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. Every grade ships from UK stock with chemical analysis and batch traceability.
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.