New energy efficient metallic hot zones for vacuum furnaces from Plansee

September 6, 2012

September 6, 2012

There are many benefits in the use of metallic hot zones in vacuum furnaces, such as short cycle times, excellent vacuum conditions and uniform temperature distribution. Historically, the only drawback has been the level of power consumption. Plansee SE, Reutte, Austria, reports that with the use of its ENERZONE® series of products, it can now provide genuine lightweight hot zones that reduce energy requirements by up to 25%.

Hot zones form the heart of every vacuum furnace. Heating elements ensure the necessary temperature, charge carriers position the material in the furnace and the shield packs minimize the amount of heat that escapes from the furnace chamber.


In a metallic hot zone, the shielding consists of molybdenum, tungsten or stainless steel

In 80% of all vacuum furnaces, the insulation consists of solid graphite plates or graphite felt. Although this design saves energy, the employed material is a poor heat absorber and takes a long time to cool down. Furthermore, the presence of carbon in the furnace is problematic when sensitive processes and materials are involved.

In a metallic hot zone, the shielding consists of molybdenum, tungsten or stainless steel. Despite the higher cost of procurement, fully metallic hot zones are gaining in popularity among furnace-makers and operators. The following properties argue in favour of the use of fully metallic hot zones:

  • long service lives
  • rapid heating and cooling
  • optimum process purity thanks to graphite-free materials
  • short pumping times
  • excellent vacuum conditions
  • uniform heat distribution

While in the 1960s, such constructions still had a reputation for high energy consumption, modern designs of fully metallic hot zones are often real energy savers.

As an expert in the field of molybdenum and tungsten, Plansee has developed a particularly energy-efficient form of heating. ENERZONE® is a series of fully metallic hot zones that consume approximately a quarter less energy than conventional designs.

Cutting energy needs by a quarter

Molybdenum charge carriers are generally used in conventional metal hot zones for vacuum furnaces. In most cases, these consist of a number of heavy rails that are supported on the furnace floor by massive caps and bolts. In the ENERZONE®, Plansee now uses particularly lightweight bearing rails made from molybdenum alloys which are bent into a U-shape. These lie directly on the bolts and simply have to be cross-pinned, caps are no longer needed.

There is a welcome side effect to this in that the new charge carriers are less susceptible to distortion and are much easier to replace than their heavyweight counterparts.


The new hearth construction

To save even more weight, Plansee has replaced pure molybdenum with the molybdenum alloys ML and TZM. Thanks to their high recrystallization temperature and creep resistance, the more lightweight shielding panels and charge carriers made from ML and TZM are rigid and non-deformable.

Stainless steel elements have also been replaced with molybdenum, as a single layer of molybdenum has the same shielding effect as five layers of steel.

In conventional shielding solutions, the spacers between the panels are arranged longitudinally. To prevent the deforming of the material, this design requires the use of particularly thick shielding panels. They ensure that the hot zone is non-deformable and guarantee that the cylindrical geometry is maintained. Circumferential spacers have now been developed and when combined with an external stainless steel support frame, these spacers guarantee adequate stability even when thinner panels are used.

The ENERZONE® system is equipped with special corner shielding elements to ensure that no heat escapes at the critical gaps between the side and ceiling or side and floor. Additional shielding discs also make sure that no energy is lost at the electrical ducts.

Plansee can also supply its ENERZONE® hot zones in a completely new hybrid design. Conventional shielding panels are supplemented by an insulating aluminum oxide paper. The operation of the unit is not affected by the aluminum paper. Heating and cooling speeds, cycle times and purity constraints are all unimpaired. In contrast, energy consumption is cut by 10-15%.

Key advantages of ENERZONE®  

ENERZONE® not only consumes less energy but also provides even better performance along the way. The improved hot zone heats up faster, cools down more quickly and therefore guarantees shorter cycle times than its heavyweight colleagues.

Using the example of a fully metallic hot zone measuring 600 mm x 600 mm x 900 mm, compared to a standard variant, an energy-efficient lightweight construction brings the following advantages:

  • 15-20% weight reduction
  • 20 % reduction in heating times in empty furnace
  • 15 kW less heat loss
  • 25-30 kWh reduction in energy consumption when heating and cooling the furnace
  • 15 % reduction in cooling times

Plansee states that this all-rounder is not the cheapest hot zone on the market, however its long service life and energy efficiency make it a good long-term investment.

Contact [email protected]     


September 6, 2012

In the latest issue of PIM International…

Download PDF

Extensive MIM, CIM industry and sinter-based AM industry news, plus the following exclusive deep-dive articles and reports:

  • Visottica Group: Integrated workflows and the value of Metal Injection Moulding in eyewear and beyond
  • In MIM’s post-smartphone era, where is China’s Metal Injection Moulding industry going?
  • Ceramic AM at scale: The story of how Steinbach AG scaled production to 12,000 parts a year for Da Vinci Surgical Systems
  • MIM F75 (Co-Cr-Mo) for high-volume production: The impact of sintering conditions on microstructure and properties
  • World PM2022: Research into the Binder Jetting of aluminium, Ni-free stainless steel, hardmetals and metallic glass

The latest news from the MIM, CIM and sinter-based AM industries

Don't miss any new issue of PIM International, and stay up to date with the latest industry news. Sign up to our fortnightly newsletter.

Sign up

Join our community

Discover our magazine archive…

The free-to-access PIM International magazine archive offers unparalleled insight into the world of MIM, CIM and sinter-based AM from a commercial and technological perspective through:

  • Reports on visits to leading part manufacturers and industry suppliers
  • Articles on technology and application trends
  • Information on materials developments
  • Reviews of key technical presentations from the international conference circuit
  • International industry news

All past issues are available to download as free PDFs or view in your browser.


Browse the archive


Looking for suppliers of materials, production equipment and finished MIM, CIM or sinter-based AM parts?

Discover suppliers of these and more in our advertisers’ index and buyer’s guide, available in the back of PIM International.

  • Metal powders
  • MIM, CIM & AM parts producers
  • Binders & feedstocks
  • Feedstock mixers
  • Furnaces & furnace supplies
  • Atmospheres & gas generation
  • HIP systems & services
  • Injection moulding machines
  • AM technology
  • Debinding systems
Download PDF
Share via
Copy link
Powered by Social Snap