Cutting tools
IPE 2111 MANUFACTURING PROCESSES
TYPES OF LATHE TOOLS
CUTTING CONDITION IN TURNING
❑ Lathe work cutting speed (CS) : the rate at which a point
on work circumference travels past the cutting tool.
1. Expressed as ft/min or m/min
❑ The feed of a lathe may be defined as the distance the
cutting tool advances along the length of the work for
every revolution of the spindle.
1. Expressed as in/rev. or mm/rev.
❑ The depth of cut is the depth of the chip taken by the
cutting tool and is one half the total amount removed from
the work piece in one cut.
1. Expressed in mm/cut
HOW TO SELECT CUTTING CONDITIONS
❑ The first step in establishing the cutting conditions is to
select the depth of cut.
1. The depth of cut has the least effect upon the tool life, so the
heaviest possible depth of the cut should always be used.
d = (Do-Df)/2
❑ The second step is to select the feed/rev.
1. So that available power is sufficient to make the required depth
of cut
2. Maximum feed possible that will produce an acceptable surface
finish
3. Travel rate f in feed/min is calculated by the formula fr=N*f
❑ The third step is to select the cutting speed.
❑ When the work piece and tool materials are known the cutting speed is
selected from the following table . The table is prepared basically
considering the heat generated and tool wear related to it.
❑ Spindle speed is calculated by using the formula
❑ N is the rpm of spindle and D is the diameter in inches or mm.
❑ Turning speeds are adjusted to the feed rate of the mini lathe (0.004/rev.), a
depth of cut of 0.040, and a tool life of 180 minutes.
SPEED AND FEED CHART
MACHINING TIME
❑ The time to machine from one end of a cylindrical workpiece to
the other is given by.
CALCULATION OF MATERIAL REMOVAL RATE (MRR)
❑ Volumetric rate of material removal can be most conveniently
determined by the following equation: MRR = v*f*d
❑ Where MRR = Material removal rate, mm3/min or in3/min
EXAMPLE
❑ The cutting speed for turning 100mm diameter bar has been
found to be 175 m/min. Using both the inch and metric
formulas, calculate the lathe spindle speed.
❑ A lathe is to take one cut on the diameter of a 1010 plain
carbon steel shaft (Brinell hardness of 200 ) 3 in. in diameter.
Calculate the rpm if a high-speed steel tool is used.
EXAMPLE
❑ A lathe, using a sharp pointed tool bit, is to take one cut off the
2-inch diameter of a 1109 soft steel shaft. The length of the
shaft is 10 inches and cut is to be made over 8 inches. The tool
bit is made from Hard coated carbide. Calculate the time to
machine one cut, Using a feed of 0.012 in/rev. Assume a total
overtravel of 3/8 in. Using the table find out the cutting speed
and spindle speed.
❑ Also calculate the MRR.
DRILLING BIT ( SHANK )
NOMENCLATURE OF DRILLING BIT (TWIST DRILL)
CUTTING PARAMETER
❑ The cuttingspeed in a drilling operation is the surface speed at
the outside diameter of the drill. It is the distance that a point
on the circumference of a drill will travel in 1 min.
1. Where N is the spindle speed rpm
2. V is the cutting speed in ft/min or m/min
3. D is the diameter of drill mm or in.
❑ Feed in drilling is specified in mm/rev or in/rev – it is the linear
distance the drll moves for every revolution.
1. Feed can be converted to feed rate like turning operation (in/min or
mm/min fr = N *f
MACHINING TIME ( DRLLING TIME )
❑ Drilled holes may either through holes or blind holes.
1. For through holes
2.For blind holes, hole depth d is defined as the
distance from the work surface to the depth of the
hole.
Blind hole machining time is given by
METAL REMOVAL RATE ( MRR )
❑ The rate of metal removal in drilling is determined as the
product of the drill cross sectional area and the feed rate.
This equation is valid only after the drill reaches full diameter
and excludes the initial approach of the drill into the work.
❑ A drill press is used to drill 4 holes into a block
of grade 55 cast iron (gray cast iron). Cal culate
the rpm of the drill bit.
TYPES OF MILLING CUTTER
CUTTING CONDITION
❑ Surface speed is how fast the metal comes into contact with
the tool at the cutting point.
1. On a milling machine, it is the rate at which the milling cutter fast the
stock, This takes into the account the diameter of the cutter.
2. Expressed in SFPM or SMPM
3. The cutting speed is determined at the outside diameter of a milling
cutter
4. This can be converted to spindle rotation.
FEED IN MILLING OPERATION
❑ The feed in milling is usually given as feed per cutter tooth;
called the chip load, it represents the size of the chip formed by
each cutting edge.
❑ This can be converted to feed rate ( the distance in inches or
millimeters per minutes that the work moves into the cutter ) by
taking into account the spindle speed and number of the teeth
on the cutter
MACHINING TIME
❑ Machining time is given by
❑ The calculation of approach for milling cutter depends on the
type of cutter used and the size of the cutter as related to the
width of the material being removed
❑ If a face milling cutter is the exact diameter as the width of the
work, the approach is one half of the diameter
❑ If the face milling cutter has a greater diameter than the width
of work
MATERIAL REMOVAL RATE
❑ MRR = d * W * fr
Where
D = depth of cut
W = width of the workpiece
fr = feed rate
EXAMPLES
❑ A milling machine uses a carbide-tooth cutter to mill a coper block.
The diameter of the cutter is 8 inches. Calculate the rpm of the
spindle.
❑ An 8 in. diameter carbide face milling cutter is used to take one cut
across the face of a block of aluminum which is 8 inches wide. The
length of the block is 18 inches. If feed is 0.015 in./tooth, and the
and the cutter has 8 teeth, how long will it take to machine one cut of
the block. The total overtravel is half inch.
❑ A 12 in. diameter carbide face milling cutter is used to take one cut
across the face of a block of aluminum which is 8 inch wide. The
length of the block is 18 inches. If feed is 0.015 in./tooth and the
cutter has 10 teeth, how long will it take to machine one cut of the
block.
❑ End
