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Benchtop Laboratory Muffle Furnace


Whether you need your floor mounted (stand alone) or Benchtop Laboratory Muffle Furnace for Heat Treatment & Pyrolysis, the table top “F” series are small furnaces for heat treating, laboratory and jewellery applications at maximum temperature of 2,300°F. These furnaces offer a rugged industrial construction with a top quality coating.

canada manufacturer


  • Sturdy Construction
  • Small Compact Design to Fit in Labs and Smaller Shops
  • Reliable
  • Easy to maintain and service
  • Incomparable service


  • General Heat Treatment
  • Research & Laboratory Work
  • Pyrolysis Process
  • Investment Casting
  • Jewellery

High Performance

Our benchtop muffle furnaces integrate quality components and superior workmanship, for maximum performance in a variety of industrial or laboratory applications, at temperatures as high as 2300°F (1260°C).

Our Heavy duty construction creates a rugged furnace design which incorporates quality hardware to a heavy gauge casing, for increased durability in all type of processes. These tabletop units are available in either a green enamel finish or oxidation resistant stainless steel.



Long Service Life & Ease of Maintenance

Accurate Temperature Control Our tabletop furnaces are equipped with state of the art ramp to set point digital microprocessor temperature controller.

The specially designed grooved bricks optimize heat transfer and fully support the FeCrAl heating elements for maximum life expectancy. The “open coil heating elements” are easily accessible for maintenance.

Quality Insulation

The highest quality low-density refractory bricks used in the construction of its chamber assure maximum insulation while minimizing heating or cooling cycles.

Superior Heat Distribution

A special attention is given to the distribution of the heating elements to assure optimal temperature uniformity throughout the furnace.

Greater Versatility

A wide choice of options gives our units the flexibility to suit a variety of commercial, industrial and laboratory heat treating applications.


Muffle Furnace Characteristicselectric melting furnace (3)

  • Cabinet design & construction choice of Enamel coated 16 gauge steel or (304) stainless steel
  • Horizontal opening door heavily hinged door With a 180° opening
  • Insulation 4½”/11cm pre-grooved refractory bricks (With the exception of the f50, which is 2 ½”)
  • Temperature controller microprocessor temperature controller, with auto tuning pid parameter offering ramp/soak program capability
  • Heating elements low watt density fecral heating elements
  • Furnace chamber hearth plate the furnace comes standard with a cordiorite hearth plate.

Furnace Options

  • Vertical opening door Counterbalanced guillotine lifting door with “Zero weight positioning”
  • Furnace floor stand Heavy-duty furnace stand
  • Ni-cr heating elements Special heating elements used in corrosive environment
  • Programmable controller 2 programs with 8 segments ramp/soak
  • Solid state relay (ssr) For increase temperature accuracy and silent operation
  • Adjustable exhaust vent Slide gate located on top of furnace to vent corrosive vapors, also comes with a peephole in door
  • High limit controller Automatically shutdown heating elements when maximum temperature is exceeded
  • Door safety switch Automatic Shut off heating elements when door is opened
  • 3 phase 208-240v Available for the F300/F400
  • Heating elements in door Offers greater heat distribution


The temperature curve presented in these graphs is based on testing performed on furnaces without chimneys, for furnaces coming with chimney option, temperature ramp-up time will increase by 15%.


Standard Laboratory Muffle Furnace Modelelectric melting furnace (4)


  • PRODUCT FEATURES: all models are made of 14 ga steel (green enamel finish).
  • QUALITY INSULATION: low-density refractory bricks, 4½” thick 2,300°F rated.
  • LONG SERVICE LIFE & EASE OF MAINTENANCE grooved bricks optimize heat transfer and make maintenance much easier. FeCrAl heating elements are located into the groove of the bricks (but not moulded into the brick) and can be replaced without taking any bricks out. By being in the brick groove, radiant heat from the element is lowered, which offers a better temperature uniformity. The elements are protected from any contact that can occur during the furnace loading. This kind of design also allows the operator to replace just a few bricks when required.
  • ACCURATE TEMPERATURE CONTROL: standard controller used is Watlow model PM6 (1/16 DIN) (Single set point controller). Base unit for simple applications. Just input you’re work temperature and let the Watlow EZ-Zone PM6 do its job with its precise PID control feedback loop. This unit also includes built in high limit (HL) overheat protection. HL is easy to program and reset.
  • HORIZONTAL OPENING DOOR: heavily hinged door with a 180° opening. We offer a rugged industrial door design.
  • FURNACE CHAMBER HEARTH PLATE: all furnaces come with a Cordierite hearth plate.

