APPLICATIONS OF POWDER METALLURGY

APPLICATIONS OF POWDER METALLURGY

The powder metallurgy process has provided a practical solution to the problem of

producing refractory metals, which have now become the basis of making heat-resistant

materials and cutting tools of extreme hardness. Another very important and useful item

of the products made from powdered metals is porous self-lubricating bearing. In short,

modern technology is inconceivable without powder metallurgy products, the various fields

of application of which expand every year. Some of the powder metal products are given as

under.

1. Porous products such as bearings and filters.

2. Tungsten carbide, gauges, wire drawing dies, wire-guides, stamping and blanking

tools, stones, hammers, rock drilling bits, etc.

3. Various machine parts are produced from tungsten powder. Highly heat and wear

resistant cutting tools from tungsten carbide powders with titanium carbide, powders

are used for and die manufacturing.

4. Refractory parts such as components made out of tungsten, tantalum and

molybdenum are used in electric bulbs, radio valves, oscillator valves, X-ray tubes

in the form of filament, cathode, anode, control grids, electric contact points etc.

5. Products of complex shapes that require considerable machining when made by

other processes namely toothed components such as gears.

6. Components used in automotive part assembly such as electrical contacts, crankshaft

drive or camshaft sprocket, piston rings and rocker shaft brackets, door, mechanisms,

connecting rods and brake linings, clutch facings, welding rods, etc.

7. Products where the combined properties of two metals or metals and non-metals

are desired such as non-porous bearings, electric motor brushes, etc.

8. Porous metal bearings made which are later impregnated with lubricants. Copper

and graphite powders are used for manufacturing automobile parts and brushes.

9. The combinations of metals and ceramics, which are bonded by similar process as

metal powders, are called cermets. They combine in them useful properties of high

refractoriness of ceramics and toughness of metals. They are produced in two forms

namely oxides based and carbide based.

LIMITATIONS OF POWDER METALLURGY

LIMITATIONS OF POWDER METALLURGY
1. Powder metallurgy process is not economical for small-scale production.
2. The cost of tool and die of powder metallurgical set-up is relatively high
3. The size of products as compared to casting is limited because of the requirement
of large presses and expensive tools which would be required for compacting.
4. Metal powders are expensive and in some cases difficult to store without some
deterioration.
5. Intricate or complex shapes produced by casting cannot be made by powder
metallurgy because metallic powders lack the ability to flow to the extent of molten
metals.
6. Articles made by powder metallurgy in most cases do not have as good physical
properties as wrought or cast parts.
7. It may be difficult sometimes to obtain particular alloy powders
8. Parts pressed from the top tend to be less dense at the bottom.
9. A completely deep structure cannot be produced through this process.
10. The process is not found economical for small-scale production.
11. It is not easy to convert brass, bronze and a numbers of steels into powdered form.

ADVANTAGES OF POWDER METALLURGY

 ADVANTAGES OF POWDER METALLURGY

1. The processes of powder metallurgy are quite and clean.

2. Articles of any intricate or complicated shape can be manufactured.

3. The dimensional accuracy and surface finish obtainable are much better for many

applications and hence machining can be eliminated.

4. Unlike casting, press forming machining, no material is being wasted as scrap and

the process makes utilizes full raw material

5. Hard to process materials such as diamond can be converted into usable components

and tools through this process.

6. High production rates can be easily achieved.

7. The phase diagram constraints, which do not allow an alloy formation between

mutually insoluble constituents in liquid state, such as in case of copper and lead

are removed in this process and mixtures of such metal powders can be easily

processed and shaped through this process.

8. This process facilitates production of many such parts, which cannot be produced

through other methods, such as sintered carbides and self-lubricating bearings.

9. The process enables an effective control over several properties such as purity,

density, porosity, particle size, etc., in the parts produced through this process.

10. The components produced by this process are highly pure and bears longer life.

11. It enables production of parts from such alloys, which possess poor cast ability.

12. It is possible to ensure uniformity of composition, since exact proportions of

constituent metal powders can be used.

13. The preparation and processing of powdered iron and nonferrous parts made in this

way exhibit good properties, which cannot be produced in any other way.

14. Simple shaped parts can be made to size with 100 micron accuracy without waste

15. Porous parts can be produced that could not be made in any other way.

16. Parts with wide variations in compositions and materials can be produced.

17. Structure and properties can be controlled more closely than in other fabricating

processes.

18. Highly qualified or skilled labor is not required. in powder metallurgy process

19. Super-hard cutting tool bits, which are impossible to produce by other manufacturing

processes, can be easily manufactured using this process.

20. Components shapes obtained possess excellent reproducibility.

21. Control of grain size, relatively much uniform structure and defect such voids and

blowholes in structure can be eliminated.

Production of Metal Powders

 Production of Metal Powders

Metallic powders possessing different properties can be produced easily. The most

commonly used powders are copper-base and iron-base materials. But titanium, chromium,

nickel, and stainless steel metal powders are also used. In the majority of powders, the size

of the particle varies from several microns to 0.5 mm. The most common particle size of

powders falls into a range of 10 to 40 microns. The chemical and physical properties of metals

depend upon the size and shape of the powder particles. There are various methods of

manufacturing powders.The commonly used powder making processes are given as under.

1. Atomization

2. Chemical reduction

3. Electrolytic process

4. Crushing

5. Milling

6. Condensation of metal vapors

7. Hydride and carbonyl processes.

The above mentioned metallic powder making techniques are discussed briefly as under.

