Linn – Inductive heated lab furnace

Linn, a specialist in industrial furnaces, needed to setup an induction for melting tests on several metals (from platinum to iron)


Induction system for melting tests on several metals (from platinum to iron)

Induction furnaces are electrical furnaces in which the heat is applied by induction heating of metal. The advantage of an induction furnace is a clean, energy-efficient and well-controllable melting process compared to most other means of metal melting.

The customer

Linn High Therm with over 120 employees is based in Eschenfelden, Germany. It is specialized in the production of industrial and lab furnaces/ kilns, microwave furnaces, sample preparation units for spectroscopy, induction heating systems, precision fine casting systems and customer-specific systems.

There are only a few companies of such qualification and production spectrum: R&D, design, production, and quality control all under one roof with outstanding experience since 1969. From prototype to pilot-scale in almost no time.

Linn is serving the following industries worldwide: metal, ceramics, chemicals, glass, building materials, research and development, medical, nuclear, recycling, education and food.

The process and the needs

As described, one of the advantages of induction furnaces is the capability to melt several different metals.

The need of Linn was to have a flexible solution, that could manage in an easy way different thermal cycles, with or without vacuum: with induction, the part to be heated never comes into direct contact with a flame or other heating element; the heat is induced within the part itself by alternating electrical current.

As a result, product warpage, distortion and reject rates are minimized.

For maximum product quality, the part can be isolated in an enclosed chamber with a vacuum atmosphere, to eliminate the effects of oxidation, but other treatment can require the supplement of chemical additives (protective gas)

Temperature regulation was also a key point: to optimize test phases of the treated material, the melting time had to be reduced as much as possible.

Traditional Vacuum Furnaces are large and powered by banks of electric heating elements: they require several hours to achieve and maintain temperature. In the induction furnace made by Linn, the temperature in the oven can rise from 650 degrees to 1100 degrees in 3/4 seconds!

The solution

The solution offered by Gefran is a system made by a compact hardware and a smart software application. The hardware is:

  • 7 inches graphic touch panel, full color, with integrated controller (softplc).
  • Remote I/O Gilogik II
  • Fieldbus CANopen

The software application gives to Linn enough flexibility, reducing in the same time the programming effort. It offers:

  • Up to 25 programs managements
  • Each program can be made of up to 50 process steps, configurable. The user can configure / parameterize freely 10 different types of Step Process that for the creation of the program (guided programming)
  • PID controller with autotuning
  • Run / Ready / Pause / Skip Controls
  • Manual controls for machine setup
  • Trend Process Value
  • Data log exportable in CSV files
  • Recipes to manage and save configuration parameters
  • Alarm display, current and historical
  • Date&Time function for automatic start
  • Multilingual
  • Access management with user / password