Electrochemical Grinding

Electro-chemical grinding is also called electrolyte grinding.

 Electrolyte grinding is a modification of both the grinding and electrochemical machining.
In this process, machining is affected both by the grinding action and by the electro-chemical process. Hence, it may also be called mechanically assisted electrochemical machining.
Electrochemical Grinding
In ECG the metal bonded grinding wheel impregnated with a non-conductive abrasive is made the cathode and the workpiece the anode as in ECM.
The electrolyte which is usually sodium nitrate, sodium chloride, sodium nitrite, potassium nitrite with a concentration of 0.150 to 0.300 kg/litre of water, is passed through a nozzle in the machining zone in order to complete the electrical bridge between anode and cathode.
The work and wheel do not make contact with each other because they are kept apart by the insulating abrasive particles which protrude from the face of the grinding wheel.
The electrolyte is carried past the work surface at high speed by the rotary action of the grinding wheel. metal is removed from the workpiece by the simultaneous electrolytic and abrasive action.

 It can be seen that the process is similar to conventional grinding in that an abrasive grinding wheel is used, and the work is fed against the rotating wheel. In fact, 10% of the work is removed by abrasive cutting and 90% by electrolytic action.

 The grinding wheel used are conventional shape and structure metal bond, diamond grit wheels are used for grinding tungsten carbide tips. carbon bond wheels are used upon the hard alloy steels such as the stainless steels. 

 The machine is similar in design to surface grinder or tool and cutter grinder and equipment includes a tank, filter and pump for the supply of electrolyte and a power unit for delivering a heavy D.C current. The current applied is in the range of 50 to 3000 A at 4 to 10 V.

 Accuracy :
  • Tolerance is about +0.02 to -0.02 are held on the rather complex grinding operation.
  • For closer tolerances, the proportion of material removed by abrasive should be increase.
  • Surface finish is held in a range of 0.2 to 0.4 micron on carbide and 0.4 to 0.8 micron on steel.
  • A sharp corner is difficult to obtain and minimum radius of 0.2 mm.
Applications :
  • Any material which is electrically conductive may be ground by the electrolytic process.
  • Mainly used for resharpening and reconditioning of carbide tools and other materials that are hard to grind.
  • Grind and cut thin sections
  • Grind difficult materials without distortion or burr.
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Stuxnet Documentry

Since Stuxnet is a worm, it has a lot of similarity with other worms. What differentiated Stuxnet from any another malicious worm is how differently capable it was to induce damage on its target. Its capability includes exploiting multiple zero-day vulnerabilities, modifying system libraries, attacking Step7 installations (Siemens’ SCADA control software) and running an RPC server and installing signed drivers on Windows Operating Systems. Stuxnet spread via several methods, but all methods were integrated to infect PLCs only. Stuxnet is capable enough auto update itself. It looks for new version in the local area network. Stuxnet hides its presence from the control panel, which is the reason behind unexplained problems in the operation cycle. It remained opaque to its user because the control panel always shows normal functioning.

 Journey of Stuxnet
The first time, Stuxnet was detected by a Belarus-based AV company called VirusBlockAda on June 17, 2010. In the initial phase of the analysis, it was not clearly known, what was the exact reason behind this malware. Even after knowing the target, it was difficult to establish the fact that how it was affecting the control system. Later some of the security experts like Ralph Langner, Symantec engineers wrote a complete technical paper which provided every detail about Stuxnet and how it affected the control systems, particularly the Iran nuclear facility. Although Iran never accepted this fact but experts believe that Stuxnet hit them.


Stuxnet is a vicious piece of code, which unprecedentedly and masterfully attacked in three phases; first, it targeted Microsoft Windows systems and networks, by repeatedly replicating itself. Then it searched for Siemens Step7 software, which is a windows based platform, used to program the ICS that operate equipment in the nuclear facility. Finally, it compromises Programmable Logic Controllers (PLC's).

 Stuxnet gets itself installed in the industrial root kit which feedbacks the false data to outside controllers so that no alarm or shutdown is done due to unexpected behavior of the process. This idea made Stuxnet more vulnerable because it was able to achieve a large part of its task without getting caught.

 The idea of Stuxnet was not only to destroy the nuclear facility completely but also to halt the program as adversely as possible. Stuxnet created a difficult situation for Iranian engineer because even if they were changing the rotors frequently they are not able to get the exact reason behind this error. Stuxnet really frustrates the Iranian engineer to their core.

