VIM

Vacuum Induction Melting

The Process - Small VIM Furnaces - Configurations - Batch or Semi-continuous - Large VIM Furnaces Configurations - Applications - Reliability- Maintenance, Cleaning and Productivity
Vacuum System Design - Material handling and charging systems - Induction Power Equipment
Vacuum Isolation Valves - Hot Tundish Insertion - Controls

The Process
The Vacuum Induction Melting (VIM) Process, initially small vim furnace
used to meet alloy requirements of specialized industries,
is becoming more and more essential in the production of
high performance materials for many industrial applications.
VIM melted alloys are used in very demanding situations, including Nickel based super alloys for high temperature applications, stainless steels for nuclear applications,
Cobalt based alloy for medical applications, high purity
copper alloys and very clean magnetic alloys for high permeability.

The VIM process involves the melting of metals by means
of electromagnetic induction while under vacuum. Melting
takes place within a furnace consisting of a refractory lining
or crucible inside a water-cooled induction coil. The furnace assembly is completely enclosed by a fabricated steel,
water cooled furnace chamber that is evacuated by a series
of vacuum pumps so that the charge may be melted down,
refined and poured into molds under vacuum or inert gas.

This process permits the refining of metals and alloys that contain elements having a strong affinity
for certain gases such as oxygen. Chemical reaction, dissociation and flotation remove dissolved
and chemically bonded impurities. Melt chemistry can be accurately adjusted thereby producing an
end product that is clean and homogeneous.

Small VIM Furnaces
PV/T have developed a range of VIM furnaces from 2-100 kg (steel) melt capacity for use in small
scale production or research applications. Standard designs are available and PV/T also welcomes
the opportunity to design a specific furnace to meet individual customer requirements and applications.

The design utilises a water-cooled vacuum chamber, providing optimum access for cold charging and servicing in a batch mode of operation. The chamber also houses auxiliary equipment with standard
and optional features provided by PV/T to ensure maximum flexibility and ease of operation.

These features can include:

Bulk charging and fine alloy additions
Sample taking
Immersion thermocouple
Mold turntable/trolley for pouring multiple molds
in a single cycle
Centrifugal casting
Sight glass viewing port(s)
High vacuum pumping system
Optical pyrometer
Bridge breaker

Configurations - Side opening & Top opening designs
Horizontal furnaces with front opening access door or Vertical chamber configurations with a top opening lid can be supplied depending on the application and available floor space.

Batch or Semi-continuous
Using a modular design concept enables this range of batch VIM furnaces to be upgraded to a semi-continuous VIM or vacuum precision casting furnace with the addition of a mold chamber at a later date.

Configurations Batch or Semi-continuous
Our engineers will design and build a system that is compatible with your process, your alloys, your
specifications and the annual tonnage you desire. This could involve a multi-chamber, semi continuous
furnace for large operations or a cost effective single chamber batch design for smaller needs.

Reliability
All PV/T VIM furnaces are efficient, easy to operate and designed for consistent and reliable operation with maximum productivity. They are reliable, rugged units that will thrive in even the most demanding factory environment.

Vacuum System Design
Vacuum pumping systems are designed to provide consistent vacuum performance to suit the individual process requirements. These pumping systems are designed with oil sealed rotary pumps, dry pumps, roots blowers, oil boosters or oil diffusion pumps as required.

Induction Power Equipment
Melting power is supplied from a solid state Inductotherm induction power supply. It is taken through the vacuum chamber by means of a vacuum sealed power feed through or power port assembly to the melting coil. A specially designed quick change power port allows melting furnace coil assemblies to be rapidly exchanged in the hot condition thereby saving production time and increasing productivity.

Controls
The Vacuum Induction Melting furnaces incorporate the latest PLC and PC SCADA controls to accurately monitor and control the melting process and provide extensive data acquisition of melt process parameters.