MILLING CUT CALCULATOR 2  (iOS)

A FEW INTRODUCTORY WORDS

The application is mainly intended for use in calculating radial machining and not for axial machining (eg drilling). Only page 1 of the application can handle both.

MAIN PROPERTIES

- Calculates the time for a milling cut by using given processing data

- Calculation of the input data also gives results for material removal rate, chip thicknesses, cutting data factors, torque and power

- Possible process-data that can be changed are tool diameter, number of teeth, cutting length, cutting speed, spindle speed, feed rate per tooth, feed rate per revolution, feed rate per minute, entering angle, diameter of round inserts, cutting depth, cutting width, air-cut width, rake angle, material, the 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 tooth, feed rate per revolution and feed rate per minute

- Possible to switch between cutting inserts with straight edges and round edges.

- Calculates material removal rate from given data

- Calculates chip thicknesses and then possible optimization factors

- Calculates a reasonably correct specific cutting force from selected material, tool rake angle, and average chip thickness

- Calculates average torque and average power from given data

- All selectable values 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 an 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

- 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

- Possibility 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 input of values ​​or for incremental values and is adapted to current value. The switching between the keypads is done with a long click on the value field.

In connection with the activation of a property, in many 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 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 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, this 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 PROCESS-VALUES AND FOR RESULTS

Page 1 is used for input and calculation of cutting data 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 rate, chip thicknesses, cutting data factors, torque and power.

PAGE 1

VALUES TREATED ON PAGE 1

- Tool diameter

- Number of teeth

- Cutting length

- Cutting speed

- Spindle speed

- Feed rate (per tooth)

- Feed rate (per revolution)

- Feed rate (per minute)

- Time

EVENTS WHEN CHANGING A VALUE ON PAGE 1

When you change a value, other values, which depend on the changed value, will be updated immediately. Let's name these values for "sub-values" for future simplicity. The three values at the top of the page, ie. tool diameter, number of teeth and cutting length, will of course never change due to change of another value.

The sub-values to be updated follow the app's priority rules. This means that in every section except the top, the following values will have priority:

Cutting speed (Priority)

Spindle speed

Feed / tooth. (Priority)

Feed / rev.

Feed / min.

Therefore, the sub-values that need to be changed are usually those that have no priority. Sub-values with priority can only be changed by other sub-values in the same section

CONCLUSION OF PAGE 1

This app's rules of priorities results in this way of changing the sub-values (and time) on page 1:

- A change of tool diameter will also change spindle speed, feed rate/min and time

- A change of number of teeth will also change feed rate/revolution, feed rate/min and time

- A change of cutting length will also change time

- A change of cutting speed will also change spindle speed, feed rate/min and time

- A change of spindle speed will also change cutting speed, feed rate/min and time

- A change of feed rate/tooth will also change feed rate/revolution, feed rate/min and time

- A change of feed rate/revolution will also change feed rate/tooth, feed rate/min and time

- A change of feed rate/min will also change feed rate/tooth, feed rate/revolution and time

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.

PAGE 2

ADJUSTABLE VALUES ON PAGE 2

- Type of inserts (straight or round)

- Entering angle (if straight inserts)

- Inserts diameter (if round inserts)

- Cutting depth

- Cutting width

- Aircut width

- Specific cutting force (kc)

• Rake angle
• Material

- Efficiency

RESULTING VALUES ON PAGE 2

- Material removal rate

- Maximum chip thickness

- Average chip thickness

- Cutting speed factor

- Feed rate factor

- Torque (spindle and motor)

- Power (spindle and motor)

EVENTS WHEN CHANGING A VALUE ON PAGE 2

The button for INSERT-TYPE switches between cutting plates with straight or round cutting edges.

If the cutting plate type is straight, the ENTERING ANGLE (Kr) should be stated and if the cutting plate type is round, the INSERTS DIAMETER (iC) should be stated. Note that the specified tool diameter (Dc) is the outermost diameter that gives the specified cutting depth (ap) during machining. All machining outside this diameter is ignored when calculating power, torque and material removal speed. The average power and average torque will be approximately the same, as the higher cutting speed should not significantly affect the tangential cutting force but may be the opposite. The rate of material removal, on the other hand, may differ slightly, but to validate this in all situations, more input data is required.

The CUTTING DEPTH (ap) is the axial depth of the cutting edges into the material. A change of the cutting depth, when straight inserts have been selected, will change the material removal rate (Q), the torque (M) and the power (P). If you have instead selected round cutting plates, the maximum chip thickness (hex), the average chip thickness (hm) and the feed rate factor will also change.