 Infection
Stuxnet enters the network through a malicious computer which is already infected by a USB flash drive. For entry in any system, Stuxnet shows a digital certificate that gives an illusion to the system that it comes from a reliable source, thus this worm is able to evade the automated detection system. Once Stuxnet gets inside the local network it proceeded to infect all the machines running Microsoft windows.

Search
After infecting the systems, Stuxnet checks whether a given machine was a part of the targeted ICS or not. By analysis of Stuxnet it was clear that even if Stuxnet gone wild in the world, it was never meant to affect any other device but only Natanz Nuclear plant in Iran. It happened because the controller which Stuxnet was searching was present in Iranian Nuclear Power Plant.

 Auto-Update
Stuxnet does not need any kind of internet service to update itself, if any updated
version is available on the local network, it can easily update itself. For auto updation, Stuxnet used RPC (Remote Procedure Call) and wait for connections.

Compromise
The worm then compromises the logic controllers of the target system by using “Zero-day” vulnerabilities. It has been reported that Stuxnet attacked only those PLC systems which were installed by Vacon and Farao paya. Stuxnet monitored the frequency of the attached centrifuge rotors and attacked only those controllers which were spinning in some specific range. Then it installed the payload on the PLC's which resulted in periodic modification of the frequency and as a resultant rotational speed of rotor change.

 Facts of Stuxnet
In order to demonstrate the sophistication of this effort, we would like to point out that Stuxnet utilized various vulnerabilities: 

“Zero-day” Vulnerabilities
Stuxnet exploited a lot of different vulnerabilities, four of which were zero-day
vulnerability. Some of the Zero-day attacks is seen before the Stuxnet but concatenating different Zero-day attacks were massive and infectious. Zero-day attack is briefed below:
  • Printer-Spooler vulnerability: This service is used to transfer the malicious code and then execute it on other systems in the shared network. Using this vulnerability Stuxnet copies itself from one machine to another machine via shared printers which are publicly available in the network.
  • .LNK vulnerability: A .LNK file is used to launch the malicious code on an infected windows machine. No test is done to verify the file even by anti-virus. The vulnerability is utilized in Stuxnet to reference a file in an infected drive that holds the virus. After installing of the virus, Stuxnet hides the .LNK file as well as the source file. Later autorun.inf is used to automatically run the file in removable media.
  • This vulnerability utilizes a similar vulnerability used in Conficker attack. Stuxnet uses this flaw in RPC call to infect potential hosts on the network. This vulnerability first ensures whether the host system has Stuxnet installed or not, if it's not infected, then it sends the Stuxnet to the uninfected machine.
Stuxnet probe phase
Stuxnet secretly recorded the every normal operation performed for full operation cycle. It plays all the recorded data back to the controllers to make sure whether industrial rootkit used to fake the data is enabled or not. During this infect other computers. Maintain the database of the infected computer, observe the variations and changes, and keep track of successfully infected systems.


Pre-Attack Phase

During the pre-attack phase, Stuxnet utilizes various tactics to spread itself to other systems: 

  • USB Flash Drives-The PLCs connected to the computers whose main functionality is to control and monitor them is not connected to the internet. In Natanz Nuclear plant, the infected flash drives may have been introduced to the control computers via some other external contractors working at the plant.  
  • WinCC-SCADA systems are hard coded with a password and used to connect into WinCC and attack the database using SQL commands to upload and start a copy of itself on WinCC computer. Stuxnet infected all the Siemens SIMATIC Step7 industrial projects that are opened on an infected system. Some modification is done on the .exe file and DLLs (Dynamic Link Library) in WinCC, so that executes Stuxnet code as well. 
  • Network Shares-Stuxnet also used windows shared folder to spread the virus to the local network. Infected computer placed a dropper file in the shared folder and schedule a task to execute this file. There is a debate between experts about the scheduled execution of the file 
Contributed By: Vivek Pratap Chaurasia
Email id: vivekpratap07@gmail.com

Chemical Machining

Chemical machining is stock removal process for the production of desired shapes and dimensions through selective or overall removal of material by a controlled chemical attack with acids or alkalis.

 The metal is gradually transformed into metallic salt by chemical reaction and is ultimately removed in this form.

