The implementation of a CAM (computer-aided machining) system into your CNC machining workflow process can help you produce parts more efficiently, maintain and improve overall quality and help you win new business.
While “automation” is the idea behind CAM software, shops around the world still struggle to become profitable, efficient in their CNC machining process while trying to maintain a competitive edge. Let’s take a closer look at the subject of CAM software and how the implementation of it can contribute to improving programming times and your overall business.
Choosing the Right CAM Software
The projected manufacturing demographics for CNC shops and CNC machine consumption for 2014 tell us that shops between 1-19 employees are expected to grow by more than 50% this year over 2013. 5 Axis CNC milling machine tool purchases are expected to see a staggering 276% increase, while horizontal machining centers follow at a 118% increase. These projections tell us that companies using CNC machines are growing and they’re going to need to automate their manufacturing processes.
Let’s face it a CNC department without a CAM programming software is like a product design department without CAD. The two should be thought of as one cohesive unit. And even though many manufacturers already have some form of CAD-CAM implemented, not one CAM software system offers everything to meet all of their job requirements. That leads us to the overall workflow process …
CAD Files & Compatibility
So how does CAD/CAM software improve production workflow? First, we have to dissect each stage of the process. It begins with how you acquire your part model. Most manufacturing businesses start with a 3D model of a part either designed by you in CAD (computer-aided design) software, from a print (paper-PDF) or a digital CAD model provided by your client. SolidWorks, AutoCAD, Inventor, PTC-Creo, and CATIA are examples of CAD programs you might get files from. Therefore it’s critical that a CAM system has the ability to import or open CAD design files.
Why start from scratch. CAD systems generally have their own native file types. Among the most common are STL, STEP, IGES, DXF, DGN, SLDPRT and others. Some CAM packages may already have some slimmed down CAD editing tools built in. Others offer fully integrated plug-ins allowing them to operate within the NATIVE CAD software, therefore reducing geometry translation issues while streamlining the design to machining process.
CAM Job Management & Setting Up Your Stock
Once the part file is ready to move into the toolpath and programming stage, toolpath strategies can be used and a program can be created in its proper sequence allowing you to turn machining operations on and off, re-order operations, post process and basically manage everything about the job program right within the software interface.
So what would be the optimum order of production in this stage of the workflow process?
- Creation of the stock for your part so that a machine setup can be created
- Followed by your material and the tools being used since it impacts the speed and feed settings within CNC toolpath.
- Workflow improvements also take place in the ability to easily access and setup your cutting conditions and tool patterns (multi-tool operations such as a counter bore or hole drilling with a center drill, drill and possibly a chamfer), tool crib and tool holder data. This is important to create an error free NC program.
- Next, you will need to access a tool library for all of your tools. The tool library should include all tool data, material, diameter, angle, length, labels and more that you will be using for all machining strategies within the job tree manager. All of this information makes the process of setting up a job faster if you have the ability to save set up details globally or separately from job to job. Another effective feature for saving time is the ability to save and load machine features. Many shops do a lot of the same types of jobs. (If you already setup your CAM for one job, then you can use that setup for another similar job. The idea here is “automation” so every opportunity to increase efficiency counts.)
- Once you have set up the stock, tools, material and cutting conditions, next, you will want to set up the post processor for your job. The post processor is the translator used in the process of converting the setup data and toolpath data and creating a numeric language (G-Code) then you will send to the machine tools controller to physically machine the part. Think of it as a print driver for your printer.
- Important note: Most CAM systems offer generic post processors. Some offer the ability to customize a post processor to meet the requirements of the controller on the machine. Check with the software provider for a library of post configuration files, particularly the one for your specific machine tool. Workflow efficiency can be achieved by having the software provider assist you in the creation or modification of posts. A correct post processor eliminates the need for you to have to hand edit code. Thus, allowing you to spend your time focusing on cutting parts.
Toolpath & Machining Strategies
The next stage in the process of using CAM software involves the creation of toolpath (cutter-path) which is the actual path that the cutting tool takes to machine the part. A CAM Tree-Job Manager will help you keep each machining operation organized and properly sequenced so that the g-code program produces the best possible cycle time for the job. 2, 3, 4 & 5 axis toolpaths are all developed to produce efficient roughing and finishing cycles.
