Moldmaker pioneers use of femtosecond laser technology

Femtosecond laser technology represents a new frontier in moldmaking. The aim of this laser is not to replace traditional machining methods but to complement them in a way that ultimately leads to increased productivity for mold shops and other part manufacturers alike.

Providence Texture LLC, Smithfield, Rhode Island, is a shop leading the way and showing how much femtosecond lasers can do. Applying the latest technology to moldmaking is a family tradition for President and CEO Matt Melonio. In 1982, his father, Hank, and uncle, Don Sr., established New Castle, Pennsylvania-based Custom Etch Inc., where Matt got his start in the industry right out of high school in 1991. Custom Etch went on to help pioneer the use of 5-axis laser texturing this decade when it was among the first shops in North America to incorporate Lincolnshire, Illinois-based GF Machining Solutions LLC’s AgieCharmilles Laser 4000 5Ax, which handles workpieces up to 4m × 3m.

In 2016, Matt left his family’s business to strike out on his own and focus on the future of laser technology, given that femtosecond lasers and 5-axis capabilities were growing in prominence. He worked closely with GF Machining Solutions’ applications engineers and R&D department as he formed Providence Texture with the AgieCharmilles Laser P series as its foundation, including the first dual-source Laser P 400 U in a North American job shop.

A femtosecond laser machined this cavity in a mold for a medical implant. Providence Texture cut the cavity, injection runners, venting, guide channels for over-molding and identification information in a single setup. The blurry lines in the foreground indicate 1mm increments. Image courtesy of Providence Texture

“The femtosecond laser technology was so new that when I got it, many aspects were undergoing active development,” Matt said, adding that he traveled to GF Machining Solutions’ global headquarters in Geneva twice in late 2016 to perform proof-of-concept work. “I quickly found myself with jobs that required the new laser technology.

Rapid Rate

Femtosecond lasers are, as their name implies, lasers with pulses in the range of a femtosecond, or one quadrillionth of a second. This pulse length puts these lasers in the category of ultrashort pulses. A prominent advantage of this extremely short pulse length is the reduction of heat absorption, a quality that has made femtosecond lasers useful for medical applications, particularly ophthalmological procedures, such as LASIK.

Naturally, the avoidance of heat transference and a high degree of precision make femtosecond lasers excellent tools for intricate mold and part production. Nanosecond lasers are widely known to produce recast and burrs during ablation and can produce sufficient heat to harden materials and damage coatings. Femtosecond lasers avoid these issues, making femtosecond lasers suitable for heat-sensitive parts. The ultrashort pulse of the laser prevents workpiece materials from entering a fusion state during ablation, thus eliminating recast or burr formation, imparting an exceptionally fine finish and avoiding residual heat-affected zones.

Unlike sinker EDMing or conventional micromachining, laser micromachining has relatively few requirements. One is simple line of sight, a far less restrictive requirement than with other machining operations. As a noncontact tool, the laser allows Providence Texture to create small mold features at working distances unobtainable with sinker EDMing and reach places otherwise impossible even with the smallest-of-diameter spindles.

Several AgieCharmilles laser texturing machines at Providence Texture are connected with a System 3R palletized automation system. Image courtesy of Providence Texture

Another requirement involves the working distance to the part or mold surface. Because lasers use amplified light as the cutting tool, they rely on lenses and relative focal distances—the distance from the lens to the workpiece—for their material removal capabilities. Many femtosecond laser options on the market are optimized for micromachining or cutting and have a working distance of only 1mm to 3mm, owing to a pulse diameter of just a few microns. This allows for amazing detail on flat or tubular surfaces but makes 5-axis work impossible.

Providence Texture’s 5-axis femtosecond laser has a flexible working distance that ranges from 73mm to 300mm depending on the lens option, which is an incredibly generous range for laser texturing and other moldmaking applications. At these distances, laser pulse diameters, or spot sizes, can range from 18µm to 70µm at full power. However, refined parameters may yield spot sizes measured in the single-digit microns. The laser’s 5-axis movement also excels in terms of angles of attack, with high-quality cuts remaining possible at up to 70° angles.

Automated Production