DESCRIPTION  (Android)

TURNING CUT CALCULATOR 2 is a mobile application tool for operators of turning lathes, CNC operators, CNC programmers etc. who work with processes in turning lathe machines. In a quick and easy way, can most data be manipulated for a turning cut. In this extended version, there are also for example several language translations to choose from.

Actual version:  1.7.1

For more milling specific calculations you can download Milling Cut Calculator 2 made by KenKe.

Main Properties

- Calculates the time for a lathe cut by using given processing data
- Calculation of the input data also gives results for surface fineness, material removal rate, chip thicknesses, cutting forces, torque and power
- Possible process-data that can be changed are diameter, cutting length, cutting speed, spindle speed, feed per revolution, feed per minute, nose radius, surface fineness, cutting process, cutting depth, entering angle, rake angle, material, specific cutting force (kc) and efficiency
- Handles both of the systems Metric and Imperial
- Possible to convert between these two systems
- Converts between cutting speed and spindle speed
- Converts between feed rate per revolution and feed rate per minute
- Calculates an approximate surface fineness from given nose radius and feed rate
- Calculates an approximate feed rate from a given nose radius and surface quality
- Calculates material removal rate from given data
- Calculates maximum chip thickness and average (equivalent) chip thickness from given data
- Obtain a good "Specific Cutting Force" via material selection
- Calculates approximate cutting forces from given data
- Calculates approximate torque and power from given data
- All selectable values, except one, can be changed with the input of absolute value or with buttons for incremental change
- Required updates of affected values occur immediately
- Switching between change methods is made by a long tap on the value's row
- Possibility to get a short explanation about a value with a fast double tap on the value's row
- Possibility to get explanations of other result values with a quick double-tap in the specific area shown
- Possible to choose 1 of 14 different languages at any time (machine translated)
- Ability to select time for viewing highlighted text and active buttons
- Ability to select color theme
- Ability to adjust color tones for the color themes
- Possibility to change the appearance of highlighted sub-values
- Possible to create new default values
- Posibility to select main font
- All settings are stored for the next use of the app
- Possible to continue with the last session when starting the app

Handling in Brief

When starting the app, all properties have values. These values can be selected as fixed basic values or saved values from the previous session. To change a value, first tap on the property's field to enable the property. The field lights up in a preset light color when it get activated. At the bottom of the screen, a keypad for value input lights up. The keypad can be selected to be for absolute or incremental input of values and is adapted to current property. The switching between the different keypads is done with a long click on the property field.

In connection with the activation of a property, in most cases other value fields are also lit to indicate that the value of these properties will also change. These values ​​are displayed in a darker hue or in a frame. Deactivation of a value field can be done with the Done button (english version) or activate another property or go to an other page or use the back-button or after a default inactivity time.

On page 2, there is also a result field that displays only calculated results and no entered values.

With a quick double click on a value field, can a brief description and a descriptive image be obtained. The same thing happens when you double tap the result field on page 2, but all results are described in a scrollable image.

Switching between pages 1 and 2 is done with the two arrows at the top of the screen.

The settings page is obtained by touching the settings icon at the bottom right of the screen. On the settings page you can choose the language, you can switch between the metric system and the imperial system, you can choose the amount of time you want to show the selection and keypad, you can choose a color theme, you can change color tones, you can select the highlight appearance for sub-values, you can select the main font and you can save new default values.

By touching the description icon at the bottom left of the screen, the description-page is obtained. In addition to the app's description, there are links to important documents regarding the app's use. Access to these requires access to the Internet.

Two Pages for Cut Data and Results

Page 1 is used for input and calculation of cutting data, surface fineness and cutting time. Page 1 manages itself and is not dependent on page 2. Nothing on page 2 can change any value on page 1 !
Page 2, on the other hand, is dependent on page 1 and is used for further data entry to calculate material removal, cutting forces, torque and power.

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 == PAGE 1 ==
============

Values Treated on Page 1

- Diameter
- Cutting length
- Cutting speed
- Spindle speed
- Feed/rev.
- Feed/min.
- Nose radius
- Surface
- Time

Events When Changing a Value on Page 1

When changing a value will other values, dependent on the changed value, immediately be updated. Let's name these values for "subvalues" for future simplicity. Of course will diameter and cutting length never be changed because of a change of an other value. The same applies to the value of the nose radius. When changing for example the quality of the surface (Ra), will feed be changed instead of the nose radius.

The subvalues that are to be updated follows this app's rules of priority.
That means that in each "section" will the following have the priority:

Cutting speed  (prio)
Spindle speed

Feed per rev.  (prio)
Feed per min.

Nose radius  (prio)
Surface

Therefore, the sub-values that need to be changed are usually those that have no priority. Sub-values with priority can usually only be changed by other sub-values in the same section (the nose radius is not included in that rule).

Conclusion of Page 1

This app's rules of priority results in this way of changing the subvalues on page 1:
- A change of the diameter will also change the spindle speed, the feed/min and the time
- A change of the cutting length will also change the time
- A change of the cutting speed will also change the spindle speed, the feed/min and the time
- A change of the spindle speed will also change the cutting speed, the feed/min and the time
- A change of the feed/rev will also change the feed/min, the surface and the time
- A change of the feed/min will also change the feed/rev, the surface and the time
- A change of the nose radius will also change the surface
- A change of the surface will also change the feed/rev, the feed/min and the time (not the nose radius)

As already written, page 1 is completely independent of page 2 but most of the values on page 1 are important for further calculations on page 2.

