What do you mean by engineering design? Why there is a need of design? - News4u95


Wednesday, 17 March 2021

What do you mean by engineering design? Why there is a need of design?

Engineering Design

  • The term design refers to a plan for the construction of an object.
  • There is no general definition of design because it has different meanings in different fields.
  • The person who designs is called as designer and a designer's sequence of activities is called as design process.
  • The term machine design or mechanical design concerns with the systems by which energy is converted into useful mechanical forms and of mechanisms required to convert the output of the machines to the required form.
  • The machine design may lead to an entirely new machine or machine element or improvement on an existing machine.

Need of Design

Need of Design
Need of Design

The process of design is a long and time consuming one. From the study of existing ideas, new and better ideas have to be conceived. These ideas are than studied, keeping in mind their commercial success and are given a definite shape. Hence in designing a machine element or machine following factors are to be considered:

  1. Functional requirement
  2. User comfort
  3. Safety
  4. Modification
  5. Appearance
  6. Cost reduction.

Functional requirement

The design of product should satisfy the purpose (task) for which it is made.

User comfort

The product so designed should be user friendly and easy to operate.


The product so designed should be harmless to the user and should not have failure for the specified time period.


The machine should undergo modification using new technologies to increase the efficiency of the product.


The product should be appealing to the customer.

Cost reduction

The design of product should be such that, it reduces the total cost of product and creates a healthy competition.


General Consideration in Design

Design considerations are the parameters which affect the design of the element or system (machine). For designing an object, the designer should have knowledge of many subjects like Mathematics, Mechanics, Metallurgy, Manufacturing processes, Theory of Machines, Engineering Drawing, etc. Following are the general considerations while designing a machine element:

  1. Type of load
  2. Selection of material
  3. Shape and size
  4. Friction and lubrication
  5. Operational safety
  6. Machine availability
  7. Use of standard parts
  8. Motion of element
  9. Production quantity
  10. Maintenance of element
  11. Life of element
  12. Capacity of element
  13. Weight of element
  14. Cost of element.


Types of load

The load on a machine component may act in different ways due to which internal stresses are set up. Hence, to reduce the stresses and for safety, the designer should know the type of load acting on the component. For example, static load, dynamic load, etc.

Selection of material

It is necessary that, a designer should have a thorough knowledge of the mechanical properties of materials and their behaviour under working conditions. For example, strength ductility, stiffness, etc.

Shape and size

The shape and size of the machine element depends upon the past experience of designer. The compact cross-section may be used, but it may be checked that the stresses induced in the designed shape and size are reasonably safe.

Friction and lubrication

There is always some loss of power due to frictional resistance and to reduce this loss adequate lubrication is required. For example, to reduce the friction in the bearings it Is assembled in oily condition.

Operational safety

Some of the machines are dangerous to operate, especially those which are speeded up to increase the production rate. Hence, it is essential that a designer should always provide safety devices for the safety of the operator but it should not interfere with the machine operation.

Machine availability

A designer should be familiar with the limitations of his owner’s workshop, to avoid the necessity of having work done in other shop.

Use of standard parts

The cost of standard parts is little bit more than the simple parts. But, the standard parts can be replaced whenever required and anywhere in the world. Hence, the designer should use maximum standard parts.

Motion of element

The successful operation of any machine depends upon the simplest arrangement of parts or elements which will give the desired motion. The motion may be rectilinear, curvilinear, etc.

Production quantity

The quantity of production affects the design in various ways. The engineering and shop costs (fixed charges) are distributed over the number of components to be manufactured.

Maintenance of element

A designed machine element should be such that it can be easily repaired or replaced.

Life of element 

A machine element should be designed for an adequate life without failure.

Capacity of element

A designed machine element should have high load carrying capacity, resisting capacity, etc.

Weight of element

A designed machine element should have a minimum possible weight but high strength.

Cost of element

The cost of element is the most important consideration involved in the design. In some cases, high cost of an article may immediately reject it from further considerations. Hence, the aim of designer under all conditions should be to reduce the cost to the minimum.

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