A Review on the Working Principles of a Vacuum Furnace13 December 2019
As a rule, the inner workings of a vacuum furnace are ordinarily composed of a series of sealed firebox chambers. At the centre of this airtight assemblage, a leakproof furnace shell is hooked to an air purging pump. Heat-inducing elements, perhaps made out of fitted graphite or ceramic, provide all workload thermal energies. Further controlling the heat treatment process, fluid-carrying pipes deliver inert atmospheric gasses and workpiece cooling liquids.
Non-Linear Vacuum Furnace Processing
Conventional heat treatment configurations adhere to a strictly linear workflow. A workpiece goes into a furnace, a flame or induction coil hardens the metal component, then the quenching stage is carried out in a water or oil-filled tank. Step after step, the heating and cooling operations proceed. In altering the procedural nature of this technique, heat treatment engineers gain more control, then more predictable results. In vacuum furnaces, the subject of this article, a non-linear approach beneficially amends that familiar heat treatment sequence. Using a fast-cycling air purging pump, the atmosphere in the sealed furnace is vacated. Heat is applied via a resistive charge through graphite or ceramic coils. The electric charge is finitely controllable, and the convection-free inner chamber lacks contaminants. Better yet, there are no airborne convection currents to subvert the way the thermal energies spread.
An All-In-One Heat Treatment Solution
Of great benefit here, every process variable is controllable. If a cooling medium is required to suddenly drop the workpiece transformative temperature in the furnace, a cooling stream of inert argon can be pumped into the airtight chamber. If a partial pressure is routed into the furnace to control the chromium vaporization effect, as experienced on chromium-steel surfaces, then another inert gas is channelled inside. Workload outgassing, vacuum carburizing, annealing and tempering work, vacuum quenching, all of these services can be performed inside a vacuum furnace. At process end, as parts emerge from the airtight firebox, they satisfy a client’s dimensional constraints and don’t exhibit any discolouration or scaling.
Fundamentally, vacuum furnaces are all-in-one equipment assemblies with several process-balancing stages incorporated. There’s the sealed shell, which utilizes a batch or single-workpiece handling mechanism. Outside, layered in several jackets of duplex hardened and welded metal, graphite and metal-ceramic electrical elements provide the heat. Water-cooled tubes and heat evacuating fans quickly displace excess thermal energies. All conventional hardening and metal-transformative services are available inside the furnace, with a quenching station completing the equipment build. For that latter service, oil or gas can be used to achieve a full quench. Remarkably, there’s also a cooling feature incorporated, as facilitated by a stream of furnace-filling inert gas.
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