Better Control, Safer Operation for Melting

Jan. 16, 2009
After being confined principally to the cleaning room, robots are advancing to the melt shop.
Taking the bath temperature is only one function for the ARMS® System; it also slags the furnace, samples molten metal, and adds trim materials.

Foundry robots are on the march. After being confined principally to the cleaning room, where they were able to take over much of the labor and drudgery involved in cleaning castings, they are now advancing to the melt shop. There, the robots protect human workers by performing the tedious furnace operating tasks that require close contact with the molten metal. Melt shop robots and related automated systems are charging furnaces, measuring metal temperatures, taking samples, adding trim alloys, and even slagging the molten bath while the furnace operator remains in the safety of the control room.

Inductotherm’s ARMS® (Automated Robotic Melt Shop) System is the first such system to be installed in an operating foundry melt shop. The melt shop consists of an automated charging conveyor, computerized furnace controls and a fully articulated robot able to use all of the needed furnace tools. This ARMS® System is directly controlled by the furnace operator using a touch-screen based HMI (Human-Machine Interface) located at a control desk. These and other control and monitoring systems allow the operator to remain safely in the control room during the entire melting cycle.

First, the operator charges the furnace using the automated charging system. Then, when the metal is molten, the operator puts the robot to work. The ARMS® System selects the correct tool for each task. The robot uses a probe tool to verify that the bath is properly grounded, inserts a thermocouple lance to measure the bath temperature, dips a cup to collect a metal sample for analysis, adds any needed trim alloys, spreads slag coagulant, and effectively removes slag from the bath. The operator can monitor all of these robotic operations via a closed-circuit video system.

In performing its melt cycle tasks, the robot uses two new features. The first is an extended temperature tool that can take temperature readings of the molten metal without opening the furnace cover. The extended temperature tool allows the robot to insert the thermocouple into the molten bath through a small port in the furnace cover. The extension not only allows the temperature to be taken with a closed furnace cover but also allows the thermocouple to reach the lower bath height after it has been lowered by furnace tapping. This feature significantly reduces heat loss and saves electricity costs by limiting the need to open the furnace cover.

The second new feature is an integrated slag-coagulant feeder. The coagulant feeder consists of a hopper to hold the coagulant and an auger to dispense the material. The hopper design ensures that coagulant is fed evenly into the auger chamber and that the desired amount of material specified by the operator is properly dispensed. Using a special pan with shifting holes, the robot then distributes the coagulant across the surface of the bath.

Inductotherm’s ARMS® robot is able to service two furnaces quickly and accurately, with lifting capabilities from 66 lbs. to 1100 lbs. (30 kg to 500 kg), and can be configured for furnaces from 100 lbs. to 30 tons.

While robots in the melt shop reduce operator error, increase efficiency, cut labor costs and ensure consistent furnace operation practices, their most important contribution is significantly enhanced worker safety. By itself, just working in proximity to molten metal is hazardous and many of the normal operations, such as charging, temperature taking, sampling, adding trim materials and slagging, present added risk of metal splash. But, when robots perform these functions, the furnace operator is able to remain in the safety of the control room.

Removing the furnace operator from the most dangerous situations and from many of the most physically taxing melt sushop tasks also aids worker recruitment and retention, always a serious concern in management of a foundry.

Joseph Belsh is senior vice president - Sales & Service with Inductotherm Corp. Visit