The machine setup should already be created in the Job Tree because you already setup your stock. A Machining Wizard is a series of dialog boxes that step you through a process with a “Next” button until done where a “Finish” button would close the wizard and save everything you set for a toolpath machining strategy. When Wizards are used in the creation of toolpath two (2) things happen.
- New users create programs in a fraction of time over toolpath creation without using wizards
- Nothing is forgotten or left behind in making a toolpath that is accurate and properly calculated based off of the tools you setup for the job.
Toolpath Wizards start by allowing you to choose the areas of the part to apply a specified toolpath (planar, spiral, z-level etc) within a boundary or an entire part, set clearances and height of rapid moves for the tool. Then you can choose the type of cutting pattern (zig-zag or single direction cutting), cutting direction (climb or conventional), roughing parameters, custom tolerance and cut-depth options, lead-in and out options, toolpath linking options (how you want to connect one path to another) and other custom machine options.
When finished, you will automatically generate the toolpath so you can visually inspect it. This takes place for each separate operation. If a change is needed you can simply go back into the operation and edit it. Then re-generate the toolpath. Once you have created toolpath for each operation, you are ready to move into the next phase of the process.
Improvements in workflow efficiency can also be accomplished by using high speed toolpaths. High Speed Machining (HSM) is a revolutionary method of cutting where the traditional hard right and left turns in the cutting path are changed to produce more rounded or circular style cutting movements.
In some cases the high speed cut paths may be longer in overall length with this type of cutting path. However, the benefits are less tool-material collision which proves to extend the life of cutting tools. In addition, cutting speeds are typically increased (high-speed) which proves to reduce overall cycle times. High Speed toolpath was initially developed for 2 Axis machining (pocketing type operations).
Other toolpath strategies include Advanced Roughing that allows the user to enter an Intermediate Step variable which tells the software to rough down to the bottom of a cavity and then come back up the outer walls stopping at each specified intermediate level and remove the material that tends to look like a large stair step on the walls of the part. This improves roughing quality and cuts down on the amount of material that the finishing tool has to remove, all in one operation.
Lastly, workflow efficiency can be achieved in what is called, “Toolpath Associativity.” Associativity is the ability to make a design change to a part and automatically update toolpath operations without having to re-create an entire job. This is highly advantageous when there are many operations within a single job.
Simulation & The G-Code Program
The final stage in the CAD/CAM programming phase is typically the toolpath simulation and creation of an NC program file that can be sent to the machine tool. The simulation process allows the programmer to visually see the process and catch any errors within the program — gouges or collisions. Simulation also offers the ability to calculate cycle times as well as “machined part deviation” where you can visually inspect the part for areas that cutting tools did not fit in or cut during the machining process.
Typically a number-color system is used to visually detect deviation areas, tools and machining operations. Advanced Machine Simulation allows you to use your machines Kinematics to simulate the actual machines motion as well as the toolpath operations.
The final stage is the generation of the NC file that is sent to the CNC machine. This is a critical stage of the process due to potential loss of valuable time due to hand editing g-code programs. Once a completed post processor is created, a CAM product should allow you to automatically create code that is clean and edit free.
RS 232 and DNC communications is then used to send the completed program to the CNC machine tool which is used to cut the part from the specified material and with the specified tools that you input.
Improving Efficiency & Beyond
These are the general stages of the CAD/CAM CNC programming process along with examples of how you can improve the efficiency of your programming workflow by using it. While it is easy to say that CAD/CAM software should be simple to use, what is equally important is training. Ask the vendor or reseller if the software comes with training? Are there training videos that allow you to learn on your own time? Are there local seminars or one-on-one web based training sessions available for you to learn on the fly and on your own time? The more options the better which includes the ability to achieve operator certification as a professional.
We hope you found this article useful in helping you either be more efficient with the CAM system you already own, or if you’re in the process of investigating one, to know what questions to ask and the benefits that come with owning one.
For more information email firstname.lastname@example.org, or call 1-844-CADCAM1.
Thank you to our contributing partner company BobCAD-CAM and Chris Corbell www.bobcad.com
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