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Micro makes sense

Laser micromachining serves as a flexible, high-precision manufacturing process

Laser technology was developed in the mid-20th century, and in the decades since then, it has emerged as a leading processing method for an extremely broad range of applications. From microelectronics and semiconductors to automotive, e-mobility, aerospace and medical devices, nearly every industry has benefited from the laser’s ability to cut, join and texture materials with a high degree of precision. Now, with recent advancements in laser technology, machines capable of high-precision laser micromachining are opening new doors in industrial manufacturing.

The medical device industry is one of the fastest growing markets for laser micromachining with medical device laser processing projected to reach $3.7 billion by 2025. Advancements in minimally invasive surgical techniques and drug delivery capabilities continually drive the need for smaller and more precise components.

Medical device manufacturing is a key application for laser micromachining as the products often require the production of small features that measure below 50 microns in size, as seen in the image shown here.

One of the most common devices in the medical device field is the catheter, a device with a broad range of applications. Small features, like ports, slots and grooves often below 50 microns in size, need to be machined into these devices to facilitate their use. The features must be extremely precise with tolerances as small as ±2.5 microns, and there is very little room for defects or imperfections.

Traditional methods like mechanical milling can leave burrs on parts, and many of these features are simply too small for mechanical tools. Laser beams, on the other hand, can be focused to extremely small diameters, and because they are pure light, there is no chance for broken or worn tools that can cause inconsistent results.

This extreme level of precision transcends the medical device industry and provides unique capabilities in other fields, as well. The energy and renewables industries use it for etching next generation solar cells and for cutting lithium ion battery foils; the aerospace industry uses it for drilling fine holes into advanced, lightweight space-grade alloys; and the semiconductor and display industries use laser micromachining for cutting and drilling ceramic wafers. Every day, new applications for laser micromachining are being created.

Micromachining defined

Laser micromachining is a tightly controlled material removal process in which a laser beam is used under highly precise conditions to reshape a material. For decades, the creation of small drill holes, narrow pockets and slots, and intricately shaped features in medical device, automotive, aerospace, and microelectronic components has been done with mechanical milling, chemical etching or electrical discharge machining.

As seen in this polymer part, laser micromachining employs a laser beam to carry out the tightly controlled material removal process.

However, progressive miniaturization and heightened quality requirements have fueled the need for improved processing techniques that can produce smaller features with fewer defects. Laser micromachining has answered this need and is beginning to replace traditional machining methods across multiple industries.

As a remote photonic processing technique that imparts no mechanical force on a material surface, laser micromachining is ideal for creating intricate, tight-tolerance features in small, delicate parts. Processes can be tightly optimized and remain repeatable in high production without the need to sharpen a drill bit, repair a broken blade or change a worn-out photomask.

One of the most exciting advancements in laser technology in recent years has been the refinement of the ultra-short pulse, or USP, laser for everyday industrial use. Traditional, older generation cutting lasers emit continuous wave energy, similar to turning on a flashlight, or pulses that last for milliseconds or microseconds.

When laser light interacts with a surface for these long time durations, it drives excessive heat conduction and melt expulsion that result in unwanted defects, like burrs, dross and material embrittlement. These defects compromise the integrity of the finished product and often require expensive and time-consuming secondary cleaning operations.

The nickel titanium struts shown here reflect manufacturers’ interest in laser micromachining to handle smaller features with fewer defects.

Modern USP lasers, on the other hand, emit extremely short pulses that may be only a few hundred femtoseconds in duration. These pulses are on the timescale of atomic interactions and are short relative to electron relaxation times. This means that each laser pulse’s interaction with the material terminates before significant thermal conduction begins to occur, allowing for nearly athermal ablation from the processing surface.

The results are highly repeatable features with ablation resolution as small as ±1 micron and excellent finish quality – no burrs, no dross and dramatically reduced heat-affected zones. The multiple wavelength options available with USP lasers mean that there are almost no material limitations – metals, polymers, ceramics and glasses can all be processed. These results and capabilities cannot be matched with traditional lasers.

Working together

The laser source is the key component of a micromachining system. As USP laser technology advances, more and more laser OEMs are beginning to offer these lasers. Thus, it is critical for a laser integrator to carefully test and vet these lasers to ensure that the best laser is selected for any particular application. This must be done with a sharp focus on the details and requirements on the process itself.

While the laser may be the heart of the micromachining system, a successful process relies on all aspects of the machine working together in harmony. Carefully selected optics and optomechanics are needed to deliver the beam to the workpiece. High-precision, top-of-the-line motion control systems and stages must work in tandem with machine vision to move the workpiece precisely and repeatably. And, integrated robotic arms, tube loaders and conveyors must work autonomously – or collaboratively with an operator – to safely handle parts to support high-volume production.

Furthermore, carefully designed user interfaces should enable intuitive machine control while custom software monitors the system to ensure that everything is functioning properly and collects data and logs errors for rapid, efficient troubleshooting. Machine faults must be handled strategically to prevent damage both to the machine itself and to the workpieces, which are often delicate and expensive.

High production can be demanding, so micromachining systems can be equipped with vibration dampeners and temperature control to stabilize and isolate the processing zone, regardless of the dynamics of the production environment. Maintenance requirements must be kept low, but when it comes time to replace a component, easy access to the machine’s subsystems can make the work easy and efficient.

Finally, operator safety is paramount. Laser micromachining systems must comply with workplace safety standards to minimize risk to operators. Class I enclosures not only seal in laser light to prevent exposure, but they also create a barrier between operators and fast-moving stages and internal mechanisms.

Specially selected fume extraction systems with extremely fine filters remove small particulate from the processing area to prevent operator exposure to hazardous dust. Machines with automated doors or loading mechanisms can be equipped with light curtains and proximity sensors to further enhance safety. Overall, the laser system integrator must place just as high of a standard on system safety as they do on system capability.

System integration

A laser system integrator or machine builder should design micromachining systems with the laser process foremost in mind. In many cases, a system integrator may need to draw on decades of experience and hundreds or thousands of successful applications in high-precision laser microprocessing in its approach to process development and integrated system design.

Application engineers should focus on a combination of academic and hands-on knowledge of laser and material interactions to optimize customers’ processes, while R&D and systems engineers put the processes to work in systems that satisfy detailed machine specifications and complex requirements.

Building strong relationships with customers and maintaining open communication channels will help to ensure that customers’ needs are fully understood and fulfilled. To be successful, system integrators that build high-quality laser micromachining systems must be as dedicated to their customers’ projects and product lines as they are to their own.

Laser micromachining promises improvements for modern high-precision processing methods as well as opportunities for new applications altogether. With the advent of industrially viable USP lasers, laser system integrators and machine builders are now able to offer systems that can provide clean, defect-free parts right after the laser process, often removing the need for secondary post-processing.

Amada Weld Tech Inc.


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