I need to heat stainless bar stock prior to bending in a forming machine. I would like to reach approximately 200 degrees F.

The material is stainless type 304/304L, 3/16" thick.

We are heating it to temporarily lower its tensile strength for a challenging bending application. Heating works quite well allow it to bend without distortion.

We are heating it in a kitchen-type oven set to 400F (and it really measures approximately that hot), yet the stainless bars never seem to reach more than 160F, no matter how long they sit in the oven.

We need to make thousands of these and they are, so using a blowtorch would be too slow and not practical given the size of the part. Any ideas for a better way to heat these?

  • $\begingroup$ Induction heaters? $\endgroup$ – Phizzy Mar 18 at 20:35
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    $\begingroup$ use an oil bath? $\endgroup$ – Solar Mike Mar 18 at 21:11
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    $\begingroup$ How much do they weigh, what is the throughput, and how long will they sit before being run through the machine? 200 F hardly seems worth the effort. That's about a 15-20% change in modulus, but at least it isn't much of a handling problem. $\endgroup$ – Phil Sweet Mar 18 at 22:35
  • $\begingroup$ And what happens to the heat? If you are running 150kBTU heater, the shop will warm up kinda quick. $\endgroup$ – Phil Sweet Mar 18 at 22:41
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    $\begingroup$ A temperature of 200 F will make no significant difference in any physical property of 304 . Precision laboratory equipment could measure something . You are doing something wrong if the 304 does not reach 200 F in a 200 F oven. Food certainly cooks in a stainless pan in the oven. $\endgroup$ – blacksmith37 Mar 18 at 23:52

How do you measure the temperature? If you use an infrared thermometer, this won‘t work because of reflection. Use a thermistor based measurement device for verification.

  • $\begingroup$ Or thermocouple. There are also wax pencils that melt at specific temperatures. Mark the part and when the mark melts, that temperature has been achieved at the mark's location. $\endgroup$ – Jim Clark Mar 20 at 18:05

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