Best Practices: Ejector Pin Grease Selection and Use

July 20th, 2022

Ejector pins, plates, and other moving mold components typically have extremely tight tolerances. For these parts, a high-quality lubricating grease is essential to ensure the proper functioning of the mold and to gain the most efficient results.

Below is a list of the most relevant questions to ask when selecting your ejector pin grease product.

1. How hot will the mold be running? All greases have maximum operating temperatures, above which the grease will melt, run into the mold, and contaminate parts. You should ensure that your product of choice is able to withstand the operating temperatures of each mold to minimize or eliminate potential bleed out.
2. Are you molding parts that will filter into the food or medical market? If so, a food-grade or NSF-certified formulation should be considered.
3. If you are molding components where the aesthetics and cleanliness of the finished parts are important, a colorless selection is the best choice. Many commonly used products have an added dye and may affect the visual quality of the molded part.
4. How will you be applying the grease to the mold components? Do you prefer to use a pure grease product or one that is made available in aerosol form?
5. Will the molded parts be painted or otherwise decorated post-molding? If so, a grease based on silicone should be avoided as it may inhibit the decorating process.

Once the appropriate ejector pin grease is selected, proper application and evaluation of that grease formulation is essential.

1. Your company should develop a preventive maintenance plan for each mold. Preliminary testing should occur to determine how many cycles could effectively run before reapplication is needed.
2. It is easy to simply grab a tube of whatever grease is just sitting around the shop and use it to lubricate your mold components, but using the incorrect formulation can lead to bleed out, part contamination, and excessive wear on the ejector pins. Top quality ejector pin grease can save tremendous amounts of money and labor with reduced downtime and less rejected parts.
3. The recommended technique for applying grease to an ejector pin or other moving mold component is to apply a heavier coating to the back half of the pin, and a lighter/thinner layer to the front portion of it. Using this method typically provides the necessary lubrication to prevent excessive heat buildup or galling of the moving segments.
4. More frequent and lighter application of a grease to the operating mold components is preferable to applying too much.
5. Molding with resins that emit gases or contain flame retardant additives can tend to affect performance by gumming up the grease formula and lead to product solidification, thereby reducing lubrication properties. Under such mold making conditions, the grease should be reapplied more frequently.

A Slide factory representative or local distributor is available to provide on-site support and recommendations to help with your selection of the most appropriate ejector grease formulation. You can request an appointment through Slide’s Top Tier Service program.