1. Atomization

In this process, the molten metal is forced through an orifice and as it emerges, a high

pressure stream of gas or liquid impinges on it causing it to atomize into fine particles. The

inert gas is then employed in order to improve the purity of the powder. It is used mostly

for low melting point metals such as tin, zinc, lead, aluminium, cadmium etc., because of the

corrosive action of the metal on the orifice (or nozzle) at high temperatures. Alloy powders

are also produced by this method.

2. Chemical Reduction Process

In this process, the compounds of metals such as iron oxides are reduced with CO or H2

at temperatures below the melting point of the metal in an atmosphere controlled furnace.

The reduced product is then crushed and ground. Iron powder is produced in this way

Fe3O4 + 4C = 3Fe + 4CO

Fe3O4 + 4CO = 3Fe + 4CO2

Copper powder is also produced by the same procedure by heating copper oxide in a

stream of hydrogen.

Cu2 + H2 = 2Cu + H2O

Powders of W, Mo, Ni and CO can easily be produced or manufactured by reduction

process because it is convenient, economical and flexible technique and perhaps the largest

volume of metallurgy powders is made by the process of oxide reduction.

3. Electrolytic Process

Electrolysis process is quite similar to electroplating and is principally employed for the

production of extremely pure, powders of copper and iron. For making copper powder, copper

plates are placed as anodes in a tank of electrolyte, whereas, aluminium plates are placed in

to the electrolyte to act as cathodes. High amperage produces a powdery deposit of anode

metal on the cathodes. After a definite time period, the cathode plates are taken out from the

tank, rinsed to remove electrolyte and are then dried. The copper deposited on the cathode

plates is then scraped off and pulverized to produce copper powder of the desired grain size.

The electrolytic powder is quite resistant to oxidation.

4. Crushing Process

The crushing process requires equipments such as stamps, crushers or gyratory crushes.

Various ferrous and non-ferrous alloys can be heat-treated in order to obtain a sufficiently

brittle material which can be easily crushed into powder form.

5. Milling Process

The milling process is commonly used for production of metallic powder. It is carried out

by using equipments such as ball mill, impact mill, eddy mill, disk mill, vortex mill, etc.

Milling and grinding process can easily be employed for brittle, tougher, malleable, ductile and

harder metals to pulverize them. A ball mill is a horizontal barrel shaped container holding

a quantity of balls, which, being free to tumble about as the container rotates, crush and

abrade any powder particles that are introduced into the container. Generally, a large mass

to be powdered, first of all, goes through heavy crushing machines, then through crushing

rolls and finally through a ball mill to produce successively finer grades of powder.

6. Condensation of Metal Powders

This process can be applied in case of metals, such as Zn, Cd and Mg, which can be boiled

and the vapors are condensed in a powder form. Generally a rod of metal say Zn is fed into

a high temperature flame and vaporized droplets of metal are then allowed to condense on

to a cool surface of a material to which they will not adhere. This method is not highly

suitable for large scale production of powder.

7. Hydride and Carbonyl Processes

High hardness oriented metals such as tantalum, niobium and zirconium are made to

combine with hydrogen form hydrides that are stable at room temperature, but to begin to

dissociate into hydrogen and the pure metal when heated to about 350°C. Similarly nickel and

iron can be made to combine with CO to form volatile carbonyls. The carbonyl vapor is then

decomposed in a cooled chamber so that almost spherical particles of very pure metals are

deposited.

Safety Recommendations for Gas Welding

Safety Recommendations for Gas Welding

Welding and cutting of metals involve the application of intense heat to the objects being

welded or cut. This intense heat in welding is obtained from the use of inflammable gases,

(e.g. acetylene, hydrogen, etc.) or electricity. The intense welding heat and the sources

employed to produce it can be potentially hazardous. Therefore, to protect persons from

injury and to protect building and equipment against fire, etc., a set of recommendations

concerning safety and health measures for the welders and those concerned with the safety

of the equipments etc., have been published by BIS and many other similar but International

organizations. By keeping in mind these recommendations or precautions, the risks associated

with welding can be largely reduced. Therefore, it is suggested that the beginner in the field

of gas welding must go through and become familiar with these general safety

recommendations, which are given below.

1. Never hang a torch with its hose on regulators or cylinder valves.

2. During working, if the welding tip becomes overheated it may be cooled by plunging

the torch into water; close the acetylene valve but leave a little oxygen flowing.

3. Always use the correct pressure regulators for a gas. Acetylene pressure regulator

should never be used with any other gas.

4. Do not move the cylinder by holding the pressure regulator and also handle pressure

regulators carefully.

5. Use pressure regulator only at pressures for which it is intended.

6. Open cylinder valves slowly to avoid straining the mechanism of pressure regulator.

7. Never use oil, grease or lubricant of any kind on regulator connections.

8. For repairs, calibrations and adjustments purposes, the pressure regulators should

be sent to the supplier.

9. Do cracking before connecting pressure regulator to the gas cylinder.

10. Inspect union nuts and connections on regulators before use to detect faulty seats

which may cause leakage of gas when the regulators are attached to the cylinder

valves.

11. Hose connections shall be well fittings and clamped properly otherwise securely

fastened to these connections in such a manner as to withstand without leakage a

pressure twice as great as the maximum delivery pressure of the pressure regulators

provided on the system.

12. Protect the hose from flying sparks, hot slag, hot workpiece and open flame. If dirt

goes into hose, blow through (with oxygen, not acetylene) before coupling to torch

or regulator.

13. Store hose on a reel (an automobile wheel) when not in use.

14. Never allow the hose to come into contact with oil or grease; these deteriorate the

rubber and constitute a hazard with oxygen.

15. Use the correct color hose for oxygen (green/black) and acetylene (red) and never

use oxygen hose for acetylene or vice versa.

