Improving CAM for Better Machining

In February, 3D Systems (3dsystems.com) acquired Cimatron (cimatron.com), an Israeli computer-aided design/computer-aided manufacturing (CAD/CAM) software company. Cimatron had merged in January 2008 with the California-based Gibbs and Associates, a CNC machining software company. When 3D Systems acquired it, Cimatron’s primary products were CimatronE, a CAD/CAM system for mold, die, and tool makers and discrete-parts manufacturers, and GibbsCAM, a CAD/CAM system for 2- through 5-axis milling, turning, multi-task machines (MTM), and wire-EDM.

All of which is to say that 3D Systems now has the wherewithal to offer an array of technology that’s beneficial for metal removal.
    
Programming for today—and tomorrow
The progress in machine tools comes with increasing complexity. More axes. More spindles. More turrets. All operating simultaneously in various combinations. Also, almost every CAM system today has some sort of capability to simulate those machines. Simulation is crucial for seeing tool and fixture paths, highlighting potential clashes, correcting CNC outputs, and maximizing the machine’s capabilities. However, a common problem exists when the simulations don’t match how the machine tool truly operates. 

“CAM systems were designed based on the way mills and lathes were originally created to move. Mill-turns and MTM started merging the two,” says Bill Gibbs, CEO and President of Gibbs and Associates. To address that, Gibbs’s company has rewritten GibbsCAM such that the upcoming release of GibbsCAM 2015 features a new underlying software engine. Called “universal kinematic machine” (UKM), this new engine can simulate and verify all machine dynamics (spinning turrets, moving fixtures, toolpaths, etc.), program multiple toolpaths, and generate postprocessors. UKM blurs the line between mills and lathes such that machine tool operators and resellers can program any machine tool, from simple mills and lathes, to state-of-the-art multitasking Swiss machines all from one CAM programming system. “It can handle any number of axes in any direction, with multiple tools cutting simultaneously,” says Gibbs. “Users can program and accurately simulate virtually any machine today and even machines that haven’t been invented yet.”

In one sense, UKM is a very sophisticated user interface for defining the kinematics and axis combinations for a machine. The result is accurate, on-screen simulations that, continues Gibbs, give “customers the confidence that what they see on the computer screen is what will happen at the machine. Machine simulation and post processors are built on the same kinematic model, optimizing the programmer’s time and ensuring complete accuracy.”

Lots new in GibbsCAM
GibbsCAM 2015 has lots of other improvements. There are new tool types: barrel, dovetail, convex tip, e-style ISO insert, and tools defined by solids. Users can dynamically view tools and tool-holders as 3D objects in the tool dialog box, which helps in visualizing the tools selected for a job. The Intermediate Tooling category helps in managing and selecting items that are neither tools nor fixed parts of a machine tool, such as fixtures (e.g., chucks, tailstocks, and steadyrests) and toolblocks (e.g., adapter blocks, and holders for toolholders). Programmers can create libraries of toolblocks to easily set up complex machines. These libraries can be shared across different parts, saving time and reducing errors.

GibbsCAM 2015 treats holes as fully associative features of solid models, including models imported from common CAD programs. Also supported are compound holes (holes with multiple segments that might each be tapered or threaded). Users can add multiple segments to a hole by dragging-and-dropping segment types (e.g., drill, chamfer, or threaded) and adjusting parameters (including simple or threaded, values for clearances, and type of end condition). New geometry tools include improved spline editing and contour tracing capabilities.

Last, GibbsCAM includes a no-cost license of VoluMill Wireframe from Celeritive Technologies (volumill.com). (Users can upgrade to the full-featured solids modeling version of VoluMill.) Some background: VoluMill was the first of the CAM software products to drive machines more intelligently at the toolpath level, thereby enabling any customer’s machining hardware to operate more efficiently and faster, leading to longer tool life. One way VoluMill does this is by automatically and dynamically varying the feed rates of the machine tool across a toolpath. According to Gibbs, machining times can be cut 30% to 70%, and tool life extended fivefold, especially when machining hard or hardened materials.

Handling inserts
The latest version of CimatronE, version 12, has two new tools for automating the insert design process, making the whole process both quicker and easier. One tool lets people design inserts by selecting faces from the mating solid geometry, or by creating a sketch to define the shape of the insert. The tool automates designing insert shapes, cutting components or areas where the insert goes through, adding reliefs, managing insert dimensions, and other steps in insert creation. After the insert is created, the sketch used to create the insert is automatically added to the insert part file, which simplifies and quickens the process of editing the associated parts and geometries.

A second tool helps users create a wedge on a select face of an object. Different wedge types are possible by applying custom shapes, such as box, circle, or enclosing polygon. Where manufacturing a wedge might be difficult, such as along all the edges of an insert base, the designer can manually define the wedges’ placement along individual edges. As needed, a cutting object, with optimized geometry, can also be defined for the wedge.

Both tools reduce the time for designing inserts, improve insert quality, and ensure better mold integrity, which are all important incremental improvements to acquire.