Automating the Process of Finishing Castings

Automating the Process of Finishing Castings

Forward-thinking foundries will recognize the most available cost-reduction opportunity: achieving consistent product quality and repeatability

An automated finishing cell during design and development.

We are reminded frequently that U.S. foundries are declining in number and output. From 6,100 foundries in 1955 to 2,380 in 2005, to less than 2,000 in 2011, production has dropped from 25 million annual tons to an estimated 14 million tons in 2011, a 44% decline. The typical explanation for this is the inability of U.S. foundries to compete on price with other casting producing countries.

This may be true when comparing domestic foundries to Asian competitors, but what about European operations? How are they able to export successfully. German foundry labor, for example, is about $2 per hour higher on the average than in the U.S., the Euro is strong, and yet they continue to export into North America. How do they do it?

They do it by mechanizing operations and reducing the need for manual labor. The three highest operating costs in the foundry are: material, energy, and labor. Of these, material and energy costs are generally beyond the control of the foundry operators and managers. Therefore, labor is the most significant cost savings available to managers, and labor is most often concentrated in the finishing department.

Additional benefits of labor reduction in the finishing department include: reducing workman’s compensations costs; improving process repeatability, and hence product quality; improving ergonomics and safety; and updating the working environment.

Unfortunately, many foundry operators believe that their plants are not candidates for mechanization, for a variety of reasons. The most frequent excuses involve the large number of casting types that are made in the shop, and the perceived small volumes that cannot justify the investment. However, Pareto’s Law still applies: typically, 20% of a foundry’s patterns make up 80% of its production volume. Yet, most foundries handle their entire product line in the same inefficient way.

One suggestion for achieving cost savings is to segregate the higher running jobs and focus the investment on them, in order to handle and finish them efficiently. Once it is determined that an investment is warranted, the next thing to be determined is the most suitable type of automation for the foundry.

There are two types of automated processes, hard automation and flexible automation. For hard automation, typical prerequisites include: high volume production; few pattern changes; stable customer base; speed; and available capital. And for flexible automation: adaptablility to high/medium/low production; a variety of casting are produced; the customer base is changeable; and modest capital is available.

In recent years, flexible automation has been making very aggressive penetration into foundry operations, including an unlikely customer, the automotive industry. This is because of the need for flexibility and the increasing sophistication and reliability of robots, as well as their decreasing cost.

Arranging robots into cells with mechanized part handling, and the ability to interchange tooling, allows the foundry to install a system that can be used on a variety of parts simply by reprogramming it. The tool cassette can hold a variety of tools, i.e., cup grinders, pencil grinders, milling heads, etc. This allows quick tool changing, so that the part can be completely finished within the cell.

Specially equipped hexapod robots using vibration-damping shock absorbers can perform even the most difficult operations for manual labor, such as pneumatic chipping. Several units can work simultaneously, if a higher output is desired.

Robots can be used to inspect castings and gauge tolerances, too. Results can be transmitted to a computer that plots a graph of the tolerances or keep a log of the final inspection results. These automated inspections are done either by touch sensing, vision or lasers. Tolerances are measured in thousandths and can be adjusted within a range.

In order to compete in the global market, foundries must control their cost. Labor cost is the highest controllable cost in the plant, and it must be minimized.

Increasingly, forward-thinking foundries use robots and automation machinery to finish castings, where the largest concentration of manual labor still exists. Not only is this an important cost reduction tool, it will increase quality by assuring a consistent and repeatable process.

For more information, visit Foundry Solutions & Design’s website, www.foundrysd.com

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