Raising Productivity, Reducing Risks on the Melt Deck

Feb. 28, 2008
Combining automation and robotics helps to maximize production, increase worker safety, and conserve energy in the melting process.
The robot removes slag from the furnace bath, without any personnel on the melt deck.

In every foundry, the melt deck is the place where two of the operation’s leading cost concerns — productivity and worker safety — collide. The innovative ARMS™(Automated Robotic Melt Shop) System replaces the furnace operator on the melt deck with a foundry robot, which can be configured for any ferrous or nonferrous foundry of any size. It establishes a new standard for automation of the melting process, as well as for worker safety.

Combining advanced automation with a creative application of robotics, the foundry can effectively maximize productivity and increase safety, while minimizing operating costs.

The ARMS™ System (particularly, the robot) performs all of the hazardous but necessary operations that otherwise would be handled by a furnace operator. It accomplishes this with a 6-axis, foundry-grade industrial robot and other automated equipment on the melt deck to perform all of the required melt deck tasks, quickly and accurately.

Multiple closed-circuit video cameras, strategically positioned on the melt deck, capture all operations and display the images on monitors in the control room. This allows the furnace operator to manage the furnace’s entire operating cycle effectively, but from a distance. Keeping the furnace operator away from the dangerous areas close to the furnace significantly improves worker safety.

All robot functions are controlled from the control room, from the HMI (Human-Machine Interface) control desk. This is where the operator selects all activities performed by the robot. It has a user-friendly, touch-screen display that allows the operator to choose from various menus to perform given tasks. The HMI also shows the status of the current operations and displays and logs alarms, error messages, as well as other operational information.

(Top) The robot reaches for a tool from the “smart” tool rack (middle) to perform an automated task; all activities are overseen from a control room (bottom), where operators use a control panel to manage the process in safety.

The robot begins each one of its fully programmed tasks by selecting a tool from the “smart” tool rack. This smart rack uses sensors to tell the robot what tools are available. The rack holds five tools: a slagging tool, a thermocouple lance, a sample lance, a bath grounding probe test device, and a trim material pan. The smart tool rack also houses a supply of replaceable thermocouple tips and metal sampling lances that are monitored by sensors to alert the operator when the supply level of each is running low. The operator can remotely refill these at any time.

From the control room overlooking the melt deck, the furnace operator remotely controls the movement of the furnace, the ARMS™ System components, and other melt shop equipment. He also initiates the five, preprogrammed operations of the robot: slag removal, checking the bath grounding, checking the bath temperature, metal sampling and analyzing, and the addition of trim materials.

Slag removal begins with the robot selecting the slagging tool from the tool rack. Then, the robot manipulates the tool across the surface of the furnace bath, following one of several “pre-taught” patterns that the operator can choose. The operator can choose to slag the entire bath surface, or to remove slag from specific areas, as needed. Then, the slag is raked into the automated slag cart.

This automated slag cart is remotely controlled and electrically operated, and complements the ARMS™ System to automate furnace slagging. It receives the slag removed from the furnace by the robot, and, when slagging is complete, the robot returns the slagging tool to the tool rack and the cart transports the slag away from the furnace and unloads it into a disposal container. The movements of the slag cart are completely under the operator’s control, monitored via the closedcircuit television system.

With an induction furnace, proper grounding of the metal bath is crucial to the safe operation of the system. To check the bath grounding, the robot dips the ground-testing tool into the bath. The results are shown on the HMI display inside the control room, to indicate whether or not the bath is properly grounded. An induction furnace must not be operated without a properly grounded bath. Grounding the bath is necessary for operation of the ground leak detection system.

To obtain a temperature measurement of the metal bath, the robot selects the thermocouple lance from the tool rack and inserts a new tip from the tool rack’s magazine. Then, the robot dips the thermocouple lance into the bath. The results are displayed on a readout visible to the operator in the control room. The operator then has the option to re-check the bath temperature or end the process. Once the process has ended, the robot discards the used tip and replaces the thermocouple lance onto the tool rack.

A bench top spectrometer will enhance productivity because it eliminates the need for lab testing.

To retrieve metal samples, the robot selects the sampling lance and picks up a new sample cup from the magazine on the tool rack. It then dips the cup into the furnace to pick up the metal sample, dropping the sample into a chute on the tool rack. The sample is sent by the robot via a chute on the tool rack to the operator in the control room. The sample will serve two functions: as an immediate determination for the operator (for example, for percentages of Si, C, and CE via a thermal analysis device); and as a sample to forward to the metallurgy lab for detailed testing and batch documentation, if desired. Always neat, the robot replaces the sample lance on the tool rack.

A bench top spectrometer, located in the melt-deck control room, can also increase production by eliminating time spent taking samples to the lab. While this process can sometimes take up to 15 minutes or more, having a bench top spectrometer is simple, effective and efficient. It also reduces the time that the metal is being held within the furnace, which reduces energy consumption and the overall time of each melt.

After the analysis of the sample is complete, the furnace operator determines what trim materials are needed to achieve the desired bath chemistry, based on the results from the thermal analysis device or spectrometer. While the operator prepares the batch of trim materials, the robot selects the trim pan from the “smart” tool rack and holds it under a chute.

The operator sends the trim materials to the robot through the chute or an automatic trim charge display hopper system. After catching the trim batch, the robot tips the trim pan into the furnace and successfully adds the trim materials to the furnace bath. By using the tool rack’s two chutes, items can be moved to and away from the furnace while limiting the operator’s exposure to melt deck hazards. Again, the robot replaces the tool on the rack.

Energy savings is a critical advantage of this automated system. Furnaces suffer significant heat losses while the lid is open, and the fast pace of the robotic operations minimizes the time required for the lid to be open.

In addition, to effectively maximize production while minimizing costs and reducing energy consumption, automated processes are precisely repeatable, ensuring consistency and improved productivity meltafter- melt.

But, the primary benefit provided by this robotic equipment is greatly enhanced worker safety. Better working conditions, with the most dangerous tasks performed by the robot and other automated equipment, make it easier to recruit and retain foundry workers and, theoretically, to reduce workers’ compensation claims. The ARMS™ System allows foundry managers to remove the furnace operator from the most dangerous areas close to the furnace decreasing the potential for injury to your most important asset – your employees.

About the Author

Satyen Prabhu | President and CEO

Satyen N. Prabhu is President and CEO of Inductotherm Corp.