Tool changes are the actions of replacing one cutting tool with another on a CNC machine, either manually or automatically. Tool offsets are the adjustments of the machine coordinates to account for the different dimensions and positions of the tools. Tool changes and offsets are necessary because different tools have different purposes, shapes, sizes, and wear rates, and they need to be aligned correctly with the workpiece and the machine.
Cutter comp will be needed when using resharpened cutters, in this case offsets are the only way to use resharpened cutters properly for finishing features.
A troca de uma ferramenta e determinada pelo o seu desgaste de geometria e pela sua capacidade de corte comprometendo a rugosidade da superfície usinada. - O desgaste da geometria pode ser "compensado" ajuste de diâmetro e comprimento no comando da máquina ou até mesmo no software CAM.Isso vai garantir o dimensionamento correto da peça que está sendo usinada. - Com o desgaste avançado da ferramenta suas arestas de corte perdem a capacidade de cortar o material a ser usinado, ocasionando um aumento na rugosidade da superfície usinada. No momento em que ultrapassar a rugosidade exigida do projeto ou até mesmo antes e a hora de realizar a troca da ferramenta.
Though in the industry I am in, we only use handful of router bits. Your cnc machines should have different sets of configurations and program files matching certain type and size of bits. This should be well labeled and communicated to operators to avoid mishaps and avoid the risk of potentially ruining the machine which will result in a downtime in production.
It's how you are able to correctly articulate a 3D object. Certain tool are designed for certain tasks and both are controlled by the program, which often need offsets to fine tune final product.
The machine only knows its home position. In order for it to know where to begin cutting, you have to tell it where the work piece is. Tool geometry offsets tell the machine where a specific tool is in relation to the work piece (the piece being cut). Tool wear offsets allow the individual tool positions to be finely adjusted in order to achieve the desired dimensions of the work piece. Work offsets allow for an overall placement or adjustment of a set of multiple tools that use that specific offset G number.
Tool changes and offsets are essential in CNC machining since they have an effect on the quality, accuracy, and efficiency of the final product. If not done properly, the tools may break or wear out faster, not cut or shape the material as intended, and even collide with the workpiece or machine, all of which can lead to costly time and money losses, defects or errors, and even damage or injury. Consequently, tool changes and offsets must be planned, programmed, and executed with great care and precision to guarantee optimal performance and safety.
Tool offsets or so called "Tool Compensations" G43/G49 are important in various aspects for example during trials we compensate sometimes on [+Z] height to dry run GCODE for checking accidents, Furthermore, post tool Presetter auto compensations happen if the CNC is connected with presetter APIS which understands the tool wear in width therefore causing tool path to be closer than before. This is used to gain higher accuracy in some industries depending on the tolerance applied by engineers.
When planning tool changes and offsets in CNC machining, the first step is to consider various factors such as the material properties and specifications of the workpiece, the desired features and tolerances of the final product, the availability and capacity of the machine and tool magazine, the cutting speed, feed rate, and depth of cut for each tool, the tool geometry, diameter, length, and tip radius for each tool, and the tool wear and compensation for each tool. This will help you determine the appropriate tools for the job, establish the order and frequency of tool changes, and calculate the tool offsets for each tool.
Any good Machinist should be able to tell a tool is worn by sound. When changing an insert, always add .005 to the offset. #1 rule of machining is, you can always take more off if needed.
Nowadays different cutting tool manufacturers developed cutting tool monitoring systems , this technology add modules with microcontroller into an adaptive sensor that graphs the spindle torque , si you could graph the whole machining process ( operations with its tool) , that system includes a software that allow to download all the data (historic) and generate a simple predictive model in pair with the correct feeds and speeds set tool life set point and the controller could generate prealarm, so as my experience those systems work pretty accurate for high mix production type.
A better rule of thumb is to add how much you intend to take for the actual finish cut, so you have similar cutting pressure. Also, you should bury at least 2/3 of the nose radius of your inserts for a finish cut.
Always find that depending on the radius of insert and cut depth that you can get discrepancies of anywhere between 2 and 8 thou , I usually offset by .5 when changing inserts , just to be on the safe side .
Al hacer el cambio de herramienta, es necesario compensar un poco para después medir ya que los insertos traen una mínima variación. En algunas ocaciones uno se da cuanta de cuando se tiene que cambiar el inserto, por sonido que se emite, para diferente tonalidad que toma el materia al maquinar.
The second step in handling tool changes and offsets in CNC machining is to program them into the machine code. This involves using commands and codes to instruct the machine when and how to change and offset the tools. For example, the command T01 M06 specifies the tool number and the tool offset number, while M06 activates the tool change cycle, moving the spindle to a predefined position, releasing the current tool, picking up the new tool, and returning to the original position. G43 activates the tool length compensation, adding or subtracting the tool offset value from the Z-axis coordinate. For instance, G43 Z100 H01 means move the Z-axis to 100 plus the offset value of tool number 1. Lastly, G49 cancels the tool length compensation, ignoring the tool offset value and using the original Z-axis coordinate.
-In this example I would say which machine control was used ie. Sinumerik, Fanuc, Heidenhain etc, since this could potentially lead to confusion and not accepting inputted commands.
When running production I will determine a baseline for my tool life along with using the software's run time calculations select an appropriate feature to terminate the tool at, then call the backup tool. When working with costly materials and long cycle times I will try to use an area of the raw material that will be cut away later to qualify a "new" tool offset. If you have probing this will automate this process as well.
The third step in handling tool changes and offsets in CNC machining is to execute them on the machine. Before starting the machine, you should check the tools and the tool magazine to ensure they are clean, sharp, and correctly loaded and aligned. Additionally, verify that the tool offsets have been measured, entered, and verified accurately. While running the machine, keep an eye on its position and movement to make sure it follows the code without exceeding the limits or colliding with anything. Finally, inspect the workpiece and product quality after each tool change and offset to ensure that they cut and shape the material as expected and meet the specifications and tolerances.
This is a vital part of machine setup, and requires the most careful attention to detail. Fail to get this bit right and the very least you are likely to do is scrap the part, and at worst you could have a crash, damaging the tooling and machine, and endanger the machinsist. Complete concentration is required. Distraction from coworkers, music, or things happening elsewhere in the machinists life can cause problem. Have a methodical approach, follow the procedure you usually use when tool setting, be sure to check that you covered each step alongt the way. Machines with tool setting probes help a lot, but you still need to remember to measure a tool after changing it. Even more important to be methodical when you are touching off manually.
Preset tooling can be a real help when it comes to speed and removing error. Even if you don't have preseting technology having the commonly used standard tools setup ready to go in the machine saves time, but remember to measure it and reset the tool length (and diameter if in use) compensations after loading it. The alternative can cause loud bangs and sparks when it goes wrong. Always check that a preset tool has the called out standout, or that can become an expensive and scary split second when the tool comes out and ploughs into the workpiece or holding.