Many of us are familiar with the world of 3d printing with plastics and metals. In the most common scenario, a computer directs a device which extrudes polymers as it moves, building the 3d structure defined by a computer model one layer at a time.
One of the primary benefits of 3d printing is that it is an additive manufacturing technique. Additive manufacturing refers to the production of items by building them up one part at a time. This contrasts with subtractive manufacturing. Where additive manufacturing is like building a sculpture out of clay by adding material over time, subtractive manufacturing is more akin to a sculptor carving a shape out of a solid block of material. Additive manufacturing is, by nature, lest wasteful, because only the amount of material that will be contained in the final shape needs to be used. In contrast, subtractive manufacturing involves waste by definition. An additional advantage of additive manufacturing is that it allows for the production of objects with complex geometries, including void spaces, that just can’t be made using subtractive techniques.
Despite these benefits, traditional, extrusion-based 3d printing techniques have shortcomings. One is that the resolution and precision are lower. In applications requiring precision, such as mechanical parts, medical devices, and other products, traditional 3d printing methods may not be able to attain a high degree of consistency. Another shortcoming is that extrusion-based methods are slow, because the machine must trace out every part of the volume of the final product.
That’s where Powder Bed Fusion using laser sintering comes in. This technique, which has become increasingly common, uses lasers and polymer powders to produce products quickly and with a high degree of precision. Here’s how it works:
First, as usual, a 3d computer model of the final product is produced and checked for errors.
Then, a layer of polymer powder, typically around a tenth of a millimetre thick, is placed at the bottom of a the 3d printer. A high-powered laser then traces out the cross-section of the first layer of the product. Everywhere the laser is directed, the powder is fused into a durable, cohesive plastic. When one layer is done, a roller or other device applies another thin layer of powder. The process repeats over and over until the final product is produced. Unfused powder remains inside the final product until after manufacturing is complete, at which point it can be removed and reused.
Powder bed sintering is becoming increasingly important – a recent report predicted that the powder bed printing device market will grow by over 60% between now and 2020. If metal-based powder bed printing is included, 40% of revenues from professional 3d printer sales were for powder bed style printers in 2016.
Powder bed fusion technology is an exciting field that is worth keeping an eye on in the coming months and years, especially as improvements such as multi-powder deposition begin to take off.