The Copper Grade Family
Ronald Britton's copper range is built around two production routes: CU-ED, electrolytic dendritic copper in five apparent-density grades, and CU-AT, gas-atomised spherical copper. Between them they cover pressing, sintering, spraying and additive manufacturing. Choosing well means matching three numbers to your process: apparent density, flow and purity.
CU-ED: Five Dendritic Grades
CU-ED is supplied as STD, SFP2, SFP3, SFP8 and SFP10, spanning apparent densities from 2.7 g/cc down to 0.65 g/cc at Cu 99.0% minimum purity. The STD grade (2.6 to 2.7 g/cc, -100 mesh) fills dies easily and suits general pressing. The SFP grades get progressively lighter and finer: SFP2 and SFP3 balance handling against surface area, while SFP8 and SFP10 (below 1.1 g/cc) maximise surface area and sintering reactivity for demanding diamond tool segment formulations.
CU-AT: Atomised Spherical
CU-AT runs the other direction: Cu 99.9% minimum purity, 4.0 to 4.8 g/cc apparent density and a 25 sec/50g Hall flow. It exists for processes that transport powder: thermal spray, cold spray and additive manufacturing, where dendritic powder simply will not feed.
Grade Comparison
Copper Powder Grades at a GlanceGradeMorphologyApp. Density (g/cc)Best ForCU-ED STDDendritic2.6 to 2.7General pressing, easy die fillCU-ED SFP2Dendritic1.95 to 2.20Diamond tool segmentsCU-ED SFP3Dendritic1.3 to 1.7Higher-reactivity segmentsCU-ED SFP8Dendritic0.95 to 1.10High surface area formulationsCU-ED SFP10Dendritic0.65 to 0.90Maximum reactivityCU-ATSpherical4.0 to 4.8Spray processes, AM
Choosing a Grade
Start from the process. Pressing and sintering: CU-ED, then pick the SFP grade whose apparent density matches your segment formulation, lower density for reactivity, higher for handling. Spraying or printing: CU-AT, with AM size cuts on request. Mixed or unusual requirements: ask, blends and custom particle size distributions are routine work. Stock grades are dispatched within 48 hours with chemical analysis and batch traceability. Other grades are made to order.
Why the Purity Figures Differ
CU-ED is specified at Cu 99.0% minimum and CU-AT at Cu 99.9% minimum, and the gap is a consequence of process rather than quality control. Electrodeposition produces high-purity copper but the powder is washed, dried and reduced afterwards, and those steps reintroduce trace surface oxide across a very large surface area. Atomisation under inert gas produces a low-surface-area sphere that never presents the same opportunity to oxidise. Neither figure makes one grade better; they make them suited to different jobs.
Reading the SFP Ladder
The SFP grades are a single lever expressed as five settings. As apparent density falls from 2.7 g/cc at STD to 0.65 g/cc at SFP10, surface area rises and sintering reactivity rises with it. STD fills a die readily and suits general pressing. SFP2 and SFP3 trade some handling convenience for reactivity. SFP8 and SFP10, below 1.1 g/cc, are chosen where sintering activity matters more than easy handling, typically demanding diamond segment formulations.
Matching Grade to Process
Pressing and sintering points to CU-ED, with the SFP number chosen by how much sintering activity the cycle needs. Thermal spray, cold spray and additive manufacturing point to CU-AT, because those processes cannot function without flow. Diamond tooling generally uses both, alongside SN-100 and FE-RED, because no single grade delivers green strength and densification together.
How to Specify
Name the grade, the apparent density range with its method, the mesh, and the purity minimum. "CU-ED SFP8, 1.0 to 1.1 g/cc Hall per ASTM B212, -325 mesh, Cu 99.0% min" leaves nothing to interpretation. "Fine copper powder" leaves everything to it.