Write a short note on: Preferred series and numbers.

Preferred series and numbers:

Preferred numbers are used to specify "sizes" of product.

Preferred numbers are the conventionally rounded off values derived from geometric series, including the integral power of 10 and having common ratios the following factors:

                                                              ⁵√10, ¹⁰√10, ²⁰√10, ⁴⁰√10, ⁸⁰√10

These ratios Ø , knows as step ratios, are approximately equal to 1.58, 1.26, 1.12, 1.06, 1.03 respectively.

The system based on use of geometric progression to develop set of numbers. There five basic series denoted as R5, R10, R20, R40, R80 series, which increases in steps of 58%, 26%, 12%, 6%, 3% respectively. 

The series are as follows:

R5 Series                                      ⁵√10=1.58

R10 Series                                  ¹⁰√10=1.26

R20 Series                                  ²⁰√10=1.12

R40 Series                                  ⁴⁰√10=1.06

R80 Series                                  ⁸⁰√10=1.03

Series is formed by taking first number and multiplying it by a series factor to get second number.The second number is again multiplied y series factor to get third number.It continues until complete series is formed up.

Differentiate between Shaper and Planer machine

Difference between Shaper and Planer Machine:

Sr. No.	Shaper	Planer
1.	Used for machining small flat surfaces. Surface may be horizontal, vertical, inclined.	Used for machining flat surfaces with bigger sizes.
2.	Less accuracy	High accuracy
3.	Light duty machine	Heavy duty machine
4.	Compact design. Requires less space	Requires more floor space
5.	One tool is used on shaper.	More than one tool can be used.
6.	Suitable when small quantities required to be machined.	Suitable for large quantities of identical shapes to be machined.
7.	Only light cuts can be employed.	Heavy cuts can be employed.
8.	Fine feed is required.	Coarse feed can be Given.
9.	Cutting and return speed in one stroke is not uniform.	Cutting and return speed in one stroke is same.
10.	Indexed feed is given to the job during idle stroke of ram.	Indexed feed is given to tool during idle stroke of work table.

Differentiate between Open die forging and Closed die forging.

Difference between Open die forging and Closed die forging:

Sr. No.	Open Die Forging	Closed Die Forging
1.	Tooling is simple.	Complex operation.
2.	Produces Work pieces with less dimensional accuracy.	Higher Dimensional accuracy.
3.	Skilled operator Required. Final shape of forging depends on skills of operator.	Required Semi-skilled operator.
4.	Process has less Reproducibility.	Process has more Reproducibility. Suitable for making negatives or duplicates of each other.
5.	More material waste.	Relatively Reduced material waste.
6.	Low costly process.	Expensive process.
7.	Difficult to maintain close tolerances.	Easy to maintain close tolerances.
8.	Applications: Crankshafts, Shells and containers, Reactor vessels.	Applications: Manufacturing of connecting rod, rocker arms, gears, shafts, Defence and aircraft industry.
9.	Also called as Smith die forging.	Also called as Impression die forging.
10.	Types: Hand forging, Hammer forging, press  forging.	Types: Drop forging. Machine forging.

Differentiate between centrifugal pump and reciprocating pump.

Difference between Centrifugal pump and Reciprocating pump:

Sr. No.	Centrifugal Pump	Reciprocating Pump
1.	Used for low head, High discharge.	Used for High Head, Low Discharge.
2.	Low space required.	Large space Required.
3.	Simple in construction, less number of parts.	Complex construction.
4.	Initial and maintenance cost is low.	Initial and maintenance cost is High.
5.	Less weight to discharge ratio.	High weight to discharge ratio.
6.	Steady and continuous flow.	Intermittent and pulsating flow.
7.	No air vessel required.	Air vessel Required.
8.	Priming is required.	Priming not required.
9.	High speed operation.	Low speed operation.
10.	Uniform torque	Variable Torque

Differentiate between Capstan lathe and Turret lathe

Difference between capstan lathe and turret lathe:

Sr. No.	Capstan Lathe	Turret Lathe
1.	It deals with rod type blanks held in collet.	It deals with chucking type jobs held in the chucks.
2.	Light duty machine.	Heavy duty machine.
3.	Not Rigid, heavy cut cannot given	Relatively more robust and rigid. Heavy cuts can be given
4.	Lengthwise turret Movement is less.	Lengthwise Turret movement with saddle is more.
5.	Collet is used to hold the work piece.	Jaw chuck is used to hold the work piece.
6.	Suitable for short work pieces.	Long work pieces can be machined.
7.	Used for machining the jobs up to 60 mm diameter.	Used for machining the jobs up to 200 mm diameter.
8.	Saddle will not move during machining.	Saddle moves with turret.
9.	Capstan head may be circular or hexagonal.	Turret head may be square, octagonal or hexagonal.

What is pressure angle and its significance in design of cam and follower mechanism?

Pressure angle and its significance:

It is defined as "angle made between the direction of motion of follower and normal to the pitch curve at any point".It varies from maximum to minimum during complete rotation. It should be small and the angle can be minimized by making bigger cam size or maintaining the offset.

If the pressure angle is high, higher the side thrust and chances of jamming the motion of follower in guideways.

If pressure angle is very small,Weight of cam will increase with increase in inertia force.

What is dynamometer ? How does it differ from brakes?

Difference between Brakes and Dynamometer:

Sr. No.	Brakes	Dynamometer
1.	It absorbs Energy.(Kinetic or Potential).Provides resistance to moving machine member.	It measures frictional resistance.Works on principle of Absorption.
2.	It is used to slow or stop the machine member in motion	It can measure absorbed energy transmitted from machine member.
3.	No torque and power is measured.	Measured  friction resistance is used to measure torque that is transmitted and also the power.
4.	Types: Hydraulic, Mechanical, Electrical.	Types: Absorption, Transmission.