Verify Precision on a Setting Ring
You can check the precision of a Plastiform impression and your own technique by taking an impression of a certified setting ring and measuring it on a non-contact machine. CETIM tested F50 on 1.000 mm and 9.995 mm setting rings following this procedure.
Why a Setting Ring
A setting ring is a reference part with certified dimensions. Take its impression, measure it, and compare your readings with the certified dimensions.
CETIM, an independent technical center specialized in metrology, took F50 impressions on two setting rings and measured them. We publish both of its reports in full on this page.
What CETIM Measured
CETIM took the impressions and measured them in its dimensional metrology laboratory in Nantes on 7 and 8 September 2026. The laboratory worked at 20 ± 1°C with a relative humidity below 65%. Both reports are dated 19 October 2026.
For these tests, CETIM used two smooth setting rings engraved 1.000 mm and 9.995 mm. It made three F50 impressions on each ring, following the test protocol and the instructions for use supplied by Plastiform.
The laboratory measured each ring and its impressions without contact on the same optical measuring machine. Because an impression is soft, a mechanical probe could deform it. Each impression was then measured three times 1 hour after removal, and three times again after 24 hours, to check that it does not change over time.
All the instruments used are traceable to the national calibration chain. Both reports are in French, and you can download them in full below.
- PDFCETIM report CET0272878_01_b: F50 on a 1 mm setting ring (in French)PDF, 476 KB
- PDFCETIM report CET0272878_02_b: F50 on a 10 mm setting ring (in French)PDF, 485 KB
How to Read the Results
The differences shown in the reports come from the uncertainty of the measuring machine, not from the product. Four observations on the 1 mm ring show this. First, the impressions are close to the part. Their mean diameter is 1.004 mm for 1.000 mm engraved on the ring, which is a gap of 0.004 mm (4 µm).
Second, part of that gap comes from the ring itself. The report calculates the replication error against the engraved diameter, which is a nominal value, whereas the same optical machine measures the ring at 1.005 mm. Compared with the ring as the machine measures it, the impressions are 1 µm away.
Third, the gap is within the measurement uncertainty. The stated uncertainty on the impression diameter is 4 µm, with a coverage factor k = 2, or about 95% confidence. A gap of 4 µm cannot be told apart from the measurement uncertainty, so with this instrument, nobody can say that the impression differs from the ring.
Fourth, the impressions match each other and do not move. The 18 readings fit within 2 µm, from 1.003 mm to 1.005 mm, and the means are the same after 1 hour and after 24 hours.
On the 10 mm ring, the replication error is −0.001 mm within the hour and 0.002 mm after 24 hours, for a stated uncertainty of 6 µm. These results hold for the diameters tested, with three impressions on each, and every diameter is evaluated separately.
| 1 mm ring | 10 mm ring | |
|---|---|---|
| CETIM report | CET0272878_01_b | CET0272878_02_b |
| Engraved nominal diameter of the ring | 1.000 mm | 9.995 mm |
| Ring diameter measured by CETIM | 1.005 mm | 10.001 mm |
| Mean impression diameter, within the hour | 1.004 mm | 9.994 mm |
| Replication error, within the hour | 0.004 mm | −0.001 mm |
| Maximum error observed, within the hour | 0.005 mm | 0.014 mm |
| Mean impression diameter, 24 hours after | 1.004 mm | 9.997 mm |
| Replication error, 24 hours after | 0.004 mm | 0.002 mm |
| Maximum error observed, 24 hours after | 0.005 mm | 0.007 mm |
| Measurement uncertainty on the impression diameters (k = 2) | 4 µm | 6 µm |
Step by Step
- Keep the cartridge at a constant temperature for a few hours, ideally 20°C.
- Degrease the setting ring with DN1 before injecting.
- Extrude a test drop right next to the ring and make sure its color is uniform, with no white streak.
- Inject starting from the bottom once the drop is good.
- Rub the surfaces with the nozzle and stir, so the product stays in contact with the ring.
- Place a demolding ring to create the grip.
- Let the product polymerize for 15 minutes.
- Pull straight to remove the impression, and never unscrew it.
- Measure the impression on a non-contact measuring machine and compare the readings with the certified dimensions of the ring.
Why 15 Minutes
The polymerization time of the product is shorter than 15 minutes. The 15 minutes in this procedure provide a deliberate margin to make sure the impression has reached its final rigidity and to rule out a premature removal.
What the Result Depends on
Non-contact measurement is the reference method with Plastiform products. At the scale of the micron, the precision of the readings depends on the instrument. The more precise the machine, the better the result.
Measure the ring and the impressions with the same instrument, then compare the gap you obtain with the uncertainty of that instrument before you conclude. A gap only has meaning against the precision of the instrument that measured it.
A white streak in the test drop means an incomplete mix. In that case, the impression would not be usable.