Railway Axle Manufacturing Processes

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Questions and Answers

What is the primary purpose of the forging process in axle production?

To reduce the weight of the axle.

To increase the surface finish quality of the axle.

To convert steel blooms into the required shapes. (correct)

To extend the length of the axle body.

Which of the following statements about the Axle Shop is incorrect?

Loco axles are typically sent in a rough turned condition.

The railway axle weighs approximately 500 kg.

The plant utilizes CNC machines in its machining lines.

The Axle Shop produces an axle every 10 minutes. (correct)

What process is used to heat the blooms before forging?

Cooling on the bed.

Heating in a Rotary Hearth Furnace. (correct)

Temperatures in a normalizing furnace.

Air cool method.

Which part of the axle is primarily responsible for connecting to the train wheels?

Wheel seat. Signup and view all the answers

What is the approximate weight of a railway axle produced by the shop?

500 kg. Signup and view all the answers

What is the function of the normalizing and tempering furnaces in axle production?

To subject rough forged axles to heat treatment. Signup and view all the answers

How many axle machining lines does RWF have, and how many of them are CNC machines?

Three lines, two CNC machines. Signup and view all the answers

What is the main purpose of using a diamond wheel dresser in the grinding process of an axle?

To ensure a perfect finish on the axle Signup and view all the answers

During the Magnaglo testing, what indicates the presence of surface cracks on the axle?

A bright yellow-green fluorescence under black light Signup and view all the answers

At what speed does the grinding wheel operate in the cylindrical grinding process?

1240 rpm Signup and view all the answers

What is the significance of the depth of cut during the grinding process described?

It influences the surface finish quality Signup and view all the answers

What is the maximum crack size allowed for the axle to pass the Magnaglo test?

21.88 mm Signup and view all the answers

What is the role of the billet cutting machine in the forging shop?

To cut blooms into smaller pieces Signup and view all the answers

Which material is used for manufacturing locomotive axles?

R43 Signup and view all the answers

At what temperature are the billets heated in the Rotary Hearth Furnace?

1200 °C Signup and view all the answers

What type of fuel is used in the billet cutting machine?

Oxygen and LPG Signup and view all the answers

How many burners are there in the heating zone of the Rotary Hearth Furnace?

9 Signup and view all the answers

What process immediately follows billet cutting in the forging shop?

Heating in a Rotary Hearth Furnace Signup and view all the answers

What is the purpose of the preheating zone in the Rotary Hearth Furnace?

To prepare the billets for heating Signup and view all the answers

Which of these types of axles has the largest cross-sectional area?

Locomotive axles Signup and view all the answers

What is the total number of burners across all zones in the Rotary Hearth Furnace?

20 Signup and view all the answers

What is the angle at which three holes are drilled in BOX-N axles?

120 degrees Signup and view all the answers

What type of tool is used to perform countersinking?

Conical shaped countersink tool Signup and view all the answers

What is the speed at which the tapping tool is rotated?

90 rpm Signup and view all the answers

How many threads are formed for each inch during the tapping process?

8 threads Signup and view all the answers

What coolant method is utilized during the drilling, countersinking, and tapping operations?

Flood coolant Signup and view all the answers

What is the feed rate used during drilling operations?

50 mm/min Signup and view all the answers

What is the diameter of the twist drill used in drilling operations?

27.5 mm Signup and view all the answers

What type of tool is used for the turning operation to provide a good surface finish?

Carbide tool with Titanium coating Signup and view all the answers

What type of defects could lead to the rejection of axles?

Multitude of defects including undersize components Signup and view all the answers

During which operation is it crucial to have a continuous supply of coolant?

Drilling, countersinking, and tapping Signup and view all the answers

What is the primary purpose of end cutting in the metal cutting process?

To remove irregular deformed metal from the ends. Signup and view all the answers

During the normalizing process, what condition do the axles need to reach before they are placed in the furnace?

They should be heated 40-50°C above their upper critical temperature. Signup and view all the answers

What influences the type of grain structure obtained after the normalizing process?

The thickness of the cross section of the axles. Signup and view all the answers

What is the expected cooling duration for the high-temperature axles after the end cutting process?

Half an hour in an open area. Signup and view all the answers

In the context of end cutting, which gas mixture is utilized to perform the cutting process?

Oxygen and LPG. Signup and view all the answers

What is the cycle time for the end cutting process described?

Less than a minute due to the high temperature of the axles. Signup and view all the answers

What is the maximum number of axles that can be accommodated in the normalizing furnace?

