ALL ABOUT CUTTING SPEED,FEED ,DEPTH OF CUT IN MACHINE TOOLS

CUTTING SPEED:-

Cutting speed is defined as the speed at which the work moves with respect to the tool (usually measured in feet per minute)
. The cutting speed, expressed in FPM, must not be confused with the spindle speed of the lathe which is expressed in RPM. To obtain uniform cutting speed, the lathe spindle must be revolved faster for workplaces of small diameter and slower for workplaces of large diameter. The proper cutting speed for a given job depends upon the hardness of the material being machined, the material of the tool bit, and how much feed and depth of cut is required. Cutting speeds for metal are usually expressed in surface feet per minute, measured on the circumference of the work 

FEED RATE:-

Feed rate is defined as the distance the tool travels during one revolution of the part. Cutting speed and feed determines the surface finish, power requirements, and material removal rate. The primary factor in choosing feed and speed is the material to be cut. However, one should also consider material of the tool, rigidity of the workpiece, size and condition of the lathe, and depth of cut. For most Aluminum alloys, on a roughing cut (.010 to .020 inches depth of cut) run at 600 fpm. On a finishing cut (.002 to .010 depth of cu t) run at 1000 fpm. To calculate the proper spindle speed, divide the desired cutting speed by the circumference of the work. Experiment with feed rates to achieve the desired finish. In considering depth of cut, it's important to remember that for each thousandth depth of cut, the work diameter is reduced by two thousandths.


DEPTH OF CUT:-

Depth of cut is the distance that the tool bit moves into the work. usually measured in thousandths of an inch or in millimeters. General machine practice is to use a depth of cut up to five times the rate of feed, such as rough cutting stainless steel using a feed of 0.020 inch per revolution and a depth of cut of 0.100 inch. which would reduce the diameter by 0.200 inch. If chatter marks or machine noise develops, reduce the depth of cut. 

NOTES ON WATER JET MACHINING

Introduction :-

• Water jets alone (without abrasives) can be used for cutting. Thin jets of high pressure and high velocity have been used to cut materials such wood, coal, textiles, rocks, concrete, asbestos.
• The mechanism of material removal rate is by erosion. When high pressure water jet emerges of a nozzle, it attains a large kinetic energy.
• High velocity jet strikes the work piece, its kinetic energy is converted into pressure energy including high stresses in the work material.
• When the induced stress exceeds the ultimate shear stress of the material, rupture takes place.

Characteristics of Water Jet Machining (WJM):

• The pressures normally used in WJM are 1500 to 4000 MPa.
• Nozzle is made by sintered diamond and exit nozzle is about 0.05 to 0.35 mm.
• No moving parts in the system, so less operating and maintenance costs and safe process.
• No thermal damage to work and intricate shapes can be cut.
• The process is convenient for cutting soft and rubber like materials because teeth will get clogged in conventional methods.
  

Advantages of Water Jet Machining (WJM):

1. Water jet machining is a relatively fast process.
2. It prevents the formation of heat affected zones on the workpiece.
3. It automatically cleans the surface of the workpiece.
4. WJM has excellent precision. Tolerances of the order of ±0.005″ can be obtained.
5. It does not produce any hazardous gas.
6. It is eco-friendly.

Disadvantages of Water Jet Machining:

1. Only soft materials can be machined.
2. Very thick materials cannot be easily machined.
3. Initial investment is high.

Applications of Water Jet Machining:

1. Water jet machining is used to cut thin non-metallic sheets.
2. It is used to cut rubber, wood, ceramics and many other soft materials.
3. It is used for machining circuit boards.
4. It is used in food industry.

COMPRESSION RATIO

In internal combustion engines the compression-ratio may be defined as the ratio of the maximum cylinder volume when
the piston is at its outermost position (BDC) to the minimum cylinder volume (the clearance volume) with the piston at its innermost position (TDC) - that is, the sum of the swept and clearance volumes divided by the clearance volume.

Mathematically,

Compression Ratio=Swept Volume+clearance volume/clearance volume

Swept volume is the volume between TDC (Top Dead Centre) to BDC (Top Dead Centre) of cylinder and clearance volume is the remaining volume at the top of the piston.

