Eric Huang
Eric Huang is an Engineering Manager at Alcon, where he has been employed since January 2017. With over two decades of experience in the injection molding industry, he is committed to mentoring younger employees in molding techniques and fostering a culture that embraces challenges to achieve success. Huang earned his Ph.D. in mechanical engineering from the University of Maryland and completed his undergraduate studies at Zhejiang University.
Recognizing Eric Huang’s strategic leadership and industry expertise, this exclusive interview explores his approach to innovation, business transformation and the evolving industry landscape.
AT A GLANCE:
• Rigid adherence to standard fill-stage guidelines may overlook opportunities for optimization, as demonstrated by unexpected findings in optical quality.
• Process variations across different machines highlight the need to adapt and refine rules rather than follow them blindly.
• Open knowledge-sharing within the industry could drive innovation, improve yields, and enhance overall manufacturing standards.
Breaking the Mold: Optimizing Injection Molding Processes
In schools, we learned lots of rules and applied them to our daily work and most often, it worked. As an injection molding engineer, I learned lots of rules as well and it did a genuinely nice job, too. However, is it a “that’s it”? If we can always make good parts, sure, it is. In the medical device industry, we have a lot of plastic parts to make, and I guess that no one has ever made bad parts.
Rules aren’t perfect. To build better devices, we need to break them when necessary. And sometimes, in doing so, we stumble upon unexpected improvements
There will be two situations. First, we did not execute correctly; maybe we bottomed out our screws while trying higher holding pressures; perhaps simply just, the process was not stabilized. Second, our adapted rules may not be the best for your system. We just did not explore hard enough to find the optimized process.
When Less is More: The Benefits of Lower Fill Percentages
The fill-only part is a critical principle of plastic injection molding process development. Most experts will use 95 to 98 percent complete for the first stage filling. So, I started my process development in the same way. Then, I made a DOE with four factors: Injection Speed, Hold Pressure, Hold Time and Cool Time. As a company making contact lenses, the optical quality is paramount. For example, we will check the radius difference across our part’s sphere region, the smaller the difference, the better the quality. At a lower injection speed, we achieved the least R difference. I returned to weigh the fill-only parts, which were only at 56 percent. It was far off from the standard practice. Should I ignore this and stick with 95-98 percent fill? I have no hesitation with using the 56 percent fill, but I want to understand what caused that.
So, I pulled out the machine graph for the injection process and noticed something interesting. The injection pressure was 100 bar below the set hold pressure, so during the holding stage, the pressure kept increasing. If we fill at 95 to 98 percent, there is a pressure drop first, then an increase to the set point. That means the lower injection speed supplied a smoother transition of the pressure. And that is what we think has achieved the better optical quality.
Should we stop here? I intended to explore more profoundly and complexly. Then, I found another interesting phenomenon. We used a newly purchased precise machine with all kinds of controls. But I had a challenging time to make a short shot. I tried to stop the screw at the 18 mm position, but it went beyond that and stopped at the 10 mm position. The higher the injection speed, the more distance it moved. And this is much more than the other machines we used.
The takeaway? Rules aren’t perfect. To build better devices, we need to break them when necessary. And sometimes, in doing so, we stumble upon unexpected improvements.
Collaboration Over Competition: A New Path to Innovation
Nowadays, competition is intense, and each competitor tends to hide their secret technologies. What if we have more transparent conversations to exchange experiences? Would it benefit our customers? We may help each other improve our device quality, production yield, cycle time, etc. Then why don’t we just act? It may rely on a few leaders to change the industry, or it may be every one of us. Do we have the courage?
