It’s common to machine parts with complex geometries and fine surface finishes in the aerospace and automotive markets. A common axiom in manufacturing for space applications is “there’s no repair shop in space.” Every part must be perfect in quality, precision, and reliability because once it leaves Earth, millions of dollars are on the line if it doesn’t.

That’s an even larger consideration when using machining or laser processing for medical implant manufacturing. Take, for example, an orthopedic implant (which readers can find out much more about in MPO’s sister publication Orthopedic Design & Technology, if interested). If a knee or hip replacement—two implants commonly requiring a slew of machining processes to make—don’t work, the patient’s health and well-being are at stake. When the surgery is finished, it just has to work.

Like other manufactured parts, orthopedic implants involve several machines or computer numerical control (CNC) cutting processes, including grinding or potentially even metal additive manufacturing. For example, machining operations on a knee implant can include roughing, tray base roughing/finishing, chamfer milling, T-slot undercut machining, wall finishing/chamfering, and undercut deburring.

Machining and laser processing are used for a wide variety of medical devices and components. Surgical equipment, catheters and catheter delivery systems, stents, medical pumps, and parts for various implantable devices are all commonly made via machining and laser processing. And as the aging population grows, the need for implants will increase.

“We recently invested in an additional CNC machining center to support growing demand for precision machined components,” noted Victor Grin, sales director at Component Engineers Inc., a Wallingford, Conn.-based manufacturer of critical components and assemblies for OEMs and contract manufacturers across industries including medical, automotive, aerospace, defense/firearms, electronics, and consumer products. “We try our best to stay in tune with our customers, their applications, and the industry to see where we might place our strategic investments to make a positive difference.”

Two process technologies that have been cornerstones for medical component manufacturers are five-axis machining and Swiss turning. These continue to evolve beyond their original turning and milling purposes to include multitasking capabilities for the machining center to try and completely machine components in a single handling. Speed is always crucial for becoming a strong machining partner, and the equipment continues to improve throughput volume. Faster speed also translates to cleaner cutting, reducing secondary steps required. This allows manufacturers to save costs and get products to market faster.

“We recently installed a Nakamura turn/mill work center,” said Gary Marion, director of operations at Providien Machining and Metals, a Sylmar, Calif.-based provider of precision medical machining that specializes in electromechanical assemblies, NPI management, and precision miniature bearings. “This dual turret/dual spindle machine gives us the ability to reduce cycle times on existing parts and reduce the number of setups for the machining process, as the machine can make complete parts (whereas before, these parts had multiple setups across multiple machines). We also recently invested in an automated pallet system for our Makino horizontal mills. The 24 available pallet locations give us the ability to run longer periods lights out.”

Lasers are also integral to the fabrication of implantable medical devices. Because of their accurate control, lasers can be used to micromachine many materials to implantable devices’ necessary intricate and precise geometries. Lasers were used to successfully micromachine coronary stents from the beginning since early stents were stainless steel and relatively large. Laser cutting with nanosecond-duration pulses was accurate enough for machining at this level.

Considerable post-processing steps like cleaning, deburring, etching, and final polishing were needed due to non-optimal surface finish and a narrow heat-affected zone (HAZ) bordering the cut edges, however. Implantable devices are becoming increasingly intricate and are composed of materials more difficult to machine. The fine control necessary to fabricate precision microstructures also can’t happen with such lasers. Firms that offer laser micromachining services, therefore, must invest in machines with far shorter pulses, into the picosecond range and beyond.

“Our latest addition is a femtosecond laser micromachining center,” said Scott Vormbrock, a product development engineer at Weiss-Aug Surgical, a Fairfield, N.J.-based developer and manufacturer of device components and assemblies used in surgical instrumentation. “It will improve and expand our machining capabilities as we can now add ceramics and glasses to our already diverse range of product materials.”

