Innovative CNC machining programming thanks to CAM class solutions
Numerically controlled machines have developed remarkably in recent decades. Compared to analog machines, they are much better prepared for serial production, easier to use for the younger generation and, above all, have the ability to work with computer programs to obtain much more complex shapes and speed up programming. Along with their development, CAM programs are also developing, which work perfectly with them.Standard machining on analog machines looks like this: having 2D documentation, the operator writes the program manually using G code. It uses all the dimensions in the drawing and must add the appropriate number of passes, adjust the feed, entry, etc. When it comes to working on the full 3 axes (not to mention a larger number of them), creating a program for the machine is virtually impossible without a CAM program.CAM program and "traditional machining"
CNC machines have developed incredibly over the last decades. Compared to analog machines, they are much better prepared for serial production, easier to use for the younger generation and, above all, have the ability to work with computer programs to obtain much more complex shapes and speed up programming. Along with their development, CAM programs are also developing, which work perfectly with them.Standard machining on analog machines looks like this: having 2D documentation, the operator writes the program manually using G code. It uses all the dimensions in the drawing and must add the appropriate number of passes, adjust the feed, entry, etc. When it comes to working on the full 3 axes (not to mention a larger number of them), creating a program for the machine in them is virtually impossible without a CAM program.
This is where new solutions come to the rescue, which have developed a lot over the last dozen or so years.
CAM programs allow:
Shortening the time that must be devoted to creating technology for the machine.
Creating programs for complex shapes containing full 3-axis properties. The only limitation here is the designer's imagination.Creating HSM paths
Shortening the time needed to check the code - simulation on a virtual machine model. Thanks to this, we can also avoid costly collisions.Quick introduction of changes in model paths.
Model associativity.
Procedure for working with CAD/CAM program
3D CAD programs are currently in common use in the construction industry. Their advantages do not need to be presented. Creating a 3D solid and then flat documentation is much simpler and faster than in the case of a 2D program. The drawing is created automatically along with dimensions, and the solid or assembly itself is much easier to create in 3D than on projections. Having a spatial representation, we no longer have to rely on flat documentation from which the technologist will laboriously copy the appropriate coordinates to the G code in the machine and add the appropriate transitions.When we transfer the solid to the CAM program, we can select geometry and add processing to it in a much simpler way. We select a given geometry and then add the appropriate operation to it, e.g. roughing. We adjust the parameters, e.g. by changing the input type or the cutting size, and we get the tool paths. Machining simulation checks whether we will not get collisions and whether we will machine the detail precisely - we use this functionality in our CNC Machining Center. Finally, we generate G code using a prepared postprocessor, which changes the tool paths in the CAM program into a code understandable for this specific machine, which we can use in the machine tool. However, CAM programs differ from each other. Here we can recall the classic text that we will reach our destination in both a Maluch and a Mercedes ... So there are some catches, through which some CAM programs speed up work much more than others.
Fig. 1 Working in the CAMWORKS program
Generally using a CAM type program shortens the machining preparation time by about 80%. Not to mention the fact that some shapes cannot be obtained using the machine's desktop. Unfortunately, there are still cases of fear of improvements regardless of the obvious benefits for the company. The reason here is the habit of manual programming, used for years. This is a very common fear of change and reluctance to learn new solutions. Some operators even go so far as to say that they will program the machine faster without using a CAM program. This may indeed be true when we want to add one pass from point A to B. In the case when we already have more movements, this is not possible. However, improving the company using a CAM program brings with it multiple benefits. It is an investment that pays off after a short time.
CAM program - what do we gain?
A typical CAM program speeds up the process of creating technology itself by not having to describe the coordinates to which the tool is to move, we just select a feature with one click, which selects its entire shape for us, and then add a specific operation to it. Adding an operation and possibly changing its parameters takes a few moments, and describing the entire contour takes much longer. Here, however, we have two levels of acceleration of our work. What if we have 100 holes arranged irregularly? Selecting each of them will take less time than entering its coordinates, but the time gain is not large here. Here, a better solution is automatic recognition of features. This is a tool that finds all the shapes in the model. If we have a complex part, it will help us save a lot of time. The next step is to add the operation to the properties. This can also be done automatically by generating a technology plan. The operation parameters should be added by the program automatically based on the selected strategies, i.e. the customized machining saved by us. Thanks to this, we create parameter templates appropriate for a given strategy once. Feeds and speeds are also important. Of course, we can choose them at our own discretion. However, there are tools that automatically choose the feed and speed based on the selected material, tool and cutting size. All these solutions significantly speed up the time needed to prepare the machining, which means that investing in a CAM program pays off very quickly, because time is money. Let's use the example below.The program for the part below takes almost two thousand lines. Writing it "by hand" takes a very long time and is tedious, craftsmanlike work. Programming it in a CAM program using work automation takes about a minute.
