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Showing posts from February, 2015

Lathe Operations: Facing

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Facing Operations Facing is the process of removing metal from the end of a workpiece to produce a flat surface. Most often, the workpiece is cylindrical, but using a 4-jaw chuck you can face rectangular or odd-shaped work to form cubes and other non-cylindrical shapes.

When a lathe cutting tool removes metal it applies considerable tangential (i.e. lateral or sideways) force to the workpiece. To safely perform a facing operation the end of the workpiece must be positioned close to the jaws of the chuck. The workpiece should not extend more than 2-3 times its diameter from the chuck jaws unless a steady rest is used to support the free end. Cutting Speeds

If you read many books on machining you will find a lot of information about the correct cutting speed for the movement of the cutting tool in relation to the workpiece. You must consider the rotational speed of the workpiece and the movement of the tool relative to the workpiece. Basically, the softer the metal the faster the cutting. D…

Designing of Die Block in Press Form

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Points Covered


Introduction.
Designing of Die Block.
Process of making 1800 Press Form Points to be Covered.

Introduction

Rubber parts are used in aircraft.
Rubber parts are moulded under heat and pressure in a die.
The dies or moulds are commonly called as Press Forms.
Moulds are made from mild steel by machining, milling and finishing by hand.

Designing of Die Block

Design of die block depends upon work piece size and thickness.
Overall dimensions of the die block will be determined by the minimum wall thickness of the die required for strength.
Sharp corners may lead to crack during heat treatment, therefore it requires greater
Two dowels should be provided in each block, for accurate and permanent positioning.
Thickness of the die block depends upon the size of the seals to be manufactured.
The minimum thickness of the die should not be less than 12.5mm.
In the process of rubber moulding, the accuracy of the product depends upon the construction of the dies.

Process of making 180 degreePress Form

T…

Different Types Keys and Cotters With Images

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A machine runs by the power supplied to it by a prime mover such as, motor, engine, etc. The power is transmitted from the prime mover to the machine through a coupler which couples the shafts of the prime mover and the machine. The most commonly employed method to connect a shaft and a part is to drive a small piece of metal, known as key between the shaft and the hole made in the part mounted over it. The key will be driven such that it sits partly into the shaft and partly into the part mounted on it. To introduce the key, axial grooves, called key ways are cut both in the shaft and the part mounted on it. The key is fitted between the shaft and the part mounted over it. While transmitting the power, the key will be subjected to shear and crushing forces. Keys are extensively used to hold pulleys, gears, couplings, clutches, sprockets, etc., and the shafts rigidly so that they rotate together. They are also used to mount the milling cutters, grinding wheels, etc., on their spindles…