Mold Maintenance & Repair

OCT 2015

Mold Maintenance & Repair

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October 2015 9 CONTRIBUTOR: Steve Wilson is managing director of vertical markets for Cold Jet LLC. 10°C after 30 seconds. This curve in Figure 7 illustrates that the thermal effect essentially occurs only at the surface where the contami- nant is bonded to the mold substrate and has no detrimental effect on the overall mold. Because dry ice blasting is considered non- abrasive and relies on this thermal effect, the process may be applied to a wide range of materials without damage to those substrates. Soft metals such as brass, beryllium and alumi- num cladding can be dry-ice cleaned to remove coatings or contaminants without creating sur- face stresses (pinging, pitting or roughness). The bottom line is that an effective way to extend the asset life of a tool and to facilitate mold warranties is to better manage mold cleaning techniques, and dry ice cleaning is a vehicle for doing just that. Molders should be as intentional with their mold maintenance practices as they have been with their scientifc molding practices. For More Information: Cold Jet / 513-831-3211 / / illustrate this principle, thermocouples were im- bedded into a steel substrate at varying depths (from fush with the surface to 2-mm deep). A dry ice particle stream was swept across the test specimen for 30 seconds (a relatively long time for this process), and the thermo- couples recorded the changing temperatures at the various depths. As shown in Figure 7, the surface-mounted thermocouple recorded a temperature drop of 50°C in about 5 seconds. In contrast, the other thermocouples imbedded deeper in the substrate recorded slower, gradual drops in temperature corresponding to the overall test plate temperature drop. The thermo- couple embedded 2-mm deep only dropped FIGURE 7: A study by James Snide showed the temperature response of thermocouples placed at various depths within a mold substrate. FIGURE 6: Dry ice microparticles (left) remove thin, hard contaminants (off-gasses). Traditional 3-mm pellets of dry ice (right) remove thick, brittle contaminants (screw cleaning). VIDEO: Dry Ice Blasting for Molds

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