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== PAGE 2 ==
============

Adjustable Values on Page 2

- Lathe process (the external or internal feed direction)
- Cutting depth
- Entering angle
- Specific cutting force (kc)
   · Material
   · Rake angle
- Efficiency

Resulting Values on Page 2

- Material removal rate
- Material removal
- Maximum chip thickness
- Equivalent chip thickness
- Cutting force Fc (Ft)
- Cutting force Ff (Fa)
- Cutting force Fp (Fr)
- Torque - spindle
- Power - spindle
- Power - motor

Events When Changing a Value on Page 2

The TURNING TYPE is important for obtaining relevant values for the material removal, the torque and the power.
The value of the diameter on page 1 indicates the diameter at the tool-tip (finished diameter). Normally, this diameter is indicated at e.g. NC programming and it is on this diameter the programmed cutting speed is kept. The amount of removed material, the torque and the power depends on which side of this diameter the specified cutting depth is located. When calculating torque and power, the diameter is applied at half the deep of the cut (the diameter is actually a bit bigger but for the simplicity).

Example of cutting a diameter:
Diameter = 100 mm (3.937 in)
Cut. length = 50 mm (1.97 in)
Cut. speed = 200 m/min (656 ft/min)
Sp. speed = 637 rpm
Feed = 0.5 mm/r (0.0197 in/r)
Cut. depth = 4 mm (0.1575 in)
Kc = 2000 MPa (290075 psi)
Time = 0.157 min

This gives different results depending on the selected type of turning.

Approx. results when turning an outside diameter:

Material removal≈ 65.3 cm³ (3.988 inch³)
Material removal rate ≈ 416 cm³/min (25.39 inch³/min)
Diameter for calculation of torque and power = 104 mm (4.094 inch)
Spindle-power ≈ 13.9 kW (18.6 HP)
Spindle-torque ≈ 208 Nm (1841 lbf-inch)

Approx. results when turning an inside diameter:

Material removal ≈ 60.3 cm³ (3.681 inch³)
Material removal rate ≈ 384 cm³/min (23.43 inch³/min)
Diameter for calculation of torque and power = 96 mm (3.78 inch)
Spindle-power ≈ 12.8 kW (17.2 HP)
Spindle-torque ≈ 192 Nm (1699 lbf-inch)

The CUTTING DEPTH is the depth of the cutting edge into the material perpendicular to the direction of movement. A change of the cutting depth will change the material removal rate, the chip thicknesses, the cutting forces, the torque, the power through the spindle and the power of the spindle-motor.
The ENTERING ANGLE is the angle between the cutting edge and the direction of movement. A change of the entering angle will normally change chip thicknesses and some of the cutting forces.
The SPECIFIC CUTTING FORCE (kc) is the tangential force required to cut a metal chip with a certain cross sectional area. Most important parameters to obtain a reasonably correct kc-value are the material being processed, the feed rate and the cutting tool's geometry. Cutting speed on the other hand, usually has a minor impact on the value. The value of the specific cutting force can be obtained from e.g. some suppliers of tools / materials. A change of the specific cutting force will change the cutting forces, the torque, the spindle-power and motor-power. A list of materials can be accessed from the description window of the specific cutting force. With the help of this list you can get a reasonably well calculated value of kc. What is required is to select a material that is as similar to the current material as possible and to specify the rake angle of the cutting tool.
The EFFICIENCY is a value as a percentage of the amount of motor power remaining in the processing position. A change of the efficiency will change the power of the spindle's motor.

About the Approximate Results on Page 2

These results are calculated on the values from both page 1 and page 2.

The MATERIAL REMOVAL is the volume of material removed by the current lathe cut. The removal volume depends on the turning process, the diameter, the cutting depth and the cutting length.
The MATERIAL REMOVAL RATE is the volume of material removed per minute with the current speed of removal. The rate depends on the current time and the current removal volume.
The MAXIMUM CHIP THICKNESS is the calculated largest uncut chip thickness along the cutting edge including the nose radius.
The EQUIVALENT CHIP THICKNESS is a calculated uncut chip thickness. In this application it will be interpreted as an average chip thickness of the chip thicknesses along the cutting edge including the nose radius.
The CUTTING FORCE (Fc or Ft) is the important tangential force. The calculation of this force depends on the feed rate, the cutting depth and the specific cutting force (kc).
The CUTTING FORCE (Ff or Fa) is the axial force which is the force in the direction of movement. The calculation of this force depends on the feed rate, the nose radius, the cutting depth, the entering angle and the specific cutting force (kc).
The CUTTING FORCE (Fp or Fr) is the radial force which is the passive force perpendicular to the direction of movement. The calculation of this force depends on the feed rate, the nose radius, the cutting depth, the entering angle and the specific cutting force (kc).
The TORQUE value is the load the current machining exerts on the turning spindle. The calculation of the torque depends on the lathe process, the diameter, the feed rate, the cutting depth and the specific cutting force (kc).
The SPINDLE POWER is the power required at the machining position. The calculation of the spindle's power in this app depends on the values of the lathe process, the diameter, the cutting depth, the cutting force (Fc) and the spindle speed.
The MOTOR POWER is the power required by the spindle's motor. The calculation of the motor power depends on the spindle power and the efficiency.

As already written, illustrated and short explanations of the results can be obtained by double-clicking in the result area.

Conclusion of Page 2

In addition to changes on page 1, the resulting values are affected by changes in the changeable values on page 2 as below:
- A change in the lathe process will also change the material removal rate, torque and power
- A change in cutting depth will also change the material removal rate, sometimes maximum chip thickness, almost always equivalent chip thickness, cutting forces, torque, and power
- A change of entering angle will also almost always change the chip thicknesses and some of the cutting forces (Ff and Fp)
- A change of the specific cutting force will also change cutting forces, torque and the spindle's / motor's power
- A change of efficiency will also change the power of the
spindle motor

Finally

Most of the values shown are rounded values, but in the background these are calculated with much higher precision.