The CUTTING WIDTH (ae) is the radial depth of the cutting edges into the material. A change in the cutting width can at most change the material removal rate (Q), the maximum chip thickness (hex), the average chip thickness (hm), the cutting speed factor, the feed rate factor, the torque (M) and the power (P).

The AIRCUT WIDTH is the width of the part of one side of the milling-tool that does not cut into the material (one of the sides next to the specified cutting width). If, for example, a plane with a width of 10 mm is milled with a cutter with a diameter of 25 mm, the air-cutting widths can be e.g. 7.5/7.5 or e.g. 5/10 or e.g. 0/15. If you instead are milling a groove, the width of both sides is zero (0/0) because there is no space on the sides. It does not matter which of the two sides' width is specified. To obtain some calculated results, the sum of the cutting width (ae) and the air cutting width must not exceed the diameter of the cutter (Dc). The width of the air-cut is a way of describing where the lateral milling takes place on the milling tool. This affects the value of the chip thicknesses which in turn affects the feed rate factor.

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 in the specific cutting force will change the cutting forces, which in turn affect the torque (M) and power (P). In the information window of specific cutting forces, it is possible to go to a list of some common materials. When selecting a material and specifying the rake angle (γ) of the cutting tool, there are a whole number of calculation parameters that are used to calculate a more accurate kc value.

The EFFICIENCY is a value as a percentage of the amount of motor power (Pm) remaining in the processing position (spindle power or cutting power - Pc). 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 RATE (Q) is the volume of material removed per minute with current cutting data. The calculation of the removal rate in this app depends on the cutting depth (ap), the cutting width (ae) and the table feed (Vf).

The most common chip thicknesses used are MAXIMUM CHIP THICKNESS (hex) and AVERAGE CHIP THICKNESS (hm). In this app, chip thickness is used in calculation of cutting data factors that can be used for possible optimization.

There are often opportunities to optimize cutting data. In this application, CUTTING SPEED FACTOR and FEED RATE FACTOR are used to contain possible values ​​for this. The following things affect these factors.

- Reduce the entry angle (Kr)

- Increase the diameter of inserts

- Reduce the cutting width (ae)

- Milling on only one side of the milling center

The chip thickness decreases with a reduced entry angle (for straight inserts) or with an increased diameter of the cutting plates (for round inserts and when the cutting depth is less than the cutting plate radius). Thickness reduction can be compensated by increasing the feed rate. When cutting on one side of the milling center, the chip thicknesses is less than the feed per tooth. The thickness reduction can be compensated by increasing the feed rate.

The two specified adjustment factors in this app are based on the above points, but they are not included in the current cut-off data values. These factors are only suggestions that can be tested under optimal conditions.

The TORQUE (M) value is the load the current machining exerts on the milling spindle. The calculation of the torque uses the spindle speed (n) and the spindle power (Pc) in this app. The spindle power itself is calculated using the cutting depth (ap), the cutting width (ae), the table feed (Vf) and the specific cutting force (kc). With the help of the efficiency of the machine, you can then obtain the required torque from the spindle motor. Both torques are reported.

Calculation of SPINDLE POWER (Pc) or cutting power and required MOTOR POWER (Pm) is performed and reported in this application. The spindle power is the amount of power required to be able to cut the material. Depending on the efficiency (losses in gearbox, bearings etc.) the necessary power on the spindle motor can be calculated. Calculation of the spindle motor's power depends on the cutting depth (ap), the cutting width (ae), the table feed (Vf), the specific cutting force (kc) and the efficiency.

As already written, some illustrations and 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 of entering angle (when straight inserts) will also affect the chip thicknesses and the feed rate factor

- A change of the diameter of the inserts (when round inserts) will also affect the chip thicknesses and the feed rate factor

- A change of cutting depth (when straight inserts) will also affect the material removal rate, the torque and the power

- A change of cutting depth (when round inserts) will also affect the material removal rate, the chip thicknesses, the feed rate factor, the torque and the power

- A change of cutting width will also affect the material removal rate, the chip thicknesses, the cutting speed factor, the feed rate factor, the torque and the power

- A change of air-cut width will also affect the chip thicknesses and the feed rate factor

- A change of the specific cutting force will also affect the torque and the power

- A change of efficiency will also affect the torque and power of the spindle motor

FINALLY

Sometimes values can seem wrong but it is most likely that it has to do with rounding of values. Most of the values shown are rounded values, but in the background these are calculated with much higher precision.