Mold Maintenance & Repair

OCT 2015

Mold Maintenance & Repair

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October 2015 7 FIGURE 2: Mold damage can occur when vents are not properly and routinely cleaned. Here, air trapped inside the mold cavity began to jet or diesel. The four common contributors to mold wear are maintenance practices, process conditions, mold design and corrosion (see Figure 1). With- in maintenance practices, cleaning techniques, or the method a molder chooses to clean a mold, can particularly contribute to mold wear. As shown in Figure 2, actual mold damage can occur when vents are not properly and routinely cleaned. Here, air trapped inside the mold cavity began to jet or diesel, resulting in damage to the mold. Reasons a molder may not clean molds more frequently include the fact that traditional manual cleaning methods can cause extended down- time; molds can be too hot from use in molding to handle; cleaning often involves the use of chemicals containing VOCs that employees don't like to handle and that can leave a residue on the mold that requires further cleaning; and wipes, brushes and other media can be abrasive and contribute to mold wear. Often, traditional manual methods wear away critical mold toler- ances of parting lines, rolling over edges, shut- offs and vents. Over time, these cleaning meth- ods reduce the asset life of the mold. The fact is, molds have to be cleaned, but why does it have to be done in a way that pre- maturely wears out the mold? What if you could clean your molds not only more often, faster and cheaper, but in a non-abrasive, sustainable, environmentally responsible manner? What if mold cleaning could be better managed, facil- itating a platform for mold warranty programs and therefore providing a win-win situation for both the mold builder and molder. One modern method offers these benefts and makes offer- ing mold warranties more attractive to mold builders: dry ice cleaning. Showing the Data A study conducted by Kettering University (form- erly GMI) in Flint, Michigan, evaluated the effec- tiveness of non-abrasive mold cleaning with dry ice on various metal substrates. These substrates were subjected to cleaning by full-size dry ice pellets, shaved pellets and shaved block. In Figure 3, the die steel on right side of the green FIGURE 3: In a study conducted by Kettering University, the die steel on right side of the green line was blasted with shape block dry ice for 60 seconds at a distance of 1 inch and was found to show "no noticeable damage." The die steel on the left side of the green line was not blasted. line was blasted with shape block dry ice for 60 seconds at a distance of 1 inch and was found to show "no noticeable damage." The die steel on the left side of the green line was not blasted. Another independent study drew a similar conclusion. Figure 4 shows a micrographic examination of the metallurgical structure of martensitic stainless steel (440C) after dry ice cleaning. Noted was the unaltered carbon Figures courtesy of Cold Jet.

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