Testing and Calibration Procedures Reliability in 3D Printing Redefined

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3D Systems has developed a proprietary testing and calibration procedure for its laser-based Direct Metal Printing (DMP) systems. Users and their end customers benefit from parts manufactured with the highest reliability.

The possibilities of additive manufacturing never cease to amaze: delicate structures, complex custom parts, and components with fascinating properties emerge as if out of nowhere. In 1986, 3D Systems enriched the industry with the innovation of 3D printing. Today, the company is one of the largest players in the field of additive manufacturing and develops AM solutions at locations around the world.

Since 3D Systems' solutions are particularly widespread in highly regulated industries such as healthcare and aerospace, the question often arises as to how repeatable and stable the processes really are. Users, for example, need to demonstrate and document the process stability of the machines they operate over time.

3D Systems aimed to remove this hurdle for users. The goal was to provide advanced measurement and calibration procedures on-site, including dedicated documentation functions, allowing machine users to meet the highest standards.

Demanding Industry Standards

In additive manufacturing, every layer counts. The laser-based optical systems in metallic 3D manufacturing must precisely meet the specifications. This is the only way to ensure that each manufactured part possesses the desired properties. The key optical process parameters are laser power, beam caustics, and the position of the laser beam.

The engineers at 3D Systems monitor these process parameters during the development and production of equipment for metallic 3D manufacturing. At the same time, service technicians should also be able to regularly check the performance and stability of optical systems on-site at the customer's location. Wouter Polspoel, R&D Program Manager at 3D Systems, explains: "Our customers, especially in regulated industries, need to demonstrate that the manufactured parts meet high quality requirements. They must comply with ISO standards such as ISO 52941, which govern control procedures and acceptance criteria for laser powder bed fusion machines for metallic materials in aerospace. Our goal was to create a package of service procedures that takes into account all relevant requirements of the applicable standards and guidelines."

A particular challenge was measuring the caustics at build level for lasers with high power. Just in time, MKS introduced a new solution for this: the Ophir BeamPeek power and beam caustic analysis system. Thanks to innovative measurement technology, the device offers short measurement cycles and versatile application possibilities in service.

Extensive Tests for Best Practices

As part of long-term tests with the Ophir Beam Peek device on the DMP Factory 500, a scalable solution for additive manufacturing of metal parts with a build volume of 19.69 inches × 19.69 inches × 19.69 inches and three fiber lasers, the 3D engineers developed specific measurement routines, defined deviations, and created a comprehensive checklist that is implemented as part of the Advanced Service Package.

"The Ophir Beam Peek system proved its versatility and is very easy to use," says Wouter Polspoel.

The stability of the output power, along with the accuracy of the beam caustics, is crucial for manufacturing high-quality parts. Additionally, with the BeamPeek system, we also measure the beam quality factor M2 of each laser at the center of the build plane.

Wouter Polspoel, R&D Program Manager at 3D Systems

Additionally, as part of the Advanced Service Package routine, a thermal Ophir sensor is used to check the stability of the laser power. The air-cooled FL1100A-BB-65 sensor is paired with a handheld display device to measure the power values during laser setup and after a setup time of 15 minutes at maximum power.

Measurement Technology Builds Trust

With the additional service offering, 3D Systems' customers gain security and flexibility, explains Wouter Polspoel: "We do not expect significant changes in laser parameters, as we use high-quality components and our processes are very stable. Nevertheless, we want to provide users with a way to check their process parameters and document this inspection. Thanks to the Ophir Beam Peek system, we are able to meet the stringent process control and calibration requirements of the ISO standard as part of our Advanced Service Package. All parties gain confidence in the manufactured parts, and that is exactly what the market needs: reliability!" The recommended frequency for performing an Advanced Service Package is every six months.

Optimized Design

However, Ophir Beam Peek is not only used by service technicians, as Viktor Valckenaers, R&D Project Engineer at 3D Systems, explains: "We conducted intensive tests with the Beam Peek system, particularly during the design phase of our new laser-based system for additive manufacturing. Specifically, the measurements of the beam waist position revealed interesting correlations between gas flow, component contamination, and beam parameters. These insights have been very helpful in optimizing the new system."

The argon flow in the build chamber significantly affects the quality of additively manufactured parts. For this reason, engineers at 3D Systems invest considerable development effort into optimally positioning the gas inlet nozzles. During the design phase, they first use simulation software to explore possible geometries. Once the first tests on the prototype can begin, the Ophir Beam Peek measurement device is used. The beam position is measured before and after each build job under different gas flow scenarios. During the development of the DMP Factory 500, these tests demonstrated the direct correlation between gas flow and the position of the beam waist. The illustration on page 35 shows the change in beam waist position with optimized and non-optimized gas flow. Since any shift in the beam waist directly affects laser performance at the build level, a deterioration in part quality can be expected.

It is well known that the quality of a 3D-printed component strongly depends on the gas flow in the build chamber. However, it is very helpful to be able to precisely quantify how much the minimal beam waist is affected by contamination caused by suboptimal gas flow.

Viktor Valckenaers, R&D Project Engineer at 3D Systems

Once all parameters are defined and the prototype is finalized, each machine undergoes several months of intensive testing. During this phase, the laser beams are regularly checked using the measurement device. These measurements play a central role in verifying the beam caustic and documenting process stability. Another advantage of the device becomes apparent here, as Victor Valckenaers explains: "The Ophir Beam Peek caustic analysis system can be used for both high and low laser powers. This feature is extremely valuable to us as it allows us to use the device for the entire series of measurements."

Success Through Collaboration

Both during the intensive testing phase and integration, questions were clarified directly with the Ophir developers. The result is already a great success: "We were able to significantly improve our on-site services within just a few months. At the same time, the more extensive measurement capabilities shorten the development times for our machines."

*Dagmar Ecker, Marketing & PR, MKS | Ophir Spiricon Europe GmbH

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