Model Power Output

  • “HP” MODELS: ramp up time is faster than standard models (see brochure for time Vs. Temperature curves). The “HP” version is especially appropriate when ordering the slide gate chimney option described below.


Controls & Instruments

  • PROGRAMMABLE TEMPERATURE CONTROLLER (4P/10S): Basically the same unit as the single set point unit but with programmable Capabilities. You have four (4) programs with 10 segments per program for a total of 40 segments. You can program your ramp-ups, soak and ramp down time temperature. This system permits you to have defined programs linked to your processes and treatment necessities. This unit also includes built in high limit (HL) overheat protection. HL is easy to program and reset.
  • USB COMMUNICATION: This add-on USB port links up to your programmable temperature controller. By using you’re the freeware provided by Watlow and a laptop permits you to quickly modify or set recipes and change desired parameters.
  • PROCESS TIMER: This unit paired with standard single set point temperature controller makes the easiest way to use our furnace when dealing with simple process requirements. Just set quantity and desired units, countdown will start when set temperature is obtained giving you consistent soak times. After soak time is finished unit shuts down and awaits next command from operator.
  • 7-DAY TIMER: This option permits you to have the furnaces start automatically at defined time. Perfect to pre-heat furnace.
  • SSR: This electronic part increases control accuracy in soaking and is much quieter than the mechanical contactors. Makes for a more sturdy electrical system because you don’t cycle contactor.
  • PAPER CHART RECORDER: Info to come

Furnace Door

  • VERTICAL OPENING DOOR: counter weighted vertical opening door offered on all models. Makes loading parts in furnace easier and safer. Both hands can be used to handle parts.
  • HEATING ELEMENTS IN DOOR: Elements in the door are available for F300 and F400 models only. Customers will need this option usually for burn-off applications or to prevent condensation on the door. Can also help in lower temperature uniformity (around 1100°F).
  • DOOR SAFETY SWITCH: automatically shuts off the power to the elements as door is opened and restores it as door is closed. Prevent accidental electrical socks if operator touches live element with metal tongs. This option is also provided with horizontal hinged door with elements in door to prevent accidental scorching.

Other Options

  • ADJUSTABLE EXHAUST VENT: it’s a slide gate on top of the furnace in case corrosive vapours have to be vented. When this option is selected, a peephole is included.
  • NiCr HEATING ELEMENTS: at no extra charge. These elements are usually used for corrosive applications, in Nitrogen atmospheres and for Dental Lab applications.
  • CORRUGATED HEARTH PLATE: This hearth plate is corrugated permitting you to complete lost wax process thus letting melted wax to be funnelled in the bottom of the furnace.
  • SS 304 CASING: This option especially suited for dental laboratories and corrosive applications.
  • FURNACE FLOOR STAND: we offer a heavy-duty floor stand. Can be ordered at specific high.
  • INERT ATMOSPHERE (OPTION): This option allows you to generate a protective atmosphere in your oven at high temperature. Such type of atmosphere minimizes oxidation of the steel pieces. This option includes the following items:
    • N2 gas panel
    • Pressure regulator – 30ZAA201595680100000
    º flow meter calibrated for nitrogen (N2) with integrated flow control – MAX 9.5 scfm (N2)

Laboratory Muffle Furnaces Specifications


Other Gases


  • Valves & Piping necessary; mounting oven
  • Ports: Input / Output

Benchtop Muffle Furnace Maintenance

Lets take a minute to talk about some of the parts which need to be maintained in your furnace. First, it’s the heating elements. We use a heavy-gauge wire with a low lob loading for a longer life. The wires are supported in removable plates. When a wire does burn out, the entire assembly with the wire slides out, a new plate with the wire slides back in. You do not have to touch or remove the insulation when replacing one of our heating elements.

Next, is the hard plate. The floors in our chambers are aligned with a dense plate which we call the hard plate. It protects the softer insulating fire brick underneath and supports the workloading. If the plate cracks, it can be removed, slides out through the front, the new plates slides right back in. Next, is the insulation. The insulation in our furnaces has always consisted of insulating firebrick. Our models is dry fit; it’s wedged in place which is better for thermal contraction and expansion as the furnace heats and cools. The bricks can be replaced individually. Mortaring is neither necessary or recommended.