Femtosecond lasers are commonly referred to as ultrafast or ultrashort-pulse lasers. Ultrashort laser pulses are an attractive option for high-quality micromachining of many materials because they minimize damage and enable precise processing of more complex medical device components. Stents are now being used for peripheral arteries with tiny dimensions. There is also a trend toward adding a controlled surface texture or geometry to stents and prosthetics to boost biocompatibility, reducing the risk of restenosis (abnormal narrowing following surgery). Bio-absorbable materials have also been recently introduced for stents. These are highly challenging to machine because of their low melting point, and even picosecond lasers weren’t up to the task.

Femtosecond lasers have pulse durations 1,000 times shorter than picosecond lasers. Because of these ultrashort pulses, the laser energy enters and departs the material with the expanding plasma before it’s transferred within the material as heat. This is often called “cold” or “athermal” laser ablation. This produces exceptionally clean micro-scale machined features, virtually free of burrs, melting, re-case, and HAZ.

“Bringing on the femtosecond system allows us to process a wider range of polymers, metals, and dielectric materials,” said Matt Nipper, director of engineering at Laser Light Technologies, a Hermann, Mo.-based service provider of laser micromachining. “Ultrafast lasers are absolutely the best choice for processing materials that have strict HAZ specifications. Additionally, as femtosecond laser system architecture has evolved, the systems are now designed for high-uptime manufacturing environments and provide the added benefit of multi-wavelength selectability.”

There is also much interest in hybrid machine tools, which combine laser cutting and conventional CNC machining into one process. These machines can perform several processes in one setup, streamlining validation and driving costs down by shortening lead times for prototyping and production.

“Our hybrid approach takes the traditional Swiss turning machine and combines that with laser cutting/welding technology,” said a spokesperson for MW Industries, a Rosemont, Ill.-based manufacturer of highly-engineered industrial springs, fasteners, bellows, and related metal components. “We have a variety of Citizen L220 Type 8 and Type 12 machines, including one of the first five released in the United States.”

Citizen L220 is the latest generation of the company’s L-series lathes. The sliding headstock type automatic CNC lathe features full servo axes and other advanced technologies to enable faster CNC machining operations while reducing non-cutting idle time. The L220 series can be converted between guide bushing and non-guide bushing mode to achieve a reduction in running costs.

“Citizen-Cincom got with a local laser expert to integrate a laser cutting head inside the machine to replace one of the live tooling posts,” the MW Industries spokesperson went on. “With this technology released to the world, we now have the ability to turn, mill, and do all the operations done in a high-precision Citizen Swiss machine, with the additional capabilities of laser cutting and laser welding. This is a huge benefit—multiple operations are already eliminated because there’s so much capability inside the machine by itself. Adding the laser capability eliminates yet another operation that would have been something interior if you went about it in a traditional manner.”

Another form of hybrid manufacturing combines traditional machining with additive manufacturing. Hybrid systems used to fabricate metal parts are usually composed of a mill or lathe equipped with a directed energy deposition head to deposit metal powder or wire. Other systems exist that combine machining with powder-bed fusion. There are also hybrid systems to process polymers, which usually use extrusion as the additive portion.

Applying the additive and subtractive processes in sequence is one of the most common methods of hybrid manufacturing. The machine could 3D print a near-net-shape part that substitutes casting or forging. Then, machining could be used to finish the part. It’s also possible to alternate: for example, the system could machine a blank, 3D print needed features onto the part, and then machine those printed features. Machining could also be used to finish internal features as they’re printed.

“Some mold tool components are best served using a hybrid approach,” explained Armand Pagano, senior engineer of advanced product development at Weiss-Aug Co. “One example is additive manufacturing a complex conformal cooling part, then finish with machining to size. Another example might be starting with additive and refining with conventional machining for prototype parts.”

Because additive manufacturing can add material to existing parts, it’s also possible to build up and repair damaged parts or reduce machining work by only adding material where needed. 3D printing also enables the use of multiple materials for one part. Further, combining the processes reduces error because the printed part doesn’t have to leave the build space and be separately reset.

