CUTTING SPEED AND FEED Calculation:
Before the programmer starts the software of the program, it must extract the cutting speed, feed and revolution number information. This information is determined by taking the relevant tables and making the necessary calculations. However, the values ​​in the chart are general values. These values ​​can be changed depending on the state of the machine, the way the workpiece and the cutting tool are attached, and the way of machining. The programmer should evaluate these conditions using his own knowledge and experience and be able to make the necessary changes. Correctly selected and cutting speed values ​​are the key to an ideal cutting condition.

Cutting Speed: Cutting speed is the path that a point on the cutter takes in meters per minute. This speed is also called surface speed. The factors that affect the cutting speed are as follows.

-The tool of the cutting tool

-Material of the workpiece

-The way the cutting tool and the material are bonded

-The power and condition of the bench

-Cross section of chips to be removed

There is a connection between the coolant cutting speed used and the number of revolutions. And it is directly proportional. If the cutting speed increases, the number of revolutions increases. If the cutting speed decreases, the number of revolutions decreases.

In CNC programs, either constant cutting speed or constant speed is given. If the G96 command is entered, the value entered for the following S code is the cutting speed. The S code following the G97 command defines the number of revolutions. If G96 command is entered, the control unit constantly checks the number of revolutions according to the changing diameter value. For example, in a face turning process, as the cutting tool approaches the spindle axis (as the diameter gets smaller), the control unit will continuously increase the number of revolutions by putting the diameter value into the formula.

Note: the speed is inversely proportional to the cutter diameter.

Cutting speeds in milling and turning

Material of the workpiece Cutting material HSS Sintercarbide Mild steel 28 170 Cast iron 18 100 Brass 120 250 Aluminum alloys 75 180 Calculation of the number of revolutions V = ??. DN 1000 V: Cutting (mm / min) D: Workpiece door (mm) (in milling The diameter of the knife or cutter) N revolution number (rpm cutter diameter) V = ??. DN 1000 The cutting speed value in this formula is given by the cutting tool manufacturer companies.

EXAMPLE: Face turning will be done on cast iron material of 60mm diameter with a hard metal insert cutter on the lathe. Calculate the revolutions of the lathe at 60mm diameter and the number of revolutions when the diameter is 35mm. a) b) D = 60mmD = 35mm V = 100mm / dkV = 100mm / min N =? V.1000 N =? V.1000? .D? .D = 100.1000 =? 100.1000 3,14.603,14.35 = 530dev / min = 910dev / min EXAMPLE: A steel workpiece will be machined with a 16mm diameter end mill. The cutting speed value selected from the table is 20mm / min. Calculate the number of revolutions to be given to the machine accordingly. D = 16mmN = V.1000 /? .DN =? 20000 V = 20mm / minN = 20.100050,24 3.14.16N = 398dev / min or 400rpm N = 20000 3.14.16

EXAMPLE: Face turning will be done on a 40mm diameter steel material with a hard metal cutter on the lathe. Since the cutting speed is 18mm / min from the table, find the number of revolutions to be given to the machine. N =? V.1000N =? 18.1000N =? 18000N = 143dev / min? .D3,14.40125,6

Feed: The speed at which the cutting tool moves across the workpiece surface. The cross section of the chip removed depends on the feed values ​​together with the depth of cut. The progress value is given by the F code in the program. The unit is either mm / min or mm / rev.? Depending on the code entered.? dir. G. Code Definition Unit G 94 Feeding Speed ​​mm / min G 95 Feeding Speed ​​mm / rev. If the unit of feed is given as mm / rev, its mm / min? Conversion to either is done using the formula below. Feed (mm / rev) = feed (mm / rev) Number of revolutions (rev / min) or feed (mm / min) feed rate (rev / min)

EXAMPLE: In a turning process, the spindle revolution of 1200 rpm, the feed rate is 0.2mm / rev from the chart. Calculate the feed rate in mm / min? V = 1200dev / min F = 0,2mm / rev Mm / min = 0,2.1200 = 240mm / min

FEEDING SPEEDS IN MILLING AND LATHE FEEDING SPEED

Milling HSS Sintered Carbide Mild Steel 0.13 0.50 Cast Iron 0.20 0.50 Brass 0.18 0.30 Aluminum Alloys 0.28 0.50 Turning HSS Sintered Carbide Ductile Iron 0.20 0.80 Cast Iron 0, 40 1.00 Brass 0.80 1.50 Aluminum Alloys 0.30 1.50 Feed Per Tooth: For cutting tools with indexable inserts on the milling machine, it is more common to give feed rate as feed per tooth. Naturally, as the number of teeth increases, the cross section of the stone will decrease for each tooth. In the cutting tool with more teeth in two cutters of the same diameter, neither one tooth will cut the chip cross section will be less than the cutter with a lower number of teeth. For this reason, entering the feed per tooth value provides a more weighted result. Feed rate (mm / rev) = feed rate (mm / tooth) x number of teeth

