【正文】 How Surface Treatments Keep Molds Operating Longer Important tips and information about mold coatings to help you achieve the level of production that you and your customers desire. By Steven . Bales Mold making technology January 2020 Abstract There’s an awful lot to know these days about molding plastic and how to get the very best performance from the valuable tools you build or run. This guide has been written to provide important tips and information about mold coatings. After reading this, you should have a very good idea of what coatings—from the very traditional to the very latest—will help you to achieve the level of production you and your customers desire. After all, these tools are an investment and they need to be protected for the life of the products they mold. Key Words mold coatings preventive maintenance (PM) program benefit nickel Cobalt diamondchrome nickelPTFE nickelboron nitride electroless nickel texture The Key Role of Coatings Before introducing you to the wide range of coatings on the market today, it’s important to note the role coatings can play in an effective preventive maintenance (PM) program. PM is really the key to protecting your tooling, your investment. Why? Because it saves time and money. Once you invest in a mold coating to improve tool performance, then a PM program is always a good idea to ensure you get the maximum benefit. These two steps should be a given in any shop. Remember, no coating lasts forever, and producing substandard parts from a mold with a worn coating is no way to win customers and stay profitable. PM is probably the most costeffective strategy you can put in place. The key is to educate your personnel on how mold coatings wear during production. Every coating is different, so it’s of benefit to have employees learn how to tell when the coating is showing deterioration, especially in highwear areas such as gates and runners. For example, wear in and around gate areas plated with hard chrome is the first sign that your mold needs servicing. How can you tell there is wear? The chrome coating is approximately 20 RC points harder than the base steel, so exposed steel will wear much faster than the coated surfaces surrounding it, causing a slight or pronounced edge or “step” on the surface. Conversely, nickel will wear almost evenly, causing a kind of feathering effect, making it more difficult to recognize wear. A more identifiable difference will be the color because when nickel coating wears, it produces a shadow or halo effect on the steel. No step or edge will be evident. The steel also will have a more silver appearance pared to the somewhat tarnished look of the nickel coating. This knowledge makes pulling a mold for maintenance before the coating wears through an ultra important aspect of a PM program. To miss important wear signals means more costly repairs and additional polishing expense. Measuring Wear A remended tool for measuring the wear level of any coating is an electronic thickness gauge that uses a bination of magism and eddy current to accurately measure surface thickness. When the mold first arrives in your plant, take the time to measure the surface thickness—especially in highwear areas—using this specialized tool. As you run production on the mold, occasionally pause to remeasure those areas. When you have determined that the finish is wearing to a critical level, pull the mold and send it out for maintenance. Part Counts Be sure to record the measurements taken with the thickness gauge and use the notes to create a history of maintenance requirements for the tool. A cycle counter installed on the mold will allow your tooling engineer to record wear levels as pared to piece part counts, thereby doubling the effectiveness of your PM program. Part counts are a great way to determine maintenance needs, especially with highvolume molding projects. From the very first time you run the mold, keep an accurate piece count until it is ready for its first maintenance work. Use that count as a gauge for when the next maintenance is due. Because you know approximately when the mold will be ready to be refurbished, you can arrange the service in advance with your coating vendor. This not only gives him ample time to schedule your mold maintenance, but it also allows you to optimize the use of the mold and the machine that’s running it. Coating Challenges Even today, there are those who question the benefits of using fancy—sometimes more expensive—coatings to prolong tooling life