16. Always protect hose from being trampled on or run over. Avoid tangle and kinks.

Never leave the hose so that it can be tripped over.

Hazards of fumes, gases and dusts can be minimized by (i) improving general ventilation

of the place where welding is carried out (ii) using local exhaust units, and (iii) wearing

individual respiratory protective equipment.

CLASSIFICATION OF WELDING AND ALLIED PROCESSES

CLASSIFICATION OF WELDING AND ALLIED PROCESSES

There are different welding, brazing and soldering methods are being used in industries today.

There are various ways of classifying the welding and allied processes. For example, they may

be classified on the basis of source of heat, i.e., blacksmith fire, flame, arc, etc. and the type

of interaction i.e., liquid / liquid (fusion welding) or solid/solid (solid state welding). Welding

processes may also be classified in two categories namely plastic (forge) and fusion. However,

the general classification of welding and allied processes is given as under

(A) Welding Processes

1. Oxy-Fuel Gas Welding Processes

1 Air-acetylene welding

2 Oxy-acetylene welding

3 Oxy-hydrogen welding

4 Pressure gas welding

2. Arc Welding Processes

1. Carbon Arc Welding

2. Shielded Metal Arc Welding

3. Submerged Arc Welding

4. Gas Tungsten Arc Welding

5. Gas Metal Arc Welding

6. Plasma Arc Welding

7. Atomic Hydrogen Welding

8. Electro-slag Welding

9. Stud Arc Welding

10. Electro-gas Welding

3. Resistance Welding

1. Spot Welding

2. Seam Welding

3. Projection Welding

4. Resistance Butt Welding

5. Flash Butt Welding

6. Percussion Welding

7. High Frequency Resistance Welding

8. High Frequency Induction Welding

4. Solid-State Welding Processes

1. Forge Welding

2. Cold Pressure Welding

3. Friction Welding

4. Explosive Welding

5. Diffusion Welding

6. Cold Pressure Welding

7. Thermo-compression Welding

5. Thermit Welding Processes

1. Thermit Welding

2. Pressure Thermit Welding

6. Radiant Energy Welding Processes

1. Laser Welding

2. Electron Beam Welding

(B) Allied Processes

1. Metal Joining or Metal Depositing Processes

1. Soldering

2. Brazing

3. Braze Welding

4. Adhesive Bonding

5. Metal Spraying

6. Surfacing

2. Thermal Cuting Processes

1. Gas Cutting

2. Arc Cutting

TWIST DRILL GEOMETRY.

Twist Drill Geometry
Twist drill geometry and its nomenclature are shown in Fig. 22.5. A twist drill has three
principal parts:
(i) Drill point or dead center
(ii) Body
(iii) Shank.

Drill axis is the longitudinal centre line.
Drill point is the sharpened end of the drill body consisting of all that part which is
shaped to produce lips, faces and chisel edge.
Lip or cutting edge is the edge formed by the intersection of the flank and face
Lip length is the minimum distance between the outer corner and the chisel-edge
corner of the lip.
Face is that portion of the flute surface adjacent to the lip on which the chip impinges
as it is cut from the work.
Chisel edge is the edge formed by the intersection of the flanks.
Flank is that surface on a drill point which extends behind the lip to the following flute.
Flutes are the grooves in the body of the drill, which provide lips, allow the removal of
chips, and permit cutting fluid to reach the lips.
Flute length is the axial length from the extreme end of the point to the termination
of the flutes at the shank end of the body.
Body is that portion of the drill nomenclature, which extends from the extreme cutting
end to the beginning of the shank.
Shank is that portion of the drill by which it is held and driven,
Heel is the edge formed by the intersection of the flute surface and the body clearance.
Body clearance is that portion of the body surface reduced in diameter to provide
diametric clearance.
Core or web is the central portion of the drill situated between the roots of the flutes
and extending from the point end towards the shank; the point end of the core forms the
chisel edge.
Lands are the cylindrically ground surfaces on the leading edges of the drill flutes. The
width of the land is measured at right angles to the flute.
Recess is the portion of the drill body between the flutes and the shank provided so as
to facilitate the grinding of the body. Parallel shank drills of small diameter are not usually
provided with a recess.
Outer corner is the corner formed by the intersection of the lip and the leading edge of
the land.
Chisel edge comer is the corner formed by the intersection of a lip and the chisel edge.
Drill diameter is the measurement across the cylindrical lands at the outer corners of
the drill. .
Lead of helix is the distance measured parallel to the drill axis between corresponding
points on the leading edge of a flute in one complete turn of the flute.
Helix angle is the angle between the leading edge of the land and the drill axis.
Rake angle is the angle between the face and a line parallel to the drill axis. It is bigger
at the face edges and decreases towards the center of the drill to nearly 0°. The result is that
the formation of chips grows more un-favorable towards the centre.
Lip clearance angle is the angle formed by the flank and a plane at right angles to the
drill axis; the angle is normally measured at the periphery of the drill. To make sure that
the main cutting edges can enter into the material, the clearance faces slope backwards in
a curve. The clearance angle is measured at the face edge, must amount to 5° up to 8°.
Point angle is the included angle of the cone formed by the lips.