 The process can be suitably applied to different types of operation such as milling on a milling machine, blanking, and engraving. The chemical machining process can be classified as :
  • Chemical milling
  • Chemical blanking 
  • Chemical engraving

Chemical Machining
Chemical milling :

Chemical milling sometimes called chilling or contour or etching is used mainly to produce shapes by selective or overall removal of metal parts from the relatively large surface area.
The main purpose is to achieve shallow but complex profiles, reduction in weight by removing unwanted material from the surface as in the skin of an aircraft.

Chemical milling complete in four steps :
  1. Cleaning
  2. Masking
  3. Etching
  4. De-masking
Application of CHM :
  • Chemical machining has been applied successfully in a great number of usages where the depth of material removal is critical to a few microns and tolerance are closed.
  • The surface finish obtained in the process is in the range of 0.5 to 2 microns.
  • One of the major application of CHM is in the manufacture if burr-free, intricate stampings.

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Advantages and disadvantages of chemical machining

Chemical machining is stock removal process for the production of desired shapes and dimensions through selective or overall removal of material by a controlled chemical attack with acids or alkalis. The metal is gradually transformed into metallic salt by chemical reaction and is ultimately removed in this form. Let us have a deep insight into the pros and cons of chemical machining in this article. 

Advantages of Chemical Machining :

  • Components are produced burr-free.
  • The process is relatively simple.
  • Can be applied to almost any material.
  • Thin sections.
  • Several components can be produced simultaneously.
  • The process does not distort the machined components.
  • Most difficult to machine material can be processed.
  • High surface finishing is possible.

Disadvantages of Chemical Machining :

  • The metal removal rate is slow.
  • Metal thicker than 2 mm can not be usually machined.
  • High operator skill is required.
  • Corrosive etchant damages the equipment.
  • Required the handling of dangerous chemicals.
  • Disposal of potentially harmful byproducts.
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Types of all wheel drive system

All-wheel drive cars have a different drive system according to the road surface. There are mainly four types of the all-wheel drive system.

  1. Part-time all-wheel drive
  2. Full-time all-wheel drive
  3. Automatic all-wheel drive
  4. Selectable all-wheel drive
The part-time all-wheel-drive system cannot be used in the non-slippery condition you will have to drive such cars in rear-wheel drive condition.
AWD is not necessarily that it is a full-time all-wheel drive and 4 wheel drive is not just four off-road vehicles. They both are same but there is a minor difference between AWD and 4WD.

  • Part-time all-wheel drive 
This is a temporary all-wheel-drive system. In normal condition, just one axle is driven while in slippery condition another axle is engaged by the driver by leaver or button.
This type of all-wheel drive does not have a centre differential.
When all-wheel drive is engaged the front and rear driveshafts are mechanically connected and rotated at the same speed.
  • Full-time all-wheel drive 
This is a permanent all-wheel drive or permanently engaged all-wheel-drive system.
All-wheel is powered at all times and the vehicles with full-time all-wheel drive are equipped with a centre differential that lets each wheel travel different distances while turning.
This type of all-wheel drive used both on and off-road condition.he
In slippery condition, the centre differential can be locked, whether manually or automatically depending on the vehicle.
  • Automatic all-wheel drive 
This is an on-demand all-wheel drive. Under the normal driving condition, only one axle is powered. when wheel slipping occurs at that condition the driving driveshaft rotates faster than the driven driveshaft and a multi-plate hydraulic clutch or other similar traction control device locks and engages another axle.
The difference between the traction devices that are used in full-time all wheel drive and automatic all wheel drive systems is that the device used in automatic all wheel drive system replaces the center differential.
  • Selectable all wheel drive 
In selectable all wheel drive driver can choose between the 2WD mode or 4WD mode with automatic distribution of torque via viscous coupling vehicle behaves like the one with full time all wheel drive.
4WD with locked differential behaves like part-time all wheel drive.

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All wheel drive differential

It is important to know how all-wheel drive works on your car.

 Most of manual AWD cars have 3 differential one in between the front wheels, one in between the rear, and one in between the other two. but in a cheaper car like SUVs designed for city driving uses only 2 differential one front and one rear, and a viscous coupling in the centre.

 For better understanding, you should know first 
Types of the all-wheel drive system 
Difference between AWD and 4WD.

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All wheel drive benefits

There is a lot more difference between AWD and 4WD or difference between front wheel drive and real wheel drive but more important to know the benefits of all-wheel drive.