Compression-ratio is a very important parameter for measuring engine performance.

Let's make it more simple,

Look at the diagram below,

Here total volume is 14 and clearnace volume is 1 so compression ratio becomes 14:1

Petrol engines have compression-ratios of the order of 7:1 to 10:1; but, to produce self-ignition of the charge, diesel engines usually double these figures and may have values of between 14:1 and 24:1 for naturally aspirated (depression-induced filling) types, depending on the design.

POWERFUL TOP 10 FORGOTTEN MOTORBIKES OF INDIA

There are a bunch of bikes that you may have never seen, or even heard about. We bring you ten such bikes
, in what’s a blast from the past.

10.Hero-BMW Funduro 650

Did you know that Hero once sold India’s “first” real ADV bike, in the form of the Funduro 650? Yes, this bike was priced at a princely 5 lakh rupees back in 1996. By Indian standards, 48 Bhp was a lot of power that this bike put out, but it bombed. The reason is easy to see. The market simply wasn’t ready to afford a motorcycle that competed with the Maruti Esteem in terms of pricing.

9.Rajdoot RD175

The Rajdoot RD175 is a very simple and rugged motorcycle that still enjoys a fan following in rural and semi-urban India. Known as the Doodhwalla bike, the RD175 featured a single cylinder, 175 cc two stroke engine and a 3 speed manual gearbox. Simple to fix, the bike motor put out 7.5 Bhp.

8.Royal Enfield Mini Bullet

For those who found the 350cc Bullet too heavy, Royal Enfield came up with an alternate: the Mini Bullet. The smaller bike featured a 200 cc two stroke engine, and was intended to rival the upcoming Indo-Japanese 100cc two stroke motorcycles that were soon to be launched. The Mini Bullet never really took off, which explains why you may have never heard of, or seen one.

7.Royal Enfield Bullet Diesel

Royal Enfield did sell a diesel version of the Bullet by combining the Bullet’s chassis with a Greaves diesel engine. Extremely frugal, this engine delivered about 65 Kmpl. Performance was very relaxed though, with the bike making just 6.5 Bhp.

6.Yezdi 350

Ideal Jawa could never really match Escorts-Yamaha and its RD350, but the Indo-Czech motorcycle brand did try hard. The Yezdi 350 was one such effort from the Mysore based bike maker. The Yezdi 350 featured a two stroke parallel twin petrol engine with 21 Bhp on tap. It was no patch on the RD350, and wasn’t really bought by those who wanted to go fast.

5.Kinetic GF170 Laser

The GF170 Laser was the most powerful bike that Kinetic ever built for the Indian market. The bike was powered by a 165 cc four stroke petrol engine with 14.8 Bhp-14.2 Nm. A five speed manual gearbox was standard on the bike, and so were 4 valves/cylinder.

4.Royal Enfield Fantabulous

Royal Enfield wanted a pie of India’s scooter market, and the odd-ball Fantabulous was born. The scooter never really took off though, and few know about it. The Fantabulous featured a 175 cc Villiers 2 stroke engine with 7.5 Bhp on tap. It also got a self starter.

3.TVS Supra

TVS Motors was one of the first companies to get out of the gate and begin producing affordable and reliable 100 cc Indo-Japanese motorcycles in India.  The Ind-Suzuki AX100 was the first such vehicle. Then, the Yamaha RX100 came along, promoting TVS to bump up outputs of the AX100. The Supra was born, with the same 100 cc motor making 11 Bhp, the same as the output of the RX100.

2.Bajaj Boxer 150

Bajaj built the Boxer 150 to sell it mainly in the African markets. To see if India’s rural and semi-urban market will warm up to it, the Boxer 150 was launched here, but it never really took off. The bike still represented the best that the Boxer brand offered.

1.Royal Enfield Fury

Royal Enfield’s short lived tie up with German bike maker Zundapp saw the Indian brand building the Fury, a 163 cc two stroke engined bike that was meant to compete with the Yamaha RX100. The Fury used a hydraulic disc brake, a 5 speed manual gearbox, and a hard chromed cylinder barrel.

HAVE YOU SEEN "HET" WRITTEN ON HONDA VEHICLE? CHECK OUT ITS MEANING HERE.