MACHINE DE FORAGE

MACHINE DE FORAGE

1 INTRODUCTION ..
De forage est une opération de fabrication d'un trou circulaire en enlevant un volume de métal de
le travail en coupant outil appelé foret. Un foret rotatif est une extrémité de coupe-outil avec un ou plusieurs coupe
les lèvres et le plus souvent une ou plusieurs flûtes pour le passage de copeaux et de l'admission de fluide de coupe.
Une machine de forage est une machine-outil destiné à percer des trous dans les métaux. Il est l'un des plus
machines-outils importants et polyvalent dans un atelier. Outre le forage des trous ronds, de nombreux
d'autres opérations peuvent également être effectuées sur la machine de forage tels que contre-ennuyeux,
fraisage, rodage, alésage, rodage, sablage, etc
2 CONSTRUCTION DE MACHINE DE FORAGE
Machine de forage dans le forage est mis en rotation et recevant le long de son axe de rotation fixe dans l'
pièce. Différentes parties d'une machine de forage sont discutés
ci-dessous: (i) La tête contenant un moteur électrique, V-poulies à courroie en V et qui transmettent rotatif
mouvement de la broche de perçage à un certain nombre de vitesses. (Ii) de la broche est constituée d'acier allié. Il
tourne ainsi que se déplace de haut en bas dans un manchon. Un pignon en prise avec une crémaillère fixée sur le
manchon pour fournir un mouvement vertical de haut en bas de la broche et donc du forage, de sorte que le
même peut être introduit dans la pièce à usiner ou en être retirés lors du forage d'. Vitesse de rotation ou de la
vitesse de la perceuse est changée avec l'aide de la courroie trapézoïdale et V-beaux-poulies. Les grandes machines de forage sont
ayant boîtes de vitesses dans le but déclaré. (Iii) de mandrin de forage est maintenu à la fin de la broche de perçage
et à son tour, contient le trépan de forage. (Iv) réglable table de pièce à usiner est supporté sur la colonne
de la machine de forage. Il peut être déplacé à la fois verticalement et horizontalement. Les tables sont généralement
comportant des fentes de telle sorte que l'étau ou de la pièce peut être solidement tenue à ce sujet. Table de base (v) est
un casting lourd et il prend en charge la structure de la perceuse. La base supporte la colonne, qui
à son tour, prend en charge la table, la tête etc (vi) la colonne est une tour verticale ou caisson qui repose
sur la base et supporte la tête et la table. La colonne ronde peut avoir des dents de crémaillère coupé
sur lui afin que la table peut être soulevé ou abaissé en fonction des exigences de pièce.
Cette machine se compose de pièces suivantes
1. Base
2. Pilier
3. Entraînement principal
4. Percer la broche


3 TYPES DE MACHINE DE FORAGE
Machines de forage sont classés sur la base de leurs caractéristiques de construction, ou le type
de travail qu'ils peuvent manipuler. Les différents types de machines de forage sont les suivants:
(1) Perceuse portable
(2) machine de forage sensible
(A) Banc de montage
(B) de montage au sol
(3) machine de forage vertical
(A) section de la colonne ronde
(B) la machine la section Boîte colonne
(4) Perceuse radiale
(A) Plaine
(B) Semiuniversal
(C) universelle
(5) machine de forage Gang
(6) machine à multiple de forage de broche
(7) Perceuse automatique
(8) Machine à perçage profond
(A) verticale
(B) Horizontal
Peu de machines de forage couramment utilisées sont décrites au titre:



1 perceuse portative
Une machine de forage portatif est une petite unité compacte et utilisé pour percer des trous dans worpieces
dans n'importe quelle position, qui ne peut pas être foré dans une machine de forage standard. Il peut être utilisé pour
percer des trous de petit diamètre dans les pièces moulées ou pièces soudées de grandes à cet endroit même où ils
sont couchés. Perceuses sont équipés de petits moteurs électriques, qui peut être
motivée par la nécessité et l'alimentation A.C. D.C.. Ces machines de forage fonctionnent à assez élevé
vitesses et accueillir des exercices jusqu'à 12 mm de diamètre.
2 Machine de forage sensible
Il s'agit d'une petite machine utilisée pour percer de petits trous dans les travaux légers. Dans cette machine de forage,
la pièce à usiner est monté sur la table et de forage est introduit dans l'ouvrage de commande manuelle purement.
Haute vitesse de rotation de la perceuse et nourries à la main sont les principales caractéristiques des forages sensibles
Machine. Comme les sens l'action des opérateurs de forage dans la pièce, à tout instant, il est
appelé machine de forage sensibles. Machine de forage sensible consiste en une table horizontale,
une colonne verticale, une tête de support du moteur et le mécanisme d'entraînement, et une broche verticale.
Forets de diamètre de 1,5 à 15,5 mm peut être mis en rotation dans la broche de perçage sensible
Machine. En fonction de la fixation de la base de la machine, il peut être classé dans
les types suivants:
1. Banc de montage machine de forage, et
2. Monté au sol machine de forage
3 Machine de forage vertical
La machine de forage verticale est plus grande et plus lourd que l'une machine de forage sensibles. Il
est conçu pour manipuler des pièces de taille moyenne et est fourni avec dispositif d'alimentation de puissance.
Dans cette machine un grand nombre de vitesses de rotation et des aliments pour peut être disponible pour le forage
les différents types de travail. Machines de forage verticaux sont disponibles en différentes tailles et avec
capacités de forage divers (allant jusqu'à 75 mm de diamètre exercices). La table de la machine
a également différents types d'ajustements. Sur la base de la construction, il ya deux générale
types de machines de forage verticale:
(1) section de la colonne ronde ou à la machine de forage pilier.
(2) section de la colonne Box.
La section ronde de colonne de forage Machine verticale comprend une colonne ronde que
la machine de forage verticale a une section de colonne boîte. Les autres caractéristiques de construction de
les deux sont identiques. Machines colonne de zone de posséder plus de force de la machine et la rigidité par rapport
à ceux ayant la colonne de section ronde.
4 Perceuse radiale
 La machine de forage se compose d'un radiale
lourde, rond colonne verticale supportant un bras horizontal qui porte la tête de forage. Bras peut
être soulevé ou abaissé sur la colonne et peut également être pivoté autour d'une position quelconque sur le
travailler et peut être bloqué dans n'importe quelle position. La tête de forage contenant mécanisme de rotation et
alimenter le forage est monté sur un bras radial et peut être déplacé horizontalement sur les guidages
et serrée dans la position souhaitée. Ces ajustements de bras et la tête de forage permettent l'
opérateur de localiser le foret rapidement sur n'importe quel point sur le travail. Le tableau de perçage radial
machine peut également être tourné par 360 °. La taille maximale du trou que la machine
peut forer n'est pas plus de 50 mm. De puissants moteurs d'entraînement sont adaptés directement dans la tête
de la machine et un large éventail de sources d'alimentation sont disponibles ainsi que sensible et adaptée
manuel se nourrit. La perceuse radiale est principalement utilisé pour le forage de moyenne à grande et
pièces lourdes. Selon les différents mouvements de bras horizontal, une table et de forage
la tête, la machine de forage verticale peuvent être classés en types suivants-
1. Plaine perceuse radiale
2. Semi perceuse universelle, et
3. Perceuse universelle.