Also, just to dispel concerns about the white insulating material, please note that insulating fire brick does not and has never contained asbestos. Finally and perhaps most important is your thermal couple. The thermal couple is the probe which senses the chamber heat, sends a signal to the temperature controller telling the furnace to cycle on and off. We recommend replacing the thermal couple every 6 months to a year to maintain accurate control and help your heating elements operate more efficiently and last longer.

We stocks all of these parts I talked about and can be generally shipped in one to two days. Installation is easy with minimum downtime and will help keep your furnace in operation for many years.

Zinc Base Scrap Situation

About 1935, the die cast scrap situation became increasingly acute for scrap dealers. This scrap was accumulating from dismantling automobiles and household appliances which contained die cast parts. Efforts to find an outlet for this type of scrap were intensified.

The International Smelting and Refining Co. began to study the possibilities of a commercial process for the recovery of values from die cast scrap. At that time most of the die cast metal

muffle furnaces distribution of products produced by melting die cast scrap

reclaimed was melted down in small kettles of from one to five tons capacity, the iron inserts being removed by skimming. The dross was skimmed off and disposed of as a zinc dross. The drossed metal was cast into slabs and was given the trade name “die cast slabs.”

American Process Experiments

A method considered for the production of zinc oxide from die cast scrap was an adaption of the standard American Process of zinc oxide manufacture. Thus some die cast scrap was mixed with oxidized zinc materials and charged to Wetherill grates. The zinc oxidized to zinc oxide but, while the aluminum and copper largely remained in the residue, the color of the zinc oxide produced was impaired by copper contamination. As the proportion of die cast scrap was increased, liquation took place; that is, the metal trickled through the charge then solidified in the openings of the grates.

Distillation in Belgian Retorts

It was then decided that, rather than attempt to use scrap die cast metal or scrap zinc for the production of zinc oxide, it would be advisable to redistill the die cast slab metal in a Belgian retort furnace.


muffle furnaces results of experiments

All of the zinc produced contained varying amounts of copper, tin and aluminum in sufficient quantities to make it unmarketable. The metals produced, however, were found satisfactory for use in making zinc oxide provided the quantities used were limited to a small fraction of the total metal charged.

Experimental Muffle Furnaces

Initial investigation began with the use of a laboratory muffle furnace. This was a rectangular muffle constructed of carborundum tile cemented at the joints. Attempts were made to hold the

muffle furnaces experiments

level of liquid metal at not over 2 in. in depth. Even with this small depth of metal, serious leakage occurred.

At about the same time, a pilot unit was constructed which provided means for heating the metal bath from above and below. Heat was introduced below the bath by means of a gas flame within a refractory tunnel. This furnace leaked badly after every effort had been made to make it tight enough to contain molten die cast metal.

Shortly afterward a larger experimental unit 5 ft long with a carborundum arch 3 ft wide was built and tested. This unit is illustrated in Fig 1 which shows cross-sectional and longitudinal-sectional views of the furnace.

This pilot unit established the fact that zinc could be vaporized, practically, by means of a large shallow bath and that such vaporizing is less violent and more easily controlled than in the more restricted areas of small retorts.

muffle furnaces improved

muffle furnaces results obtained


Commercial Muffle Furnace

The first commercial unit, producing 5 to 7 tons of zinc oxide per day, was equipped with a vertical riser. This brick riser received zinc vapors from the vaporizing chamber and provided for contact of zinc vapor and air to produce zinc oxide. The zinc oxide was conveyed through a steel duct into a baghouse.

The melting unit now in use consists of a sloping hearth inclined toward a central point, which discharges into a trough to the vaporizing unit. With controlled melting unit temperatures, the oxidation of zinc is maintained at a minimum. The results obtained with this melting unit are shown in Table 3.

Muffle Furnace

Assembly drawing Fig 2 and sectional views (Fig 4, 5 and 6) along planes as indicated in the plan as shown in Fig 3 may be helpful in a more detailed study of the furnace design. The letters apply to Fig 1 to 6 inclusive.
A—Melting Unit
B—Combustion Chamber
C—Vaporizing Chamber


muffle furnaces plan

and provides for inspection of the bottom of the furnace pan.