EXAMPLE: The surface of the workpiece will be milled with an end mill with 8 teeth. Giant. Since the number is 1040dev / min and the feed is 0.3mm / tooth, calculate the feed rate to be given in the program as mm / min and mm / rev? Number of teeth = 8 Feedrate = 0.3mm / tooth Number of revolutions = 1040rpm Feedrate = (mm / min) = 0.3.8 = 2.4mm / rev Feedrate (mm / min) = feedrate (mm / rev) x dev number = 2.4 × 1040 

= 2496mm / min
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CUTTING SPEED CALCULATIONS
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Cutting speed and cutting speed of the cutting tool used and cutting tip are the leading factors affecting productivity in machining.

Poor cutting conditions such as unsuitable feed, speed, material affect the cutting speed and tool life to a great extent.

The contribution of modern tools to the desired speed and precision of production with machines such as CNC is unquestionable.

Turning and Milling operations have a very important place in machining. Development of the tools that will do these works with new inventions also has a special place in production technology. Efficient use of inserts is possible by complying with the recommended cutting data.

Suitable cutting speeds according to the material to be processed are written on the boxes and catalogs of the inserts.

Using the cutting speed more or less than necessary causes deterioration of the tip and poor surface quality.

Cutting speed is expressed in Vc. Its unit is meter / minute. In other words, cutting speed is the distance that the cutting tip must travel in 1 minute. If this value is too much, it causes tip wear, vibration, if less, chip accumulation, bad surface and small cracks on the tip.

The operator should adjust the speed and feed according to the recommended cutting speed.

Vc = Cutting speed in meters / minute
n = spindle revolutions per minute
d = Milling diameter for turning work diameter mm
Vf = Table feed mm / min
z = number of incisors
fz = feed per cutting tooth mm / tooth number
fn = feed per revolution mm / rev (Vc should decrease as fn is increased or vice versa)
Vc = (3.14 x d x n) / 1000
n = (Vc x 1000) / (3.14 x d)
Vf = n x z x fz

Example: We will be milling with a 50 mm diameter cutting tool. The cutting speed is given as Vc = 200m / min in the cutter box, let's find the revolution to be given to the machine.

Vc = 200 m / min
d = 50 mm

n = (Vc x 1000) / (3.14 x d)
n = 200 x1000 / 3.14 × 50
n = 1273 rpm

We should set our bench to this cycle or the closest value.
As a result of the researches, it has been proven that the most important factor affecting tool life is the cutting speed (Vc).

It has been stated that depth of cut (ap) has little effect on tool life, feed (fn) is an important factor affecting tool life after cutting speed.

ap = depth of cut mm
fz = feed per cutting tooth mm / tooth number
fn = feed per revolution mm / rev (Vc should decrease as fn is increased or vice versa)
Vf = Table feed mm / min
z = number of incisors

Example: Let fz = 0.14 mm, Vc = 200 m / min, tool diameter d = 25 mm, number of cutting teeth z = 3
n = (Vc x 1000) / (3.14 x d) rev / min
n = 2546 rpm

Vf = n x z x fz mm / minute
Vf = 2546x3x0.14
Vf = 106 mm / minute

The machine feed should be set at 106 mm / minute or close.

The values ​​recommended by the insert manufacturer may not be suitable for our machine's specifications.

If our machine is weak in strength and suitable for vibration, we should change these values ​​by looking at the chip, sound and surface quality in line with experience.

In small machines, small diameter milling heads should normally be used and deep passes should be taken as multiple cutting. The machine may not be able to cut with a larger diameter milling head.

The inserts are produced in different shapes and sizes, with different hardness values. Qualified powder alloys are compressed under high temperature and pressure and the surface is covered with abrasion and heat resistant material. They are manufactured in different cutting angles and different bonding styles.

Tool manufacturers produce different types of tools according to the needs of the industry according to these cutting tips. We can see the same cutting tip in tools suitable for different cutting shapes produced differently.

NUMBER OF MILLING MACHINE REVOLUTIONS - PROGRESS CALCULATIONS

The Cutting Speed ​​value must be known in order to calculate the revolution number.

Cutting Speed ​​is the path in meters per minute that a point on the milling cutter takes. Cutting Speed ​​is calculated with the following formula;

Factors Affecting Shear Rate:

- Type of cutting tool material,

- the type of material of the workpiece,

- The surface quality to be achieved,

- Depth of cut,

- the power of the machine,

- Whether cutting fluid is used or not.

