Machining Woes? Leave it to the Pros
by Jim Buchanan

Think about optimizing toolpaths for machining molds and dies.

Toolpath software optimized for production applications is typically not ideal for mold and die machining. Mold and die toolmakers have to think differently, and mold and die toolpath software has to be different too. Enter Pro/TOOLMAKER 8.1.

Fundamental differences. Unlike typical production machining, where a cutting machine might shave off just 10 or 15 percent of the material to create a finished part, the mold and die machining process can end up cutting as much as 80 or 90 percent of the original mass. Because of this, and because of the abstract nature of the actual toolpath design, mold and die machining software has to be especially good at removing large volumes of material at high-speed with great accuracy.

“It can take hours or even days to machine a large, complex mold, so your first priority is speed,” says PTC Director of Product Management Francois Lamy. “You need to maximize big-tool usage. So you want to set up your toolpaths to do roughing and re-roughing with the biggest tools possible, and then finish with the smaller tool, all the while letting the software detect the left over material automatically.

“Pro/TOOLMAKER 8.1 can help you determine the best toolpath strategy and can execute the actual toolpath processing very fast.”

When we talk about cutting precision, toolpath accuracy is critical because of the abstract nature of the task.

With a production job, like an engine block, the programmer can watch to see how the cutting is going. If a tool isn’t going far enough into a hole or on a planar surface, the programmer can easily make a correction then and there.

“But with mold machining, you can’t do that,” Lamy says. “It’s impossible to visualize the final mold part when it’s still hidden inside the stock. You have to trust the software to know exactly how far each roughing tool can go, and where the finishing tool should go. You can’t do that by eye.”

Toolpaths themselves are, in large, repetitive, with each smaller tool coming back to remove the left over material by the larger tool. If the toolpaths are designed correctly, the process can be automated. But that’s a big if. Pro/TOOLMAKER 8.1 simplifies design and setup and offers inherent advantages both in cutting speed and toolpath precision.

Making passes. With Pro/TOOLMAKER 8.1, setup is a four-step process. The programmer selects the strategy and the tool and then creates the passes. The software helps here, making informed suggestions based on best-practice parameters.

Next, the programmer edits the passes based on job-specific details—the stock material, unusual surfaces, and so on.

The programmer then links the passes, with the software showing the most efficient routes, and—with the software’s help—creates optimized approaches, retractions, and plunges for the cutting tools.

Finally, the software builds an in-process stock model, allowing the programmer to visualize how the part is going to look at each step of the process, check the job progress and help optimize the following toolpaths.

“These features help minimize air cut and optimize material removal rate,” Lamy says.

Once the job is underway, Pro/TOOLMAKER 8.1 displays its performance advantages. Lamy explains that these are “inherent” because they derive from the design of the product architecture itself.

“One big advantage comes from the tessellation mesh that the software uses to represent the model’s geometry,” he says. “The Pro/TOOLMAKER internal model representation is typically 40 percent smaller than comparable software for the same accuracy. So the file sizes are 40 percent smaller. This helps toolpath computation performance, and it makes it possible to handle larger models.”

The other advantage comes from the software’s multi-threaded architecture. Multi-threading allows users to continue working inside Pro/TOOLMAKER while toolpaths are calculated in the background, optionally utilizing multiple processors, dual cores and hyper-threading technology.

“The difference between Pro/TOOLMAKER 8.1 and conventional machining software can be huge,” Lamy says. “In one test, we did a toolpath processing in about a minute that would have takes 45 minutes without this software. And customers are already reporting major improvements in performance.”