Operating Procedure

The furnace is preheated with a gas flame, gradually raising the temperature to 1600°F. The oil burners are then started and the temperature of the combustion chamber elevated to 2400°F. Preheating requires about ten days.
Charging of metal is started at 2400°F and the production of zinc vapor begins almost at once. Charging is continued at as rapid a rate as possible until a depth of 5½ in. of metal has accumulated in the vaporizing unit.

Conditions which determine the end of the cycle are: The rate of zinc vapor production for economical operation of the furnace, a low zinc content in the residue metal, as tapped from the furnace, and a lead content low enough to meet the requirements of the particular zinc oxide being produced.

The cycle is ended by tapping residue metal from the vaporizing chamber, emptying it as far as possible. This metal is drained through a tap, not shown, into cast iron molds. The temperature of the furnace is held constant while it is being drained.

muffle furnaces section

Production of Zinc

Of the various types of risers tried at East Chicago, several of them indicated the possibility that zinc metal could readily be produced from the muffle furnace. The relative position of the riser with respect to the molten bath of metal in the vaporizing unit seemed ideal to exclude or at least reduce contamination of the zinc metal by copper, aluminum and tin.


muffle furnaces zinc oxide

Zinc Produced from Secondary Metal

With this type of riser on the furnace, the distillation of zinc from secondary metals became a commercial possibility because the zinc produced in test runs was Prime Western, Brass Special or Intermediate grade. The results of such an experimental run are given in Table 5. In this run die cast slabs and die cast scrap were used as the source of zinc.


muffle furnaces redistillation


development of muffle furnaces for the production of zinc oxide and zinc at east chicago indiana


This particular model has a chamber size of 12 inches high, 14 inches wide and 18 inches in length. These are versatile models and offer inexpensive means of bringing your heat treating in-house; ideal for most tool room applications because they combine a high temperature hardening chamber stacked above a tempering or draw oven.

Heat treating most of your common tool steels involves a 3-step process of first hardening the steel at high temperature in the furnace chamber under radiant heat. Typically, this is done in the 16-1900 degree temperature range. After the hardening, the parts will be removed and they’re quenched in either air, oil or water. After the quench cycle, the parts are loaded into the oven chamber to remove the hardness out of the steel at low temperature under convection heat. The oven is equipped with a fan assembly to recirculate the air which is critical for achieving uniform heat at low temperatures.

Our models feature heavy gauge coil wound heating elements, mounted in removable panels on the side walls. The chambers are lined with a hot faced fire brick layer backed up with a mineral wall for great heat storage. The floor of the chamber has a hard plank to support the work load and protect the floor insulation. The doors on the furnace models are a horizontal swing type for quick operation. A micro switch shuts off the heating elements when the door is open. Both chambers operate independently using digital temperature controls. The furnaces are completely wired and assembled and test fired and we ship directly to your plant.

These models are compact, easy to install and operate. Bringing your heat treating in-house will save you money by eliminating the live charges from your commercial heat treater, will save on your turnaround time and help maintain better control on your production schedule.

Today we want to talk about economy box furnaces. These models offer an inexpensive means of bringing your heat-treating requirements in-house. The models are rated for operation up 2200 degrees Fahrenheit under air, and ideal for hardening small parts and processing light loads. When combined with foil wrapping of tool steels, a scale 3 finish can be achieved. Most parts will have a dull gray finish with hardness to the surface.

The models feature heavy-gauge coil wound heating elements with a low Watt loading for longer element life. The elements are mounted in removable holders on both side walls. The chamber is lined with a combination of a fire brick hot face, with a backup layer of mineral wall for better heat storage and low outside shell temperature. A hearth plate on the floor of the chamber supports the workload and protects the floor insulation. A horizontal swing door with a cam latch provides a tight, brick to brick seal and a microswitch automatically shuts off all power to the heating elements when the door is open.

All models are standard equipped with a Honeywell digital temperature controller. The furnaces are completely wired, assembled and shipped directly to your plant, ready for connection to your main power supply. These particular models are also equipped with a ten recorder and a fusible disconnect switch. Additional accessories are available, including high-limit safety systems, programmers, timers and various door arrangements. These models are compact, easy to install and operate. Bringing your heat treating in-house will save you money by eliminating minimum life charges from your commercial heat treater, save on turnaround time, help maintain better control of your production schedule and improve the quality of your product.

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