Transforming medical machining with CAD/CAM software from OPEN MIND

Computer-aided design (CAD) and computer-aided manufacturing (CAM) software are fixtures in machine shops. Medical device manufacturers are subject to increasing pressure to deliver precision, quality, and customization on time while meeting stringent regulatory requirements.

CAD/CAM software developer OPEN MIND Technologies, with North American headquarters based in Needham, Massachusetts, created its hyperMILL CAM software to help companies gain that competitive edge through a range of automation and simulation capabilities.

“CAM automation provides users with the tools to reduce or eliminate redundant tasks common to every programming example so they can focus on more skilled programming,” says Alan Levine, managing director at OPEN MIND Technologies. “Automation should be flexible enough to adapt to differences in geometry and should always be defined by the programmer utilizing their best practices.”

OPEN MIND’s hyperMILL Automation Center technology was originally used as an internal development tool that was then made available to customers. The software allows users to automate complex manufacturing processes by defining each individual step from preparation to programming. Once a manufacturing workflow is mapped, it’s stored and can be standardized and applied to new components in seconds.

“This works well with medical components that either have various standard sizes with the same design features, or unique parts where the same cutting processes can be applied to similar geometry,” Levine continues.

The software includes toolpath strategies for a full range of medical device parts. Extensive programming experience isn’t necessary, as it offers a programming wizard allowing users to generate automation scripts without writing code. An advanced version, however, gives experienced users more control over defining processes.

The importance of the right barrel cutter

Standard or customized, medical components are tricky to manufacture due to increasingly small sizes and complex features, as well as strict surface finish requirements. A reliable, efficient finishing strategy is essential for reducing processing time, which is addressed by the hyperMILL MAXX Machining finishing module for conical barrel cutting, a milling strategy pioneered by OPEN MIND Technologies.

Using a conical barrel cutter, it’s possible to machine radii of 1,000mm or larger, compared to ball endmills that typically have a radius from 4mm to 12mm. By mapping only a segment of a large radius on the end mill, the barrel geometry can more quickly achieve the high-quality surface finish medical components require. It enables large stepovers that cut wider swaths of material in fewer tool passes, reducing cycle times while maximizing tool life and efficiency and minimizing cusps. And the conical aspect of the cutter allows clearance from part surfaces and use of a shorter and stiffer cutter. With the conical barrel cutter finishing strategy in hyperMILL MAXX Machining, users can improve surface finish while reducing cutting time by at least 90%.

“For each barrel type, a range for the base diameter and barrel radius can be defined, so that the optimal cutter geometry is displayed during the analysis,” Levine explains. “Additionally, users can optimize the usable barrel radius through the analysis of the lead angle or determine the best barrel radius using the contact parameter control and the maximum barrel radius distance parameter.”

Surface finish solutions for any geometry

The machining of medical components is further complicated by the frequently necessary incorporation of holes in parts such as bone plates, surgical tools, and catheters. Cleaning up the burrs and sharp edges left by machining is an absolute must for parts being used in or on the human body, but it can add significant processing time, especially the smaller and more complex parts become. The solution? Automation, of course! hyperMILL’s 5-Axis Hole Deburring feature automatically recognizes holes and marks sharp edges – the user needs only to select the desired edges and the software automatically calculates all toolpaths. A new hole brushing tool further enables users to deburr or improve surface quality of cross holes or threads.

OPEN MIND prides itself on thinking ahead and working closely with customers to ease the headaches created by labor shortages, fluctuating demand levels, and the need for constant adaptation to new technologies. It’s all about simplification and guidance, as demonstrated by the hyperMILL programming assistance and analysis feature CAM Plan. Its predefined workflow steps guide users through preparation and programming, automatically create required geometries, and flag potential errors for removal.

Once the data is organized, the CAM workflow can be processed with new True Shape technology, offered within hyperMILL’s High Performance Surface Mode. It analyzes the topology of a component to create a precise, repeatable toolpath with optimized point distribution for milling, improving the definition of features such as fillets, rounds, boundaries, and creases.

Levine also highlights hyperMILL’s Smooth Overlap programming technique as a useful tool for medical component manufacturing. The feature helps to avoid ridges and visible edges at transitions from flat to steep component areas or when there is a cutter change.

“Smooth Overlap is used to blend adjacent tool paths,” he explains. “This technique allows different sizes or styles of cutters to be used without fear of mismatch that can also lead to stress concentrations.”

This is vital particularly for tight, difficult to reach areas, such as the box area of a femoral knee implant which demands a perfectly smooth, homogeneous surface finish.

Simulation for process optimization

Automation is becoming a staple in machine shops of all sizes. OPEN MIND’s focus on Industry 4.0 manufacturing solutions goes a step further, however, with its simulation technologies for machining process optimization. Simulation and digital twins are well-known in many manufacturing sectors where physical testing is time- or cost-prohibitive, allowing manufacturers to design, test, and redesign parts or entire products in a virtual environment. The concept, when applied to machining processes, enables early identification of potential issues and optimization of toolpaths and cutting speeds.

hyperMILL Virtual Machining software simulates, generates, and optimizes NC code and creates a digital twin of the machine for reliability and efficiency.

“The digital twin of the actual machine tool with all the information about the control, PLC, machine kinematics, and interference contours is already available during creation,” Levine says. “This means the digital twin of the machine is not only used for NC code simulation but also for generating the programs. This makes it possible to generate NC programs that are perfectly matched to the machine. Further, an NC Optimizer reduces transition time between tool paths or multiple holes within a tool path, or part alignments to fit a part within the machine limits.”

OPEN MIND prioritizes consistency at every process stage from importing CAD data to final machining, which is why it’s put so much effort into developing such a comprehensive software environment. Consistency and control often equal safety, providing collision-free, efficient machining, which is paramount in medical manufacturing. The hyperMILL suite allows users to automate time-consuming processes while maintaining control and oversight – keeping them competitive without sacrificing quality or compliance.

OPEN MIND Technologies
https://www.openmind-tech.com

About the author: Clare Scott is associate editor for GIE Media’s Manufacturing Group of publications. She can be reached at CScott@gie.net.