Materials Research Furnaces, Inc

 

    

 

 MRF technical info.

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Pic.
Tunsten mesh heating element

Furnace Chambers
Heaters & heat shielding
Vacuum systems
Gas systems
Control systems

Hot hamber
1.5"x1" tungsten hot zone


Furnace Chambers

All of our Furnace chambers are fabricated from stainless steel with a fine exterior and interior finish. This not only gives a clean and appealing appearance that will last through the years, it promotes good vacuum chamber practice by eliminating excess surface area that causes "virtual" leaks.
Our high temperature chambers are all double walled with water passages in between walls, thus eliminating any exterior temperatures above 150F (55C) while internal temperatures can be as high as 3000C. The furnace chambers are designed to take unusually high water pressures or extreme interior chamber pressures. Our chambers also provide ample ports and feed-throughs typically consisting of the following:

Furnace chamber
  • Vacuum ports
  • Gas ports
  • Sight windows
  • Thermocouple ports
  • Power feedthroughs
  • Vacuum sensor ports
  • Physical test ports
  • Loading door
  • Water feed-throughs

Our chambers are designed so loading and unloading your product is no more difficult than it has to be. In most cases, all shields and parts will clear the loading area with the door so no disassembly is required in between runs. For our productions furnaces, we can even supply you with a separate loading chamber and/or an automated loading and transfer system. Multiple chamber furnaces are also available for our batch furnaces to obtain high throughput, with one a centralized control system.
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Heaters & heat shielding

MRF, Inc. builds resistive heaters with excellent uniformity designed in-house and built by our refractory department. We also supply induction heaters. Our unique heat zone designs can guarantee a superior uniformity over long distances. Our range of metallic mesh-heaters adds to this excellent uniformity, high temperature ramp-up speeds, high watt-densities, and an exceptionally long useful life with no performance degradation over time.
Depending on the temperature range and the working environment, we will select the material for the heater and chamber insulation for maximum performance, longevity and compatibility.

Our most common heater materials include:
  • Graphite
  • Molybdenum
  • Tantalum
  • Tungsten
  • NiCr
  • Moly-Dicilicide

Mesh element

 Common insulation materials (shields):
  1. Graphite
  2. Molybdenum
  3. Tantalum
  4. Tungsten
  5. NiCr
  6. Ceramics
  7. Stainless steel
Power is brought to the heater elements by means of water cooled feed-throughs. Water cooling these conductors offers the advantage of substantially reducing the conductor sizes (power cables & power feed-throughs) and allows for greater possible distances between the hot chamber and the power supply enclosure. Most of our high temperature furnaces apply this technique as the heater designs require low voltage - high current power supplies.
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Vacuum systems

MRF, Inc. supplies its furnaces with the necessary vacuum pumps to obtain the specified pressures. Our vacuum range stretches all the way down to the 10-11 Torr range for ultra low vacuum requirements. For processes requiring ultra clean conditions, we also build oil-less "dry" vacuum systems, where no pumping oil vapors can ever make their way into the vacuum chamber and contaminate your work. For our pumping systems we intergrate Leybold, Varian and Edwards pumps and components. Other brands available on request.
Following is a list of our vacuum system options in function of the required vacuum levels.

Diffusion pumping system

6" Diffusion pumping system

 

1. Evacuation kit : ATM (760 Torr) to 1x10-2 torr

This basic vacuum kit comes with a mechanical vacuum pump that can reach ultimate pressures in the 10-3 torr range. It includes all the vacuum lines, vacuum valves, vacuum sensors and instruments needed for monitoring and operating the vacuum system. In systems where vacuum pump oil vapors can contaminate your work, (oil vapors always manage to "back-stream" into the vacuum chamber at lower pressures) we can supply a dry-pump where no pumping parts will ever see contact with the pumping oil and thus eliminate pumping oil vapors from back-streaming to the chamber.
In processes where high out-gassing loads are expected, we can also add a booster (acting much as a turbo on a car) to speed up pump down times and handle larger gas loads.

