Beyond conventional machining

In addition to needing a machine tool that can perform both additive manufacturing, such as laser metal deposition, and subtractive machining, hybrid manufacturing requires a CAD/CAM software package that accommodates building and removing material.

One such package is hyperMill from Needham, Massachusetts-based Open Mind Technologies USA Inc., a subsidiary of Open Mind Technologies AG in Wessling, Germany.

“Hybrid to us is very similar to subtractive machining in some ways where we are using many strategies for planar and nonplanar building materials followed by the machining process to typically bring a slight oversize condition to a finished component,” said Managing Director Alan Levine. “Additionally, on the hybrid side we’ve built in the necessary technology to properly control the heat source whether it’s powder- or wire-based.”

He said the foundation of the hybrid manufacturing market began with powder bed, which is considered a simpler method than the directed energy deposition technique. However, when manufacturers want to add a hard coating of material to repair a part, such as a mold, turbine blade or disc brake, they tend to turn to directed energy deposition.

Lothar Glasmacher, head of additive and process technologies at ModuleWorks GmbH in Aachen, Germany, said other common hybrid applications include building aerospace parts like blisks and propellers; prototyping structural parts, including those made of multiple workpiece materials; and creating modular parts that cannot be machined from stock material because of their part geometry. The company developed software for MU-V Laser EX hybrid machines from Okuma Corp. that combines additive path planning and subtractive toolpath calculation components.

Material is added to an aerospace nozzle using hyperMill CAD/CAM software from Open Mind Technologies. Image courtesy of Open Mind Technologies USA

He said ModuleWorks can deliver single modules to close the complete process chain from workpiece input to path planning and simulation to NC output. With its post-processing framework, the company is able to send the appropriate NC code and specific commands to any machine or controller for additive manufacturing.

“The closed-chain manufacturing from CAD to the hybrid machine allows productive part manufacturing without manual toolpath editing or teaching,” Glasmacher said.

In addition, he said 3D constant step-over and offset slicing for additive path planning ensure a stable additive process without gaps in the weld bead. This capability provides a smooth look-ahead function for five-axis orientation motions and effective mesh- and surface-based path planning.

New Versus Repaired Parts

Another CAD/CAM package for additive and hybrid manufacturing, such as programming cladding on five-axis milling and mill/turn machines, is available from SprutCAM America in Waunakee, Wisconsin. Founded in Naberezhnye Chelny, Russia, SprutCAM Technology Ltd. also has an office in Germany.

According to one Greek client, 95% of its applications are for part restoration with revisions and corrections accounting for the remainder. Another customer from Greece noted that restoration accounts for 100% of company applications, including propellers, propeller shafts, turbine shafts and turbine impellers. Both companies concurred that there are no problems with integrating the CAD and CAM systems in SprutCAM’s software.

Nonetheless, Glasmacher said one of the main deficits of conventional CAD/CAM systems is that they are positioned well in the milling area but do not offer effective additive solutions to optimally support the process. As a result, an operator often has to use several systems that interact with each other in a cumbersome manner, and a continuity from component preparation to hybrid path planning to NC output therefore is not possible. However, he said this chain can be closed because of ModuleWorks’ expertise in both subtractive and additive applications.

Technicians program an Okuma MU-V Laser EX hybrid machine using software from ModuleWorks. Image courtesy of ModuleWorks

Levine agreed that integration of the CAD and CAM sides is not an issue for hyperMill software.

“For us, you are simultaneously working in the CAD and CAM environments,” he said. “It’s very easy to access any functions you need at any time.”

Lattice Optimization

Glasmacher said lattice support structures, which only can be produced additively, make it possible to reduce the weight and amount of workpiece material with constant mechanical properties.