Carbon DLS Accuracy for Engineering Materials

The Carbon DLS™ process has accuracy and repeatability capabilities that depend on resin and part geometry. General Accuracy is described as a constant offset plus a ratio, for example, ±70 μm +1 μm per mm dimension size. General Accuracy is what you could expect when first printing any given geometry. After a part has been optimized for production, some of the sources of variation are removed. The remaining variation is cited as Production Repeatability.

Previously, we gave very conservative high-level guidance around our tolerances. We now offer more granular guidance based on several years’ worth of CT scans and field data on both general first-print accuracy and production accuracy following process optimization. The following figures are a summary of the updated guidelines, followed by a deeper dive into the data itself.

Updated General Accuracy Guideline
Metric Units ±65 μm + 1 μm per mm dimension size
Imperial Units Up to ±0.003 in + 0.001 in per in dimension size

Updated Production Repeatability Guideline
Metric Units Up to ±35 μm
Imperial Units Up to ±0.002 in

Accuracy Definitions

Two numbers describe the general accuracy capabilities of the Carbon DLS process: 1) the constant offset and 2) the dimensionally-dependent μm per mm. The constant offset is determined by the stack-up of variation sources that affect what we call “local offset accuracy.” This is measured with a test part that has both horizontal and vertical struts (below). Excess curing of the vertical and horizontal struts is called “overcure” and “cure-thru,” respectively.

The second number that describes accuracy is a factor that is multiplied by the length of the dimensional span. In this way, larger spans are expected to have larger deviations from nominal dimensions compared to smaller spans. These values are meant to include inaccuracies due to uniform part shrinkage and warpage (i.e., non-uniform shrinkage). The values are determined from a series of stair-step test parts with different wall thicknesses. The percentage we report is determined by subtracting the shrinkage of the 3-mm wall thickness part from that of the 1-mm part.

Sources of Variation That Affect Local Offset Accuracy

  • Lot-to-lot variation in resin characteristics
  • Printer-to-printer light engine peak wavelength
  • Build area variation across the printer
  • Temperature variation during printing
  • Print speed variation
  • Resin pot life age
  • Variation in lab environment

Accuracy Data

Metric Units
General Accuracy Production Repeatability
(95% of points)
Resin M1, M2, L1 M3, M3 Max M1, M2, L1 M3, M3 Max
MPU 100 ±75 μm + 1 μm/mm ±70 μm + 1 μm/mm​ ±55 μm ±50 μm​
UMA 90 ±70 μm + 1 μm/mm ±65 μm + 1 μm/mm​ ±50 μm ±45 μm​
RPU 70 ±70 μm + 11 μm/mm ±65 μm + 11 μm/mm​ ±40 μm ±35 μm​
RPU 130 ±65 μm + 18 μm/mm ±60 μm + 18 μm/mm​ ±50 μm ±45 μm​
FPU 50 ±50 μm + 11 μm/mm ±45 μm + 11 μm/mm​ ±40 μm ±35 μm​
EPX 82 ±80 μm + 13 μm/mm ±75 μm + 13 μm/mm​ ±55 μm ±50 μm​
EPX 86FR ±80 um + 6 μm/mm ±75 μm + 6 μm/mm​ ±55 μm ±50 μm​
CE 221 ±75 μm + 4 μm/mm ±70 μm + 4 μm/mm​ ±65 μm ±60 μm​
EPU 40 ±70 μm + 10 μm/mm ±65 μm + 10 μm/mm​ ±60 μm ±55 μm​
EPU 41 ±75 μm + 10 μm/mm ±70 μm + 10 μm/mm ±65 μm ±60 μm​
SIL 30 ±115 μm + 18 μm/mm ±110 μm + 18 μm/mm​ ±85 μm ±80 μm​
Henkel IND 405 Clear ±115 μm + 4 μm/mm (estimate) ±110 μm + 4 μm/mm (estimate)​ ±100 μm (estimate) ±95 μm (estimate)​

Imperial Units
General Accuracy Production Repeatability
(95% of points)
Resin M1, M2, L1 M3, M3 Max M1, M2, L1 M3, M3 Max
MPU 100 ±0.003 in + 0.001 in/in ±0.003 in + 0.001 in/in ±0.002 in ±0.002 in
UMA 90 ±0.003 in + 0.001 in/in ±0.003 in + 0.001 in/in ±0.002 in ±0.002 in
RPU 70 ±0.003 in + 0.011 in/in ±0.003 in + 0.011 in/in ±0.002 in ±0.002 in
RPU 130 ±0.003 in + 0.018 in/in ±0.002 in + 0.018 in/in ±0.002 in ±0.002 in
FPU 50 ±0.002 in + 0.011 in/in ±0.002 in + 0.011 in/in ±0.002 in ±0.002 in
EPX 82 ±0.003 in + 0.013 in/in ±0.003 in + 0.013 in/in ±0.002 in ±0.002 in
EPX 86FR ±0.003 in + 0.006 in/in ±0.003 in + 0.006 in/in ±0.002 in ±0.002 in
CE 221 ±0.003 in + 0.004 in/in ±0.003 in + 0.004 in/in ±0.003 in ±0.002 in
EPU 40 ±0.003 in + 0.010 in/in ±0.003 in + 0.010 in/in ±0.003 in ±0.002 in
EPU 41 ±0.003 in + 0.010 in/in ±0.003 in + 0.010 in/in ±0.003 in ±0.002 in
SIL 30 ±0.005 in + 0.018 in/in ±0.004 in + 0.018 in/in ±0.003 in ±0.003 in
Henkel IND 405 Clear ±0.005 in + 0.004 in/in (estimate) ±0.004 in + 0.004 in/in (estimate) ±0.004 in (estimate) ±0.004 in (estimate)
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