Furnace Temperature Uniformity: Raw Data From PTCR Tests

Temperature uniformity is of the utmost importance as you’re comparing furnace models. For some applications, it’s arguably the single most critical factor.

It’s also an area in which SH Scientific furnaces excel—a fact which we point out at every opportunity.

But why, exactly, are we so confident in that claim?

It comes down to rigorous and continual testing.

We want you to have the same confidence that we do, so we’ve decided to do something a bit unconventional in this industry, and share our raw internal PTCR test results.

Our PTCR Testing Methodology

We use different uniformity testing techniques at various stages of R&D, production, and QC.

One of the most important is process temperature control ring (PTCR) testing. It’s a simple and trustworthy method that’s easily adapted to any chamber size and heating configuration.

1. Select appropriate PTCRs for the test temperature range.
2. Place them according to the chamber style:
   1. In a muffle furnace, put one in the exact center, two in diagonal corners near the top, and two in the other diagonal corners near the bottom.
   2. In a tube furnace, arrange them consecutively along the full length of the heating zone(s). Use as many as needed, e.g., 15 x 20 mm rings to cover a 300 mm heating zone.
3. Ramp at 5° C/min to the target temperature, then hold it for two hours.
4. Measure each ring with high-precision calipers (resolution ≤ 0.01 mm).
5. Use the PTCR vendor’s chart to translate each caliper reading into a temperature.

To keep results comparable, we have a specific positioning protocol for each chamber variation. For instance, our 5-liter muffle furnace is set up as follows:

Sample Results by Model

Now that we’ve walked through our methodology, here are some actual results obtained during recent in-house testing.

Muffle furnaces (uniformity: ± 0.2%–0.7%)

SH-FU-5MGE (max 1050° C)

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SH-FU-11MGE (max 1050° C)

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SH-FU-5MG (max 1200° C)

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SH-FU-27MG (max 1200° C)

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SH-FU-11MH (max 1500° C)

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SH-FU-36MH (max 1500° C)

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Tube furnaces (uniformity: ± 1.0%)

SH-FU-80STG (1 zone; max 1200° C)

Need More Info?

The above is just a sample of our internal test results. Upon request, we’re happy to provide comprehensive data for other designs and temperature ranges.

For more information, simply reach out to our Portland-based sales team, and let us know how we can help!