all ideas entering their mind without any constraint:

Any idea which appears wild and unrealistic may contain an essential element of the ultimate solution. Therefore, all members of the group should divulge all ideas entering their mind without thinking about the feasibility of the ideas.

Provide as many ideas as possible within available time:

The participants should float as many ideas as possible within the available time. The ideas should be described roughly without details. The group can easily generate 20 to 30 ideas in a brainstorming session of 30 minutes.

Optimization (Selection of Best Possible Solution):

Objective of Optimum Design:

For any design problem, a large number of solutions are available which fulfil the performance, cost, safety and robustness requirements. In the present days of competition, it is very important to select the best of the available design solution.

The optimization techniques provide the tools for selecting the best design solution from the feasible solutions. An optimum design is the best attainable solution to the design problem within the given constraints.

The optimum design targets a single parameter for optimizing i.e. maximizing or minimizing, while fulfilling the other requirements.

The optimizing parameter may be one which is to minimized like cost, weight, size, stress, deflection etc. or one which is to maximize like power transmitting capacity, load carrying capacity, etc.

Detailed Design:

Once the optimum design solution is identified, the next step is the detailed design of the product.

The purpose of the detailed design phase is to furnish the complete engineering description of the product so that it is ready for production.

Steps in detailed design:

a. Overall design of all subsystems

b. Overall design of components

c. Detailed design of parts

d. Preparation of drawings, computer models and report

Overall design of subsystems:

Each product or system consists of number of subsystems. In preliminary design, the emphasis is only on the concept of the product or system and subsystems are examined only to evaluate the quality of the overall product or system.

In this step, each subsystem is looked at as an individual entity and compatibility of one subsystem with the other is verified.

The subsystems are designed and master layout drawing is prepared for each subsystem.

For example, in solar powered car, transmission system, suspension system, electrical systems are subsystems.

Overall design of components:

Each subsystem consists of number of components. In this step, all components of subsystem are designed and master layout drawing is prepared for each component.

For example, in a transmission system of a solar powered car, gear box is a component.

Detailed design of parts:

Each component is made from number of parts. In this step, all parts of the component are designed.

CAD techniques are used for designing purpose.

Preparation of drawings, computer models and report:

After the parts are designed, the next step is preparation of drawings. Computer aided drafting software can be used for preparation of drawings.

The various drawings are:

a. Part drawings with dimensional tolerances, geometrical tolerances and surface finish.

b. Assembly drawings for components

c. Assembly drawings for subsystems

d. Assembly drawing for product or system

In addition to two dimensional drawings, three dimensional computer models for parts, components and subsystems are also prepared.

Finally, the detail design report of the project is prepared

Evaluation of the Product:

Evaluation of the product involves the testing of prototype in the laboratory or testing by creating the model on computer.

Evaluation verifies the feasibility of the product and it is the final proof of a successful design.

References:

Taken from Mechanical Machine Design-I by R. B. Patil

Wikipedia Article about Product Design