Equipment Cleaning, Purging

Dry ice cleaning extends the running time of the mold, prevents damage The situation Performance Plastics specializes in high performance injection molding. The company produces small, complex, high quality parts with material attributes that solve their customers’ toughest problems. For 30 years, they’ve focused on the application of these highly engineered plastics for the performance advantages that they provide when producing intricate part geometries with extremely tight tolerances. They excel at helping companies in the medical device, energy, aerospace/defense, industrial, electronics and food and beverage industries solve current product problems or to create competitive next generation advantages. “From designs through production, we do what others have dreamed of, failed at or said can’t be done,” said Tom Mendel, president and CEO. “We are defined not by the industry, but by the material we run, the sophisticated tooling we use and the tight tolerances we hold.” The company has aggressively lowered their per part cost with a proprietary, high volume direct gating hot runner injection molding process that significantly reduces waste and costs. They have molded PEEK since the material was first introduced in the early 1980’s and they have deep experience as an approved processor of Torlon. They have also been involved in development work for liquid crystal polymer (LCP) resins. The company is one of the few able to mold fluorinated ethylene propylene (FEP) using eight- cavity, high volume molds with hot runner systems to produce critical fluoropolymer parts. They do not mold commodity plastics or bid in auctions. They concentrate on the high-end materials that give customers the properties they need for very specific applications. In other words, the really tough stuff. And they are growing. Almost 30 percent of the components produced are shipped to international customers providing “Best in Class” value. “We are pushing the envelope here – running 150 miles per hour in a 20 mph zone,” said Mendel. “We do lots of R&D, lots of engineering and lots of hard stuff.” The problem As any mold manufacturer knows, keeping the mold clean is a must in the mold making process. But there are two problems. First, the mold is heated (in Performance’s case) to an extreme of 450 degrees Fahrenheit, and the plastic coming into the mold can be up to 800 degrees Fahrenheit. As this happens, gas is generated as a natural byproduct and, as it liquefies, the volatiles generated will stick to the mold. With the extreme materials Performance uses in their molds, this gas sticks tough – Mendel said the contaminants can resemble tar. Another issue occurs when the plastic is poured from one end of the part and flows around to the end-of-fill. At the end-of-fill the gas must be vented through a very accurate opening in the mold – one that lets the gas out, but does not allow the plastic to escape. This vent at the end-of- fill gets clogged from the buildup of the particulate gases that condense when the mold is cooled. If the tool doesn’t vent properly, problems will occur. The gas can destroy the metal of the mold, or a part may not meet standards for quality. This is why all molders aim to keep their vents clear in order to maintain a clean mold. As Mendel explains, good molders have a predictive preventative maintenance program where they address the phenomenon of gas buildup in the mold. Properly cleaning the mold is not only required, it is an acquired skill. No one wants to destroy the mold, because they can be a huge expense to replace – in Performance’s case, some molds can cost as much as $250,000. When a mold is cleaned it usually requires a complete teardown – the assembly is stopped, the mold taken out, disassembled, and every nook and cranny is cleaned. Then it must be put back together. This is very time consuming, and because Performance Plastics is moving at high speeds they don’t like to stop. Performance’s traditional method of cleaning molds can include any type of grit blasting, or using solvents and wire brushes. The secondary waste from solvents and other media can be a big problem environmentally, in addition to sometimes eating into the metal. These types of cleaning methods can also be time consuming because the metal often needs to be soaked, or a wire brush must be later used