What is HET (Honda Eco Technology)? How does it increases mileage of the vehicle?

HET focus on reducing friction in engine components by usage of lightweight materials that increases overall efficiency of engine by 11%. HET technology also results 

reduction in weight by 8% than earlier engine, thereby increasing power to weight ratio. 

For e.g in Honda Activa the combustion has been improved with a new spark plug and optimised inlet port. Friction has been reduced with an offset crank, lighter materials, a low tension piston ring and improved bearing oil seal. The ratios and mechanicals 

of the V-matic drive have also been optimized which has resulted in a smoother transmission and an overall increase in fuel efficiency of 4.11 kmpl.

KNOW HOW A CHECK VALVE WORKS

Working of check valve nicely explained :-

A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid
(liquid or gas) to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave.

So,now you know how a check valve works.

KNOW THE DIFFERENCE BETWEEN DTS-i , DTS-SI ,DTS-FI AND DTS-I TRIPLE SPARK ENGINE TECHNOLOGY.

DTSI (Digital Twin Spark Ignition System)

Digital Twin Spark ignition engine has two Spark plugs located at opposite ends of the combustion chamber and hence fast and efficient
combustion is obtained. The benefits of this efficient combustion process can be felt in terms of better fuel efficiency and lower emissions. The ignition system on the Twin spark is a digital system with static spark advance and no moving parts subject to wear. It is mapped by the integrated digital electronic control box which also handles fuel injection and valve timing. It features two plugs per cylinder.

Main characteristics

• Digital electronic ignition with two plugs per cylinder and two ignition distributors.
• Twin overhead cams with camshaft timing variation.
• Injection fuel feed with integrated electronic twin spark ignition.
• A high specific power.
• Compact design and Superior balance.

DTS-Si Engine -

DTS-Si stands for “Digital Twin Spark Swirl Induction”, a ‘Bajaj Patented Technology’. Like DTS-i the engine has 2 spark plugs, but, instead of conventionally positioned straight ports, the offset positioning of the ports generate high swirl and turbulence of the air fuel mixture in the combustion chamber. This results in highly efficient combustion that further results in exceptional mileage. Like the mother DTS-i technology, the DTS-Si technology is a patented technology developed by Bajaj Auto R&D. This technology is used by Bajaj in its recently launched 125 cc Bajaj XCD.

DTS-Fi Engine-

DTS-Fi stands for “Digital Twin Spark Fuel Injection”, a ‘Bajaj Patented Technology’. In fuel injection the conventional carburettor has been replaced by injector which injects fuel in to the engine in a spray form based on the instructions of the Engine Control Unit (ECU) which is a part of the Engine Management System EMS. The Electronic Control Unit (ECU) is microprocessor based and is the brain of the fuel injection system. It processes information sent by various sensors and instantly determines optimum fuelling and spark timing for various engine operating conditions. The ECU contains detailed information of the engine’s characteristics from which it picks the necessary data for commanding both fuelling & spark timing.

DTS-i Triple Spark Engine-

Here DTS-i Stands for “Digital Triple Spark Ignition”. Three spark plugs provide unprecedented performance and efficiency – Fast and optimal combustion at part load conditions results in better fuel efficiency and ensures lower emissions.The high performance triple spark engine controlled by an advanced Electronic Control Unit, is the technology of the future. Combustion in a triple spark engine is 27% faster than a twin spark and 50% faster than a single spark engine.

To make use of 3 spark plugs, the pulsar engine houses a pent roof combustion chamber which in turn allows to house 3 spark plugs in the engine chamber. Out of the three plugs, the primary plug is the center one and is mounted in an angle and enters the chamber at the top-center. The other two secondary plugs are mounted below, each opposite each other and one of them being vertically underneath the primary plug.

The secondary plugs fires a bit after the primary one has fired and the timings are controlled by the ECU depending on various parameters like throttle position, engine revs,load on engine and many other stuffs. According to Bajaj, these plugs gain a advantage in low-rev riding condition where it extracts the best economy.Compared to KTM Duke 200 in similar conditions it gives as much as 10-13kmpl more,however the difference vanishes at higher revs and high speed.