In the rapidly expanding playground of gadgets, gizmos, and all things tech, it’s sometimes hard to believe that some of the latest breakthroughs aren’t from the mind of an eccentric Hollywood director. We find ourselves in an age of self-driving cars and levitating trains—so why do so many care about printing flimsy toy models and fancy keyrings?
In my ten-month placement at a leading British engineering company, I saw the research and design that went into evolving 3D printing from plastic polymers to metals through direct metal laser sintering—the formal name given to the process of blasting metal with an extremely powerful laser to make structures, also know as metal 3D printing.
The inner workings are extraordinarily complicated: in essence, metal 3D printing works through a powder chute that dispenses a set amount of powdered metal beads, and a wiper blade not dissimilar to a car windscreen wiper that spreads the powder over the ‘bed’—a flat metal sheet. A programmable laser (or even multiple lasers nowadays) blast certain areas of the powder, selectively ‘welding’ parts of the current layer to the layer below. After this the bed drops down and a new layer is spread on top, and the process repeats.
Other than re-creating battle scenes from Star Wars, there are actually some extremely profound consequences of this method. In building the structure layer by layer, complexity in design comes with almost no extra time cost.
This is where the remarkable promise of metal 3D printing comes to hand—it turns out that nature itself has already put in a few million years’ worth of research and development for the industry, through the design of lattice structures—the idea of interweaving and convoluting thinner support structures to maximise strength whilst minimising the weight.
Think of a spider’s web: a dinner plate style web with no gaps would just as efficiently capture a fly, however this would cost the spider dearly in extra time and materials to spin such a dense web. Instead, the spider intuitively picks a low energy, low resource, and sparse design that’s just as functional in doing the job.
This is also applicable with metal 3D printing as these spacious and ‘low-cost’ designs check all the boxes of what we need in a good metal 3D printing design—they distribute the energy evenly, use less metal powder, and tend not to have as many ‘sharp edges’ or overhangs.
Lattices structures also avoid a ‘thermal gradient’ from arising. Think about trying to bake a cake using only a small Bunsen burner: the cake should come out semi-presentable providing you distribute the heat evenly and don’t heat any overhanging parts, or else they’ll sag and deform the cake.
Given that the laser is ignorant to the order of how you want to heat things, a spacious and spread-out structure would keep the thermal gradient at bay by distributing the energy evenly across the bed, whereas something like a block of metal would turn out horrendously, causing warps and deformation almost instantly.
So why can’t lattices be used in normal manufacturing outside of 3D printing? Theoretically they can: there just isn’t a machine yet that’s capable of building anything to that level of precision or complexity, bar 3D printers. But these lattice designs and 3D printing have unlimited potential in changing our world.
During my internship, the 3D printing division was contracted to print the steering wheel for the Bloodhound SSC, a car attempting to beat the world land-speed record with a projected top speed of 1000 miles per hour. The steering wheel was designed in-house and printed as a bespoke fit for the driver’s hands, something of phenomenal importance when every square inch of cockpit bites into your room for fuel.
With rising profit margins, we are getting ever closer to a future where a 3D printed titanium lattice structure could be inserted onto someone’s skull to reconstruct it after an accident—a future where weight minimisation yields phenomenal profit though fuel savings, from reducing the weight of seats, door hinges to maybe someday fuselages—all without losing any structural strength! It would be a radically different world: one defined by 3D printing.