Robotic problem solving: successful robotic applications in the metalcasting facility help firms reduce operational costs, improve quality and increase productivity.

Implementing robotics into your metalcasting facility is a sure-fire solution to cutting labor costs, but robotics can solve more problems than just too many workers on the payroll. Maybe your metalcasting facility is seeing too much variation in the coating of its cores or too much time is spent on starting up new casting cycles. Perhaps your employees are complaining about working among the fumes during spraying applications.

Robots' durability, high repeatability and ability to instantly communicate with other functions in the system allow them to improve quality, reduce operation times and keep metalcasting facilities on pace to achieve production goals.

This article shows how robotics were used to help metalcasting facilities improve their process, either through reducing operational costs, decreasing the necessary work force or meeting quality standards not achievable through manual operation.

Handling Diecast Parts

Audi AG, Ingolstadt, Germany, was investing in a new diecasting pilot plant for its experimental metalcasting facility and wanted an automatic handling solution. A robot was required to remove the castings from the die and placed them on an outgoing conveyor. During this time, the die mold needed to be sprayed with a parting agent for the next casting cycle. Requirements for the automatic handling included process reliability, repeatability, short cycle times and high flexibility in order to produce as large a range of parts as possible in a limited space.

At Audi AG's Ingolstadt facility, a six-axis robot was chosen to handle the aluminum and magnesium castings, which were produced using both conventional and vacuum diecasting. The robot is programmed to grip the casting by the sprue and remove it from the mobile half of the mold once it is opened. At the same time, ejectors integrated into the mold eject the casting to help its removal.

Once the robot has removed the casting, it holds it up to an inspection station fitted with sensors to check whether the part is complete. Defective parts are sprayed with a red dot for easy identification by the operating personnel.

Flawless castings are transferred by the robot to a water spray where they are cooled from 752F (400C) to a temperature at which they can be handled manually.

The six-axis robot uses the wait time to mount its spraying tool and apply a parting agent to the mold. This cools the mold and generates a film of parting agent. Blowing the mold dry eliminates any residual moisture in the mold. The robot then sets the spraying tool back down, fetches the cool casting from the water spray and places it on the outgoing conveyor. The conveyor starts up when the robot passes a light barrier.

Because the robot gripper is designed for various reference castings, Audi can produce a wide range of parts in a limited space. Using a linear unit extended the system's work envelope and gave flexibility to the robot.

Pre-Treatment of Sand Casting Dies

Linde Material Handling's Weilbach, Germany plant uses the nobake sand casting to manufacture 51 structural iron counterweights for forklift trucks. Linde was looking for a more cost-effective alternative to manually applying an alcohol-based wash as a protective layer between the sand and the molten iron.

The company found its solution in a jointed-arm robot, which uses a nozzle to blow loose sand residues out of the counterweight molds and a flood lance to apply the alcohol-based wash.

In this application, a roller conveyor transports one of the molding boxes to a turnover station. There the robot controller reads the code of the box and thus recognizes which box types are to be processed in the cell and in what order. As soon as the conveyor system receives the appropriate signal from the robot controller, the box is moved forward on the roller conveyor until it stops underneath a manipulator.

The manipulator picks up the box and swivels it into a position where the robot can blow the sand out of the mold. After that, the manipulator lifts the molding box over the wash-collecting basin. The robot then picks up its flood lance and applies the wash to the mold. Subsequently, the manipulator rotates the box to allow wash residues to drip into the flood basin and then sets the box back down on the roller conveyor.

The installation of the robot in the pretreatment process eliminated one operator per shift, and payback for the system was expected to be two years.

Handling Automotive Safety Parts

The diecasting company Eisenmann Druckguss, Villingen-Schwenningen, Germany, wanted to automate the production of flanges for electrical steering systems in cars. The special challenge here was that there was practically no tolerance with regard to repeatability for these safety-related components. The margins for die inserts were 0.000787 in. (0.02 mm). A six-axis robot could meet this tolerance repeatability requirement while featuring the flexibility to handle changes in the parts.

For Eisenmann Druckguss's flange cell, the inserts are fed to the robot cell via a shaker conveyor, which separates the parts and presents them to the robot in the correct position. Using one half of its pneumatic double gripper, the robot picks up six inserts, one after the other, and places them in the die all at the same time.

While the casting process is running, the robot uses the other half of its gripper to hold a part (that has already been cast and removed from the machine earlier) up to an inspection station. The inspection station checks whether all of the inserts are present and transfers the casting to the locating fixture of a cooling basin. Once the blank is cooled, the robot loads it into a press, which removes the sprue.

Through automation using the robot, Eisenmann Druckguss saw a 40% increase in productivity and an annual cost reduction of $301,000. The company's workforce for this operation was reduced by three employees.

Mold Handling

In its core molding workshop for full mold casting, Gebruder Gienanth-Eisenberg GmbH, Germany, makes sand cores for the casting of cylinder crankcases, with an output of 400 cores per day. The company was looking for an automated solution for coating and handling the cores and opted for two heavy-duty robots to replace the manual handling.

The cores, which weigh up to 57 lbs. (260 kg) and are up to 44.7 in. (113.5 cm) tall, are moved on a conveyor from the furnace to the pickup station of the first robot. A light barrier sends a signal to the first robot when a sand core is present. The robot then determines its exact position using a laser and picks up the core using a clamping gripper to dip it into a bath of water wash. This protects the sand from the molten metal, thus preventing burn-in on the product.

