Heat Treat Tips: SCR Environmental Conditions and Furnace Downtime

June 24, 2020 / HEAT TREAT NEWS INDUSTRIES, MANUFACTURING HEAT TREAT

One of the great benefits of a community of heat treaters is the opportunity to challenge old habits and look at new ways of doing things. Heat Treat Today’s 101 Heat Treat Tips is another opportunity to learn the tips, tricks, and hacks shared by some of the industry’s foremost experts.

For Heat Treat Today’s latest round of 101 Heat Treat Tips, click here for the digital edition of the 2019 Heat Treat Today fall issue (also featuring the popular 40 Under 40).

Today’s tips come to us from Control Concepts, covering SCR Environmental Conditions. Another contributor, Messer, also shares a tip on “Preventing Furnace Downtime.” These are great tips to make those fixes that can fly under the radar.

Heat Treat Today welcomes you to submit your own heat treat tip for the 2020 Heat Treat Today fall issue to benefit your industry colleagues. You can submit your tip(s) to karen@heattreattoday.com or editor@heattreattoday.com.

Heat Treat Tip #50

Using a Grounding Rod in Noisy Environments

This may be beneficial if you have a bad system ground. (Control Concepts)

Heat Treat Tip #51

Seal Away Dirt or Dusty Environments

Use a sealed enclosure or alternative cooled power controllers for dirty and dusty environments. For heavy dirt or dusty environments, a sealed cabinet with air conditioning or filters is recommended. Alternatively, select a SCR manufacturer that offers external mount or liquid cooled heatsinks to allow you to maintain a sealed environment in order to obtain maximum product life. (Control Concepts)

Heat Treat Tip #52

De-Rate Controller Above 6,000 Feet

De-rate controller for installations above 6,000 feet. As the air thins at increased elevations, natural convection and forced air cooling becomes less efficient. Follow the manufacturer’s recommendations for de-rating the SCR power controller above 6,000 feet altitude. (Control Concepts)

Heat Treat Tip #64

Prevent Furnace Downtime

If your atmosphere heat treatment furnace is experiencing frequent downtime, and circulation fans fail, it is probably time for an upgrade. New injection mixing technology uses nitrogen to stir the atmosphere and maintain its uniformity. (Messer)

Box Furnace Comparison Before/After (photo source: Messer)

Heat Treat Tips: SCR Environmental Conditions and Furnace Downtime Read More »

Applying PID to Temperature Variances in Vacuum Furnaces

Source: Solar Manufacturing

Controlling process temperature with accuracy and without extensive operator involvement is a crucial task in the heat treat shop and calls for the use of a temperature controller, which compares the actual temperature to the desired control temperature, also known as the setpoint, and provides an output to a control element. This comparative process relies upon an algorithm, the most commonly used and accepted in the furnace industry being the PID, or Proportional-Integral-Derivative, control.

“This popular controller is used because of its robust performance in a wide range of operating conditions and simplicity of function once understood by the processing operator,” writes Real J. Fradette, a Senior Technical Consultant with Solar Atmospheres, Inc, and the author of “Understanding PID Temperature Control as Applied to Vacuum Furnace Performance” (with William R. Jones, CEO, Solar Atmospheres, Inc, contributing).

The PID algorithm consists of three basic components, Proportional, Integral, and Derivative which are varied to get optimal response. If we were to observe the temperature of the furnace during a heating cycle it would be rare to find the temperature reading to be exactly at set point temperature. The temperature would vary above and below the set point most of the time. What we are concerned about is the rate and amount of variation. This is where PID is applied. ~ Fradette

In this week’s Technical Tuesday, we direct our readers to Fradette’s article at Solar Manufacturing’s website where he and Jones cover the following on PID temperature controllers:

Definitions, e.g., Closed Loop System; Proportional (GAIN); Integral (RESET); and Derivative (RATE)
Actual operation of a PID temperature controller, including understanding PID dimensions and values; and general rules for manually adjusting PID
The art of tuning, a manual
Autotuning
Tweaking the furnace PID controller
and other factors

Photo credit

“Understanding PID Temperature Control as Applied to Vacuum Furnace Performance”