Combining post-processors, verification: 5-Axis Machining

More than ever, North American part manufacturers must constantly improve their processes and upgrade their technology to compete globally. As production runs continue to shorten and part geometries get more complex, 5-axis machine tools are starting to go mainstream. Many shop owners are taking advantage of the efficiency and return on investment possible with what once were considered specialty machines.

Even though the benefits of 5-axis machining are attractive, many potential users eye the technology with caution. Adding that 5th axis drastically increases the level of complexity, and programmers must consider new machining scenarios. New users can expect a learning curve, and it’s important to minimize errors during that time to get a timely ROI from such a significant capital investment.

The biggest benefit of 5-axis machining is its ability to produce complex shapes in a single setup. Having this flexibility and versatility increases machine throughput compared to performing the job in a series of setups and virtually eliminates the time and cost of preparing fixtures.

All images courtesy of CAMplete Solutions

The blue path represents the CAM-programmed cutting tool trajectory, and the red path represents the actual physical tool motion when considering the machine kinematics. Having the proper verification software tools to analyze these differences is critical to overcoming 5-axis motion errors.

Another important advantage is the ability to apply significantly shorter cutting tools, because 5-axis machining enables the head to be lowered toward the workpiece and the cutter to be oriented toward the surface.

In addition, 5-axis technology eliminates the multiple setups required to reposition a workpiece at complex angles. Not only does this save time, it also reduces potential errors and the cost of tooling and fixturing to hold the workpiece.

With shorter tools, 5-axis machining can complete an entire part without refixturing it or applying the long tools required when producing a similar part with 3-axis machining. As a result, 5-axis machining delivers the final product in less time and with a finer surface finish.

Shorter tools automatically enable higher cutting speeds without putting excessive load on the cutter, increasing tool life and reducing breakages. This also reduces the tool vibration typically seen when machining deep cores or cavities with 3-axis machines.

When a company makes the plunge into 5-axis machining and programming, however, the possibility for errors becomes much higher than with 3-axis machining. Therefore, programming five axes makes some new users nervous.

Software packages are available to make this task less intimidating, such as the latest CAD/CAM software, but it’s important to make sure what is programmed is actually what will run on the machine.

The post-processor—the critical link between the programming software and the machine—is often the weakest link in 5-axis machining, but it doesn’t have to be. The post-processor is typically the weakest link because developers focus on creating toolpaths and tool motion in the CAM software instead of the post-processor. Also, given the large number of different machine styles, configurations and options to support, an application engineer must often modify a post-processor to the customer’s specifications, tying up personnel and the machine until the post-processor meets those requirements. And this modification would only be to support standard operations. As the customer gets more involved with the machine and explores its more advanced functions, the post-processor follows the same learning curve as the user did and evolves accordingly.

In the worst-case scenario, when implementing a new machine does not go as smoothly as planned, the software vendor can get stuck between a rock (the customer) and a hard place (the machine vendor) because the post-processor creates the particular commands required by the machine to follow the instructions programmed in the CAM system. Having an integrated and proven platform dedicated to a particular machine tool eliminates the need for lengthy post-processor prove-outs.