Salt Bath

Overview

Prestige Thermal Equipment systems are available in several equipment formats. Stages can be included to accommodate pre- and post-treatments. Fully programmable systems are offered for in-line processing; batch units are also available. Material handling interfaces are custom-designed to individual requirements. Test processing is available to qualified manufacturers.

Molten salt quenching for austempering or martempering requires a furnace capable of several functions, and the resulting designs are much different from salt bath furnaces employed in heating or austenitising work.

Salt Baths

Prestige Thermal Equipment considers four primary factors for all Quench Furnaces:

1.Bath Temperature Uniformity – This is essential for consistent metallurgical properties. Internal heating of the bath can be accomplished electrically by using either immersion heaters or electrodes. Gas-fired immersion tubes can also be employed. It is important to automatically dissipate heat from work being quenched by either internal or external cooling means. For light duty, forced air or air/water can be directed to the exterior of the pot. For heavy duty, controlled cooling is provided by internal coils, using water or air/water injection.

2.Proper Agitation of the bath – Thorough agitation is necessary to remove heat quickly and efficiently from the work. Constant or variable speed propeller agitation provides a uniform flow through the workload being quenched.

3. Removal of bath contaminants – To achieve optimum hardness and other physical properties, foreign contaminations must be removed. This is accomplished by a continuous filtering and automatic dumping system such as the Prestige Thermal Equipment Sludge Dumper. Comprised of a scoop-shaped filter basket connected to a driving cylinder mounted adjacent to the furnace wall, the basket is automatically raised up and out of the bath – automating chloride removal. Readily installed on new furnaces, the mechanism can also be retrofitted on existing salt baths.

4. Water addition to the quench bath – For isothermal quenching of heavier sections, water increases quenching power. Small amounts of water added to a nitrate-nitrite salt drives vapor from the bath as hot work enters and gives a faster cooling rate. Both manual and automatic systems are available for adjusting the frequency and duration of water additions.

Applications

• Solution heat treating • Melting • Annealing non-ferrous alloys • Descaling & desanding ferrous parts • Coloring & curing certain plastics • Glass stripping & paint removal • Tinning & babbittin g • Annealing • Nitriding • Melting • Tempering • Hardening
• Brazing • Galvanizing • Aluminizing • Surface treatment of various metals & alloys

Standard Features

The PTE series with submerged electrodes provides long life & trouble free service with periodic maintenance. Electrodes, embedded in the wall, below the salt line, are sealed against corrosive attack at the air-salt interface.

The submerged electrode design also lends itself to economical 3 phase operation in deeper furnaces when 2 or more tiers of electrodes are utilized.

Benifits
  • Controlled radiation & convection heating
  • Fast recovery & heat up
  • Low energy consumption