DRILLING MACHINES

DRILLING MACHINE

..1 INTRODUCTION
Drilling is an operation of making a circular hole by removing a volume of metal from
the job by cutting tool called drill. A drill is a rotary end-cutting tool with one or more cutting
lips and usually one or more flutes for the passage of chips and the admission of cutting fluid.
A drilling machine is a machine tool designed for drilling holes in metals. It is one of the most
important and versatile machine tools in a workshop. Besides drilling round holes, many
other operations can also be performed on the drilling machine such as counter- boring,
countersinking, honing, reaming, lapping, sanding etc.
2 CONSTRUCTION OF DRILLING MACHINE
In drilling machine the drill is rotated and fed along its axis of rotation in the stationary
workpiece. Different parts of a drilling machine are  discussed
below: (i) The head containing electric motor, V-pulleys and V-belt which transmit rotary
motion to the drill spindle at a number of speeds. (ii) Spindle is made up of alloy steel. It
rotates as well as moves up and down in a sleeve. A pinion engages a rack fixed onto the
sleeve to provide vertical up and down motion of the spindle and hence the drill so that the
same can be fed into the workpiece or withdrawn from it while drilling. Spindle speed or the
drill speed is changed with the help of V-belt and V-step-pulleys. Larger drilling machines are
having gear boxes for the said purpose. (iii) Drill chuck is held at the end of the drill spindle
and in turn it holds the drill bit. (iv) Adjustable work piece table is supported on the column
of the drilling machine. It can be moved both vertically and horizontally. Tables are generally
having slots so that the vise or the workpiece can be securely held on it. (v) Base table is
a heavy casting and it supports the drill press structure. The base supports the column, which
in turn, supports the table, head etc. (vi) Column is a vertical round or box section which rests
on the base and supports the head and the table. The round column may have rack teeth cut
on it so that the table can be raised or lowered depending upon the workpiece requirements.
This machine consists of following parts
1. Base
2. Pillar
3. Main drive
4. Drill spindle






3 TYPES OF DRILLING MACHINE
Drilling machines are classified on the basis of their constructional features, or the type
of work they can handle. The various types of drilling machines are:
(1) Portable drilling machine
(2) Sensitive drilling machine
(a) Bench mounting
(b) Floor mounting
(3) Upright drilling machine
(a) Round column section
(b) Box column section machine
(4) Radial drilling machine
(a) Plain
(b) Semiuniversal
(c) Universal
(5) Gang drilling machine
(6) Multiple spindle drilling machine
(7) Automatic drilling machine
(8) Deep hole drilling machine
(a) Vertical
(b) Horizontal
Few commonly used drilling machines are described as under:

1 Portable Drilling Machine
A portable drilling machine is a small compact unit and used for drilling holes in worpieces
in any position, which cannot be drilled in a standard drilling machine. It may be used for
drilling small diameter holes in large castings or weldments at that place itself where they
are lying. Portable drilling machines are fitted with small electric motors, which may be
driven by both A.C. and D.C. power supply. These drilling machines operate at fairly high
speeds and accommodate drills up to 12 mm in diameter.
2 Sensitive Drilling Machine
It is a small machine used for drilling small holes in light jobs. In this drilling machine,
the workpiece is mounted on the table and drill is fed into the work by purely hand control.
High rotating speed of the drill and hand feed are the major features of sensitive drilling
machine. As the operator senses the drilling action in the workpiece, at any instant, it is
called sensitive drilling machine. A sensitive drilling machine consists of a horizontal table,
a vertical column, a head supporting the motor and driving mechanism, and a vertical spindle.
Drills of diameter from 1.5 to 15.5 mm can be rotated in the spindle of sensitive drilling
machine. Depending on the mounting of base of the machine, it may be classified into
following types:
1. Bench mounted drilling machine, and
2. Floor mounted drilling machine
3 Upright Drilling Machine
The upright drilling machine is larger and heavier than a sensitive drilling machine. It
is designed for handling medium sized workpieces and is supplied with power feed arrangement.
In this machine a large number of spindle speeds and feeds may be available for drilling
different types of work. Upright drilling machines are available in various sizes and with
various drilling capacities (ranging up to 75 mm diameter drills). The table of the machine
also has different types of adjustments. Based on the construction, there are two general
types of upright drilling machine:
(1) Round column section or pillar drilling machine.
(2) Box column section.
The round column section upright drilling machine consists of a round column whereas
the upright drilling machine has box column section. The other constructional features of
both are same. Box column machines possess more machine strength and rigidity as compared
to those having round section column.
4 Radial Drilling Machine
 The radial drilling machine consists of a
heavy, round vertical column supporting a horizontal arm that carries the drill head. Arm can
be raised or lowered on the column and can also be swung around to any position over the
work and can be locked in any position. The drill head containing mechanism for rotating and
feeding the drill is mounted on a radial arm and can be moved horizontally on the guide-ways
and clamped at any desired position. These adjustments of arm and drilling head permit the
operator to locate the drill quickly over any point on the work. The table of radial drilling
machine may also be rotated through 360 deg. The maximum size of hole that the machine
can drill is not more than 50 mm. Powerful drive motors are geared directly into the head
of the machine and a wide range of power feeds are available as well as sensitive and geared
manual feeds. The radial drilling machine is used primarily for drilling medium to large and
heavy workpieces. Depending on the different movements of horizontal arm, table and drill
head, the upright drilling machine may be classified into following types-
1. Plain radial drilling machine
2. Semi universal drilling machine, and
3. Universal drilling machine.