After dipping the core into the bath, the robot lifts it out and transfers it to the apron conveyor of the drying furnace. During this process, the robot carries out rotational motions to allow the wash residues to drip off, thus preventing "runs." Once on the conveyor, the sand cores pass through the 338F (170C) drying oven and a cooling zone.

The second robot, which has three different tools, picks up the cores and sets them down on pallets. For the most common cores, the company uses a tool that is lowered into an aperture in the top of the individual core and expanded by means of compressed air. A laser beam is used to find the aperture. Other cores are provided with a lifting eye, which makes it possible for the robot to pick them up using an additional gripper. The third tool is a plate gripper that clamps the cores between its jaws.

The complete cycle time, from picking up sand cores to setting them down, is two to three minutes, depending on the product. The company calculated that the system will pay for itself in three years with normal utilization.

RELATED ARTICLE: Easing labor, scrap costs with robotic pouring system.

In the past, melting and pouring by hand at TPiArcade, Arcade, N.Y., was a difficult job that required two people per shift. Scrap rates were high at the shop, which specializes in V-process aluminum casting, and pouring with a hand ladle would often lead to impurities in the ladle, which would get into the mold and migrate to the top of the casting. The implementation of a robotic pouring system with a bottom-pour ladle helped reduce the melt labor costs at TPiArcade by 50% and scrap by 30%.

TPiArcade had difficulty automating pouring using a traditional tilt-pour ladle because the robot was unable to duplicate the manual pouring process and avoid impurities that float to the top of the melt. But by integrating a custom bottom-pouring ladle with an industrial robot, the firm successfully completed the automation and achieved a cost savings within the year.

The biggest advantage of the robotic pouring system was that operators were no longer exposed to hot metal. Additionally, the number of employees needed to operate the melt shop was reduced from three per shift to one.

Information in this sidebar is taken from a Feb. 2004 MODERN CASTING product innovation.

RELATED ARTICLE: Decoring aluminum castings using automation.

Robotics and automation can aid in reducing costs in nearly every aspect of a metalcasting facility, from pouring to finishing. A robotic hammering unit that combines a decoring machine and hammer equipment into one design is one example of saving energy, labor and production costs by integrating multiple tasks into one smooth operation.

In this example, after manual or automatic charging, the robot clamps a component into place while the corecracker hammer moves into position to crack the core. Once the core is cracked, the frame with the impact cylinders is rotated away and positioned above the robot. Spring mass oscillation introduces energy into the component, crushing the core. As the fixture rotates, the core sand is discharged at the bottom into a sand hopper.

Due to parallel vibration and rotation, the sand core is crushed and ejected out of the component's openings. After the vibration process, the clamping unit automatically opens so the component can be removed.

Because the core is quickly cracked before the decoring process begins and the system uses spring-mass oscillation rather than a conventional crank mechanism, energy consumption and maintenance work is reduced.

Information in this sidebar is taken from an Aug. 2005 MODERN CASTING product innovation.

RELATED ARTICLE: Automated finishing for better profitability.

Often, the finishing room is one of the biggest drivers in the total manufacturing cost and quality of a casting. Utilizing a high-speed precision trim press with robotic loading and unloading for high volume castings can reduce costs associated with finishing.

At one metalcasting facility, a trim press with accelerated performance and accurate trimming ability in both horizontal and vertical planes was integrated with robotic loading of the equipment, automatic unload onto a conveyor shot blast machine to remove loose shavings, cosmetic touch-up of the trimmed surfaces, and an automatic rust inhibitor application taking the finished castings to their packaging location. The system required no manpower from the robotic loading up to the packaging point.

After 4.5 years, the installation processed more than 10 million castings with only routine maintenance. Payback was seen in less than 11 months on the $1.2 million project.

Information in this sidebar is taken from a Dec. 2005 MODERN CASTING product innovation.

RELATED ARTICLE: Robotic impregnation reduces cycle times.

In 2001, General Motors Power Train (GMPT), Massena, N.Y., decided that instead of shipping large batches of castings to an impregnation facility, it would install an impregnation vessel directly connected to the casting machining facility. This allowed for the cylinder head castings to be delivered one at a time by a conveyor and sparked the creation of continuous flow impregnation.

During the automated impregnation at GMPT, an operator visually inspects the cylinder head castings on a rotating fixture. When the inspection is complete, a robotic arm picks up the cast component and loads it onto the impregnation vessel. Once the vacuum is drawn, the component is lowered into the resin and pressure is applied for fast and deep penetration of the resin into the evacuated porosity.

Following the impregnation process, the component is centrifuged and moved to a wash station. When the process is complete, the robot moves the casting to an outbound conveyor, where an operator once again visually inspects the casting and places it into shipping containers.

In two years of operation, the system achieved 97.4% uptime and zero ppm for damage and contamination. Cycle times were under 2.5 minute/component.

Information in this sidebar is taken from a Jan. 2005 MODERN CASTING product innovation.

Kevin Kozuszek is a marketing manager for Kuka Robotics, Augsburg, Germany.

"Seeking Robotic Payback," K. Bauer, MODERN CASTING, April 2005, p. 22-25.

Kevin Kozuszek, Kuka Robotics, Clinton Twp., Mich.