Lock Out Tag Out



Many serious accidents have happened when someone thought a machine or the power to it was safely off. "Lock-out tag-out" is a way to protect yourself and others by ensuring that machines remain completely, temporarily off. Without a lock-out tag-out system there is the possibility that a machine will unexpectedly start up, either because of stored energy which was not correctly released or through the actions of someone starting the process without realizing that it isn't safe to do so.

The lock-out tag-out standard requires that hazardous energy sources be "isolated and rendered inoperative" before maintenance or servicing work can begin. These energy sources include electrical (either active current or stored as in a capacitor), pneumatic, hydraulic, mechanical, thermal, chemical, and the force of gravity. It is important to remember all of the energy sources must be "isolated and rendered inoperative." Overlooking an energy source has proved fatal on several occasions.

                                               Sequence of lockout

1.Notify all affected employees.   The authorized employee shall refer to the company procedure to identify  the type and  magnitude  of  the  energy that the machine  or equipment utilizes,  and    shall  understand  the hazards of the energy and know  how to control the energy.

2.If the machine or equipment is operating, shut it down by the normal stopping procedure (depress the stop button, open switch,  close valve, etc.).

 

3.De-activate the energy isolating device(s)  so that  the machine or equipment is isolated from the energy sources.

4. Lock out and Tag out the  energy  isolating   device(s)  with assigned individual locks and Tags.

5. Stored or residual energy  (such as that in capacitors, springs, elevated  machine members,  rotating  flywheels,  hydraulic  systems,  and  air,  gas,  steam,  or water pressure,  etc.)  must  be  dissipated  or  restrained  by methods such  as  grounding, repositioning, blocking, bleeding down, etc.

 

6.Ensure  that  the  equipment  is  disconnected  form the energy source(s) by first  checking  that  no  personnel  are exposed, then verify the isolation of the equipment  by  operating  the  push button or other normal operating control(s) or by testing to make certain the equipment will not operate.

 

 

 

 

 

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Safety for Lathe

CARE AND MAINTENANCE OF LATHES

Lathes are highly accurate machine tools designed to operate around the clock if properly operated and maintained. Lathes must be lubricated and checked for adjustment before operation. Improper lubrication or loose nuts and bolts can cause excessive wear and dangerous operating conditions.

The lathe ways are precision ground surfaces and must not be used as tables for other tools and should be kept clean of grit and dirt. The lead screw and gears should be checked frequently for any metal chips that could be lodged in the gearing mechanisms. Check each lathe prior to operation for any missing parts or broken shear pins. Refer to the operator's instructions before attempting to lift any lathe. Newly installed lathes or lathes that are transported in mobile vehicles should be properly leveled before any operation to prevent vibration and wobble. Any lathes that are transported out of a normal shop environment should be protected from dust, excessive heat, and very cold conditions. Change the lubricant frequently if working in dusty conditions. In hot working areas, use care to avoid overheating the motor or damaging any seals. Operate the lathe at slower speeds than normal when working in cold environments.

SAFETY

All lathe operators must be constantly aware of the safety hazards that are associated with using the lathe and must know all safety precautions to avoid accidents and injuries. Carelessness and ignorance are two great menaces to personal safety. Other hazards can be mechanically related to working with the lathe, such as proper machine maintenance and setup. Some important safety precautions to follow when using lathes are:

Correct dress is important, remove rings and watches, roll sleeves above elbows,no gloves,wear goggles.


Always stop the lathe before making adjustments.


Do not change spindle speeds until the lathe comes to a complete stop.


Handle sharp cutters, centers, and drills with care.


Remove chuck keys and wrenches before operating


Always wear protective eye protection.


Handle heavy chucks with care and protect the lathe ways with a block of wood when installing a chuck.


Know where the emergency stop is before operating the lathe.


Use pliers or a brush to remove chips and swarf, never your hands.


Never lean on the lathe.


Never lay tools directly on the lathe ways. If a separate table is not available, use a wide board with a cleat on each side to lay on the ways.


Keep tools overhang as short as possible.


Never attempt to measure work while it is turning.


Never file lathe work unless the file has a handle.


File left-handed if possible.


Protect the lathe ways when grinding or filing.


Use two hands when sanding the workpiece. Do not wrap sand paper or emory cloth around the workpiece.

Introduction To Lathe

Lathe Machine

• machine tool which spins a block of material to perform various operations such as cutting, sanding , knurling, drilling or deformation with tools that are applied to the work piece to create an object which has symmetry about an axis or rotation.
• usually lathe is used in wood turning, metal working, metal spinning and glass working.
• lathe also can be used to shape pottery and lathe is the best known design being the potter's wheel.

