LPW Technology
LPW Technology PowderFlow
LPW's PowderFlow kit, which allows Hall and Carney flow testing, apparent density test and angle of repose to be performed on-site
LPW Technology, a developer and supplier of metal powders, has published a laboratory service data sheet focusing on the Hall Flow testing of metal alloys.
The Hall Flow test is conducted to ASTM B213 standard, which includes rigorous requirements concerning the accuracy of equipment and its calibration. Hall Flow testing is essential in gauging the material’s behaviour. Moisture content, morphology, and Particle Size Distribution can all influence the flow and deviation in the material’s behaviour can impact the final build part’s mechanical properties during an additive manufacturing process.
Seeking to confirm consistency between batches, the test can prevent the failing of builds. Metal powder is timed as it flows through the orifice of a Hall Flowmeter funnel. If any problems with the powder’s flow are detected, the cause can be examined and a decision taken on whether to proceed with the build, and unnecessary downtime can be avoided.
Undertaken in a laboratory environment using specialised equipment, the testing sees 50g of powder taken from a provided sample and measured into a clean weighing dish. The discharge of powder form the orifice at the bottom of the funnel is blocked with a dry finger, preventing any of the powder being poured into the funnel, without any tapping or moving of the funnel, seeping through. Then, an emptied dish is placed below the funnel, and on the start of a stopwatch, the finger is removed. From here the flow of the material is assessed. If the powder fails to flow, a single tap of the rim of the funnel is permitted. If the powder does flow, the stopwatch is stopped as soon as the last of the material leaves the funnel – time being recorded to the nearest 0.1 second. While end users often request feedback of a simple flow/ no flow result, the timing data can provide a more thorough comparison against the powder’s historic parameters and previous powder batches.
LPW’s PowderFlow kit enables additive manufacturers to carry out the testing themselves in their own lab. Containing a complete suite of powder flow measurement techniques, the kit enables the measurement of a variety of parameters to relevant ASTM standards.
Lisa Holman, LPW’s Quality Engineer explains: “The ASTM B213 standard recommends that Hall Flow is the first test undertaken to check a metal powder’s flow. Not only do we conduct this metal powder flow test in our state-of-the-laboratory, we also include the equipment in the LPW PowderFlow kit, allowing Hall and Carney flow testing, apparent density test and angle of repose to be performed in the end-user’s own facility.”
LPW’s Hall Flow data sheet can be read in full and downloaded here.
