Things to consider when purchasing an Industrial Oven or Furnace
This blog explains the importance of hardness, heat treating, stress, and design that must be considered when purchasing an industrial oven.
- Hardness requirements describe which hardness tests (Rockwell, Brinell, etc.) and range are required.
- For tool steels, a three-point hardness range is desirable, such as “Rockwell C 60-62.” Five to six points below Rockwell C 50 should be allowed in hardness.
- Inspection locations and critical areas in which hardness tests are not allowed should be noted.
- Stock removal for preparing surfaces for hardness checks should be noted, if critical.
- Parts requiring heat treating to a specified tensile strength should be accompanied by tensile test specimens. Conversion from tensile strength to hardness is not reliable and should be done only with the customer’s written approval.
Related Information for Heat Treating
- Guarantee times, temperatures and atmospheres supported with repeatable performance. Leading-edge automated heat treating eliminates the guesswork involved in manually operated heat treating equipment.
- Understand the processing steps and soak times required, and the related delivery schedules for the particular metal processing you will be doing.
Know the Relationship Between Part Design and Heat Treating
Sources of stress come from 3 main points in the heat treating process:
- Stress created at the mill when the material was cold formed
- Stresses resulting from the mere application or removal of heat,
- Stresses resulting from changes in the crystalline structures of the steel.
Simple cooling causes a metal part to shrink, but the structural change which causes hardness also results in an increase in volume. As long as these changes occur uniformly throughout a piece, the resulting stress is minor. If the shape of a piece is such that a thin area cools faster and becomes hard while a thicker area is still cooling and becoming hard, the resulting stress can be great enough cause fissures or cracks.