Powder Handling – Blending Emerging Technology with Tried and True Methods
One of the challenges that technology driven startup businesses face is how to package their invention into a product platform that will be well received in the market, is operator-friendly, robust, and reliable (just to name a few of the desirable attributes that drive sales). Many times, these small companies are focused on staffing to develop their proprietary know how and associated process equipment. Unfortunately, they do not necessarily have the engineering resources to actually design and build a production worthy system that will embody their new technology and have the needed features and performance for use out in the general manufacturing environment.
As a startup company begins to experience some success with their new technology, there is a natural tendency to have their high-end research scientists and engineers move on to product development and design. In some cases this may work, but in many cases what emerges is a product or system that uses subsystems or components that are unique to the company and its engineers, and is not necessarily cost effective and/ or robust.
If this packaging approach of the breakthrough technology were to be examined closely and critiqued by a broad range of industry experts, what would be found is that much of the packaging content (or the product delivery platform) could have been constructed utilizing subsystems, components, and knowhow that was already available in the industry.
One such example exists in the emerging 3D printing industry. As this new segment in the manufacturing industry grows and gains capability, we expect to see an increasing number of innovative designs and parts that take advantage of the complex internal structures that can be printed (as opposed to forged, molded, or machined, which are today’s options).
Load bearing parts are now being printed using fine metal powder as the starting medium. These machines utilize a dispersing method to deposit a thin layer of powder, and then a laser is used to selectively fuse the powder in the shape of the desired part, for the first .001 in. of thickness. The un-fused powder is removed (dusted off), a second layer of powder is distributed over the table, and the laser then fuses the next .001 in. of the part. This continues for many passes until the final part is built up.
Successful companies in this segment are typically strong in optics and have the needed knowledge of laser applications so as to be able to aim the light beam and apply the fusing energy to build the requisite structure.
Where there may be opportunity to enhance the strong laser application knowledge occurs from a very different technical vector. The fine metal powder, which can start out as an expensive alloy such as a stainless steel, becomes even more costly as it is ground down and classified to a particle size that is required to enable the laser fusing function in the printer. Powder that is not consumed by being attached to the part is collected and recycled. As a part of this recycling process, the powder needs to be reclassified down to the correct particle size, due to the fact that the fusing process does produce some larger beads of melted particles that are not part of the part, and these larger beads get carried away with the loose powder. Many of the current 3D printing system manufacturers supply their machines with elaborate onboard powder recovery and screening subsystems, to then redirect the clean powder back to into the supply stream. These recovery systems are capacity constrained and not effective in providing the high quality particle size distribution, as they lack space and do not take advantage of the available existing methods in the powder handling industry.
Consider the powder recovery cart shown above. In this example, a highly effective centrifugal screener/separator is utilized to classify the metal powder offline. The benefits of this approach are that it utilizes a proven method that has high throughput, it does not take up valuable machine space, it is cost effective, and it can be a shared resource for multiple machines. The waste stream from the printer would be diverted into a collection bottle, which when full is brought to the cart, and fed into the screener. The powder is quickly processed, and oversized particles collected into a waste container. The recovered powder is deposited back into the client’s bottle, and can then be taken from the cart and fed back into the printer at the input side of the printing process.
All of the onboard printer powder handling piping, valves, controls, and screening hardware can be deleted in favor of this simple cart. Since throughputs are low, multiple printing machines can take advantage of the cart’s high throughput capability.
If the OEM printer manufacturer had reached out to the powder handling industry, they could have taken advantage of this mature powder handling capability, and avoided all of the costs they built in to the design and fabrication of their printing machine to provide powder recovery capability that frankly is not as effective as this industry standard.