Designing electronic control systems specific to additive manufacturing machines is a fast
evolving practice, developments in which spur continual performance improvements,
which in turn improve the quality and economic viability of parts produced (Hu &
Kovacevic, 2003).
Research methods used for this work comprise of; taking receipt of externally designed
and built experimental rigs, recording performance data and making incremental changes
in attempts to improve performance. Focus is given to the automation and speed of the
processes and research is limited only by the availability of time and funding.
This work has investigated several potential significant improvements to SLS cycle times
and part quality, with the wider project continuing beyond the scope of this dissertation.
Experimentation with serial data transmission protocols using ASCII (American Standard
Code for Information Interchange) found it could provide a fast, robust link between
central control system elements, which is critical and can be achieved this way without
great monetary cost.
Distribution of temperature across the build area surface can be optimised with a single
control feedback loop to a level acceptable for the use of PA-12 (Polyamide 12) powder,
though methods that are more complex may yield better results.
Rapid deoxygenation of the build chamber at the beginning of each build cycle offers a
slight improvement in cycle time, and proper loop feedback can assist in mitigating safety
concerns.
Current, commercially available stepper motor control systems are capable of greater
accuracy than is necessary in such applications but are limited by the accuracy of their
mechanical linkage, which can introduce significant backlash into the system.
Powder can be loaded into the machine using augers fed from an external hopper in such
a way as to minimise powder waste through uneven feeding.
Separating power systems allows individual control of sections of the machine, improving
safety, monitoring possibilities and potential for recovering failed builds.
A removable build platform, comprising the build piston and associated hardware on a
movable trolley frame, significantly reduces the machine cycle time by allowing part
removal and cleaning to be performed concurrently with the start of the next build.
Visibility of the process status via beacon stacks allows for quick human interaction where
required, potentially reducing failure rates and improving cycle times.