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Mold Components Cleaning and maintenance. A porous metal is generally a low-maintenance material, but proactive cleaning is still needed occasionally. There are two times cleaning must be performed with this material. The first is when the tool shop has prepared the insert or cavity. The material is 25 percent air by volume, and the cutting fluids will displace the air, thus filling and clogging the pores. After the permeability has been restored, by either stoning or EDM of the venting surface, the steel should be placed in an oven at about 350°F for 2 to 3 hours. This will thin and remove most of the fluids in the pore structure. Once cooled to room temperature, the material should be placed in an ultrasonic cleaning unit built for flammable solvents that is filled with acetone. Cleaning is also needed after the insert or cavity has been in operation and a film—a thin layer of mold release agent, resin residue, shop oil or any other contaminate—has partially or totally blocked the air flow. In addition to these cleaning methods, it may be necessary to use air pressure to back-flush the porous metal inserts with acetone in order to thoroughly clean them. However, waterlines should not be run through a porous material, since they are difficult to seal and will rust the material. Additionally, polymers with flame retardants will require more frequent cleaning. This is where the reverse blow-back 26 MoldMaking Technology December 2013 capability is ideal, as reverse air flow will happen with each cycle of the mold to assist in keeping the porous metal clean. Summary The unique properties of a porous sintered metal make it an ideal material to use in core pins and plugs. By preventing wasted or burned materials during a part's production, moldmakers can help their customers achieve better part aesthetics, while also saving time and money. This material helps vent the unwanted gases that build up inside a mold and lead to imperfections. As a result, core pins and plugs made with a porous metal can help molders prevent burning and shrinkage as well as flow and knit lines, all while reducing cycle times and enhancing part appearance. 1 DME Company manufactures a line of core pins and plugs made of Porcerax II called Vortex. CONTRIBUTOR Bob Salhaney is a product engineer for DME Company with more than 33 years of experience in developing and applying solutions within the plastics industry. FOR MORE INFORMATION: DME Company / bob_salhaney@dme.net / dme.net