90 axles at a time. Signup and view all the answers

What is the primary function of the different zones in the normalizing furnace?

To facilitate pre-heating, heating, and soaking of the axles. Signup and view all the answers

Which of the following pressures is applied for damping during the metal processing?

80 bar. Signup and view all the answers

Study Notes

Axle Shop Processes

The axle shop is a section of a facility that manufactures railway axles.
Axles are produced every 5 minutes.
Three axle machining lines are present, two of which are CNC machines.
Axles are made from forgings.
Railway axles are 500 kg weight, cylindrical, and made of alloy steel.
Axles consist of four parts: body, wheel seat, dust guard, and journal.
The axle shop is divided into three parts: forging, machining, and assembly.

Forging Process

Blooms (long bars with a square cross-section) are cut into billets (smaller pieces) using gas welding.
The material is cut from different steel plants, including Durgapur, Maharashtra, and Pune.
This step takes 3 minutes per billet.
The cutting process uses a mixture of oxygen and LPG.
Axle types vary based on cross-sectional area (locomotive, BOX-N, and coaching).

Heating Process

Billets are heated in a Rotary Hearth Furnace (RHF) up to 1200°C.
The RHF has four heating zones: preheating, heating, soaking I, and soaking II.
A robot arm inserts the billets into the RHF.
The preheating zone is the first stage, and the soaking zones are the final stages.
Some zones take longer than others.
Each section in the heating area has a specified range of temperature.
The RHF has a capacity of 80 billets, and one cycle takes 6.5 hours.

Forging

Forging transforms a heated billet into a specific axle shape.
The long forging machine uses multiple types of hammers to obtain the desired shape.
The entire process is computerized.
Forgings are then subjected to dimensional checking.

End Cutting

Excess material is removed from the ends of the axle using end cutting.
It is done because the ends usually have irregularities after forging.
Oxygen and LPG flame mixtures are used with high pressure.
This process takes less than one minute.

Normalizing

The axles are air-cooled and then normalized.
The normalized axles are placed on the base of a normalizing furnace, and fire is set on the sides.
The fuel used is diesel.
The normalizing furnace has three zones: pre-heating, heating, and soaking.
The cooled axles regain their grain structure.
Grain size depends on the section thickness.

Quenching

Quenching is the sudden cooling of heated metal using a cooling agent.
The process involves dipping or spraying the heated metal into a cooling agent, like a mixture of polymer oil and water in a 1:20 ratio.
Not all axles require quenching.

Tempering

Tempering is a heat treatment process to increase ductility and reduce hardness.
It reduces internal stresses caused by heating, forging, and quenching.
The tempering furnace has a preheating zone, a heating zone, and a soaking zone.
The axles are heated at 600-650°C.

Sampling

After tempering, axles are cooled for 24 hours and then inspected.
Destructive tests may be carried out on some axles.

Axle Machine Shop

Station 1: End milling, centering, and cup turning:
End milling cuts excess material using a rotating end mill.
Centering creates a central hole.
Cup turning smooths the ends.
Tools are made of high-speed steel.
Station 2: Rough turning:
Rough turning shape using a single-point cutting insert (carbide) to shape the axle.
Carbide inserts are in cassettes.
Station 3: Drilling, countersinking, tapping, and recentering:
Drilling creates holes for the bearings.
Taps are used to create threads.
Countersinking slightly enlarges holes.
Station 4: Smooth turning:
Provides a good surface finish to the axle using a turning tool with a titanium coating.
Station 5: Cylindrical grinding:
The axles undergo cylindrical grinding on the journal to obtain a smooth finish.

Magnaglo testing

A method for detecting surface cracks in the axles using magnetic flux powder and black light.

Ultrasonic testing

A non-destructive test used to detect interior defects or flaws in the axles.

Wheel Seat Measuring Station

The axle and wheel fits are checked using interference fit criteria and tools like measuring gauges.

Wheel Boring

The axle is bored to the wheel seat specification using an Octagon shaped carbide tool in the vertical boring machine.

Wheel Mounting

The wheel is pressed onto the axle's wheel seat using a mounting press.
Additional Information*
Coolants are used in most machining processes to reduce heat production.
Axles must comply with specific dimensions.
Quality testing is essential.
Some axles are rejected due to defects.

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Description

This quiz explores the intricate processes involved in the manufacturing of railway axles, including forging, machining, and assembly. Learn about the materials, weights, and specifications of various axle types as well as the machinery used. Test your knowledge on the steps and technologies that contribute to the efficient production of railway components.