Ultrasonic Cleaning Options for Plastic Injection Molds

Injection-molded plastic parts are everywhere a part of our daily life.  Polymers in a variety of formulations are used to produce these components by being injected into intricately designed molds and subjected to heat and pressure.  Because molds represent substantial investments they must be cleaned on a regular basis.  Ultrasonic cleaners are recognized across the injection molding industry as a safe, thorough alternative to manual scrubbing, which is a time-consuming process that can damage highly finished mold surfaces while missing contaminants in blind holes, cavities, cores and pins.

The contaminants produced by injection molding operations are tenacious.  Examples include flashing, mold release compound, burned-on plastic residues, carbonization and vent outgas residue that if not safely removed will quickly shorten mold life.

The solution is the powerful cavitation action of an ultrasonic cleaner that creates millions of minute bubbles in an ultrasonic cleaning bath comprised of water and a biodegradable ultrasonic cleaner concentrate.   When the bubbles contact the surfaces of forms used for injection molding – even the smallest cracks, crevices and blind holes – they violently collapse to strip away contaminants without damaging surfaces.  The process can take as little as 10 – 15 minutes although complex molds may require longer periods in the ultrasonic bath. The molds are then rinsed, dried and either stored for future use or put back on line.

Selecting an Ultrasonic Cleaning System

Industrial ultrasonic cleaners such as manufactured by Elma and offered by Tovatech are available in several sizes and configurations for fast, through cleaning plastic injection molds.

An example is the single-tank Elmasonic X-tra Basic system available in 6 tank capacities from  ~ 6 to 66 gallons and designed for up to 12 hours of continuous operation. These dual-frequency X-tra basic ultrasonic cleaners operate at either 25 kHz to quickly remove tenacious contaminants or 45 kHz for normal cleaning operations.   Cleaning is further supported by a Sweep mode to evenly distribute the ultrasonic energy throughout the bath and an operator-activated Pulse mode for bursts of intensified cleaning power.

Multi-stage cleaning of plastic injection molds is accomplished with the Elmasonic X-tra Flex Line of industrial ultrasonic cleaning systems operating at 25/45 kHz or 35/130 kHz and available in 5 tank sizes from ~ 7 to 30 gallons.  An added feature of the Flex Line is a precise vertical oscillation that depending on the cleaning requirement can increase cleaning speeds by up to 20%.

The X-tra Line Flex 1 single workstation comes with an optional shower rinse station for post-cleaning wash down before drying.  The X-tra Line Flex 2 has a co-mounted separate rinsing tank to remove residue by ultrasonic energy and agitation, and an optional final rinse shower.  A drying oven can be added to either line.

Extending Solution and Equipment Life

Residues removed from injection molds by ultrasonic cleaning can quickly reduce the effectiveness of the ultrasonic cleaning bath.  If hard substances fall to the bottom of the cleaning tank ultrasonic energy can create mechanical abrasion that damages the tank.  Oil separators and solution filters address both concerns and might prove economical options for large-scale cleaning of forms used for plastic injection molding.  There should also be in place a standard operating procedure for periodically draining and cleaning the tanks using approved cleaning processes.

In summary, plastic injection molds represent substantial investments.  Proper cleaning procedures should be in place to protect the investment in injection molding equipment and ensure efficient plant operation.  The scientists at Tovatech are available to help you specify the most cost-effective standard or custom-designed industrial ultrasonic cleaning system for your particular operations regardless of mold size.

How does your plant clean injection molds?  Please share your experiences with particularly challenging mold cleaning operations

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world. Read More