Stress Strain Diagram is very important diagram to understand the concepts of mechanical engineering. It depicts the variations of strain alongside stress and the various points on the graph i.e. limit of proportionality, yield stress and others
Objective Questions and Solutions, Mechanical/Production
(a) Manufacturing is the process of converting raw material into ______Finished Product_____
(b) The ductility of a piece of chalk is ____approx. zero_______
Answers are marked bold
(c) The % of carbon in medium carbon steel varies
(i) Less than 0.20 (ii) 0.10 to 0.30
(iii) 0.30 to 0.60 (iv) More than 0.60.
(d) Stainless steel comes under the category of
(i)...
Grinding : Abrasives, Grit, Classification of wheels, Bond and Grade
The grinding process is capable of producing very accurate sizes, equally accurate geometry like flatness or circularity and extremely good surface finish. The grinding wheel is capable of machining hardened steel and even hardened high speed steel, which cannot be done by other machining processes.
CHOICE OF ABRASIVES
Emery and corundum, are...
Following are major types of drilling ;
Step drilling: More than one diameter can be ground on the drill body which saves an extra operation.
Counter boring: Often a flat surface is needed around a hole to provide a good seating area for washer and nuts/head of a bolt. The counter boring tool has a pilot, which ensures that...
Pick out the most appropriate option:
Answers are marked bold ;
1. Mild steel is an alloy of iron and carbon with percentage of carbon ranging from
(a) up to 0.2% (b) 0.15–0.3
(c) 0.3–0.5 (d) above 0.5.
2. IZOD test measures
(a) hardness (b) ductility
(c) impact-strength (d) grain size.
3. Copper is used for making electrical conductors because it is
(a) ductile (b) resists corrosion
(c) has...
ALLOYS OF NICKEL
(i) German silver. It is a cupro nickel to which zinc has been added. A typical composition is 60% copper, 30% nickel and 10% zinc. Addition of zinc brings down the cost. Its colour is silvery with a slight pale tinge. It is very ductile and malleable and corrosion resistant. It is used for making electrical contacts,...
Non Ferrous Metals and Alloys - Properties and Uses :
Non-ferrous metals and alloys do not contain any significant quantity of iron. The most common non ferrous metals used in engineering applications are copper, aluminium, tin, lead and zinc. Nickel, magnesium and antimony are also used for alloying the aforesaid non-ferrous metals.
Copper.
Copper is a corrosion resistant metal of an attractive...
Bronze ;
Bronze is an alloy of copper and tin however commercial bronzes may contain other elements besides tin. In fact, alloys of copper with aluminium, silicon and beryllium, which may contain no tin are also known as bronzes. This article describes about different types of Bronze and their practical applications.
Tin bronzes are of a beautiful golden colour. As in...
CNC Machines have these advantages :
High Repeatability and Precision e.g. Aircraft parts.
Volume of production in CNC is very high
Complex contours/surfaces need to be machined. E.g.
Turbines
Flexibility in job change, automatic tool settings, less
scrap
More safe, higher productivity, better quality
Less paper work, faster prototype production, reduction
in lead times.
Disadvantages :
Costly setup, skilled operators are always needed.
...
NC - Numeric Controlled and CNC - Computer Numeric Controlled Machines differ in these ways :
The difference between NC and CNC is one of age and
capability. NC is older compared to CNC
The earliest NC machines performed limited functions
and movements controlled by punched tape or punch
cards.
As the technology evolved, the machines were equipped
with increasingly powerful microprocessors (computers)
with...