Boiler

Boiler 
It's called boiler to a container used to heat water. In systems of heating , the boiler is the device that heats the water by means of a fuel , which is then distributed by the transmitters through a network of pipes .

 Description

Basically consists of a boiler house , where combustion occurs and a heat exchanger where water is heated. Also must have a system for evacuating gases from combustion.
The water can be heated to different temperatures. In normal boilers are usually not exceed 90 ° C below the boiling point of water at atmospheric pressure. In larger boilers, to serve neighborhoods, you get to 140 ° C, maintaining high pressure in the pipes so it does not boil dry (superheated water). There are also steam boiler in which water is conveyed to evaporation and the vapor is distributed to the terminal elements, but in Europe is quite out of use, because the surface temperature thereof is very high and cause danger of burns. There are also boiler in which water is heated to temperatures below 70 ° C and high performances ( condensing boiler ).
The fuel used can be solid ( wood , coal ), liquids ( fuel oil , diesel ) or gaseous ( liquid petroleum gas or LPG , natural gas ), which determines the shape of the boilers.


 boiler fluid fuels
The fuel is prepared and burned in a burner in which fuel is mixed with the precise amount of air within the home is driven by a fan, where combustion occurs. When the fuel is liquid ( oil ) is required to achieve the pulverized mixture. Gaseous fuels also be mixed with air, but need not pulverize.
There are also specific boiler fuel gases with atmospheric burner . The gas is let out through a nozzle so that, by Venturi effect , sucks air and mixes with it in proper proportion and burned in a suitable burners, divided into small flames, within a suitable heat exchanger. The best known of these boilers are called murals, but also exist in large sizes. 1
Regulating the power in the two types is made by regulating the size of the flame (modulating burners) or by stopping and starting the burner.
 solid fuel boiler
In the solid fuel, the home consists of two superimposed compartments. In the upper hearth , put the fuel on a grate. The bottom ash , receives fuel ash. On the door it enters the air required for combustion and fumes are drawn through a duct (flue or chimney) portrait, thermal draft . The heat is shooting itself in the home creates a lack of pressure sucks the combustion air. The power regulation is done by opening or closing the air inlet.
Coal is used as fuel, or now biomass.
 Accessories
They must also have accessories such as:
burners
Expansion vessel
gauges
thermometers (temperature probes)
Safety lines
safety valve
and control valves

The most common accessories are as follows:
Observing Accessories to monitoring the operation of the boiler:
level tubes
test cocks
gauges
thermometers
gas analyzers
Accessories Security, designed to avoid excessive pressure steam generation in the boiler:
lever and counterweight
Direct weight
spring
fusible plug
alarm systems
Water feed accessories:
water feed pump
water injector
Accessories supply of fuel:
burners for liquid and gaseous fuels
Mechanical burners for solid fuel
manual elements
Cleaning accessories:
records, or cleaning caps
punga valves
pungas retention Estaque
escabiadores
chimney sweeps

RAPID THERMAL PROCESSING

Rapid Thermal Processing


Rapid Thermal Processing (dt: rapid thermal processing ) is an umbrella term for the processing of wafers in a high-temperature process in which a very rapid heating of the wafer with halogen lamps is achieved.

Principle 

Integrated into the wafer processing chamber by several halogen lamps (usually 150-250 pieces at 200 mm wafers) with a total capacity of 40 kW and more heated to a temperature of 1000 ° C.
Due to the high efficiency of the lamps are heating rates (engl. ramp-up ) above 100 degrees per second. After switching off the halogen lamps of the wafer cools down again very quickly (English ramp down , about 50 degrees per second). Most RTP processes take place under vacuum to an unwanted oxidation to avoid
Processes 

Rapid thermal annealing 


Rapid thermal annealing (RTA, dt: rapid thermal annealing ) is used for healing of the crystal structure of the wafer, for example, after implantation processes . By this method, are crystal lattice defects in the wafer treated reduced and thus improves the electrical properties. To achieve this, the wafer 10-20 seconds to temperatures around 1000 ° C is brought. May balance out any minor dislocations in the crystal and dopants include at interstitial places better in the crystal lattice. By the short process times, however, the further diffusion of the dopants is limited to a minimum.
Rapid thermal oxidation
Rapid thermal oxidation (RTO, dt: rapid thermal oxidation ) is used to produce very thin oxides (<20 angstroms), primarily silicon dioxide on silicon substrates, for example, the screen oxide than for implantation processes are used. The process builds upon the thermal oxidation of silicon dar. In contrast to thermal oxidation, in which a plurality of wafers are processed simultaneously in an oxidation furnace, it is at RTO system usually to single wafer processing equipment. RTO is in terms of oxide growth is not significantly faster than the oxidation in high oxidation furnaces, considering, but the entire process (loading, high heat, oxidation, and cooling) reduces the time effort from hours to a few minutes, but only for one instead of 50 wafers.
Other applications