If you live in an area frequently hit by harsh winter storms and paralyzed by slippery streets then you have to think about to buy AWD car but for those who don't have to deal with such difficult climates, you might not need it as much as you think because the cost is the main issue in AWD cars.  

Another case people sometimes buy an AWD or 4WD vehicle for the occasional off-road outing while 90 per cent of the time they will be sitting in traffic or using the vehicle on paved roads. This would save them money both on the price of the car plus the lower fuel costs.
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Disadvantages of all wheel drive

An all-wheel-drive vehicle is one with a powertrain that can supply power to all its wheels, whether full-time or on-demand. Let us have a deep insight into the disadvantages provided by car used to all-wheel drive.

Disadvantages of all-wheel drive :

  • More expensive to buy.
  • Uses more fuel.
  • Higher maintenance and repair costs.
  • Tires need to be the exact same size may need 4 new ones if one destroyed.
  • Better traction in slippery road conditions can make a driver over-confident in their ability to stop or turn, often resulting in an accident.
  • Heavy more parts mean more weight.
  • Unusual handling characteristics.
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Difference between front wheel drive and rear wheel drive

Both the rear-wheel drive and front-wheel drive are relatively same just a minor difference FWD stands for front-wheel-drive which means that the engine is powering only the front two wheels while RWD stands for rear-wheel-drive means that the engine is powering the rear wheels. Let us have a deep insight into the comparison and difference between them.


Difference between FWD and RWD :

  • The clutch, gearbox and differential in FWD are made from one unit and are called transaxle where the clutch and gearbox are at the front in RWD while the differential is driven at the rear by the propeller shaft.
  • RWD vehicle is being pushed from behind while an FWD vehicle is being pulled.
  • The fuel consumption is usually similar to the FWD and RWD vehicles.
  • In FWD the front wheels of these vehicles are exclusively powered while in RWD the power from the power train is transmitted to the rear wheels via a driveshaft.
  • Only front wheels are responsible to drive the vehicle in FWD while RWD real wheels are responsible to drive the vehicle.
  • RWD cars usually tend to be more powerful and sportier than FWD.
  • The front-wheel weight in FWD is higher than in RWD.
  • FWD configuration provides low floor compared to RWD as there is no longer propeller shaft.
  • Because of the presence of differential at the front, there is more luggage space at the back in FWD compared to RWD.
  • The FWD vehicle has more adhesion on the road than RWD due to more weight on the front wheel.
  • In FWD, the weight shifts to the rear wheel are reduced on a gradient or while accelerating, which is not desirable, thus reducing tractive effort.
  • The steering is hard because of more weight on the front wheel in FWD and there is always understeer.

RWD cars offer a better overall driving experience and are the better cars for drifting and can accelerate faster and provide better grip. As for reduced traction in wet conditions, this can be remedied with modern electronic traction control but are almost always more expensive.
On the other hand, FWD cars may not be as fun to drive, but they are cheaper and more sensitive. It makes more sense to travel within the city at low speeds and to use cheap FWD cars in general on a daily basis.


Front-Wheel Drive cars : 
  • Maruti Suzuki Dzire
  • Alto K10
  • Wagon R
  • Hyundai Verna
  • Skoda Rapid
  • Tata Indigo 
Rear Wheel Drive cars :
  • Chevrolet Tavera 
  • Mahindra Scorpio
  • Mahindra Bolero
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Cheapest rear wheel drive car

Top Affordable Rear Wheel Drive Cars

  • Chevrolet SS

  • Nissan 370Z

  • Chrysler 300/Dodge Charger

  • Dodge Challenger

  • Scion FR-S/Subaru BRZ

  • Hyundai Genesis Coupe

  • Mazda MX-5

  • Chevrolet Camaro

  • Ford Mustang

  • Smart Fortwo

  • Nissan Z

  • Jeep Cherokee

  • Toyota MR2

  • Dodge Charger

  • BMW 3 Series

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Best all wheel drive wagons

The best all-wheel drive wagons are listed below :
  • Audi Allroad
  • BMW 3 Series Sports Wagon
  • Ford Flex
  • Lincoln MKT
  • Mercedes-Benz E-Class 4MATIC Wagon
  • Mini Cooper S Countryman ALL4
  • Subaru Outback
  • Toyota Venza
  • Volvo XC70
  • Volvo V60 T6 R-Design AWD


