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Selective Laser Sintering Process Preparation and Control

DMC software can be used to control laser-based additive manufacturing processes, like selective laser sintering (SLS), selective laser melting (SLM), or stereolithography (SLA). In this particular case, the customer was developing a new SLS system. During the prototyping stage marking software was used for machining control. However the process was not fast enough, the system often crashed and new developments were needed for system-specific software functionality. The previous software was replaced with DMC to have a complete solution for SLS process preparation and control.

Challenge

The customer had a prototype SLS system assembled for process testing and demonstration purposes.

  • STL file preparation. 3D printing/additive manufacturing uses files in the STL format to import models to be printed. After the import models are sliced, hatching parameters are computed for the volume and the object is printed layer by layer. Some of the objects to be printed have a lot of small features and the STL file for them might have millions of triangles and hundreds of megabytes of information. Handling of this information and to converting it to motion data that can be used by positioning stages and/or scanners is a big challenge as conversion uses a lot computational resources. Marking software and similar solutions created for simpler processes tend to crash or take hours for calculations to finish when working with large and complex models.
  • Long term stability and reliability of processing. The customer was designing a cost-effective solution for SLS. To keep the costs at bay, budget galvo and stage controllers were used. To ensure long term stability, safety measures had to be taken in the software to keep the process running for >20 hours at a time. Each crash means aborted processing and wasted production time.
  • Integration of custom hardware. Unique hardware was designed by the customer to add safety measures, temperature control and other machine functions. The hardware had to be accessible and controllable via the DMC software.
  • Recipe testing. A prototype machine was used for the R&D of sintering recipes for different materials and different printing resolutions. Creating and performing testing routines on existing tools was taking a lot of time. Speeding up the process would allow to achieve better printing quality and reduce machine time to market.

Solution

Several Q&A sessions with the customer took place to determine which features are needed. The specifications for the OEM version of the DMC software were prepared. These are some of the features and advantages of the DMC software which helped the customer with their additive manufacturing challenge.

  • DMC has state of the art geometry handling algorithms. This provides our customers with the fastest in the market STL slicing, hatching and preparation for printing. Taking full use of the 64-bit system, preparation (slicing and hatching) of 5 million triangle STL files is done within 30 seconds. Efficient computing resources handling makes DMC reliable and stable when working with large and complex models.
  • The flexible architecture of DMC allowed the quick and easy implementation of new stage and galvo scanner controllers. During the testing phase, special safety measures were implemented to prevent the system from crashing during long term fabrications.
  • Support for custom control electronics was developed to implement temperature control and interlock safety features. With these features, the operator now can set a specific temperature to be reached before fabrication and add cooling parameters. Temperature is constantly monitored and displayed to the operator. If the temperature goes out of a set range, the process is paused to correct it. Fabrication does not start until doors are closed and locked to prevent accidents.
  • DMC has a flexible recipe creation tool to create highly automated and easy to customize recipes. Using this a special recipe was created to print an array of parts, each with a different set of parameters. Each part also has a number printed on it for identification purposes. This allowed the user to print 40 parts with unique parameter sets and find the best parameters quickly. Which parameters are tested (scanning speed, laser power, volume filling density, layer thickness, etc.) and ranges for testing can be easily selected in the recipe.
  • A special user interface was created for an operator to streamline the working process.
STL model for printing prepared with DMC
A sample printed via process controller by the DMC software
Recipe for printing parts with different parameters
Operator interface for 3D printing

Results

DMC simplified the 3D printing process, as all preparation and control of the machining process is done via a single software interface. There is no need for code generation and upload.

The time of process preparation was reduced due to DMC efficiency in 3D model handling and preparation.

Time to market for the machine was greatly reduced as well since DMC needed just minor adaptations to control the machining and they were implemented within 15 days. A combination of online and onsite testing helped to make the testing process cost-efficient, yet assured a reliable operation of customers SLS machines.