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Ten times cheaper

01 February, 2018

When plate glass got ten times cheaper, it changed the way buildings are designed and built. Here’s the next process to get ten times cheaper. Jon Bruner* and Eduardo Torrealba* reports.

Until the 1950s, plate glass was difficult and expensive to manufacture. Glassmakers either drew it out of molten glass on a frame, like a ribbon pulled from a pool of soap, or formed it between hot metal rollers. Both methods required a lengthy grinding and polishing process to produce glass reasonably free of distortion. Even so, plate glass remained somewhat irregular, was limited in practical size, and was fragile.

In 1952, Sir Alastair Pilkington invented a new glassmaking process known as float glass, in which molten glass is poured over a pool of molten tin and allowed to spread into a flat pane under the force of gravity. Without marks left by rollers or distortions from drawing, float glass required no costly grinding or polishing, was easy to post-process for a variety of uses, and could be exceptionally strong.

After seven years of development, Pilkington began commercial float glass production. Glass output soared, and today roughly 90 percent of flat glass is manufactured using Pilkington’s float glass process. Hundreds of lines around the world operate continuously, each typically producing 6000 kilometres of glass per year.

The new process-ten times more efficient than its predecessors-transformed the market for glass and led to new applications, both superficial and structural. Architects seized on the invention as glass curtain walls became cheaper and faster to build than masonry, and the strength of float glass made large atria immense glass-enclosed public spaces practical. Perhaps no feature is more characteristic of modern architecture than large plate glass windows; today’s glimmering exterior streetscapes and bright, open interiors both reflect the profound impact of Pilkington’s invention.

Now another fundamental manufacturing process is becoming ten times cheaper: selective laser sintering (SLS), a 3D printing technology that offers remarkable advantages in both strength and geometric flexibility. With it comes another revolution in aesthetics, functionality, and commerce. SLS machines use lasers to fuse plastic or metal powder, producing finished products as strong as their conventionally-manufactured counterparts, but without the constraints of tooling.

Until now selective laser sintering has been available in machines that cost upwards of $100,000. A new generation of benchtop SLS printers costs less than $10,000—the fruit of careful re-engineering and dramatic improvements in sensors, processors, and laser modules. What has been an exotic, strictly industrial technology is now accessible to practically any company. 3D printing, which has become ubiquitous in prototyping and product development, will now be broadly practical for production runs at increased scales. And just as Pilkington’s float glass process changed the buildings we live and work in, so will SLS printing transform many of the objects we interact with every day.

The first thing we’ll notice is objects around us changing shape. Most of our plastic and metal goods today are fabricated by injection molding or machining. Both of these manufacturing techniques impose considerable constraints on designers and engineers, who must ensure that a mold can be pulled apart cleanly around a formed piece, or that a machine tool has easy access to every cavity at certain angles. Especially in machining, design complexity adds substantial cost to every part: each cut from a mill or lathe represents machine time and tool wear.

Additive manufacturing, however, offers nearly complete geometric freedom. 3D printers can fabricate any shape without regard to mold design or toolpath layout. And on a 3D printer, an intricate shape is just as fast and easy to fabricate as a simple one. As former Autodesk CEO Carl Bass has often pointed out, in 3D printing, complexity is free.

Complex designs are particularly easy to realize on SLS printers. Many common 3D printing processes, including fused deposition modelling (FDM) and stereolithography (SLA), need to build support structures alongside the parts they fabricate. SLS machines support their prints with each layer’s unfused powder. Even the modest requirement that local minima and overhangs be supported disappears.

Expressive designs and sophisticated, ultra-efficient lattices could become commonplace in everyday products, reducing weight and material usage and addressing every product requirement precisely.

Milled or injection-molded products with complex geometries often need to be fabricated as many parts that need to be welded, glued, or fastened together. On a 3D printer, multiple parts can be consolidated into single, complex parts, easing design for manufacturing (DFM) and reducing supply-chain risk. SLS printers can even fabricate mechanical assemblies that function straight out of the machine, opening up a new range of novel mechanical designs that would otherwise be impossible to put together, like fabric made of 3D-printed chain links.

With additive manufacturing, designers and engineers can spend less time worrying about tooling, geometrical constraints, and assembly processes. That will lead to a revolution in product development. Even more important than the time recovered from DFM and tooling is the reduction in risk that 3D printing brings about. Because the upfront tooling costs in traditional manufacturing processes—especially molding—are so high, product developers are reluctant to give the go-ahead on manufacturing until everything is perfect. 3D printing shortens product development cycles by letting designers interact directly with the tools that will fabricate their products, and by reducing the cost of design iterations.

Iterate quickly enough and you wind up with universal customization: every product optimized for its function and its user. On a 3D printer, design variations are practically free, and variations are becoming easier to invent. AI-driven generative design software could produce efficient, optimized designs to meet any requirement; this type of software is beginning to become available and could be widespread in a few years.

Taken together, these changes in the way that we design, engineer, and execute physical products amount to a considerable shift. In ten years we may reflect back on today’s world, with SLS printing about to get ten times cheaper, and think of the cities of the 1950s, whose plate-glass windows were just beginning to pierce the masonry.

*Eduardo Torrealba is director of engineering at Formlabs

*Jon Bruner is director of new digital factory platform at Formlabs

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