“We have been employing additive manufacturing for a few years, with the most recent acquisition being a unit capable of producing items used in production for part fixturing or in the automation used to manufacture our products,” Pagano added.

The Path to Smart Machining
Like all manufacturing, machining operations are driving toward a more streamlined, intelligent, and connected network of machines, devices, and systems, in a trend known as “Industry 4.0.” In time, connected processes may well replace conventional machines completely, or else by synchronized with legacy systems to ensure large data streams are available. Today, many machine shops are equipped with computer-aided manufacturing software. But this doesn’t necessarily make them Industry 4.0 compatible unless those computers have internet connectivity to download new programs or specifications. And while it is a time-consuming and costly process to upgrade the shop with Industry 4.0 technologies, in the long run, the cost savings for manufacturers can outweigh the initial investment.

For example, manufacturing technologies and machine tools aren’t always reliable. Downtime raises costs—production, labor, and maintenance fees included. However, Industry 4.0 remedies this with technologies that facilitate preventive maintenance. Tracking performance and real-time data allows manufacturers to better prepare for equipment malfunctions or errors. Further, predictive models and algorithms can be used to identify potential failure points, many of which might have gone unnoticed by the naked eye.

Data collected from IoT sensors and platforms can also help more effectively inform operations. Smart meters can be installed to efficiently manage the flow of energy, or equipment could be automated or powered appropriately to reduce environmental and resource impact.

“We have implemented multiple smart manufacturing technologies to streamline production processes and provide high- performing products to our clients,” said Nipper. “Among these innovations, we have employed cloud-based technologies to monitor machine up-time and live statistical performance control (SPC) data. These monitoring services provide critical insight to make real-time decisions to improve process performance, ultimately increasing the value for the services we provide.”

Enterprise resource planning (ERP) emerged years ago as an integrated software system to increase efficiency in manufacturing operations, shop floor activities, and front-office management. The centralized solution holds company data in one place, serving as a repository of information necessary for each department to effectively carry out its role. Depending on the type of product, ERP supports functions like estimating and quoting, shop floor scheduling, job tracking, purchasing, production and manufacturing resource planning, shipping, and financial management. They also provide a historical view of resources required on prior jobs which can help plan new work.

ERP systems have been available and have been extensively implemented well before anyone began thinking about data-driven manufacturing, however. Today, manufacturing companies are aiming to connect machine and laser processing tools and other devices to a network to collect machine-generated data for analysis and reporting. The data lets shop managers boost productivity and reduce downtime to further save manufacturing costs. Much of the generated data can feed predictive analytics systems, as well. For instance, a function like AI-driven scheduling can derive assumptions for modeling scenarios from ERP data, including processing times at multiple workstations, locations of potential bottlenecks, and orders of operations.

“We have optimized logistics and supply chains through multi-site ERP implementation,” said Anthony Meade, senior manager, global medical market for Hermetic Solutions Group, a Trevose, Pa.-based global supplier of hermetic packaging, components, and services. “An interconnected supply chain can adjust and accommodate when new information is presented. If a shipment is delayed, an interconnected system can react in real-time and modify manufacturing priorities.”

Any shop’s primary goal is fabricating dimensionally accurate parts at the lowest cost possible. As medical parts become smaller and more complex, conventional dimensional measurement methods like coordinate measuring machines (CMM) for machined or laser processed parts aren’t efficient. Due to this, 3D scanning has become an integral tool in many manufacturers’ measurement and inspection arsenals. It has been hailed as accurate, reliable, quick, and easy to use—3D scanning is non-contact and flexible, making it ideal to measure a wide range of parts in a wide range of places.

“We have also added specialized metrology, as you cannot make what you cannot measure,” said Pagano. “Complex surfaces are not best measured with a CMM and or contour profilometer. A quicker way is with modern scanning technology to understand the whole surface accuracy. No special programming is required and you get a 3D view instead of just a peek at a given location.”

