Whether you’re heat treating knives or making jewelry, understanding electric heat treat furnace controls is essential to successfully executing your firing schedule.
Understanding Heat Treat Schedules
During heat treat, the elements of your electric furnace must reach specific temperatures (or setpoints) for specific periods of time (also known as hold times or soak times). This ensures that your metal or alloy reaches sufficient temperature to alter its properties.
A sequence of setpoints and hold times is known as a firing schedule.
Ramp rate (the speed at which an electric furnace heats up or cools down) usually isn’t an important factor for electric heat treat furnace controls. That’s because cooling typically occurs outside of the furnace through quenching or air cooling. Additionally, firing schedules for heat treat typically only include a single step.
Below is an example of what firing schedules for heat treat typically look like:
A heat treating controller is a device that acts as an interface between the artist and the elements of their electric furnace. You use a heat treat controller to input the desired setpoint(s). The controller then cycles the relays leading to the elements of your furnace, comparing inputs from the thermocouple against your setpoints, until your electric heat treat furnace reaches the desired temperatures.
Different Types of Electric Heat Treat Furnace Controls
There are a lot of different types of electric heat treat furnace controls that provide different levels of functionality and very different user experiences. Below are quick summaries of different controller methods:
- Manual Controller: With a manual controller, the artist adjusts knobs and dials until their electric heat treat furnace reaches the correct temperature. This method requires constant user oversight and input (especially since a kiln sitter usually isn’t a viable solution for heat treat!).
- Single Setpoint Controller: A single setpoint controller is a simplified controller method, usually intended specifically for heat treat. With a single setpoint controller, you just enter the setpoint and the controller automatically heats up the furnace to that temperature indefinitely. The artist is still responsible for managing the hold time.
- Multi-Setpoint Controller: A multi-setpoint controller, also known as a programmable controller or process controller, is capable of automatically executing schedules with multiple setpoints and specific ramp rates. This capability can provide a greater degree of precision and convenience for heat treat artists. However, for quenching there will still be a degree of manual oversight and intervention required.
User Interfaces for Single Setpoint and Multi-Setpoint Controllers
Additionally, single setpoint and multi-setpoint controllers can have different types of user interfaces.
Key-Based Electric Heat Treat Furnace Controls
The most common input method for electric heat treat furnace controls is key-based control. Keys are like buttons – similar to the ones on calculators or old school home phones. These types of controllers usually come in 3-key and 12-key configurations.
The only problem is that you also have to use these keys to navigate your controller – so most inputs require dozens of presses, the screens are typically very small, and these controllers can be very difficult to use. In fact, our own frustration with key-based controllers inspired us to develop the TAP Kiln Controller.
Touchscreen Electric Heat Treat Furnace Controls
In 2015, the original TAP Kiln Controller revolutionized electric heat treat furnace controls. Compared to key-based controllers, touchscreen interfaces streamline the heat treat process by allowing you to navigate menus and create schedules with an easy-to-use, responsive touchscreen.
Additionally, touchscreen controllers provide a larger screen than key-based controllers, so that you’re able to easily see all schedule details.
Remote Electric Heat Treat Furnace Controls
One heat treat control method, which is currently only available through the TAP Ecosystem, is remote control through the TAP Kiln Control Mobile app. With remote heat treat control, you can control all furnace functions through your smartphone or tablet.
This kiln control method provides a ton of convenience and peace of mind for heat treat artists by letting them control and monitor their heat treat projects while multitasking or if they need to step away from their furnace.
How to Use a Heat Treat Furnace Controller
Now that we’ve covered the basics of heat treat schedules and different furnace control methods, we wanted to provide an explanation of how to use your furnace controller. Obviously, the type of controller you’re using will impact the specifics of using your controller, so we’re going to keep things super high level.
Whether you’re programming an industrial furnace or an at home oven, you have to start by figuring out your heat treat schedule. First, you’ll want to determine what setpoint and hold time you will need in order to successfully execute your heat treat process. For this example, we’ll be taking a quench hardening schedule for 1095 steel.
Written out, this schedule would look like this:
- AFAP°F/Hr to 1600°F – hold for 15 minutes.
- Remove knife or blade from the oven and quench in fast oil to 150°F.
Like most heat treat firing schedules, this is a single setpoint schedule with a setpoint of 1600°F and a 15-minute hold time. After 15 minutes, you’ll be removing your steel from the furnace and quenching it in fast oil until it reaches 150°F before allowing it to air cool.
Using Single Setpoint Electric Heat Treat Furnace Controls
For a single setpoint electric heat treat furnace controls, you would simply program your controller to 1600°F. Once your furnace reaches that temperature, you’d put in your knife, blade, or other project into the furnace and set a timer for 15 minutes. After 15 minutes, you’d use tongs to remove your project and then submerge it in your quenching oil.
Using Multi-Setpoint Electric Heat Treat Furnace Controls
For a multi-setpoint controller, you would program your furnace to 1600°F with a 15-minute hold time. Then, you’d remove your project and place it in your quenching oil.
So why bother with a multi-setpoint controller for a heat treat furnace?
The answer is convenience. If you’re using a TAP Kiln Controller, your controller would make an alert once the hold time has been reached – and if you’re using TAP Kiln Control Mobile you would also receive a push notification to your smartphone or tablet. This means that you wouldn’t have to set a timer or keep your eye on the clock.
Additionally, with a TAP or TAP II Controller, you’re able to save an unlimited number of firing schedules – so that you can easily save and access all of your firing schedules for different processes.
Explore TAP Electric Heat Treat Furnace Controls by SDS Industries
Are you looking to upgrade your electric heat treat furnace controls? TAP by SDS Industries has got you covered!
The TAP and TAP II Controllers by SDS Industries provide advanced, precise, and easy-to-use multi-setpoint controls for your heat treat oven and offer responsive controls and an intuitive graphical UI on a large, easy-to-read touchscreen and allow you specify ramp rates and hold times for each step for maximum convenience.
The soon-to-be-released TAP&Go is a single setpoint controller designed specifically for heat treat. With simplified controls and a more affordable price point, TAP&Go provides the fundamental functionality you need!
All of the TAP Controllers are compatible with any relay-controlled furnace or oven and integrate with the TAP Kiln Control Mobile app to maximize your productivity while always keeping you informed on the status of your project.
We invite you to explore our selection of programmable kiln controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP Controlled Kilns and Heat Treat Ovens through one of the following distributors:
- Evenheat
- Hot Shot Oven & Kiln
- Mobile Glassblowing Studios, LLC
- Jen-Ken Kilns
- Kiln Frog
- Sheffield Pottery
- Delphi Glass
