MARKING & MARKING TOOL ( ITI THEORY ) PART 2

SCRIBER :-

1. IT IS MADE FROM HIGH CARBON STEEL & HARDENED STEEL.
2. IN LAYOUT WORK, IT IS NECESSARY TO SCRIBE LINES TO INDICATE THE DIMENSION OF THE WORK PIECE TO FILED OR MACHINED.
3. WHEN MARKING WITH SCRIBER IS INCLINED (75-80) DEGREE TOWARD THE DIRECTION OF MOVEMENT.
4. IT'S POINT ANGLE IS (12-15) DEGREE.
5. OFFSET SCRIBER IS USED IN VERNIER HEIGHT GAUGE.

DIVIDER:-

1. DIVIDER ARE USE FOR SCRIBING CIRCLE, ARC & FOR TRANSFERRING & STEPPING OFF DISTANCE.
2. DIVIDER ARE AVAILABLE WITH FIRM JOINTS AND SPRING JOINT.
3. THE MEASUREMENT ARE SET ON THE DIVIDER WITH A STEEL RULE ACCURACY IS 0.5 MM , TRANSFER DIMENSION.
4. FOR CORRECT LOCATION & SEATING OF DIVIDER LEGS PRICK PUNCH MARK ARE USED.
5. DIVIDER ARE SPECIFIED BY THE TYPE OF THERE JOINT AND LENGTH.
6. DIVIDER POINT SHOULD BE FREQUENT SHARPENING WITH OIL STONE IS BETTER THEN SHARPENING BY GRINDING.
7. IT IS MADE OF HIGH CARBON STEEL OR TOOL STEEL WITH POINT HARDENED & TEMPERED.

TRAMMEL:-

IT IS USED TO DRAW ARC & CIRCLE OF GREATER RADIUS, THAT CAN BE DRAW WITH DIVIDER. 

HERMAPHORDITE CALIPER:-

1. IT IS ALSO CALLED JENNY CALIPER OR ODD LEG CALIPER.
2. HERMAPHORDITE CALIPER HAVE ONE LEG WITH AN ADJUSTABLE DIVIDER POINT WHILE OTHER LEG IS BENT.

USES

1. FOR MAKING LINES PARALLEL TO THE INSIDE & OUTSIDE EDGE.
2. FOR FINDING THE CENTER OF ROUND BAR.
3. CALIPER WITH BENT LEG ARE USED FOR DRAWING LINE PARALLEL ALONG ON INSIDE EDGE & ALSO OUTSIDE EDGE.
4. IT CAN ALSO BE USED FOR SCRIBING LINES ALONG CURVED EDGDE.

PUNCH:-

1. PUNCH ARE USED IN ORDER TO MAKE CERTAIN DIMENSIONAL FEATURE OF LAYOUT PERMANENT.
2. PUNCH ARE MADE OF HIGH CARBON STEEL & POINT OF PUNCH ARRE HARDENED & TEMPERED.
3. HOLD THE PUNCH AT 45 DEGREE ANGLE & PLACE THE POINT ON THE LAYOUT LINE.
4. HRC OF PUNCH IS (55-59).

THREE TYPES OF PUNCH

1. DOT PUNCH- THE ANGLE OF POINT IS 60 DEGREE & IT IS USED FOR MAKING WITNESS MARK.
2. CENTRE PUNCH- THE ANGLE OF POINT IS 90 DEGREE & IT IS USED FOR LOCATING HOLES & WIDE PUNCH MARK GIVES A GOOD SEATING FOR STARTING DRILL.
3. PRICK PUNCH- THE ANGLE OF POINT IS 30 DEGREE & IT IS USED FOR MAKING LIGHT PUNCH MARKS NEEDED TO POSITIONING THE DIVIDER.

MARKING & MARKING TOOL (ITI THEORY) PART 1

MARKING MEDIA 

THE LINES DRAWN ON THE METAL ARE NOT VISIBLE PROPERLY, FOR THIS, SOME MARKING MEDIA APPLIED ON THE JOB.

TYPES OF MARKING MEDIA :-

1.  WHITE WASH - IT IS APPLIED TO ROUGH FORGING & CASTING SURFACE. WHITE WASH IS NOT RECOMMENDED FOR WORK PIECE OF HIGH ACCURACY. IT MADE OF CHALK POWDER WITH WATER, CHALK MIXED WITH METHYLATED SPIRIT OR WHITE LEAD POWDER MIXED WITH TURPENTINE.
2. PRUSSIAN BLUE - THIS IS USED ON FILLED OR MACHINED FINISHED SURFACE. THIS WILL GIVE VERY CLEAN LINE BUT TAKES MORE TIME FOR DRYING THEN THE OTHER MARKING MEDIA.
3. COPPER SULPHATE (BLUE VITROL)- THE SOLUTION IS PREPARED BY MIXING COPPER SULPHATE IN WATER AND FEW DROPS OF NITRIC ACID. COPPER SULPHATE IS USED ON FILED OR MACHINED FINISHED SURFACE.
4. CELLULOSE LACQUER- THIS IS EASILY AVAILABLE MARKING MEDIA. IT IS MADE IN DIFFERENT COLOURS & DRIES VERY QUICKLY.  

SURFACE PLATE :-

1. IT IS ESSENTIAL TO HAVE A DATUM PLANE WITH A PERFECTLY FLAT SURFACE.
2. SURFACE PLATE ARE GENERALLY MADE OF GOOD QUALITY CAST IRON, GRANITE OR CERAMIC. (GRANITE IS A DENSE & STABLE MATERIAL)
3. THE WORK SURFACE IS MACHINED & SCRAPED. THE UNDERSIDE IS HEAVILY RIBBED TO PROVIDE RIGIDITY.
4. A THIN COATING OF RED LEAD MIXED WITH OIL IS SPREAD EVENLY OVER THE SURFACE PLATE.
5. THE SURFACE PLATE SHOULD BE SUPPORTED ON THREE LEGS FOR AVOIDS ROCKING & TWISTING.
6. SURFACE PLATE ARE FOUND IN THREE GRADES- 1,2,3
7. THE WORKING HEIGHT BEING ABOUT 800 MM FROM THE FLOOR.
8. ACCURACY OF SURFACE PLATE USED IN WORKSHOP IS 0.025 MM, INSPECTION SURFACE PLATE IS 0.0025 MM, MASTER SURFACE PLATE IS 0.00025 MM.

SPECIFICATION OF SURFACE PLATE

SPECIFIED BY THEIR LENGTH, BREADTH, GRADE & THE INDIAN STANDARD NUMBER. FOR EXAMPLE- CAST IRON SURFACE PLATE 

                                     2000 x 1000 GR.1 I.S 2285

MARKING TABLE:-

1. IT IS MADE OF CLOSE GRAINED CAST IRON.
2. THE MARKING TABLE PROVIDE A ' REFERENCE PLANE ' ON WHICH THE WORK & THE MARKING OUT TOOLS STAND.
3. THE WORKED BEING MARKED MUST BE PLACED AT 90 DEGREE TO THE REFERENCE PLANE.
4. THE MARKING SHOULD BE PROTECTED BY WELL FITTING WOODEN COVER, WHEN NOT IN USE.
5. PARALLEL LINES ARE ENGRAVED IN BOTH DIRECTION AT A SET DIRECTION, THESE LINE SERVE A GUIDE FOR POSITIONING THE COMPONENTS WHILE SETTING AND MARKING.
6. HEIGHT FROM THE FLOOR IS 75-90 CM.

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