Using the Sentry Diamond Block System

Diamond Blocks are removable furnace linings, designed as an easy-to-use, highly effective method for ensuring the most reliable tool hardening. They are primarily made for use in our Model AY furnaces, but may also be adaptable for some other furnaces.  Contact the Sentry Company for details on how to adapt your furnace to the Diamond Block atmosphere.

While controlling atmospheres may sound complex, you'll actually appreciate the simplicity of working with the Diamond Block method. Once the Diamond Block and tray are installed, the furnace is automatically maintained at the proper hardening temperature throughout the process.

After using the tongs and shovel to load small tools onto the tray, the tools are then heated to the furnace temperature and held at temperature for a predetermined soaking time. Tools and tray are then transferred to the quench. The same procedure is followed for large tools, except they are handled with special tongs, hooks or fixtures. For production applications of small tools, two Diamond Blocks can be used in the same muffle.

Heat from cold with no damage

Tools heated from cold in the Diamond Block atmosphere will heat at a rate slow enough to avoid damage in all but extreme design cases. Years of experience with all types of tool hardening applications have proven that preheating is not necessary to obtain top quality results. By avoiding preheating, you can often eliminate the need for an additional atmosphere furnace, decrease heat processing time and even decrease exposure to oxidation.

Diamond Blocks are available in multiple heights. With proper care, the average life of a block is about 40 hours for small and up to 60 hours for large. They can be used continually or for short intervals until they are consumed to an extent that they lack the physical size required to surround the work with a protective atmosphere.

Diamond Block accessories

Diamond Blocks are normally used with an open-ended, high heat conducting muffle to protect the outside of the block while allowing internal atmosphere generation. Other accessories include:

  • Refractory Trays -- to isolate tools from contact with Diamond Blocks and to carry small tools to the quench
  • Baffles -- to close the front of the muffle and shut out excessive air, extending block life
  • Cover Plates -- to protect the top of the block when it does not fill the muffle chamber
  • Tongs -- to load and handle trays
  • Shovels -- to load and handle trays

America’s oldest steel heat treating furnace maker.