Marking pharmaceuticals with a laser

A provider of cold laser technology develops custom-built turnkey systems for marking capsules and tablets.

Advances in laser technology could transform the marking and tracking of capsules and tablets. Alex Kerner, president of Tri-Star Technologies, says printing during this phase can be a “last-minute bottleneck when you least want it—right at the end, after time and money have already been committed in the earlier part of the production run.”

The El Segundo, CA–based provider of laser marking systems has developed a complete turnkey system for noninvasively marking capsules and other pharmaceutical products: the Nd:YAG UV Cold Laser System.

“The system removes the final obstacle and brings marking up to the same technological level as the rest of the manufacturing chain,” says Kerner.

In addition to marking, Tri-Star’s system features complete product handling and quality control. It is designed to simplify capsule handling mechanisms and inspection procedures, and it is environmentally friendly, with no chemicals to consume (inks and make-up fluids) and none to waste (cleaning solutions), Kerner explains.

Tri-Star’s system employs a pulsed solid-state laser that permanently marks alphanumerics, 2-D bar codes, and detailed graphic images directly on pharmaceuticals. It can also mark such items through blister packaging. The UV laser light reacts to commonly used additives in capsules or other materials such as titanium dioxide, producing marks visible to the naked eye.

Because these marks are no more than microns deep, the processes does not damage the pharmaceutical content, its coating, or even the package.

Laser marking is an alternative to ink-jet printing. Explains Kerner: “Gelatin capsules have oily surfaces that are hard to mark. To degrease the capsules for ink-jet printing, companies typically have to use chemicals-based drying, which can lengthen production.” No such cleaning is needed for cold laser marking, he adds.

Tri-Star’s senior scientist, Igor Murokh, PhD, explains that ink-jet printing could result in “stray ink-jet droplets. A complex algorithm is needed for identifying and distinguishing these from the intended markings. This puts extra time in the inspection process.” And, Murokh adds, ink needs to dry—otherwise it smudges, which can further increase marking and inspecting times.

Kerner points out that because marking is the last step in a complex sequence, inadequate printing could result in a late-stage loss of otherwise legitimate and often costly product. “The Cold Laser radically streamlines the process, since marking quality does not depend on capsule surface properties, and the laser imprint stays intact until the capsule is digested,” he says.

In addition to eliminating ink, direct-product marking with a laser can decrease the number of other consumables, such as labels or individual pouches, says Kerner. In addition, “by marking right on the capsule or tablet, even through the packaging, you can achieve full traceability and fight product diversion,” he adds.

Kerner says that the Cold Laser is not the fastest marking method available to pharmaceutical manufacturers. “Ink-jet printing, which has been in use for decades, is quicker,” he says. But marking speed isn’t everything. “When you factor in the need for drying, cleaning, and other preliminaries to ink-jet, along with issues like smudging, image distortion, clogging and spattering, it can add up to a lot of downtime in a situation where every second really does count,” he says.

Tri-Star is also a systems integrator, so to support the laser-marking system the company provides custom-built systems for ensuring the capsules are oriented and fed properly, says Kerner. “We have a history of automating, feeding, orienting, marking, and moving small parts, and our forte is separating the good from the bad,” he says.

The turnkey system consists of a feeding mechanism, vibratory bowls, laser-marking system, and the quality control system, which itself consists of an inspection system, a scale for counting accepted capsules, a rejection system, a mechanism to validate rejection, and reconciliation of rejected capsules. Two wheels advance capsules at speeds up to 13 capsules per second.

Complying with GAMP 5 methodology, the system compares marks with a specified pattern and produces an alarm and rejects the capsule should one of the checking parameters fall out of range. It performs 100% verification and stores images of defective capsules. Collected data is also used for process monitoring. “We know very well the importance of building an automatic audit trail and an inline quality control system.”

To help one of its pharmaceutical customers qualify laser marking for its product, Tri-Star developed a prototype system for testing before purchase. The company also offers free marking and testing services to help companies with their own studies.

Pharmaceutical applications also require strict control of temperature and humidity, so Tri-Star custom-built one of its turnkey laser systems within an exact simulation of the customer’s pharmaceutical manufacturing environment. This proved that the system could operate under strict conditions while maintaining customer specifications and mandatory safety requirements. And cleaning was critical. “There could be no place for capsules to hide, and the system had to be fully cleanable,” says Kerner.

Kerner says that acceptance of this new application for cold-laser marking is growing, with global pharmaceutical companies already using the system. Production is ramping up as orders are increasing, he reports.