What are designing criteria?

Designing criteria are described as the precise or predefined goals that a project or product must accomplish to be successful during its manufacturing.

In other words, the design criteria are a set of rules followed by an ideal product.

Following are the two types of design criteria:

• Primary design criteria
• Secondary design criteria

Primary design criteria

Primary design criteria are the criteria of the project or system; without them, the project will become unsuccessful or will fail. Function, dimension, cost, durability, and other specific product parameters come under primary design criteria.

Secondary design criteria

Secondary design criteria are the criteria of the project or system; without them, the project will not become unsuccessful or will not fail. Secondary design criteria are not the essential ones; they only add some additional features to the project or system. Corrosion resistive, smooth surface, easy to use, and other specific product parameters come under secondary design criteria.

The block diagram for the design criteria of a product is shown as:

Types of design criteria

Following are the various types of design criteria:

• Product size and shape
• Performance
• Producibility
• Aesthetics
• Safety and legal issues
• Ergonomics
• Environment
• Life cycle
• Maintenance
• Reliability

Product size and shape

The product size and shape are important characteristics of the product that specify the product's dimensions to be manufactured. Nowadays, the products are made compact so that they occupy less space and have less weight. The different components used in electronic devices like cell phones, televisions, laptops, and many others are becoming more compact and powerful with time.

Performance

Performance is described as a term that specifies the functional ability of the product. The product must be designed in such a manner that it performs its function optimally. The function of the product depends upon the customer's need. It is a primary design criterion of the product.

Producibility

The product should be designed in such a manner that it can be produced in large quantities with ease at a minimum production cost. The manufacturing process of the product must be accessible with less equipment or machining cost.

The material of the product is the main factor in the producibility of the product. It is a substantial compound chosen by a designer to manufacture the product. It is chosen based upon the product's function, working environment, availability of material, and others.

Aesthetics

Aesthetics is a term that defines the look of a product based on its color, surface treatment, sound, and others. The product designers always keep the product's aesthetics in mind to make the product attractive, compact, and convenient to use. It is an essential aspect nowadays; without proper aesthetics, the product will fail in the market.

The aesthetics of the product comes under secondary design criteria.

Safety and legal issues

Safety is the prime concern in most organizations. The product should be designed so that it is less hazardous or does not endanger life when used by a consumer. The various products or machines used in industries take these considerations very seriously.

In other words, the safety and legal issues are the product liabilities which expose manufacturers to lawsuits if the product fails.

Ergonomics

Ergonomic is described as the science of product design which ensures that the product is designed as per comfort, efficiency, and ease of use. It is an additional add-on to the product that improves its feature as per human comfort.

Environment

The environment is described as a surrounding condition at which the product performs its function. The functional ability of the product mainly depends on its surrounding environment. The surrounding temperature, pressure, humidity, and others are the factors that directly affect the functional ability or capacity of the product.

Life cycle

The life cycle is described as a period of ideal working of the product. It is classified into two types:

• Service life
• Product life

Service life shows the period of a product to operate properly without the need for repair. While a product life is a period a product will undergo before being replaced with a new one.

Maintenance

Maintenance is described as the repair that needs to be done over the product when it is not performing its proper function. The product is designed in such a manner that it is can easily be repaired. The product repair must be done quickly and should have low repair cost or less maintenance cost. During maintenance, the product will not perform any effective function.

Reliability

Reliability is described as a customer's dependency on a product. The consumer always buys those products which are cheaper and perform their function optimally for a long duration without any maintenance or failure. The product should not require frequent maintenance.

The diagrammatical representation for the essential requirements of good product design is shown as:

What are design constraints?

Design constraints are the limits on the design and production of a product. The common design constraints are shown as:

Following are the common design constraints:

• Resource availability
• Budget
• Time
• Energy
• Material
• Limited manufacturing processes

Resource availability

The resources like skilled labor, required machines, raw material, and others should be easily available for producing the ideal product.

Budget

The budget for the product directly decides its built quality, durability, appearance, and many more. A sufficient budget helps in producing an ideal product.

Time

Time is also an important factor during the manufacturing of the product. The various manufacturing or machining processes are the time taken. These processes should be complete as per standards to achieve the best results.

Energy

Energy is a prime source for operating manufacturing processes. The common energy sources used in industries to manufacture product is electrical energy, diesel, coal, and others.

Material

The material used for designing or manufacturing the product should have sufficient strength and easy availability. The cost of raw material also plays a vital role in selecting the suitable material for the product.

Limited manufacturing process

The material used for manufacturing products has some manufacturing limits like machining temperature, not being easily drilled, required coolant during machining, and many more.

Common Mistakes

Following are the common mistakes performed by students:

• Sometimes, students get confused between primary and secondary design criteria.
• Sometimes, students forget the real meaning of the terms aesthetics and ergonomics.
• Sometimes, students get confused between the service life and product life.
• Sometimes, students forget the design constraints of a product content.

Context and Applications

The topic designing criteria is significant in various courses and professional exams of undergraduate, graduate, postgraduate, doctorate levels. For example:

• Diploma in Mechanical Engineering
• Bachelor of Technology in Mechanical Engineering
• Bachelor of Technology in Production Engineering
• Bachelor of Architecture
• Master of Technology in Machine Design
• Doctor of philosophy in Design

Related Concept

• Product design
• Machine design
• Engineering design process
• Need of designing

Practice Problems

Q1. Which of the following design criterion add some additional features to the product?

1. Primary design criterion
2. Secondary design criterion
3. Both design criterion
4. None of these

Correct option (b)

Q2. _____is not a primary design criterion.

1. Appearance
2. Cost
3. Function
4. Durability

Correct option (a)

Q3. What is the term that defines the look of a product based on its color, surface treatment, sound, and others?

1. Reliability
2. Ergonomics
3. Aesthetics
4. Producibility

Correct option (c)

Q4. The period of a product to operate properly without the need for repair is called as _____?

1. Life cycle
2. Product life
3. Service life
4. Reliability

Correct option: (c)

Q5. Which of the following is not a design constraint?

1. Resource
2. Time
3. Budget
4. Maintenance

Correct option:(d)