【174】Medical Device Failed Four Mold Trials – Fengchuang Breaks the Deadlock with a Small Order

【174】Medical Device Failed Four Mold Trials – Fengchuang Breaks the Deadlock with a Small Order

Keywords: Fengchuang Plastics medical devices parts and components sample making

Xiao Chen is a structural engineer at a medical device startup in Suzhou. His company had developed a portable electrocardiograph (ECG) device with a tightly packed housing design and complex internal geometry. He approached four injection molding shops for mold trials — and all four failed.

The first shop: the part deformed during ejection. The second shop: the snap-fits broke. The third shop: dimensional deviation prevented the PCB from fitting inside. The fourth shop said bluntly, “Your design can’t be mass-produced. Change the structure.” But the design was already frozen. Changing the structure would mean redoing regulatory testing — at least another three months.

Xiao Chen posted one sentence in the company group chat: “The housing failed again.” The boss replied with an ellipsis. Xiao Chen could read the disappointment in those three dots. He began to doubt his own design skills. He couldn’t sleep at night and was still reading injection molding resources at 3 a.m.

Later, he met someone from Fengchuang Plastics at a trade show. After hearing about his predicament, the person said, “Send us the drawings.” Xiao Chen sent them over. An engineer from Fengchuang called him back at midnight: “We’ve seen this problem before. You’ve chosen the wrong gate location. The thin-wall area of your product is at the end of the flow path — by the time the melt reaches there, there’s no pressure left.”

Fengchuang’s solution was threefold: move the gate from the end to the middle, so the melt flows outward in both directions and the thin-wall area is no longer at the end; add a set of auxiliary ejector pins to solve the ejection deformation; and implement zone-controlled mold temperatures, with separate heating at the snap-fit locations. All three modifications required no change to the product structure.

Xiao Chen presented the plan to his boss. The boss said, “Let’s try. We have nothing left to lose.” Twenty-two days later, the samples arrived. Xiao Chen tested the snap-fits with a tool — crisp clicks, ten consecutive times without failure. He fitted the PCB — a perfect match. He ran aging tests: 72 hours at room temperature plus 24 hours at elevated temperature — the housing remained intact.

Xiao Chen posted on his WeChat Moments: “I almost resigned after the fourth shop failed. Thank you, Fengchuang, for saving my project.” Today, that ECG device has obtained its registration certificate, and Xiao Chen is working on the second-generation product — the molding proposal went straight to Fengchuang.

Failed medical device mold trials? Fengchuang breaks the deadlock on a small order. No product structure changes — only mold modifications — and first-try success.