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Bottom Drop Furnaces meeting AMS 2750E specifications

Heat treatment of materials is performed to change or improve mechanical properties. The heat treat process for aluminum is called "precipitation hardening or solution heat treatment" mostly accomplished in a drop bottom furnace with integrated quench tanks. When heating alloys above a certain temperature, it goes into a "solid solution". When held at this temperature long enough, all of the alloys will have gone into solution, hence "solution heat treatment". To preserve this state, the material needs to be quenched within seconds in a drop bottom furnace. Process specifications such as AMS 2750E or NADCAP specify the pyrometric requirements for the furnace. Material specifications such as AMS 2770, AMS 2771, BAC 5621, Milspec 6088 specify for each material the heat treatment process such as soak temperature, drop times and quench temperature. The solution heat treat process is followed by a precipitation hardening process done in separate coolers or ovens.

Bottom drop furnaces can be heated by electricity or fired by fuel gas. If the aluminum heat treat specification allow direct fuel gas firing, this technology has an economic advantage. If material specification do not allow products of combustion, then electric or indirect fuel gas fired furnaces are the choice. Keith company has built class 1 furnaces according to AMS 2750E process specifications using all these technologies. To insure best temperature uniformity over a long period of time, we often choose downdraft designs for gas fired bottom drop furnaces for solution heat treatment processes. Electric heated kilns are often built with updraft air circulation if the load needs to be shielded from direct heating radiation.

Quick quench drop bottom furnaces are the industry standard for solution heat treating of aluminum and magnesium alloys. Depending on material, the quench solution must be less than 90 degrees F or above 150 degrees F. Keith Company builds integrated systems with quench tanks (electric or gas heated, cooled or both) and subsequent rinsing. 

Codes, process and material specifications:  
AMS 2750E Covers pyrometric requirements for thermal processing equipment used for heat treatment. It covers temperature sensors, instrumentation, thermal processing equipment, system accuracy tests and temperature uniformity surveys.
BAC 5621 Establishes equipment classifications and instrumentation types for processes requiring controlled temperatures. (similar to AMS 2750E) Boeing process specification title: “temperature control for processing materials”
RPS953 Rolls Royce specifications for “laboratory control procedure for heating furnaces and Associated equipment and the thermal processing of materials”. Equipment shall meet AMS 2750E Class 2 for temperatures <1380degF
NADCAP AS7102 This aerospace standard (AS) establishes the requirements for heat treating accreditation by the National Aerospace and Defense Contractors Accreditation Program (NADCAP)
Specifications for materials:
AMS 4439G This specification covers magnesium alloy in the form of castings
AMS 2759E Establishes general requirements for heat treating of steel parts
MS 2759/11 Establishes general requirements for thermal stress relief treatments of steel parts.
  • Carbon and low alloy steels
  • Tool steels
  • Precipitation hardening, corrosion-resistant and maraging steel
  • Austenitic corrosion-resistant steels
  • Martensitic corrosion-resistant steels
AMS 2770J Heat treatment of wrought aluminum alloys parts
AMS 2771E Heat treatment of aluminum alloy castings
AMS 2772F Heat treatment of aluminum alloys raw materials


Quick Quench Drop Bottom Furnaces

For over 20 years, Bottom Drop furnaces (Drop Bottom Furnaces) have been the industry standard to solution heat-treat of aluminum.

General Capabilities:

  • Meets above aluminum heat treat specs
  • Safe and simple operation
  • 60 minute recovery and precise temperature control
  • Automatic quenching of parts 7 second or better
  • Space-saving design, requires minimal floor space
  • Heavy duty construction for long service life

Special Options

  • Higher temperature operation for ferrous metal heat-treating
  • Programmable temperature controls
  • Data acquisition and integration with remote monitoring
  • Customized parts, racks and hoists
  • Gas or electric heating systems
  • Custom sizes are available

Periodic redesigns assure these furnaces are always cost effective and efficient and will meet the most rigorous heat-treating specifications in effect. To best suit a shop layout, the quench tank may roll beneath the door or from side to side. Moreover, a single quench may service two or more furnaces

Contact Keith Company if you need any additional details regarding our furnaces.