Fig. 2. Code for the part next to it.
3-axis paths are practically unattainable for an operator writing programs by hand, not to mention shapes requiring the use of the fourth and fifth axes. For example, how to describe the following 3-axis detail using transitions and arcs, additionally in such a way as to machine it well and obtain the appropriate surface quality? It is impossible manually. The CAM program enables surface machining that adapts to the shapes of the solid created in the CAD program, where modeling it does not pose any problems.
Fig. 3. 3-axis part.
HSM machining was not used in machining a dozen or so years ago. Currently, it is mandatory for most plants. This is machining at higher speeds, with characteristic paths and cutting with the full depth of the cutter. It provides a much higher rate of material removal, which makes it possible to shorten the production time by as much as 80 %. It uses lower cutting forces and provides more favorable dispersion of thermal energy. It uses appropriate paths (based on trochoidal geometry) so that we do not have sharp or abrupt transitions and cutting takes place at the full depth of the tool, which extends its service life. We can only create such paths in a CAM type program. We also have to select appropriate parameters , where unfortunately we have a small margin of error. CAM programs of course offer certain solutions that automatically select appropriate parameters for the HSM path.We all know how expensive collisions are. Destroying a milling cutter is the smallest penalty. However, when the spindle is damaged, the costs are drastically higher. In most cases, this results from unforeseen movements or departures. The solution to this problem is G-code simulation that takes into account the kinematics and logic of the machine. Thanks to this, we can reproduce the entire structure of the machine and its movements 1:1 based on the NC code. We can see any collisions already in the program and often avoiding just one of them returns the cost of the program. This is also an additional time saver because we do not have to check the entire code on the machine that can be working at the time.
Fig. 4. G-code simulation on a virtual machine model.
Some controls have very advanced ways of using cycles, even for machining, e.g. rectangular pockets. Thanks to this, when we want to change its length in the code, for example, we do not have to write the code from scratch. But what if the machine does not have such cycles, the change is more complicated, the shape is not a simple pocket or it is some other, complicated shape? Then we have to start everything from the beginning... In CAM programs, on the other hand, we can change its parameters very quickly in the operation window. Generating a new code takes a second. A very important issue regarding CAM programs is associativity , i.e. combining machining with the model. Imagine that we want to make some changes to the part. The paths should rebuild themselves, adapting to changes in the model. Otherwise, we have to add the entire machining anew .
CAMWORKS – the CAM program that speeds up work the most
A modern CAM program should meet the above assumptions, from the moment of modeling the part in the CAD program, detecting features, assigning appropriate parameters to generating the code and its simulation. Such possibilities are provided in the CAMWORKS program, which is part of the SOLIDWORKS interface (as another tab) and saves machining data to its file. Since we are in one program all the time, there are no errors related to transferring the model. An additional advantage is the automatic reconstruction and adaptation of paths after changes in the geometry of the solid. It has, of course, advanced three-axis and multi-axis modules, as well as HSM Volumill, a solution that allows for generating very effective roughing paths, thanks to which the time of such machining can be shortened by as much as 80 %! The creation of technology itself is also incredibly shortened, because the program contains the best-developed automatic recognition of properties among programs of this class, finding all not only holes, but also pockets, surfaces, grooves. Strategies with operations and appropriate settings are also generated for these properties (the program can be "taught" to select parameters). Thanks to this, the time of creating technology is drastically reduced. Another saving of time (and above all money!) is simulation on the virtual CAMWORKS machine, integrated with the program. All this makes CAMWORKS indispensable in every plant with CNC machines, for which both innovation and saving time and money are important.