General Motors is developing new mold making technology that reduces skill levels required to design optimum conformal cooling channels as well as improves cooling times.
The technology is interesting for several reasons, including the automaker’s plan to use selective laser sintering (SLS) to produce conformal cooling channels, presumably to mold large interior parts. Use of direct metal SLS in mold making has been slow to develop because of the cost of the equipment and the lack of expertise in its use. Its potential value has never been in question.
GM’s new approach is outlined in U.S. Patent Application 20160052185 published Feb. 25. The inventors are Jeff Konchan, engineering group manager at GM and Julien Mourou, lead engineer-Advanced Vehicle Development at General Motors.
Layout of conformal cooling channels is traditionally determined by trial and error, a time-consuming process highly dependent on the skill of the mold designer. GM says it has developed an optimization algorithm that can accurately predict where the channels should be located for best cooling performance to reduce cycle times. The method is based on the calculated temperatures of the tool surface elements.
One of the interesting design elements of the invention is the use of “fins” or pillars that act as a structural support for the tool and bear pressure loading during the molding process. They are positioned to establish the coolant flow paths and are sized to ensure that tensile stress, shear stress, and deflection of the tool element are below predetermined maximum limits.
The capability to produce such intricate internal features is only possible with additive manufacturing processes such as SLS.