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Mold Materials 14 MoldMaking Technology —— MARCH 2018 By Cynthia Kustush Mold material suppliers are working to develop new, improved mold-material grades that will deliver on customers' need for machinability, toughness, thermal conductivity and price. Performance and Price Drive Developments in Mold Materials W ith increasingly complex mold designs comes the need for mold materials that enable moldmakers to machine cores and cavities more efficiently, keep production costs down and meet short delivery times. MoldMaking Technology approached a few materials suppli- ers to get the latest scoop on mold material trends and the driving forces behind them. Material Usage Trends All five material supplier companies participating in this feature called out the resurgence in moldmakers' use of pre-hardened materials. Rich Polenick, technical manager at Ellwood Specialty Steel (New Castle, Pennsylvania), says, "Moldmakers are looking for higher hardness levels that promote the ability to polish for critical-finish molded parts like lenses. Consumers like all the design-driven frills that are offered in the automotive sector. For example, there are these large instrument panel tools with geometric pat- terns, Class 8 highway trucks with large, textured internal and external parts and lens components that keep increasing in size. With all these new demands come challenges like achieving a perfect result using acid etching methods for intricate texture patterns, especially for tools that have large, molded surface areas." Paul Britton, vice president and director at International Mold Steel Inc. (Florence, Kentucky), attributes the revival of pre-hardened materials to moldmakers' need for quicker turn- around on lead times. He adds that customers also are looking at non-traditional mold steels for certain applications. "For example, one customer had a 48-percent glass-filled material and needed something harder than a typical H-13 or S-7 mate- rial so he would not have to coat the mold," he says. "Others are building molds for thin-walled parts, with cores that are very thin—thin enough where, if the cores are not inserted, they will break. For that, they need something tougher because P20 or H13 just isn't strong enough." John Stocker, sales director at Schmolz + Bickenbach USA (Carol Stream, Illinois), says that in addition to the increased use of pre-hardened materials, many moldmakers are look- ing to material suppliers for additional, value-added services like phase-one machining, which includes providing six-sided machining and holes for eyebolts. "The benefit is that they can streamline their processes by eliminating the time-consuming preparation work, which in turn enables them to use their high- ly skilled employees more efficiently and effectively," he says. Kilian Wagner, sales director at Edro Specialty Steels, exclusive distributor of Bohler tool steels in the United States (Walnut, California), says, "The introduction of low-carbon steel grades combined with new re-melting techniques (like pressurized electroslag re-melting processes (ESR)) has resulted in the development of new grades with improved toughness, cleanliness and thermal conductivity. For example, a new modified 420-type has shown similar levels of toughness (in impact-bending strength) to H13 ESR and thermal conductiv- ity improvements that exceed 30 percent in comparison to standard 420 ESR," he says, noting that for superior toughness, vacuum melt and re-melt (VMR) grades also are commonly used. "Other interesting developments are powder metallurgi- cal grades and special, high-alloyed products that offer other outstanding properties for a variety of special requirements. Finally, additively manufactured mold components designed with new, conformal-cooled geometries are trending." This article is part of a series of roundtable discussions with industry suppliers addressing recent trends in moldmaking, the challenges moldmakers are experiencing and the latest solutions that are or will be available to resolve them. Moldmakers are looking for higher hardness levels that promote the ability to polish for critical-finish molded parts like lenses.