In the quest for faster cycle times and better parts, 3-D technology that tests the performance of a mold configuration before it is built is helping some medical molders get the process right the first time.
Virtual molding also is used by silicone and natural rubber molders, according to Matt Proske, vice president of Sigma Plastics Services Inc., which is based in Schaumburg, Ill.
The two customer bases make up the early users of Sigmasoft Virtual Molding, but designers and manufacturers of technical plastic products and tools in other industries like automotive and electrical are interested in how their operations might benefit from technology for the production floor.
Proske had a full audience when he talked about ways virtual molding can help injection molders overcome challenges at the Manufacturing Association of Plastic Processors benchmarking conference in Indianapolis on Oct. 17.
Virtual molding reproduces the entire injection molding process and all of its complex interactions over several cycles to show possible part defects and process inefficiencies. For about $4,000, the molder can visualize problems as they occur, understand the root causes and find solutions.
The latest technology, which Proske likens to a 3-D heat flow system, gives process engineers information about how to pack a part, get the right shapes, know where heat builds up, see what areas solidify earliest and latest, figure out if there will be part shrinkage or sink marks, and more.
“If we have hot spots in the mold and we can't change anything from a part design perspective, then we're going to have to do it in the tool design,” Proske said. “We want the tool maker to know that on the first day.”
Different solutions can then be tested, like putting in vents, gates and inserts, changing the mold material or wall thickness, and adding cooling lines.
“We can talk to customers and say, ‘We're going to have sink marks here and they're going to look like this. Is that going to be acceptable or not? If not, we might have a higher tool cost because we're going to have to put in some kind of insert or water cooling to control this.'”
The goal is not only first-shot success but to improve the way problems are communicated, shorten the learning curve on new products, and predict cycle times.
“If our target fill time is a half second then I want to make sure my gate size if big enough that I can fill it in 0.4 seconds,” Proske said. “I want to be able to fill it faster if I really have to because we will try to push cycle time even further and we'll try to take it out of filling and cooling time.”
After working 16 years at a die cast facility earlier in his career, Proske said that industry operates very differently from the plastics industry.
“They don't build tools and then try to find processes and keep making changes to make good parts. They haven't done that for probably 5 or 10 years. They're getting first-shot successes,” Proske said. “I know we can, too. Polymers are little more complicated. They're chemically more complicated but there still should be better ways to do these things.”
He said Sigmasoft, which currently has about 700 materials in its library, has a good track record: “Ninety-five percent of the time you'll be 90 percent right.”