Going even further, advanced measurement software lets machine tools themselves perform measurements like a CMM. The machine tool can be programmed to perform complex measurement and reporting tasks thanks to offline programming with virtual machine models and utilization of CAD data. This information can be used immediately to adapt machining parameters like work and tool offsets. It becomes very easy to program and make changes for machine tool configurations thanks to features like realistic program simulations, collision avoidance, and optimum measurement path generations for multiple geometric features.

The Machinist’s Skill Set
High-precision machining has gone way beyond just lathes and mills. CNC Swiss machines can now go up to 13-axis to make parts with complex geometries and can be programmed for optimal speeds and feeds. Multiple spindle machining can complete parts in one setup, and some machines have capabilities of live tooling or wire electrical discharge machining. And no matter how much processes become automated, these machines will require human operators. Machinists and laser processors must evolve their skill sets as quickly as the equipment evolves. 

Basic CNC programming is the foundation any successful machinist must build on. Since CNC programmers read blueprint designs of the product to be fabricated then set their machines to produce the components, they need familiarity with computer-aided design (CAD) software. CNC programmers also write formulas necessary to program mills and lathes using computer-aided manufacturing (CAM) software. This means entering tool registries, start and endpoints, offsets, and conditional switches, which requires a working knowledge of geometry and trigonometry.

It’s also up to the programmers to make sure their machines stay in top operating shape. (This is where Industry 4.0-generated predictive maintenance helps machinists instead of supplanting them!) CNC programmers also must periodically check each machine to ensure the positioning of drills, mills, and lathes stays perfectly aligned.

“Basic CNC machining skills are the starting point for any successful machinist,” said Marion. “Machinists today need to be able to multi-task and work without supervision, as they are being asked to run two to four machines simultaneously. Strong fundamental knowledge of machining and metals is required—as in, does the machinist understand which cutting tool should be used for a specific feature on a certain type of metal.”

And although there is some overlap in the skill sets necessary for precision machining and laser processing, it’s rare to find someone adept in both areas.

“You need to have a machinist trade background that includes CNC programming abilities,” explained the MW Industries spokesperson. “The difference in the modern manufacturing environment is the laser process. You are primarily not going to find people with both disciplines, and if you do, you hit the jackpot! Since laser technology is advancing every day, we make it priority to stay ahead of it. We work closely with laser experts and training facilitators to keep our machinist/operators up to date.”

More and more, machinists in the medical device industry have to become hybrid engineer/technicians. They must be as comfortable using CAD/CAM and ERP software as operating a machine. Proper application of design principles throughout the development also vastly streamlines the process. Understanding what can and can’t be done both saves time and money, and vaults the individual and company ahead of the competition. During the design process, a machinist with engineering experience can observe the project from different perspectives.

This helps develop a clear vision of the part to be made, the methodical approach to the sequence in which to machine, and thorough knowledge of manufacturing options. There are many ways to create a component, but the secret sauce is finding the easiest, most repeatable, and efficient way to accomplish it.

“An analytical mindset is desired in the modern manufacturing environment,” said Pagano. “In short, it is the engineering background or interest that is most important. It’s not enough to know how to set up and program a machine, it is also important to understand how to improve the interaction. This means being able to create your own macros and implement them in a post to any machine desired using the given CAM software. This means being able to look at the workflow and know enough to continuously improve the output.”

Medical device manufacturers are constantly asking their manufacturing partners to push the limits of technology. Advanced laser micromachining methods can now achieve features as small as a single micron. These advanced manufacturing technologies require ever-evolving skill sets, which will continue to transform as lasers progress.

“We provide system-specific training in regards to the manufacturing of componentry, but in general machine operators who are comfortable operating office-suite software, exhibit a high attention to detail, and can quickly respond to changing demands are a strong fit for the company,” explained Nipper. “Given the push towards automation of highly-repetitive maneuvers, operators in our facility are often asked to learn many manufacturing protocols so we can quickly meet the demands for short-run pilot studies. As our client demands continuously evolve, so do the manufacturing processes we execute.”