At this year’s Formnext (15–18 November), the gas giant Linde will display a number of its most innovative gas technologies, including its custom gas mixture designed to optimize printing in laser powder bed fusion processes, cutting-edge gas atomization solutions for metal powder production, its turnkey offering to help accelerate the use of the special alloy nitinol, as well as the chance to confidentially discuss cutting-edge technologies to compete with the market for controlled gas.
Turnkey solution for nitinol printing
A metal alloy made of 50/50 nickel and titanium called nitinol (NiTi) has unique qualities like superelasticity and the ability to change shape when heated and return to its original form when cooled. Manufacturers of nitinol products face problems
because they are difficult to machine and product design is constrained to simple structures.
Nitinol products are used more frequently in the medical and dental industries for orthopaedic implants, stents, and orthodontic parts as well as in aerospace for solar panels. Traditional machining also causes surface degradation, high cutting pressures, and excessive tool wear. Even though laser bed powder fusion (LBPF) additive manufacturing allows for more design flexibility and improved production efficiency, printing with nitinol still presents challenges.
The nickel can vaporize during the laser-enabled process, causing the nickel/titanium ratio to drop and the transformation temperature to rise.
Additionally
, oxygen pick-up inside the substance can impact the transformation temperature, having a negative impact on shape memory and the intended application’s overall effectiveness. Surface oxidation might also be an issue., which means the part needs intensive cleaning after production. It is crucial to lowering the oxygen level in the print chamber in order to prevent both problems.
Linde and 3D Medlab have worked together to improve the print atmosphere utilizing Linde’s ADDvance O2 precision oxygen monitoring system,
and ADDvance Laser230 process gas combination in order to achieve strict control of oxygen levels.
Ideal Print Temperature
Minor impurities may still be present in the print chamber atmosphere even after the most thorough purging.
The mechanical characteristics of alloys sensitive to oxygen can be affected by incredibly minute fluctuations in oxygen levels,
including process-induced ageing of the metal powder.
The gas environment is continuously analyzed by ADDvance O2 precision.
In order to maintain ideal atmospheric conditions, ADDvance O2 precision starts an automatic purging operation when it detects O2 concentrations as low as 10 ppm.
The ADDvance® Laser230 process gas, a custom gas mixture created exclusively to improve printing results in laser powder bed fusion (LPBF) processes,
blends argon and helium to lower particle redeposition, porosity, and powder loss by up to 20%. Additionally, it lengthens the printer’s lifespan and reduces maintenance time because fewer filter replacements are necessary. Additionally, it reduces fume production, quickens cycle times, and lowers the cost per part by making printing safer. It is suitable for the additive manufacture of lattice structures and is alloy-independent.
ADDvance Sinter250
ADDvance Sinter250, a gas-enabled binder jetting solution, enhances sintering atmospheres to prevent oxidation in metal fused deposition modeling (FDM).
From pure argon and hydrogen to specific argon/hydrogen gas blends for superior atmospheric management,
Linde has created a variety of highly customized gases.
For assuring the strength and integrity of items printed from stainless steel powders, ADDvance® Sinter250 is the best option.
High pressures and large volumes of gas must be injected through a nozzle in order to produce metal powders.
The gas can pass more quickly through the nozzle and reach temperatures of several hundred degrees by employing a heater to raise the temperature of the gas. This allows for the production of finer powders or lower gas usage.
Linde provides a turnkey solution that includes a heater,
control panel, and gas supply, and the gas heater can be retrofitted.
Innovative 3Dprinting
When it becomes operational in March 2023, the test bench laboratory will make it possible to evaluate industrial-scale gas parameters to improve our understanding of how gases behave in typical metal powder atomizers.
The market for new metal powders has expanded dramatically as a result of major improvements in additive manufacturing processes.
Standard metal powder atomizers are enormous and expensive, but they are not suited for observing and analyzing gas behavior when parameters are changed.
In addition to being a much smaller scale (1.60 meters high) version of a normal atomizer, Linde’s new lab incorporates windows, illumination, high-speed cameras, and Schlieren imaging [1] that have been specially modified to allow for the observation and data collection of each change in a gas parameter. It does not rely on the addition of molten metal; rather, it uses data from the simulated process to show how gases behave under specific circumstances.
The various factors that must be evaluated include gas type, gas volume, pressure, and temperature,
and the tiny atomizer can quickly swap over to examine hundreds of combinations in just a few minutes.
With the help of the lab,
Linde will be able to create new technologies that will enhance the atomization procedure,
particularly by raising yield and process stability.
Additionally,
Linde will work with OEMs and powder producers to assist them in evaluating particular gas behaviours on a test bench so that they can later scale up the results on their huge atomizers.