Production of titanium silicide by coating a titanium layer of approximately 40 nm thickness and subsequent conversion into a silicide by RTP

ANNEALING

Annealing
The annealing of a metal part or of a material is a method corresponding to a heating cycle. This is a step gradual rise in temperature followed by controlled cooling. This procedure, common in materials science, to change the physical characteristics of the metal or the material studied. This is especially used to ease the stress relaxation that can accumulate in the heart of the matter, as a result of mechanical or thermal stresses, the steps involved in synthesis and shaping materials. At the time of annealing, the grains (single crystals) of material form again and again somehow, their "steady state".
The annealing is also used to change the magnetic properties of a room.
The crystallization annealing after cold working , aims to give the metal an optimal grain size for future use (folding, stamping , ...).

Necessity of annealing: in metallurgy 

The rolling of a cold steel contributes to hardening and loss of ductility of the metal. Grain growth is necessary to find exploitable metallurgical characteristics.
Examples of use of annealing:
adaptation of the metal grain size for optimum performance (after casting)
Elimination of residual stresses (plastic deformation)
reduction in the hardness for a machining
obtaining single-crystal pieces of unique features (eg rotor blades of turbo-machinery)
...
Process 

The annealing is obtained by raising the temperature of the metal at temperatures ranging from 500  ° C to 850  ° C . The quality of annealing requires heating cycle (time of rise in temperature, holding time) under control (it can be slow or fast).
It is necessary to respect certain values ​​coupled holding time and heating temperature for complete recrystallization.
The heating rate influences the size of grains (and their number). Depending on the original structure and the desired grain size, it will be faster or slower. The holding time, the heating temperature and the rate of cooling influencing more the grain size.
The descent is more rapid (without reaching quench rates), most grains remain small.
If quenching is desired, it can be performed instead of cooling annealing.

Slow cycle and rapid cycling 

The slow cycle of annealing a steel is performed by placing the coils in the bells for 30 to 40 hours. The continuous annealing allows for him a cycle of rapid heating (90 seconds + or - 30 seconds). the cooling step should be as slow. For example, the bell-type furnaces HICO/H2 use at the end of the heating cycle that begins with a cooler air cooling, to a temperature of 300  ° C , followed by a water spray until at a temperature of 70  ° C .

Interest of continuous annealing

Appeared in the 1960s, continuous annealing brings together on a continuous line operations annealing, cold working, inspection, oiling, marking, edge trimming and winding. It allows a significant time savings compared to the annealing bells (also called annealing base).

Microelectronics 

Annealing is a technique also used in processes for microelectronics . It allows for example:
the diffusion of dopants ( boron , arsenic , phosphorus , etc..) in a semiconductor intrinsic
in the case of one or more layers of metal (s) on a semiconductor metal diffusion in the semiconductor, thereby changing its nature and thereby enhancing or changing the nature of the junction with the metal
improvement of a ohmic contact by forming silicide - or as the term used saliciure - (case of silicon )
transformation of a Schottky contact in ohmic contact (for example by annealing a layer of aluminum on a layer of silicon)
restoring a damaged surface for a semiconductor simple: when a semiconductor single (non-binary, tertiary or quaternary, etc). as silicon or germanium is damaged, for example following a burn plasma or reactive ion etching (bombarding the surface with ions and electrons), it is possible to anneal the semiconductor in an attempt to restore the surface. This technique does not work with semiconductor binary (or tertiary, etc..) Because the heat tends to disintegrate the alloy of the two (or more) elements used.

Heat treatment

The heat treatment of a material (by the heat or cold) is designed to modify certain properties (resistance in general). It may involve materials such as glass, wood, metal, or food.

Heat treatments also play an important role in the field of tribology.

In metallurgy :

The heat treatment of a piece of metal is to apply any structural changes with predetermined cycles of heating and cooling in order to improve the mechanical characteristics: hardness , ductility , yield strength , ...

This process is often coupled with the use of a controlled atmosphere during the heating part, either to prevent its oxidation , or to make a contribution or change of molecular surface ( surface treatment ).

General :

In metals, the atoms are organized in the form of crystals  : they form an ordered structure. Foreign atoms - impurities, alloying elements - can enter the network, either by substitution of the atoms 'core', or insertion, is the notion of solid solution .

In addition, there may be several types of crystals, such as inclusions, for example. The crystals are called minority "  rushed  ".

With increasing temperature, the atoms of the crystal s' agitate around their position and diverge from each other, causing expansion . This has several consequences:

the space between the atoms increases, which can accommodate more atoms in solution integration, and larger atoms;

therefore, there may be a precipitate dissolution: the atoms of these crystals pass in solid solution;

atoms are shaking, they become mobile and can move through the crystal, a phenomenon called diffusion  ;

in some cases, the atoms of the crystal reorganize in another crystallographic phase, we speak of allotrope .

It is these mechanisms that come into play during heat treatment.

Case of ductile materials :

A ductile material is a material that can deform plastically  , this is used for shaping ( rolling , drawing , forging , ...). This deformation defects of organization of atoms in the crystal, which hardens the material: this is the work hardening .

By heating the metal in a moderate way, it gives mobility to the atoms, they reorganize and eliminate the lack of organization. It softens the material as well. This process is called annealing .

