Before you choose
- Name the machine and manufacturing route.
- Specify distribution and measurement method, not only D50.
- Keep powder properties separate from printed-part results.
Start with the installed process
Polymer SLS, metal laser powder-bed fusion, directed energy deposition and binder-based routes need different feedstock forms and process windows. State the machine model, parameter-set constraints and whether an existing grade is being replaced. Include the current powder specification if one exists.
Describe the delivered powder
For polymer powders, identify the formulation, particle distribution, conditioning and intended refresh strategy. For metals, specify the alloy designation and applicable chemistry limits alongside the particle range. Virgin, reclaimed and blended material should be identified explicitly.
| RFQ field | Why the buyer needs it |
|---|---|
| D10 / D50 / D90 and reporting basis | Shows more of the distribution than a single median |
| Measurement method and sampling | Makes repeat measurements more comparable |
| Morphology and flow method | Connects characterization to feeding and spreading |
| Chemistry, oxygen or moisture limits | Defines the relevant contamination or conditioning requirement |
| Lot number and supply condition | Enables traceability and controlled comparison |
Read a micrograph carefully
A scale bar lets you interpret the image field; a representative image alone does not establish the full size distribution, chemistry or batch conformity. Check whether the picture is grade-specific or a disclosed family reference. Ask for measured batch results when they are an acceptance requirement.
State the approval and delivery conditions
Identify required tests, methods, sampling and acceptance limits before the order. Include container size, closure, identification, storage requirements and destination. A published property for a printed and heat-treated part should be kept separate from a COA for the delivered feedstock.
RFQ structure: alloy/grade + manufacturing route + machine + particle requirements and methods + chemistry limits + new/reclaimed condition + lot documents + pack size + trial quantity.
What the same D50 can hide
Consider two illustrative volume-based reports: A has D10/D50/D90 of 15/30/45 μm; B has 10/30/80 μm. Both report a median of 30 μm, while their lower and upper portions differ. These invented values illustrate a reporting issue; they are not specifications for a catalog powder.
On a volume-based distribution, the percentile refers to cumulative reported volume. It should not be read as a count of particles. Report the method and basis with the quantiles, and request the complete distribution if the tails matter to your process. Three quantiles alone do not uniquely define the shape of a distribution curve.
Make the result reproducible at receiving
A receiving check needs a sample plan as well as a limit. Agree how a representative sample is taken, identified and conditioned, and how measurements are compared when supplier and buyer methods differ. Preserve the connection between the sample, container and production lot.
For recurring purchases, identify the report revision and any change that requires review: alloy or formulation, particle cut, supplied condition or agreed method. A clearer specification reduces the need to diagnose differences after a build has already been consumed.
Questions buyers ask
Does 15–45 μm mean every particle is within that range?
A commercial range needs a defined specification and method. Request the permitted distribution tails and acceptance criteria instead of assuming an absolute cut.
Does an open-material machine accept every matching alloy?
An open-material policy still requires feedstock and parameter validation. Match the grade, distribution, process conditions and part requirements.
Sources
- NIST — particle-size characterization guide
Particle-size distributions, measurement methods and reporting basis.
- NIST — variation in metal-AM powder feedstock
Measurement and sampling affect reported powder size distribution.
- Carpenter Additive — PowderRange brochure
Powder properties and conformity documentation; historical brochure, not a current availability or COA promise.