CNC-Fräse: Unterschied zwischen den Versionen

(8 dazwischenliegende Versionen von einem anderen Benutzer werden nicht angezeigt)

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| Aluminium (9-13% Si)|| VHM || || 300 || 0.06 || From "Praxis der Zerspantechnik"

|}

This document from Sorotec is quite useful: [http://www.sorotec.de/webshop/Datenblaetter/fraeser/schnittwerte.pdf Sorotec Cutting Speeds]. But beware! These values are a rule of thumb and we might not be able to reproduce the results on our machine!

Yet another word to datasheets: The values are usually given for a tool's lifetime of 15 minutes! Yes, you read right only fifteen minutes! If you want to keep for cutters for a longer time, then do not use those values.

A rule of thumb is the following: The lower the Youngs modulus (E-Module) of a material, the sharper the tools must be, a more rigid setup is required, heavy feeds and slow speeds produce better results and abundant cooling is required.

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| <math>z</math> || Number of Teeth || Anzahl der Schneiden ||

|-

|rowspan="2"| '''material specific''' || <math>f_z</math> || Feed per ~~Teeth~~ || Vorschub pro Schneide || <math>\text{mm}</math> ||

|rowspan="2"| '''material specific''' || <math>f_z</math> || Feed per Tooth / Chipload per Tooth || Vorschub pro Schneide || <math>\text{mm}</math> ||

|-

| <math>v_c</math> || Cutting Speed || Schnittgeschwindigkeit || <math>\frac{\text{m}}{\text{min}}</math> ||

| <math>v_c</math> || (Surface) Cutting Speed || Schnittgeschwindigkeit || <math>\frac{\text{m}}{\text{min}}</math> ||

|-

|rowspan="2"| '''calculated''' || <math>v_f</math> || Feed Rate ~~Forward~~ || Vorschub || <math>\frac{\text{mm}}{\text{min}}</math> || <math>v_f = n \cdot f_z \cdot z</math>

|rowspan="2"| '''calculated''' || <math>v_f</math> || Feed Rate || Vorschub || <math>\frac{\text{mm}}{\text{min}}</math> || <math>v_f = n \cdot f_z \cdot z</math>

|-

| <math>n</math> || ~~Revolutions~~ || ~~Umdrehungsgeschwindigkeit~~ || <math>\frac{\text{1}}{\text{min}}</math> || <math>n = \frac{v_c \cdot 1000}{\pi \cdot d} </math>

| <math>n</math> || revolutions per minute || Drehzahl || <math>\frac{\text{1}}{\text{min}}</math> || <math>n = \frac{v_c \cdot 1000}{\pi \cdot d} </math>

|-

|rowspan="2"| '''defined by process and<br>maximum load of machine''' || <math>a_p</math> || Infeed || Tiefenzustellung || <math>\text{mm}</math>

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| '''for time considerations''' || <math>Q</math> || Material Removal Rate || Zeitspanvolumen || <math>\frac{\text{cm}^3}{\text{min}}</math> || <math>Q = a_e \cdot a_p \cdot v_f \cdot \frac{1}{1000}</math>

|}

Note for the English terms: It looks like they are not as precise defined as in German.

The German terms are explained in "Praxis der Zerspanungstechnik" by Jochen Dietrich (DOI: 10.1007/978-3-658-14053-3), but I could not find any English reference book on that topic yet --[[Benutzer:Reox|Reox]] ([[Benutzer Diskussion:Reox|Diskussion]]) 10:06, 4. Aug. 2018 (CEST)

These values are connected to each other. There are two main formulars to calculate <math>n</math> and <math>v_f</math>.

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Typically you choose a specific milling cutter for the job and lookup the values for the material. The process parameter are bound by the maximum load the machine can handle (See for example [[CNC-Fräse/Technical#Und_warum_kann_man_jetzt_keinen_Stahl_bearbeiten.3F|Why can't I mill steel in the CNC?]]) and of course by the workpiece you want to produce.

The cutting speed in the datasheet of a cutter is often calculated for a service time ("Standzeit") of 1 hour. That means if you mill with the exact parameters that are posted in the datasheet, the cutter will be unuseable after ~~about~~ one ~~hour~~.

The cutting speed in the datasheet of a cutter is often calculated for a service time ("Standzeit") of 1 hour, sometimes only 15 minutes! That means if you mill with the exact parameters that are posted in the datasheet, the cutter will be unuseable after only a short amount of time.

You really need to check for what service time, the datasheet is written. Often the manufacturer will not tell you, so assume the worst (which is 15min).

=== Milling Strategy ===

Or: conventional milling vs climb milling. There are two ways of cutting material: either the spindle direction is the same as the feed or not. The first method is called climb milling or in German Gleichlauffräsen, where the latter one is called conventional milling or in German Gegenlauffräsen.

As our feedspindles have some backlash, we can not really make use of climb milling on our machine! Of course, you can use climb milling for finnishing passes, if you remove very less material. In all other cases use conventional milling.

If you mill with the full cutter diameter, there is no difference of the feed direction though, as half the cutter is in climb mode, the other half is in conventional mode.

If you are milling outer contours you have to go counter-clockwise, on inner contours you need to go clockwise to use conventional milling.

=How to=

===FreeCAD Path-Workbench===

Siehe [[CCCP|CNC-Workshop]] von [[User:ripper|ripper]], mehr Infos folgen.

Ganz wichtig:<br>

Post Processor für die CNC-Fräse von [https://github.com/Metalab/freecad-cnc-postprocessor Github] holen. Hat zB automatischen Drehzahlhochlauf inkludiert.

===CamBam Mini HowTo ===

[[Bild:CamBam_Howto.PNG|thumb|400px|Werte die man bei CamBam beim erstellen eines 2.5D oder Pocket Operation beachten muss]]

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* [http://www.carbide-tools.com/knowHow.htmld/ Was Sie über Werkzeuge wissen sollten]

* [http://de.wikipedia.org/wiki/Schnittgeschwindigkeit Wikipedia]

* [http://www.rueggeberg.de/de-de/101_DDE_HTML.htm Onlineberechnungen]

* [http://www.pferd.com/at-de/101_DEA_HTML.htm Drehzahlrechner]

* [http://www.depo.de/content/view/75/93/lang,/ Drehzahlrechner]

* [http://www.vhf.de/cgi-bin/ToolCalc?lng=de noch ein Drehzahlrechner]

* [http://www.pferd.com/at-de/101_DEA_HTML.htm ~~yet another~~ Drehzahlrechner]

= Technical Details =