IMR Materials Testing Technical Blog

Top 6 Additive Manufacturing Powder Characterization Test Methods

While the rapid growth of additive manufacturing (AM) technology has helped engineers in many industries create innovative new component designs, the unique characteristics of raw metallic and non-metallic powders has created significant materials testing challenges.

The need for fully characterized raw materials becomes increasingly important with SLS powders. Essential ongoing testing is required due to the common practice of reusing unsintered powder, insuring the dependability of the finished product.

Here are six highly effective powder characterization tests performed by materials testing labs:

 Microtrac Laser Diffraction – The Microtrac particle size analyzer is an analytical instrument which uses laser light diffraction to determine a particle size distribution. Samples are placed in a suspension and circulated through the analyzer. Sample particles pass through a laser beam and in doing so diffract light at various angles. The angles of diffraction are directly related to the size of the particles. The different angles and beam intensities are measured to quantify the range of particle sizes in the sample.

Sieve Analysis – Sieve analysis is a gravimetric analysis of particle size. The apparatus consists of a series of pans with varying size screens stacked in decreasing screen size order. The sample is placed in the uppermost pan (largest hole) and then the stack is shaken until the particles have moved as far down the stack as their size allows. The mass of sample in each pan is then measured and the percentage retained on each pan is reported.

Flow Rate (Hall/Carney) – The Hall Flow rate is conducted to ASTM B 213 (Carney-ASTM B964). Metal powder is timed as it flows through a calibrated orifice. The test gives a representation of the flowability of the powder.

Apparent Density (Hall/Carney) – A known mass of powder is allowed to flow into a container of known volume from a fixed height. The apparent density is then determined as mass of the powder per unit of volume (g/cm3)

Tap Density (packed density) – A known mass of powder is placed into a graduated cylinder which is then mounted on the Tap Density apparatus. The powder is then tapped from a fixed distance approximately 3000 times. The final volume of the powder is recorded and the tap density is determined and expressed in mass of powder per unit of volume (g/cm3).

Helium Pycnometry (skeletal density) – A known mass of powder is placed into a calibrated pycnometer. The pycnometer then determines the total displaced volume of the powder. The density of the powder is then determined and expressed in mass of powder per unit of volume (g/cm3).

To find out more about IMR Test Labs capabilities in additive manufacturing powder and product testing, click here.

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