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Best all wheel drive convertibles cars

The best all-wheel drive convertible cars are listed below :
  • Audi A3 Cabriolet
  • Audi TT/TTS Roadster
  • Audi A5/S5/RS5 Cabriolets
  • Audi R8 Spyder
  • Bentley Continental GT Convertible
  • BMW 4 Series Convertible
  • BMW 6 Series
  • Porsche 911 Cabriolets
  • Porsche 918 Spyder
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Top least expensive All Wheel Drive cars

Top least expensive all-wheel drive cars are listed below :
  • Suzuki SX4
  • Subaru Impreza
  • Subaru Legacy
  • Subaru Forester
  • Nissan Juke
  • Toyota Matrix
  • Subaru XV Crosstrek
  • Kia Sportage
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Best all wheel drive cars and SUVs

Top 10 All Wheel Drive cars are listed below :
  • Subaru Outback
  • Subaru Crosstrek
  • Subaru Forester
  • Audi Q5
  • Chevrolet Suburban/GMC Yukon XL
  • Jeep Wrangler
  • Chevrolet Tahoe/GMC Yukon
  • Jeep Grand Cherokee
  • Toyota 4Runner
  • Ford Expedition
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Difference between JAVA and Javascript

What is JAVA?

Java was first released in 1995 by Sun Microsystems. It is a class-based and object-oriented server-side programming language that is used for a myriad of technical purposes. It runs in a virtual machine and was designed to follow the “write once, run anywhere” methodology, therefore allowing the Java code to run on any platform that supported it without having to recompile.

What is JavaScript?

The JavaScript is a Object Oriented Scripting language, developed by Netscape, Inc., is not part of the Java platform. 

JavaScript does not create applets or stand-alone applications. In its most common form, JavaScript resides inside HTML documents, and can provide levels of interactivity to web pages that are not achievable with simple HTML. 


Key differences between Java and JavaScript:


JAVA Javascript
1 Java is Object Oriented Programming language. Javascript is Object Oriented Scripting language.
2 It creates applications that run in a virtual machine or browser. It runs inside browser only.
3 It is compiled. It is interpreted.
4 Java is high-level, static,compiled and strongly type language. JavaScript is text based , dynamic and weakly typed language.
4 It has block based scope. It has Function based scope
and object based context.
5 It has an implicit this scope for non-static methods, and implicit class scope. It has implicit global scope.
6 It has constructors. It has standard functions.
7 I t is class-based. It is prototype-based.
8 functions are only variadic if explicitly marked. functions are variadic.
9 It allows methods in an object to be redefined independently. object are tied to its class, and cannot be redefined at runtime.
10 Java program has file extension “.Java” and after compilation it becomes “.class” file that contains bytecodes which is executed by JVM : Java Virtual Machine. JavaScript file has file extension “.js”
11  In Java there is different datatypes like int, float, string, etc
There is var keyword is used to define variable
12 Example: 
class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}
 Example:
<html>
<body>
    <p>Beginning text</p>
    <script>
        alert('Hello, World!')
    </script>
    <p>End text</p>
</body>
</html>
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Difference between AWD and 4WD

What is the all-wheel-drive?

 AWD cars are fitted with a centre differential that contains a clutch or viscous drive unit splits torque front-to-rear, directing it away from the spinning wheel. It can go from grippy pavement (where the differentials need to allow different speeds side-to-side and front-to-rear) to slippery snow, rain, or dirt (where torque also needs to be apportioned to wheels with grip). That’s why AWD is the better choice for most drivers and why it helps you safely navigate both inclement weather and light off-road driving.


 What is the four-wheel drive?

 4WD works by locking the front and rear axles together and splitting torque half-half between them provides great traction, but a vehicle locked in 4WD cannot safely be operated on dry pavement because its front and rear axles are forced to rotate at the same speeds so you use 4WD mostly on off-road or in deep snow.


Let us have a deep insight into the difference between them. 

