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What is MACHINE DESIGN Machine design is the creation of new and better

machines and improving the existing one. A newor better machine is one which is more

economical in the overall cost of production andoperation.

OR

MD is defined as the use of scientific principles,

technical information and imagination in thedescription of a machine or a mechanical systemto perform specific functions with maximumeconomy and efficiency.

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CLASSIFICATION OF MACHINE DESIGN1. Adaptive design: The designers work is concerned with

adaptation of existing design.

2. Development design: This type of design needs

considerable scientific training and design ability in order

to modify the existing designs into a new idea.

3. New design: This type of design needs a lot of research,

technical ability and designers and creative thinking.

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GENERAL CONSIDERATION IN

MACHINE DESIGN(i) Type of load and stresses caused by the load.

(ii) Motion of parts

(iii) Selection of materials

(iv) Frictional resistance and lubrication

(v) Convenient and economical features

(vi) Safety of operation

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Design requirement of machine

elements

(i) Strength and stiffness

(ii) Surface finish and tolerances

(iii) Manufacturability

(iv) Ease of handling(v) Working atmosphere

(vi) Cooling and lubrication

(vii) Safety

(viii) Noise requirement

(ix) Cost

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Design Procedure

Market Survey

Define Specifications of aProduct

Prepare Assembly and Detail Drawings and Modify

Drawings after Testing Prototype Model

Design IndividualComponents

Prepare General Layout of Configuration and Select JoiningMethods between Individual Components of Product

Study Alternative Mechanisms for productand Select proper Mechanism

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Use of Standards in Design Standardization is defined as obligatory norms, to

which various characteristics of a product shouldconform. The characteristics include materials,dimensions and shape of the component, methods oftesting and method of marking, packing and storing ofthe product.

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Standards used in MED Standards for Materials, their chemical

compositions, mechanical properties and heattreatment, e.g. I.S. 210 specifies seven grades of greycast iron designated as FG 150, FG 200, FG 220, FG 260,

FG 300, FG 350, FG 400.Note:- The number indicates UT Strength in N/mm2.

Standards for shapes and dimensions ofcommonly used machine elements like nuts, bolts,screws, rivets, belts etc. e.g. I.S. 2494 specifies thedimensions and shape of the cross-section of endlessV-belts for power transmissions.

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Standards used in MED Standards for fits, tolerances and surface finish of

components:, e.g. selection of the type of the fit fordifferent applications is illustrated in I.S. 2709 on Guide

for selection of fits. Standards for testing of Products: e.g. I.S. 807 is a code

of practice for design, manufacture, erection and testing ofcranes and hoists.

Standards for engineering drawing of components:e.g. a special publication SP 46 by BIS on EngineeringDrawing Practice for Schools and Colleges that cover allstandards related to engineering drawing.