Everything You Need to Know About Controlling Your Kiln

Guide for explaining heat treat processes, use-cases, and supplies
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Scott Shannon

Heat Treat 101: Guide to Heat Treating

Let’s talk heat treat! Whether you’re crafting knives, blades, jewelry, tools, industrial components, or any other metal object, you’ll want those objects to have specific qualities – whether that’s shape, hardness, toughness, flexibility, or even electrical conductivity.

That’s where temperature comes into play.

Heat Treat Definition

Heat treat is the process of exposing metal or alloys to specific temperatures to change its molecular structure, which in turn alters its physical (and sometimes chemical) properties. Through controlled heating and cooling, heat treat can alter a metal’s hardness, ductility, malleability, temperature resistance, corrosion resistance, and material strength.

What Is Heat Treat Used For?

As you can imagine, heat treat has a wide range of applications – both artistic and industrial.

Artistic Use

Artists use heat treat to create knives, blades, jewelry, or ornamentation – basically any art or craft that involves metal. Heat treat artists use a series of specific firing schedules, along with cooling techniques, to shape metal and imbue it with the desired qualities, textures, and mechanical properties they want for their finished piece. These qualities may be decorative, functional, or both.

Single setpoint kiln controllers can be the perfect solution for bladesmiths, such as Delight Valley Blades.
Knife makers like Brock from Delight Valley Blades use heat treat to craft high quality blades that are both artistic and functional.


Industrial Use

In industrial processes, heat treat is an integral part of most manufacturing processes involving metal. Industries that rely on heat treat include medical, automotive, and electronic manufacturing.

Manufacturing processes that commonly involve heat treat include:

  • Machining: Creating the desired shape, size, or finish.
  • Joining: Connecting multiple objects into a unified structure.
  • Casting: Pouring liquid metal into a mold and allowing it to harden into a single object.
  • Shaping: Shaping raw metal into a specific shape or structure.
  • Molding: Pouring or pressing liquid or semi-liquid metal inside a mold.
  • Assembly: Connecting, fitting, and joining various components into a finished object.
  • Finishing: Making final adjustments to the finished object to make sure it fits the final design requirements.

Types of Heat Treat Processes

Different heat treat processes are used to alter the specific qualities of the metal or alloy. Often, different processes are used subsequently on a single piece. Below are common heat treating processes, as well as the effects they have on the metal:

  • Normalizing: The metal is heated to an extremely high temperature for a defined time period and then air-cooled. Normalizing relieves internal stress and ensures uniformity, resulting in harder, stronger metals.
  • Annealing: The metal is heated beyond the upper critical temperature and then slowly cooled to soften it and increase its workability. Annealing increases ductility and toughness, while relieving stress, making the metal more resistant to fractures.
  • Hardening: The metal alloy is heated until it forms an even solution and then allowed to cool to increase its hardness.
  • Case Hardening: Only the outside of the metal is hardened, creating a durable outer layer while ensuring the metal retains flexibility and doesn’t become brittle.
  • Quench Hardening: After heating, the metal is cooled rapidly by dipping it into an oil, polymer, or water, resulting in very hard, very brittle metal.
  • Tempering: After hardening, the metal is heated to a lower temperature to reduce excessive hardness and relieve internal stress. Tempering makes metals less brittle.

Stages of Heat Treat

Each heat treat process typically occurs in 3 main stages:

  • Heating: Heating the metal or alloy to a specific temperature, ensuring that it heats evenly.
  • Soaking (or Holding): Keeping the metal at temp for a specific period of time.
  • Cooling: Bringing the metal or alloy back to room temperature.

Depending on the application and the desired properties of the metal, these stages may be repeated multiple times and may have specific requirements regarding Ramp Rate (how quickly the metal is brought to temp) or Cooling Rate (how quickly the metal is cooled to room temperature).

Heat Treat Schedules

Each type of metal has specific setpoints and hold times for each heat treat process. However, unlike other kiln fired mediums, ramp rates for heat treat mostly become a factor during cooldown – and largely occur outside of the kiln! As such, most heat treat firing schedules are single setpoint – and only include a single step.

