SAFETY IN THE WORKSHOP
The following are the precautions that to be followed when you are working in the engineering workshop
ü Never work while tired or taking medication.
ü Try not to rush the job.
ü Be aware of your attention or lack of it to the job – repetitive cuts can lend themselves to day dreaming.
ü Avoid distractions – never surprise someone who is working with tools.
ü A fully equipped First-Aid box should be present and readily accessible in every workshop.
ü No open flames or tobacco smoking!
ü Keep the floor area clear and wipe up all spilled liquids immediately to prevent a slipping hazard.
ü use a mask or respirator to protect against the toxic vapors from
ü Wear proper dress. It is important that the worker is correctly dressed for the work to be done.
ü Long hair must be covered up under a hat.
ü Make sure you know how to start and to stop a machine.
ü Loose clothes such as tie and cuffs must be avoided.
ü Always wear safety shoes.
COMMON ACCIDENTS OCCUR IN THE WORK SHOP
ü Loose of body parts eg. hand
ü Loss of hearing due to noise.
ü Loss of eye due to abrasive materials like sparks.
ü Loss of life.
ü Falling of objects.
Benchwork
Is any type of labor or work that is managed using a workbench rather than with the use of heavy machinery in a workshop.
THE BASIC BENCHWORK CONDUCTED IN THE WORKSHOP
The following are the bench works that are common conducted in the workshop, namely;
ü Tapping; Involves the operation of making threads.
ü Drilling; is the process of cutting round holes in a work piece.
ü Filling; is the process which involves shaping and final smoothing of materials.
ü Chiseling; They are used for cutting out and shearing of sheet metal
ü Clamping; Holding of a work piece.
TOOLS WHICH ARE USED IN BENCH WORK
ü Vise
ü Taper
ü Hand Drill
ü File
ü Grinding wheel
ü Chisel
ü Hand saw
ü Smooth plane
MACHINE PROCESS
The following are the machines that can be found in the workshop
1. LATHE MACHINE
Is the machine that used to produce different shapes which are in cylindrical shapes and upon which a range of operations can be performed. Its basic function is to produce internal and external cylindrical shapes but it can also be used to produce flat, tapered, or contoured surfaces and screw threads to a high degree of accuracy.
MAIN PARTS OF LATHE MACHINE
Head stock; The headstock holds the spindle and drive mechanism for turning the work piece.
Tail stock; The tailstock supports long work that would otherwise sag or flex too much to allow for accurate machining
Bed; The lathe bed is a mounting and aligning surface for the other machine components
Carriage; The carriage provides mounting and motion control components for tooling. The carriage moves left and right, either through manual operation of a hand wheel, or it can be driven by a lead screw.
Cross Slides; The cross-slide is mounted to the top of the carriage to provide movement perpendicular to the length of the bed for facing cuts.
Also the other parts are;
Tool post; hold cutting tools
Compound slides; It is used for turning tapers, to control depth of cut when screwcutting or precision facing.
Chuck (three jaws and four jaws chucks); hold a workpiece
Lathe centers; made from high speed steel (HSS) and then hardened to support work between the head stock and tail stock
Steadies; they are used to give addition support when machining long lengths of bar. (Reduce the vibration of the workpiece)
2. MILLING MACHINE
is the machine that carry out the process of machining flat, curved, or irregular surfaces by feeding the workpiece against a rotating cutter containing a number of cutting edges.
MAIN PARTS OF MILLING MACHIE
Base; The base of the machine is Grey iron casting accurately machined on its top and bottom surface and serves as a foundation member for all the other parts which rest upon it. It carries the column at its one end. In some machines, the bage is hollowed and working as a reservoir for cutting fluid.
Column; The column is the main supporting frame mounted vertically on the bage. The column is box shaped. Heavily ribbed inside and houses all the driving mechanisms for the spindle and table feed. The front vertical face of the column is accurately machined and is provided with dovetail guide ways of supporting knee. The top of the column is finished to hold an over-arm that extends outward at the front of the machine.
Knee; The knee is the rigid gray iron casting that slides up and down on the vertical way of the column face. The adjustment of height is effected by elevating screw on the base that also supports the knee. The knee houses the feed mechanism of the table, and in different controls to operate it. The top face of the knee forms slid way for the saddle to provide cross travel of the table.
Saddle; The saddle is placed on the top of the knee, which slides on guide ways set exactly at 90 to column face. A cross feed screw near the top of the knee engages a nut of the bottom of the saddle to move it horizontally, by hand or power, to apply cross feed. The top of the saddle is accurately machined to provide guide ways for the table.
Table; The table rest on ways on the saddle and travels longitudinally. The top of the table is accurately finished and T-slots are provided for clamping the work and other fixtures on it. A lead screw under the table engages a nut on the saddle to move the table horizontally by hand or power. The longitudinal travel of the table may be limited by fixing trip dogs on the side of the table. In universal machines, the table may also be swiveled horizontally. For this purpose the table is mounted on a circular bage which in its turn is mounted on the saddle. The circular bage is graduated in the degree.
Over hanging arm; Over hanging arm is mounted on the top of column extends beyond the column face and serve as a bearing support may be provided nearest to the cutter. More than one bearing support may be provided for the arbor.
TYPES OF MILLING MACHINE
Vertical milling machineIn the vertical mill the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis. The spindle can generally be extended (or the table can be raised/lowered, giving the same effect), allowing plunge cuts and drilling. Or a milling machine with a worktable that is parallel to the ground and a spindle that is positioned vertically.
Horizontal milling machineA horizontal mill has the same sort of x–y table, but the cutters are mounted on a horizontal arbor across the table.
3. DRILL PRESS MASHINE
This is the another type of machine which used to perform different activities (operations) such as; boring, reaming, countersinking, counterboring, tapering, drilling.
Diagram of drill press machine
Main parts of drill machine
The drill machine has got four main parts namely; base, column, table and head.
Head; control the motion and contain the gear
Column; is used to support the table.
Table;place a workpiece
Base; support the whole machine
The following are the operation done by drill machine
Drilling;is an Operation of producing hole by removing metal from solid mass using twist drill
Countersinking is an Operation of producing tapered or cone-shaped enlargement to end of hole
Tapping is the process of Cutting internal threads in hole with cutting tool called tap
Counterboring is the Enlarging of previously drilled hole to given depth to provide square shoulder for head of bolt or capscrew
Reaming is the Operation of sizing and producing smooth, round hole from previously drilled or bored hole
Boring is the process of enlarging hole by means of single-point cutting tool
