Seeking Better Balance in Medical Molding
Medical injection molding demands shot-to-shot consistency of part and process—a fundamentally challenging task in multicavity molding—is there better path to flow balance?
Kevin Rottinghaus of Beaumont Technologies believes there is, and he’s prepared to share that solution with attendees at the Medical Injection Molding Workshop at Amerimold this June in Chicago. Standard operating procedure for molders facing fill variations in a multicavity tool calls for them to undertake a short-shot study, visually marking how plastic is flowing into the cavities and helping them locate where imbalanced flow might be occurring.
But what about why the imbalance might be occurring?
Rottinghaus and Beaumont are advocating a software developed by the company that utilizes the principles of plastic flow to determine if imbalances are occurring due to shear or steel variations in the mold—steel variations being physical imperfections within the tool or press, including disparities in gates, runners, vents, cavity geometry, cold slugs, nozzle blockage, and hot runners.
According to John Beaumont, company president and founder: “Not only does [the software] tell you the magnitude of the mold-filling imbalance, but also what the source of the imbalance is, allowing you to more quickly and easily troubleshoot your parts.”
At the Medical Injection Molding Workshop, Rottinghaus’ presentation aims to provide attendees with a better understanding of why balance issues occur us and how best to address them from a systematic and scientific approach.
Faster process validation will also be covered at the workshop.
Modifications to the common core pin can be a simple solution, but don’t expect all resins to behave the same. Gas assist is also worth a try.
It may seem like a dull topic, but it will overcome the emotional experience that follows when you put a new mold into a machine and you find out there is not enough barrel capacity to make a full shot.
Start by picking a target melt temperature, and double-check data sheets for the resin supplier’s recommendations. Now for the rest...