Case of steels :

At low temperatures, two-phase steel is at steady state: it is composed of crystals of iron with carbon in solid solution (α or ferritic structure), and crystals of iron carbide Fe 3 C.

Steel has an allotropic transformation: it is low-temperature bcc (ferrite α) and fcc at high temperature (austenitic structure or γ). The austenitic structure of this largest insertion sites. When heating in the austenitic area, carbides dissolve (solution treatment).

If the carbon content is sufficient, then rapid cooling allows the iron atoms to reorganize (γ → α transformation) - so-called displacive transformation - but not to the carbon atoms move to reform carbides - called diffusive transformation. Was formation of a carbon-supersaturated structure which hardens the steel. This development is supported by the presence of alloying elements in low (chromium, nickel, molybdenum). According to the cooling rate, is formed of martensite or bainite .

If the cooling rate is very fast - splat - it freezes the structure γ. Is obtained an austenitic steel at room temperature. This is true of many stainless steels.

Case of alloys of aluminum :

Some aluminum alloys have a cure by forming precipitates with alloying elements: Al 2 Cu for copper-containing alloys, Mg 2 Si for alloys containing magnesium and silicon, ... This is called hardening .

With the rise in temperature, to 500  ° C , the precipitates dissolve, that is dissolving. Tempering prevents the reformation of the precipitates. Unlike steel, tempering therefore causes a softening of the alloy.

Grinding

In industrial production , the grinder is a machine tool that can make the correction . This machine tool uses a grinding wheel to produce a perfect surface after machining by a milling machine or a turn .

There are two types of grinding:

1)the surface grinder,

2)The cylindrical grinding.

Surface grinder:

  "Surface Grinder" is commonly used to denote the surface grinder. This term implies, in the current technical use, the grinding surfaces are substantially planar. Several methods of surface grinding are adapted and used to produce surfaces characterized by elements in parallel lines and right angles. Naturally, one can obtain precision surfaces which may consist of long, straight pieces at different angles (such as guides the carriage of a tower, blades and tools of all kinds, for example). In other cases, we obtain curved surfaces or profiled.

The third type of grinder is a grinding machine, but it is equipped with a rotating flat table. Often used for surfacing the blades and industrial knives.

Advantages of the surface grinder 

Alternative methods for engineering surfaces similar to those obtained with a grinder is the use of a milling machine and a much more limited degree, the "Glider". However, the grinder has a clear advantage over alternative methods with respect to cutting tools. Examples of potential benefits:

Rectifier is applicable on hard or abrasive materials without significant effect on the efficiency of removal of material.

The desired shape and dimensional level of the work surface can be obtained at a higher level and in a manner more consistent.

Surfaces of a high precision finished, when using the appropriate system, are produced.

Tooling costs for grinding are relatively cheaper than other machine tools.

Fixing parts is generally very simple. Especially when a magnetic platform is installed on the crossing of the grinder.

Main systems of surface grinding 

Flat surfaces can be corrected using different sides of the wheel by various arrangements of the table, the wheel and the reciprocating movement. Most systems include surface grinding, with their respective capabilities, work on two major distinct characteristics:

The operation surface of the grinding wheel , or can be its periphery its face (side)

The table movement during labor may be transverse (usually reciprocal) or rotation (continu.

ELECTRIC ARC FURNACE

ELECTRIC ARC FURNACE

  

An arc furnace is a type of oven used in metallurgy . It uses the energy heat of the electric arc established between one (or more) electrode (s) of carbon and the metal to obtain a sufficient temperature to its melting .

Small (about one ton) or high capacity (up to 400 t ), it is mainly used for production of liquid steel (about 35% of world production) and also for the recycling of metals (for example to recover the zinc from dust and metallurgical wastes) (process called Electric Arc Furnace Dust (EAFD) by the Anglo-Saxon).

Dome of a rotary electric furnace steel

Miniature arc furnaces are used in some research laboratories. Some furnaces are used for reactions between solid and gas phases between.

It is found in other sectors, such as that of dentistry , with capacities from a few ounces.

Principle :

Principle: In an envelope refractory (not closed to exhaust vapors), a high voltage is applied between the electrodes ( graphite - carbon ) and the metal to melt. This tension brings out an electric arc . Electrical cables, the envelope, the roof (or the dome) and some elements are cooled with water or other coolant.

The temperature generated by the arc exceeds 1800 ° C and can reach 3600 ° C . A colder zone persists between the electrodes, a problem is usually solved by gas burners + oxygen or electromagnetic stirring of molten metal.

Filling a pocket by tilting the sole

Some ovens operate in DC and are then fitted with only one electrode.

Openings, or tilting of the furnace used to recover the molten metal and slag .

Energy 

It varies by age and quality of the oven and depending on the materials you walk inside.

A ton of steel to be produced in an electric arc furnace in theory requires about 440 kWh. The theoretical minimum required to melt one ton of scrap steel is 300 kWh (melting point 1520  ° C / 2,768 ° F). Make steel with an electric arc is therefore economical only where there is plenty of power with an electric grid stable and well developed.

Quality 

These ovens are cost-effective than using metallurgical wastes. These, often poorly controlled or rich impurities have affected the quality of steel products. Indeed, some chemical elements (such as copper , the tin , the molybdenum or chromium are very difficult to remove once dissolved in the liquid steel, which often are associated with scrap metal.

This difficulty controlling purity metal has limited the production of steel in electric furnaces with alloys less demanding:

for construction, long products (rebar, beams , ...) or flat ( sheet piling , siding , ...)

flat products for common equipment ( cans welded, furniture, ...)