2. Diffusion pumping system: ATM to 10-6 torr

Our diffusion pumping systems come in sizes from 1" to 35" and can pump up to 50,000 l/sec. Our diffusion pumping systems come standard with a cold trap (baffle). This cold trap comes with a no-maintenance, ozone friendly refrigeration unit to cool the baffle. Though the cold trap reduces the pumping speed, it offers the advantage of substantially reducing backstreaming of diffusion pump oil vapors in combination with lower ultimate pumping pressures.
Our diffusion pumping systems also come with a sized mechanical pump, all the necessary vacuum sensors, vacuum lines and vacuum controls to seamlessly operate this system. Again, all our pumping systems can be built with the components of your choice.

3. Turbo-molecular pumping systems: ATM to 10-8 torr

Our turbo systems are often found in applications where previously diffusion pumping systems were used and where cleanliness has become an issue. The turbo pumps offer the advantage of being oil-less, having high compression ratios with lower obtainable operating pressures, requiring no maintenance and taking up less space. Turbo pumps can also be operated in a horizontal orientation often eliminating large and expensive pumping elbows.
Our turbo pumping systems, as well as any of our other pumping systems, are equipped with a roughing pump, all vacuum lines, vacuum sensors and vacuum controls necessary for operation. Also available is our oil-free turbo-pumping system where the regular mechanical pump is replaced with a dry-pump for ultra clean applications.

4. Ion & Cryogenic pumping systems :ATM to 10-11

For ultra high vacuum applications such as material research and analytical applications, the ion pumping system is ideal. Its components are simple yet effective for pumping molecules that can be ionized. Regenerative Cryogenic pumps are available as well operating on the principle of condensing molecules onto a cold surface.
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Gas systems

MRF builds furnace zones for use in many atmospheres, which can often be combined. We supply gas kits built with selected quality components. Dry or wet Hydrogen gas kits for flammable or non flammable mixtures, Argon, Nitrogen, Helium, Air, etc.
MRF can also program your unit to automatically switch over to a different atmosphere at certain temperatures. We can provide you with our material compatibility chart to aid you in determining which atmospheres can be used with which materials at which temperatures.
Our gas systems come completely equipped with all the necessary controls to operate safely and efficiently. We can control gas flow, provide automatic purges and burn of hydrogen mixtures.
Our chambers will be provided with pressure relief valves, pressure switches, solenoid valves and flow meters and operating controls


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Control systems

All our furnace systems come fully equipped, configured, programmed and tested when it arrives at your plant. We always invite our customers to be present during the testing period so they can witness the results and become familiar with the operation of their furnace. Though the furnace controls can be complex, we strive to simplify the operation and maintenance of our furnaces without sacrificing functionality or flexibility. Besides our complete furnace systems, we also provide control packages for existing equipment. This way you can upgrade your old equipment with an up-to-date automated, easy to operate and reliable control system without the investment associated with new equipment. To operate our furnaces, the following solutions are common:

Control and operate your furnace the way it has been done for years :with push-buttons, indicator lights and switches on an easy to understand graphical panel.

OR

Graphical panel
A touchpanel with PLC control saving space and wiring by eliminating switches and multiple controllers

OR

HMI picture
An industrial PC running an HMI (Human Machine Interface) to automatically control, display and record every detail of your process. Actual control will be done by a PLC so even if your PC fails, your process will continue just the way you want it.

PC Control
MRF,Inc. can build your system with the controllers of your choice, or if you leave it up to us, we offer Honeywell or Eurotherm Temperature controllers, Edwards, Leybold or Varian vacuum instrumentation, Allen Bradley PLC's and WonderwareR HMI Interfaces.
We update existing furnace control systems and retrofit them with up to date controllers, PLC's and PC's for fully customized automatic control and/or data acquisition. After we're through, you'll have an easy to operate, customized yet flexible, fully configured system that will give you repeatable results and trouble-free operation for years to come. We also give you all programming code, configuration and software programs required so you're in full control of your furnace. And for your peace of mind, all our products are Y2K compliant and we are always available for further support.


To supply power to the heating elements, we supply a transformer whose output power is regulated by an SCR. This in turn controls the furnace chamber temperature. We always supply extra power in our transformers to give you plenty of temperature ramp-up speed. Thus rampspeeds of up to 600C/min towards a programmed target temperature are not out of the ordinary.
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