Difference : 

  • In an AWD a front, rear and centre differential to provide power to all four wheels of a vehicle whereas two differentials and a transfer case to provide power to all four wheels of a vehicle in 4WD. 
  • 4WD puts power to all four wheels all the time while AWD vehicles actually have the power to only one rear wheel.
  • 4WD refers to systems that allow the driver to manually switch between driving two wheels and driving all four while the driver usually cannot choose to engage all four wheels in AWD. 
For example 4 wheel drive trucks and truck-based SUVs are rear-wheel drives by default and the driver can switch to 4x4 which will engage the front axle as well, and all four wheels will be engaged until the driver switches back to 2x4 mode.
  • 4WD provides best off-road traction capabilities while AWD provides better grip and sporty feel.
  • AWD gives higher safety ratings.
  • 4WD is not suitable for all driving conditions.
  • 4WD provides equal power to the axles and is either on or off, whereas AWD can direct power as it sees fit to certain axles.
  • 4WD is generally found on trucks and SUV’s such as the Dodge Ram or Chevy Silverado while AWD are found on vehicles such as the Subaru WRX or Audi R8.
  • AWD vehicle has both 2WD and 4WD capabilities while 4WD has the only 4WD capability.
  • Most AWD vehicles are more automatic and most 4WD vehicles are designed in extreme conditions for drivers who want manual control.
  • 4WD has both high and low gear options, while AWD only has a high gear option.
If you plan for using vehicle off-road 4WD will be the best decision to make is reliable and perfect for low-speed terrain while an AWD vehicle will be the better choice if provides a better safety net on the road.
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Milling machine safety precautions

Safety Measures in Milling Operation :

Milling machine operators must be extremely careful in running this machine tool, therefore, some of the safety points should be required to know milling operators.
Following safety points must be followed by operators :
  • Learn to operate controls before operating the machine.
  • The work piece must be rigidly held on the worktable.
  • Keep hands and body away from the revolving cutter.
  • Do not change spindle speed when machining is running.
  • Do not remove or tighten the milling machine arbour nut while power is on.
  • Do not measure work while continuous operation.
  • Do not remove guards while machining.
  • Do not remove chips when the machining is running.
  • Wear snugly fitting clothing.
  • Do not lean on the machine when it is running.
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Working principle of Milling Machine

Operating Principle of Milling Machine :
Milling machine

In a milling machine operating principle machine tool used for the shaping of metal and other solid materials. By use of table and different work holding devices, the work piece is affixed and milling cutter is rotated about the spindle axis. Milling operation involves the movement of the rotating cutter sideways as well as in and out. The cutter and work piece move relative to each other producing a toolpath along which material is removed. Generally in all case of milling multi-tooth cutter is used so that the material removal rate is high and cutting action of the multi-tooth provides a fast method of machining. The machined surface may be flat, angular or curved but the most usually flat surface is produced by a milling machine. Many types of milling machine are used, ranging from relatively simple and versatile milling machine are used for the general purpose of machining to the highly specialized machine for mass production. A milling machine may be operated manually or by CNC or NC machines.
Working of milling

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Types of Milling Machine

Types of Milling Machine :

According to the general design of the milling machine are :

1. Column and knee type
For general shopwork, the most commonly used is the column and knee type where the table is mounted on the knee casting which is turn in mounted on the vertical sides of the main column.
The knee is vertically adjustable on the column so that the table can be moved up and down to accommodate work of various heights. The column and knee type milling machines are classified according to various methods of supplying power to the table, different movements of the table and the different axis of rotation of the main spindle. 
Column and knee type milling machine

  • Hand milling machine
The simplest of all type of milling machine is the hand milling in which the feeding movement of the table is supplied is the hand control.
The cutter is mounted on a horizontal arbour and is rotated by power. 
This machine is particularly suitable for light and simple milling operation such as machining slots, grooves and keyways.
  • Plain milling machine
The plain milling machine is much more rigid and sturdy than hand millers for accommodating heavy workpieces.
A plain milling machine having a horizontal spindle. In a plain milling machine, the table may be fed in a longitudinal, cross or vertical directions.
The feed is longitudinal when the table is moved at right angles to the spindle.
The feed is cross when the table is moved parallel to the spindle. 
The feed is vertical when the table is adjusted in the vertical plane.
  • Universal milling machine
A universal milling machine is named because it may be adapted to be a very wide range of milling operation. A universal milling machine can be distinguished from a plain milling machine in that the table of a universal milling machine is mounted on a circular swivelling base which has degree graduations, and the tale can be swivelled to any angle up to 45 degrees on either side of normal position. In the universal milling machine, in addition to three movements as in plain milling machine, the table may have the fourth movement when it is fed at an angle to the milling cutter. this additional feature enables it to perform helical milling operation.
It may be also produced spur, spiral, bevel gears, twist drills, reamers, milling cutters including all conventional milling operation. so universal milling machine essentially a tool room machine designed to produce very accurate work.

