MET 103 -module_-1

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MET 103 -module_-1

  1. 1. SAFETY PRECAUTIONS WHEN WORKING WITH POWER SAWS• Mount or remove work only when the saw is stopped and is M t k l h th i t d di raised well above the vise.• Clamp the w/p securely on both sides of the blade if possible possible.• Use only blades that are in good condition and which are the correct kind for the material being cut cut.• Operate the machine at a cutting speed and feed rate that does not strain the machine or the blade.• Keep hands away from the saw blade when it is running.• Stand out of line with the blade when starting an abrasive cutoff saw.• Do t bend D not b d over in front of a power hacksaw frame when the i f t f h k f h th ENG I NE ER I NG T AL EC MECH NIC HNOLOGY m/c is running. A MET1 E N T D P A R T ME
  2. 2. SAWING MACHINE TYPESClassification :1. Reciprocating : Power hacksaws2. Circular saw: Cold saw & abrasive3. Band saw: Horizontal, vertical cutoff I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET2 E N T D P A R T ME
  3. 3. Reciprocating Sawing Machines: Hacksaws :# Used primarily for cutting to length metal of various sizes & shapes.# These sawing m/c vary in design from light-duty to heavy-duty m/c. g y g g y y y# Actual cutting takes place in only one direction and the saw blade is lifted slightly on the return stroke. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 3 Fig. Reciprocating power hacksaw E N T D P A R T ME
  4. 4. Circular Sawing Machines :Commonly known as cold sawing machines.Work pieces are clamped in a vise or fixture, one or more pieces at atime.The circular blade is mounted on a power driven arbor & rotatedthrough the cut.Abrasive discs are also used for cutting off stock.An abrasive disc is a thin, flexible grinding wheel.The disc is mounted on a machine that can be adapted for either wetor dry cutting. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 4 E N T D P A R T ME
  5. 5. Horizontal Band saws :Are available in a wide variety of types and sizes.It has a flexible, "endless" blade which cuts continuously in onedirection. The thin blade travels over the rims of two pulley.di ti Th thi bl d t l th i ft llThe saw frame, hinged at the motor end, has two pulley wheels overwhich the continuous blade passes. passesThe step pulleys are used to vary the speed of the continuous blade.The roller guide brackets provide rigidity for a section of the bladeand prevent it from wandering and twisting. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 5 E N T D P A R T ME
  6. 6. The blade tension handle is used to adjust the tension on the saw blade. The vise mounted on the table can be adjusted to hold various sizes of w/p. BLADETENSION I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET6 Fig. The main parts of horizontal Bandsaw E N T D P A R T ME
  7. 7. Sawing Hints :# Never attempt to mount, measure or remove work unless the saw is stopped.# Guard long material at both ends to prevent anyone from coming in i contact with it. t t ith it# Use cutting fluid, whenever possible, to help prolong the life of the saw blade and improve the cutting action action.# When sawing thin pieces, hold the material flat on the vise to prevent the saw teeth from breaking breaking.# Use caution when applying extra pressure to the saw frame as this generally causes work to be cut out of square. g y q# When several pieces of the same length are required, set the stop gauge saws. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 7 E N T D P A R T ME
  8. 8. CONTOUR BANDSAW PARTS AND ACCESSORIESThe contour bandsaw is generally fabricated from steel. g yThe contour bandsaws has many advantages in the metal-cuttingtrade. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 8 E N T D P A R T ME
  9. 9. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET9 E N T Contour bandsaw parts D P A R T ME
  10. 10. Contour Bandsaw Parts and OperationsThe basic parts are (1) base (2) column (3) headBase :The base of the contour bandsaw supports the column and housesthe assembly that provides the drive for the blade.Column :The column supports the head, the left-hand blade guard, weldingunit, and th variable-speed handwheel it d the i bl dh d h l Head : The parts found in the head of a saw are generally used to guide or support the saw band. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 10 E N T D P A R T ME
  11. 11. Bandsaw Operations (a) Notching : Sections of metal removed in one piece (b) Slotting : Quick and accurate without expensive fixtures i fi t (c) Angular cutting : Work clamped at any angle & table may be tilted (d) Radius cutting : Internal or external contours I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET11 E N T D P A R T ME
  12. 12. Horizontal Bandsaw BladesHigh speed tungsten and high speed molybdenum steel.CONTOUR BAND SAW BLADESThree types of saw blades generally used are(1) Carbon alloy Carbon-alloy,(2) High-speed steel,(3) Carbide-tipped blades. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 12 E N T D P A R T ME
  13. 13. Tooth FormsThree types of tooth forms:(a).(a) Precision or Regular Tooth - This is the most generally used . It is used when a fine finish and an accurate cut are required.(b). Buttress or Skip Tooth - This tooth form is similar to the precision tooth; however, the teeth are spaced farther apart Used on thick work sections and on deep cuts in soft material. material(c). Claw or Hook Tooth – It has the same general application as the buttress-tooth form. buttress tooth form It is faster cutting and longer lasting than the buttress tooth, but will not produce smooth finish. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET 13 E N T D P A R T ME
  14. 14. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET14 E N T D P A R T ME
  15. 15. PITCHNumbers of teeth per standard referencelengthInch standard = No. teeth/inchMetric standard = No. teeth/25 mmThickness of material to be cut determinespitch of blade to use. useCoarse: thick, Fine: thin I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET15 E N T D P A R T ME
  16. 16. There are three common set patterns(1) W Wavy : – Alternate arrangement of several teeth to right and l ft d left. – Used to cut tubes & light sheet metal.(2) Straight : One tooth left & the other right. Used for brass, copper & plastic(3) Raker : – Three teeth in sequence left, right, & straight. – Used for steel & cast iron ENG I NE ER I NG T AL EC MECH NIC HNOLOGY A MET 16 E N T D P A R T ME
  17. 17. I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET17 E N T D P A R T ME
  18. 18. Blade Length 2* CD+3.14*D CD= CENTER DISTANCE D= DIA OF PULLEY I NE ER I NG ENG T AL EC MECH NIC HNOLOGY A MET18 E N T D P A R T ME

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