Designing solutions for medical device OEMs is the expertise of Moldworx LLC, a Gilbert, Arizona-based custom designer and builder of molds, automation solutions, and custom molding. The company’s latest innovation is automating the production of hypodermic needles using the overmolding process to reduce costs and improve productivity. Moldworx perfected the design and building of molds to inject medical grade plastic around stainless steel needles as small as 0.012 in (0.305 mm), as well as the automation for this project.
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Moldworx was asked by a medical OEM to develop a single cavity injection mold to overmold a needle that is currently being glued in place. The first stage involved designing and developing an A-Series, single cavity injection mold with slides, with the needle being hand-loaded into the mold by an operator then molded to a finished assembly to test the design.
“This allowed us to overmold the needle eliminating a step in the current manufacturing process and reduce overall production time and cost,” said Moldworx President Jim Taylor. “We encountered some unique issues in the process, including the additional challenge of making this all possible in a horizontal press, not a typical vertical press.”
The next stage was designing a production mold and automation that would robotically feed the needles into the mold cavity, thus eliminating the operator. “We designed the mold to integrate with the automation and the automation to work in unison with the mold,” explained Taylor. “In an effort to accelerate the timeline, the entire automation cell was built in parallel with the mold.”
One challenge that Moldworx had to overcome was singulating thousands of delicate, tiny needles that are bulk-packed. To do this, Moldworx designed and developed a “singulator” with a “hopper” that would introduce one needle at a time to the assembly line cell. Each needle is picked up with a robot affixed to the injection molding machine and indexed in front of a set of high resolution inspection cameras to insure it was not bent or the needle tip was not damaged, which would cause the needle to be rejected.
The needle is then placed into the mold, the mold closes for the injection cycle. When the mold opens the robot removes the molded assembly and places a newly inspected needle into the mold. All these actions require inspection and verification, and tolerances must be exact. The motors and controls used in the automated cells are of the highest quality to insure precision of the process.
After successfully completing the single-cavity mold and automation, with our customer testing and approving the parts, Moldworx built a multi-cavity mold with the required integrated automation cells. The 4-cavity production mold will quadruple the automation cell production to keep up with required demand.
“This is a prime example of the benefits of working with Moldworx,” said Taylor. “We partner with our clients to deliver innovative, automated plastic injection molding manufacturing solutions.”