• Bed is mainly support the whole machine

• Carriage is assembly that moves the tool post and cutting tool along the ways

• Carriage Hand wheel is a wheel with a handle used to move the carriage by hand by means of a rack and ponion drive

• A chuck is a clamping device for holding work in the lathe

• Apron is the front part of the carriage assembly on which carriage hand wheel is mounted

• Cross slide is a platform that moves perpendicular to the lathe axis under control of the cross slide hand wheel

• Cross slide hand wheel is a wheel with handle used to move the cross slide in and out.

• Halfnut lever is the lever to engage the carriage with leadscrew to move the carriage under power

• lead screw is a precision screw that runs the length of the bed. it is used to drive the carriage under power for turning and thread cutting operations.

• swing is a dimension representing the largest diameter work piece that a lathe can rotate

• tailstock is a cast iron assembly that can be slide along the ways and be locked in place. used to hold long work in place or mount a drill chuck for drilling into end of the work

• Ram is a piston type shaft that can be moved in and out of the tailstock by turning the tailstock hand wheel.

• Tool is a cutting tool used to remove metal from the work piece and usually made of high speed steel or carbide.

• ways is a precision ground surfaces along top of the bed on which saddle rides. the ways are precisely aligned with the centerline of the lathe
  
  
  
  
  

Types of Gears

   1) Spur Gear-Parallel and co-planer shafts connected by gears are called spur gears. The arrangement is called spur gearing.

Spur gears have straight teeth and are parallel to the axis of the wheel. Spur gears are the most common type of gears. The advantages of spur gears are their simplicity in design, economy of manufacture and maintenance, and absence of end thrust. They impose only radial loads on the bearings.

Spur gears are known as slow speed gears. If noise is not a serious design problem, spur gears can be used at almost any speed.

2) Helical Gear-Helical gears have their teeth inclined to the axis of the shafts in the form of a helix, hence the name helical gears.

These gears are usually thought of as high speed gears. Helical gears can take higher loads than similarly sized spur gears. The motion of helical gears is smoother and quieter than the motion of spur gears.

Single helical gears impose both radial loads and thrust loads on their bearings and so require the use of thrust bearings. The angle of the helix on both the gear and the must be same in magnitude but opposite in direction, i.e., a right hand pinion meshes with a left hand gear.

3) Herringbone Gear - Herringbone gears resemble two helical gears that have been placed side by side. They are often referred to as "double helicals". In the double helical gears arrangement, the thrusts are counter-balanced. In such double helical gears there is no thrust loading on the bearings.

4) Bevel/Miter Gear-Intersecting but coplanar shafts connected by gears are called bevel gears. This arrangement is known as bevel gearing. Straight bevel gears can be used on shafts at any angle, but right angle is the most common. Bevel Gears have conical blanks. The teeth of straight bevel gears are tapered in both thickness and tooth height.
Spiral Bevel gears: In these Spiral Bevel gears, the teeth are oblique. Spiral Bevel gears are quieter and can take up more load as compared to straight bevel gears.

Zero Bevel gear: Zero Bevel gears are similar to straight bevel gears, but their teeth are curved lengthwise. These curved teeth of zero bevel gears are arranged in a manner that the effective spiral angle is zero.

5) Worm Gear- Worm gears are used to transmit power at 90° and where high reductions are required. The axes of worm gears shafts cross in space. The shafts of worm gears lie in parallel planes and may be skewed at any angle between zero and a right angle.In worm gears, one gear has screw threads. Due to this, worm gears are quiet, vibration free and give a smooth output.Worm gears and worm gear shafts are almost invariably at right angles.

6) Rack and Pinion- A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of curvature. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into the left-to-right motion of the tie rod(s). Racks also feature in the theory of gear geometry, where, for instance, the tooth shape of an interchangeable set of gears may be specified for the rack (infinite radius), and the tooth shapes for gears of particular actual radii then derived from that. The rack and pinion gear type is employed in a rack railway.

7) Internal & External Gear- An external gear is one with the teeth formed on the outer surface of a cylinder or cone. Conversely, an internal gear is one with the teeth formed on the inner surface of a cylinder or cone. For bevel gears, an internal gear is one with the pitch angle exceeding 90 degrees. Internal gears do not cause direction reversal.

8) Face Gears- Face gears transmit power at (usually) right angles in a circular motion. Face gears are not very common in industrial application.

9) Sprockets-Sprockets are used to run chains or belts. They are typically used in conveyor systems.