Piab’s proven vacuum conveyors evolve automation of Additive Manufacturing
Laying the base for safe and efficient powder handling in 1972, Piab today supports the growing additive manufacturing industry with its extensive expertise.
With the additive manufacturing (AM) industry moving from prototyping and small series into mass production, processes around the actual printing need to follow suit. A crucial part particularly in metal-based AM is the safe handling of metal powders required in uncontaminated condition to ensure high quality printed parts and avoidance of human exposure to hazardous materials or heavy lifts. Piab Vacuum conveying, can solve all these issues within AM.
Today, celebrating Piab’s 70th anniversary, we are not only searching for the oldest Piab vacuum conveyor still in use, but are looking into how we can support the newest future oriented industry applications.
In 1972 Piab developed an industrial cleaning unit, which helped to free workplaces from dust by offering a closed vacuum system. In the early 1990‘s – when Piab further developed its vacuum ejectors and pumps – Piab put both technologies together to evolve from cleaning and removing to transporting and reclaiming bulk material in the chemical, pharmaceutical and food industries.
Based on Piab’s long established know-how in these highly demanding industries the company is well equipped to help evolve automation in AM operations. While Piab has been delivering vacuum conveying units to the ceramics AM industry for quite some time, the real growth factor is the upgrading of metal AM operations to industrial scale production.
Kajsa Ryttberg Wallgren, President Vacuum Conveying Division at Piab explains: “Metal powder handling requires special attention for certain alloys due to its hazardous characteristics for humans, its sensitivity to oxygen causing degradation, and its value as a high price ingredient. Today at most manufacturers the powders are manually handled to be transferred between storage and process steps. While this process may be acceptable in a lab environment, it is certainly not for mass production or printing of large components. Therefore, we at Piab see a tremendous need for the AM industry to automate the process steps around the printing and by doing this, address three core needs; safety, quality, and productivity.”
Piab’s vacuum conveyors meet these requirements as well as offering low building height, ease of cleaning and low noise levels. The contained and enclosed system eliminates the spread of dust during transportation of the material, preventing the exposure to hazardous dust of employees and freeing them from carrying heavy powder cans. Moreover, it keeps the material from contamination with impurities from other particles, meaning that the structure of the metal powder units remains, resulting in high quality 3D printed objects.
“Additive manufacturing is already quite popular in aerospace and medical technology, but we see tremendous further growing potential particular in automotive, turbo machinery, tooling, and mechanical engineering applications all based on metal powder deployment,” adds Kajsa Ryttberg Wallgren.
The use of metal powders in additive manufacturing poses particular challenges, starting with the high bulk density. Metal powders can weigh up to eight kilograms per liter (kg / l), while powders in the pharmaceutical or food sector are generally between 0.8 and 1.2 kg / l. This requires significantly more powerful vacuum systems to keep the metal powder moving. At the same time, only relatively small quantities are needed for a production process, usually no more than 100 kilograms per hour - that is 12.5 l in volume conveyed. Due to the high bulk density and the large filter in the system as well as the additionally required exhaust air filter, a correspondingly large-sized vacuum pump is required to achieve the necessary suction power. The production time in the 3D printing process is relatively long and the active conveying times are low.
Thanks to the automatic shutdown of the vacuum pump at idle, the piFLOW®p vacuum conveyor configuration for the AM industry is very energy-efficient, especially in comparison to mechanical pumps, which must continue to run at idle. Thus, the energy costs for the automated delivery and filling remain low.
Explosion protection must also be taken into account when producing parts out of metal powders, as these are generally subject to the ATEX regulations. For the configuration of a suitable vacuum conveyor, this means that appropriate seals and filters must be used, and additional grounding points must be taken into account. All plastic and rubber parts in the ATEX version of Piab’s piFLOW®p vacuum conveyors are made of antistatic nitrile butadiene rubber (NBR). In principle, all ATEX-relevant powders and gases can be transported in Piab’s vacuum conveyors as long as they do not undergo electrostatic charging under a gas atmosphere and do not exceed a specific volume resistance.
Vacuum conveying transports powder in the air stream. Another peculiarity in conveying metal powders is that they quite commonly require to be conveyed under inert gas atmosphere, usually nitrogen or argon. This means that these gases have to be fed into the system, which requires highly complex control. Piab offers respective solutions to the AM industry on a customized basis.
Kajsa Ryttberg Wallgren sums up: “With Piab we ensure our customers stay fit for the future by offering our extensive knowledge reservoir in vacuum and material handling technology. This is the basis for the innovations Piab has developed over the last 70 years and continuous to be our pathway to growth while keeping our entrepreneurial and innovative spirit. Stay ahead together with us.”