Developing New Solutions for Core and Moldmaking

March 12, 2010
Advances in process efficiency and the adoption of low-emission technologies are improving the equipment choices, even for midsized and smaller foundries.
One customer’s insight for using a core machine to produce shell molds inspire Harrison Machine Co. to develop its Dual Mold Core (DMC) series.

In recent years foundries have adopted one or more of the significant advancements in molding, melting, cleaning, and sand handling that have been introduced, with positive results. In most cases, these new technologies have proven to be effective at making those foundries more competitive: reducing production costs and improving casting quality. In coremaking, however, there have been long-standing misconceptions that there are no significant advancements available, other than switching to newer processes. The effect has been to keep many older systems in wide use. As a result, because most machine designs remained largely unchanged, long-standing problems associated with coremaking — e.g., operator-dependant machines, subjective manual process settings and monitoring, unpredictable productivity, variable quality, and the general loss of expert coremakers — have not been addressed.

One exception has been the switch to newer, cold-box processes, usually resulting in some cost savings, mainly because newer machines had to be used. However, the shift to the cold-box processes has been slow because of the large investments required, health concerns, and secondary costs.

Recently, some technical advances have been achieved in core-making — controlling the process for quality and productivity, reducing emissions, energy consumed, and costs.

Harrison Machine Co., is one company that is advancing core and mold making for small and large foundries, with dual- and single-station hot and cold process machines using a synergistic approach, integrating its new machine technology with systems and products from its LETCAST partners.

LETCAST (the acronym refers to low-emission technologies for metalcasting) is a consortium of sand-binder and process control systems developers that promotes low-emission technologies and their applications for foundries, including helping foundries work with government regulators toward implementing these capabilities. Harrison’s market-driven approach guides its research and technology development programs. By listening to the industry, HMC has engineered new core and mold making systems to help foundries improve their competitive advantage and profitability.

Regaining expertise
Recognizing the industry’s loss of expert coremakers, HMC developed a control package for less-experienced machine operators. Among its features are: auto-process monitoring to improve quality and productivity; high-reliability digital controls to improve productivity and quality; large, non-volatile memory for box settings/ programs, for less operator dependence and machine-centered process control; Smart Blow© system to improve quality consistency; and HMC-developed, advanced pneumatics to improve productivity. All of these improvements combine to establish a “whole system” solution that matches the technical advances achieved in the other foundry processes and equipment.

HMC’s Universal Quick Change Core Box Mounting System maximizes available production time, simplifying changeovers to as fast as five minutes without hand tools. More important, moving boxes from machine to machine is seamless, which eliminates mounting system conflicts, reduces the need for dedicated machines, multiple mounting systems, and long operator-driven setups. Importantly, existing boxes can be used.

The Dual Mold/Core Series machines combine coldprocess coremaking with LETCAST’s low-CO2 cured binder technologies in a compliant production process well suited to smaller foundry operations.

For job shops with short runs and frequent changeovers on hot process machines, Harrison offers a new induction box preheater that eliminates on-machine heat-up time, increasing productivity and capacity. Coupling the Quick Change Core Box Mounting System and machine-driven productivity, Harrison makes it possible to meet demand with fewer machines, cutting overall energy consumption as much as 50%.

Recognizing that their “D” Series dual-station machines are among the most productive coremaking systems available, and that many smaller foundries neither needed nor can justify the investment in that level of coremaking capacity, Harrison introduced the lower cost “S” series. It’s full line of cold- and hot-process singlestation core machines with the same technology as the “D” series and the ability to add the second station later.

Cold process models also benefit. Harrison incorporates several new technologies to shorten cure time, reduce binder usage, and reduce dependency on operators.

Combining technologies
Going to the next level of coremaking process control and binder chemistry, Harrison and LETCAST have combined their collective technologies into a fully integrated, solutions-focused “whole system” packages. Separately, each LETCAST member provides unique important advancements in the various aspects of coremaking. Some perfected low-emissions sand binders applicable to all metals and able to reduce core-related emissions more than 80%, while maintaining or lowering binder costs. Others developed process monitoring and control systems that significantly reduce cycle time, binder usage, scrap, and cost plus increase core and casting quality. All their advancements can be retrofitted to core machines as incremental improvements. Combining them into one system on Harrison’s advanced core machines leads to a greater overall benefit than the total of the separate systems.

The Smart Blow© System improves core strength and density. Monitoring each blow to maintain optimum conditions for each box, it identifies developing issues (such as a vent clog) before core quality is jeopardized; in the cold box systems a vacuum assist increases blow and purge process efficiency, as well as casting quality.