Below is an example of a normalizing schedule for 1095 steel, which relieves internal stress and ensures uniformity, resulting in harder, stronger metals:

A schedule for normalizing 1095 steel in a heat treat oven

  1. AFAP°F/Hr to 1600°F – hold for 15 minutes.
  2. Remove knife or blade from the oven and allow to air-cool.

As you can see, this heat treat schedule is extremely simplistic. You can find additional schedules for quench hardening and tempering 1095 steel in our article Understanding Kiln Firing Schedules for Glass Ceramics, Pottery, and Heat Treat.

Heat Treat Controllers

A heat treating controller is a device that uses your inputs to automatically manage the temperature of your heat treat oven. Heat treat controllers can be fully featured multi-setpoint controllers. But since heat treating schedules are typically single setpoint, a single setpoint controller like TAP&Go by SDS Industries may be a more economical solution.

The TAP&Go is SDS Industries' new, soon-to-be-released single setpoint controller designed specifically for heat treat.
The TAP&Go is SDS Industries’ new, soon-to-be-released single setpoint controller designed specifically for heat treat.

Regardless of whether you choose to go with a multi-setpoint or single setpoint controller, TAP Controllers by SDS Industries offer heat treat artists a ton of benefits, such as:

  • Work more efficiently and increase peace of mind with remote kiln control, kiln temperature monitoring, and real-time push notifications through TAP Kiln Control Mobile.
  • Improve consistency and save time by being able to save and access all of your different firing schedules for different processes and materials – without having to find the schedule you want in your firing notebook.
  • Enjoy intuitive menus and responsive touchscreen controls that make entering the correct schedule faster, easier, and more accurate than other heat treat controllers on the market.
  • Ensure maximum consistency with PID control algorithms and advanced diagnostics and preventative maintenance alerts.

Heat Treat Ovens

In addition to making sure you have the right heat treat controller, you’ll also need a heat treat oven, furnace, or knife kiln that’s capable of firing your medium of choice. When shopping for heat treat ovens, a couple factors to consider include:

  • Chamber Size: You’ll need a heat treat oven that has adequate chamber size to accommodate your medium. For instance, to heat treat blades, you’ll need a long, narrow chamber. But if you’re heat treating silver clay to make jewelry or trinkets, you may only need a small chamber.
  • Power Rating: Heat treat ovens with a higher power rating are typically capable of reaching hotter temperatures, which may be required for some metals or alloys. However, these ovens are more expensive (both for purchase and for operation) and may require installing a dedicated circuit or the installation of a special wall outlet.
  • Maximum Temperature: You’ll need an oven that’s capable of reaching the temperatures required for the metals and alloys you use.
  • Overall Dimensions & Configuration: Your kiln will have to be able to fit into your workspace or studio.
  • Durability, Reliability, & Support: A heat treat oven is a big investment. Manufacturers like Evenheat, Hot Shot Oven & Kiln, and Jen-Ken Kilns are American-made brands that have longstanding reputations for innovation, reliability, and customer service – plus, all of these manufacturers include TAP as a preinstalled option!
The Hot Shot 18K Pro Heat Treat Oven is designed for knife making, with an elongated chamber, patented cool-to-touch technology, and an integrated TAP Controller.
The Hot Shot 18K Pro is designed for knife making, with an elongated chamber, patented cool-to-touch technology, and an integrated TAP Controller.

Heat Treat Supplies

Finally, once you have your heat treat oven and controller, you’ll need supplies! For heat treat artists, the type of metals and allows you need largely depends on application. For example, silver clay is soft and pliable, making it a popular material for making jewelry and small trinkets. For bladesmithing, a wide range of metals and alloys may be used. For example, 1095 steel is easy to machine, easy to sharpen, and can hold a very sharp blade, making it a popular alloy in the knifemaking community. But it’s not stainless, and will be subject to corrosion, which means it won’t be ideal for kitchen cutlery. One of the most reputable suppliers for steel alloys for artists in the heat treat industry is New Jersey Steel Barron – if you’re looking for steel for your next knife making or bladesmithing project, they’re a great place to start!

Explore TAP Heat Treat Controllers by SDS Industries

The TAP and TAP II Controllers by SDS Industries provide users the most advanced, precise, and easy-to-use heat treat oven controllers on the market today. With responsive touchscreen controls, an intuitive graphical UI, and integration with the TAP Kiln Control Mobile app, TAP Kiln Controllers can pair with any relay-controlled kiln or oven.

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:

Shop the most advanced heat treating oven controllers by SDS Industries


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