Opening the technology hood
The laser developed and patented by 3DM is designed to optimally match the energy absorption of thermoplastics. The idea came from the realization that the industry uses the wrong light source in SLS printing technology with plastic materials. To compensate, SLS solutions either change the materials by adding absorption improving additives or they use lasers with lower efficiency and adverse heating effects. These methods require extensive material development effort, which negatively affects material costs, creating a major obstacle for high-volume AM, and, in the end, yield a very limited range of materials supported by AM applications
The 3DM laser is a semiconductor component with a very small footprint. It is a low-cost (tens of dollars), high-power light source (up to 4W equivalent of a 20W CO2 laser). The laser can be designed to emit at any wavelength in the mid IR spectrum, thus optimally matching absorption properties of all thermoplastics.
Optimal material absorption offers an additional important advantage; Our ability to very accurately melt the material in the Z axis and determine the melting and heating depth in the Z direction. This prevents printing distortions between printed layers and improves print quality compared to other commonly used SLS technologies.
The Solution – Superior Printing Head
3DM’s printing head design is based on an array of laser beams operating in parallel, where each beam is scanning independently to expose its own dedicated sub area of the print bed. The sub area size is pre-configured depending on the desired target speed of the printer. The printing table size can be designed to be in any rectangular shape needed. For example, a print bed size of 600x600mm with beam sub area of 150x150mm requires a configuration of 16 laser beams in the printer’s printing head.
The printing head includes a measurement subsystem dedicated to the alignment of the sub areas. Alignment is performed per layer in real-time based on measurements taken by the subsystem to fix X/Y scale changes, movement and rotation.
The design of the beam head maximizes the benefits of 3DM’s self developed laser light source. The goal is to deliver superior laser beam performance with high power, high resolution, for an unprecedented range of materials, at significantly lower cost. The beam head may include from 1 to 6 lasers depending on the required printer performance. Since lasers of the same wavelength are not easily combined, each pair of lasers are designed to transmit at a different wavelength that fits the energy absorption peak of a unique material family. Combining up to three pairs of lasers can either triple the power for a single material family or expand the capability of the printer to support additional material families.
Advantages of the beam optical head:
- Lower printing cost – Due to the parallel high power beam architecture the printing speed is reduced down to 1 sec per layer. This results with increased printer’s throughput (up to X10 better than current leading printers) which translates to lower printing cost.
- Industrial grade printing quality – The perfect laser-material interaction enables achieving superior mechanical performance (strength and elongation) in all three dimensions (isotropic behavior) with all materials.
- Support all thermoplastic materials – Since 3DM designs the laser to fit the material, it can support all variety of thermoplastics. No absorption additives are needed for already available materials. This minimizes the cost of materials, which is still a major factor in the cost of printed parts
- High resolution – Down to 10s of microns. 3DM prototype machines designed with 150 micron resolution demonstrate the fine detail printing capabilities and smooth surface finish that can be achieved with the 3DM laser.