  • Omniversal milling machine
In omniversal milling machine, the table besides having all the movement of the universal milling machine can be tilted in a vertical plane by providing a swivel arrangement at the knee.
The additional swivelling arrangement of the table enables it to machine taper spiral grooves in reamers, bevel gears etc.
  • Vertical milling machine
A vertical milling machine can be eminent from a horizontal milling machine by the position of its spindle which is vertical or perpendicular to the work table. The machine may be of plain or universal type and has all the movements of the table for proper setting and feeding the work.
The machine is adapted for machining grooves, slots and flat surfaces. 

Vertical milling machine
    2. Manufacturing of fixed bed type
    The fixed bed type milling machine is comparatively large, heavy and rigid and it different from column and knee type milling machine by the construction of its table mounting.
    The table is directly mounted directly on the ways of a fixed bed.
    The cutter mounted on the spindle head may be moved vertically on the column and spindle may be adjusted horizontally to provide cross adjustment. It can be classified below :
    • Simplex milling machine
    • Duplex milling machine
    • Triplex milling machine
    The name simplex, duplex and triplex indicate that the machine is provided with single, double and triple spindle heads respectively. 
    In the duplex machine, the spindle heads are arranged one on each side of the table.
    In the triplex machine, the third spindle head is mounted on a cross rail. 
    The feed cycle of the table includes the following : start, rapid approach, slow feed for cutting, rapid traverse to next work piece, quick return and stop.
      3. Planer type
      The planer type machine is built up for heavy-duty work, having spindle heads adjustable in vertical in transverse directions. It has a cross rail capable of being raised or lowered carrying the cutters their heads, and the saddles, all supported by rigid uprights.
      The use of the machine is limited to production work only and is considered ultimate in metal removing capacity.


      4. Special type
      • Rotary table milling machine
      This machine construction is a modification to a vertical milling machine.
      The face milling cutters are mounted on two or more vertical spindles and a number of workpieces are clamped on the horizontal surface of a circular table which rotates about vertical axis.
      The cutters may be set at different heights relative to the work so that when one of the cutter is roughing the pieces the other is finishing them.
      • Drum milling machine
      The drum milling machine is similar to a rotary table milling machine in that work-supporting table which is called drum and it rotates in a horizontal axis.
      The face milling cutters mounted on three or four spindle heads rotate in a horixontal axis and removal metal from workpieces supported on both the faces of drum.
      The finished machined parts are removed after on complete turn of the drum, and then the new ones are clamped to it.
      • Planetary milling machine
      In planetary milling machine, the work is held stationary while the revolving cutter or cutters moves in a planetary path to finish a cylindrical surface on the work either internally or externally or simultaneously. 
      This machine is adapted for milling internal or external threads of different pitches.
      • Pantograph, profiling & tracer controlled milling machine
      A pantograph machine can duplicate a job by using a pantograph mechanism which permits the size of the work piece reproduced to be smaller than, equal to or greater than the size of a template or model used for the purpose.
      A pantograph is a mechanism that is generally constructed of four bar which are joined in the form of pantograph. Pantograph machine are available in two dimensional or three dimensional models.

      Profiling machine duplicates the full size of the template attached to the machine. This is practically a vertical milling machine or bed type in which the spindle can be adjusted vertically and cutter head horizontally across the table.
      The movement of cutter regulated by a hardened guide pin.

      Tracer controlled milling machine reproduces irregular or complex shapes of dies, moulds etc.
      The feeding motion of the machine is controlled by means of a stylus that scans a profiled template or a contoured model which is to be reproduced.

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      Introduction of milling machine

      The first milling machine came into existence in about 1770 and was a french origin.

       The milling cutter was first developed by Jacques de Vaucanson in 1782.

       The first successful plain milling machine was designed by Eli Whitney in 1818.

       The universal milling machine was invented by Joseph R Brown a member of Brown and Sharpe company in 1861.

       A milling machine is a machine tool that removes metal as the work is fed against a rotating multipoint cutter. The cutter rotates at a high speed and because of the multiple cutting edges.

       it removes metal at a very fast rate.

       The machine can also hold one or number of cutters at a time so milling machine finds wide application in production work.

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