Although the cutting speed is calculated by the formula, it is beneficial to take as a basis the cutting speed values ​​obtained and suggested by the cutting tool manufacturers as a result of tests and experiments. For this, it is necessary to take advantage of the catalogs of the company where we will definitely use the cutting tool.

Example - 1

On a milling machine, a milling cutter with a diameter of 50 mm rotates at 425 revolutions. What is the cutting speed taken?

V = 3.14x50x425 / 1000

V = 66725/1000

V = 66.75 m / min.

Turnover Calculation

The number of revolutions is calculated by deriving the formula from the same formula.

Example - 2

Since the milling cutter to be used in a milling machine is HSS end mill, its diameter is 12 mm and the material to be processed is steel, what should the number of revolutions be given to the machine? (Select the cutting speed from the chart. V = 25 m / min. Selected from the chart)

N = 25 × 1000 / 3.14 × 12

N = 25000 / 37.68

N = 663 rpm.

Progress 

e is the linear distance of the milling cutter on the workpiece in mm per minute, and its unit is mm / min.

Since the cutting tools used in milling machines are generally multi-point tools, the feed value is given for a single insert. This given feed value is multiplied by the number of inserts on the cutting tool and first the feed per revolution is found. Then, this value found is multiplied by the number of revolutions of the machine per minute and the feed rate per minute is calculated in mm.

Example - 3

The rotation speed of the milling cutter to be used on a milling machine is 900 rpm. and the number of inserts on it is 8. Since the feed value given for each end is 0.05 mm / end, find the feed value in one minute.

Stage 1 Fd = Fuç x Z

Fd = 0.5 x 8

Fd = 0.4mm / rev

Stage 2 F = Fd x N

F = 0.4 x 900

F = 360 mm / min.

Example - 4

The type of material to be processed on a milling machine is aluminum, the diameter of the milling cutter to be used is 50 mm, and the number of cutting edges on it is 12. Since the inserts are hard metal and the recommended feed rate for each insert is 0.035 mm / insert, find the number of revolutions the machine has to be operated and the feed rate per minute. (Cutting speed 400 m / min. Selected from the chart)

Stage 1 N = Vx1000 / 3.14xD

N = 400 × 1000 / 3.14 × 50

N = 400000/157

N = 2547 rpm.

Stage 2 Fd = Fuç x Z

Fd = 0.035 x 12

Fd = 0.42mm / rev

Stage 3 F = Fd x N

F = 0.42 x 2547

F = 1069 mm / min.

CALCULATIONS ON LATHES

Cutting speed and workpiece diameter are important in RPM calculations.

Cutting Speed: The way the lathe pen travels on the workpiece in meters per minute. In other words, it is the length of the chip that the cutting tool lifts from the workpiece in one minute.

FACTORS AFFECTING THE CUTTING SPEED

The type of material to be processed,

The type of material of the cutting tool,

The power of the lathe,

Depth of cut,

The type of processing,

Cutter's advance amount

Cutting Speed ​​value is selected from technical books or catalogs of cutting tool manufacturers according to the above criteria.

Although the cutting speed varies according to the type of turning process, 25-50 m / min for HSS cutters in external turning operations. and 250-500 m / min in hard mine ends. is selected between. The reason why the values ​​are given so intermittently is that the way the cutting tool and the work piece are connected in the same metal removal process also affects the cutting speed.

Example 1:

The diameter of the workpiece to be processed on the lathe is 54 mm and the number of revolutions to be given to the machine is 375 rev / min. Calculate the cutting speed of the cutting tool to be used.

V = 3.14xDxN / 1000 m / min.

V = 3.14x (54.375) / 1000

V = 3.14 × 20 250/1000

V = 63585/1000

V = 63.5 m / min.

Let's calculate the number of revolutions using the same formula. For this, we derive a formula from the formula.

N = V.1000 / 3.14xD rpm.

Example 2:

The diameter of the workpiece to be processed on the lathe is 46 mm and the cutting speed of the HSS cutting tool to be used is 50 m / min. is. Calculate the number of revolutions to be given to the machine according to this.

N = Vx1000 / 3.14xD

N = 50 × 1000 / (3.14) 46

N = 50000 / 144.4

N = 346 rpm.

Example 3:

The diameter of the workpiece to be processed on the CNC lathe is 48 mm and the cutting speed of the cutting tool to be used is 530 m / min. is. Calculate the number of revolutions to be given to the machine according to this.

N = Vx1000 / 3.14xD

N = 530 × 1000 / (3.14) 48

N = 530000 / 150.7

N = 3516 rpm.

Progress:

The distance in mm per minute that the cutting tool takes linearly along the workpiece axis.

Factors affecting progress;

Depth of cut,

The type of chip removal process,

The quality of the surface to be obtained,

Coolant used