The Smart Cure© System monitors cold process gas and purge cycles to maximize efficiency, minimize binder usage, improve core quality and consistency, eliminate arbitrary timers, and reduce incomplete curing. Usually, oven baking can be eliminated and offgassing can be reduced significantly. Harrison’s separate gassing heads located away from the investment head keep the sand system free from prematurely cured clogs, allowing the use of optimum gas and purge temperatures for greater productivity and higher quality.

Smaller foundries have specific core and mold making problems. They have to modernize to remain competitive, but most equipment builders have not offered systems that suit the way these foundries must do business, and much less to suit their budgets.

For smaller job shops the main problem with an auto-mold machine is that it limits the operator to one pattern and flask size, which usually means additional or new tooling and excessive sandto- metal ratios. Also, the production capability of most auto-mold machines far exceeds the output level that smaller foundries maintain. Low utilization of such a big investment means a long payback, which is difficult and risky. Moreover, their existing sand systems usually are inadequate for new auto-moldmaking systems. So, if they are not replaced the foundry has a choice between hot sand or running it out, which is another big investment. Existing pour lines present the same problems.

Combining processes
Recognizing these problems, HMC revisited its moldmaking offerings, and discovered that (like other system builders) they were thinking only in terms of greensand machines. Greensand molding machines are, by design, inflexible. Harrison engineers concluded that molds do not need to be made in greensand machines. Its breakthrough came via one customer’s successful application of a HMC core machine to make shell molds.

What followed was Harrison’s DMC© Series of Dual Mold/Core machines, combining the cold-process “DC” Series core machines with new system accessories and LETCAST technologies. It’s a first-of-its-kind solution for smaller job shop foundries — a dual station mold and coremaking system that uses any cold process. The new, low-emission CO2-cured binders are recommended for maximum benefits.

The DMC System is flexible enough to make either two different vertically split molds simultaneously, or one horizontally split mold, or one vertically split mold and one core, or two different cores. It uses any size flask and pattern insert plate, within machine physical limits, for optimum sand-to-metal ratios. Using one core sand and a binder system for both molds and cores, and one operator to make them, molds and cores are made simultaneously, assembled on the spot, and sent for pour. Sand can be reclaimed using a high-efficiency non-thermal hydro-acoustic system. Usually, the existing sand delivery and shakeout can be used.

The DMC vertical molding system is especially well suited to use the latest runner and gating technology, which can increase quality and reduce energy and metal costs significantly.

Harrison’s D & S Series core machines and DMC System are complete package solutions for mold and coremaking that don’t cost a fortune or occupy a large amount of floor space. Using a fraction of the energy of traditional systems, they cut operating cost, and can significantly cut emissions. A DMC Package System will help smaller foundries to be more competitive, efficient, versatile, and responsive allowing them to differentiate themselves as progressive, technologically advanced quality casters.

Sud-Chemie Producing “Environmentally Friendly” Cores for BMW

BMW Group is the first automotive OEM to use sand cores produced with water-soluble alkali silicates in volume casting of of all engine components.

Sud-Chemie AG’s subsidiary WDGiesserei- Technik in Moosburg, Germany, started producing cores last May for casting aluminum and magnesium engine components, using the new INOTEC binder system.

The cores are supplied for a new, BMW six-cylinder diesel engine.

According to Sud-Chemie, INOTEC is an inorganic, emissionfree version core binder based on silicate. It was developed by Ashland-Sdchemie-Kernfest GmbH and optimized for automotive series production in close collaboration with BMW.

Sud-Chemie said the binders emit “virtually no emissions harmful to the environment,” unlike many organic binding agents, which means the foundry can dispense with expensive, timeconsuming processes like air extraction and amine washing.

Service, Supplies Extend LaempeReich Product Line

LaempeReich CoreCenter installations combine a core shooter, sand mixer and gas generator with a common control system.

LaempeReich reports that demand for new coremaking technology remains solid, even amid weakness in the manufacturing markets. The company is the North American affiliate of Laempe & Mssner, a designer and manufacturer of core machines, gassing systems, sand preparation, and other foundry machinery.

LaempeReich has installed over 250 Laempe CoreCenter systems in the region, including recent orders from Canada, Mexico, and Chile. CoreCenters combine the core shooter, sand mixer and gas generator under a single PC-based controller.

Equipment remains the focus for LaempeReich, but it’s also offering follow-on services: every CoreCenter installation is offered with in-house core development, prototyping, process conversion trials, tooling trials, and training on one of the LFB25 CoreCenters installed at the Trussville, AL, headquarters. The company also added a new business unit: “The CoreRoom” produces highquality, cost-effective cores for a number of high-volume and smallscale foundries.