Published 1/6/2022

Hot Runner, Mold Component Partnerships Lead to Innovative Mold Designs

Formula Plastics takes on tooling via sister company Formula Tooling using dedicated partners, 3D modeling services and highly trained engineers to develop advanced mold designs.

Edited by: Christina Fuges

Editorial Director, MoldMaking Technology

Formula Tooling

Problem: Projects require high molding machine investment and are yielding long cycle times, balancing issues, labor concerns and material waste.

Solution: Use of automation, manifold, micro nozzle and slide technology solutions.

Results: Naturally balanced fill, and reductions in required press number/size, cycle times, changeover times, waste and manual labor.

Formula Tooling’s Managing Director Ruediger W. Kuemmerle joined the company in early 2020 with a resume of building several successful businesses and 16+ years of tooling, molding and product development experience in Germany, China and Mexico.

To develop innovative solutions for customers that improve sustainability, increase production efficiency, improve process repeatability and stretch the boundaries of physics, he brought together an international team of experts—Kunstoff Institut Luedenscheid in Germany, Ewikon Hotrunner Systems, AHP Merkle Hydraulics and CUMSA standard mold parts.

Ruediger trains a young engineer on a two-component medical mold with an integrated index plate.

Partnerships and Problem-Solving

Kuemmerle believes that the key to Formula Tooling’s success is working with dedicated partners, 3D modeling services and highly trained engineers to develop advanced mold standards. Here are three examples of successful partnerships leading to innovative customer solutions:

1. Two-component (2K) nose cap included a metal insert and unscrewing cores. Previously, the team manually inserted the metal insert into the injection molding machine, overmolded it with a hard material, then manually transferred the parts to another injection molding machine, repeating that process for the final overmold with a soft material. As a result, to reach the annual volumes, it required six injection machines.

Formula Tooling fully automated the process for making this two-component metal insert and unscrewing core, reducing the number of injection molding machines from six to one.

Formula Tooling was able to substitute the six injection machines with only one fully automated injection/production cell because of the specific mold design, a high-tech hot runner solution from Ewikon and a 3D-printed end of arm tool (EOAT) from Savage Automation.

2. An electrical plug connector whose existing eight-cavity cold runner mold required removal from the press to change the part version/configuration. There were 12 different pin configurations to manufacture with only one mold. Formula Tooling replaced this mold with a full hot runner four-cavity mold, eliminating the runner, material waste and labor needed for removal.

Using innovative hot runner valve gate technology eliminated runners for these electrical connectors.

This new mold design eliminated the need for a full day to remove the entire mold from the press to change the plug connector version. In addition, a new orientation of the part within the mold now accommodates part changes on the fly with specially designed slides that allow the operator to change the plug part version on the machine in minutes. For this application, two molds (one for male connectors and one for female connectors) now create the 12 different parts with the runner eliminated—reducing cycle time by 32% and version changeover time from six to seven hours, to six to seven minutes.

3. A medical test plate with 384 individual microwells comprised of two different materials. The part requires over 9,000 controlled dimensions. The most challenging aspect was creating a naturally balanced runner for the second material with 384 individual gates that are the size of the palm of your hand.

This two-component life science test plate has 384 individually gated wells and more than 9,000 dimensions.

The existing process used a solid runner plate requiring high injection pressures, longer cycle times and significant balancing issues yielding high scrap rates. Formula Tooling worked closely with Ewikon to develop a hot half containing a manifold with 24 custom-made micro hot nozzles in a 4 x 6 orientation per cavity, totaling 48 tips. This stretched the boundary of physics as the nozzle pitches (the distances between the hot nozzles) were so small that the plate on which they are mounted resembles Swiss cheese.

The Formula team used FEM (finite element calculation and simulation) to determine the required plate thickness to ensure no bending or cracking under the injection pressure and thermal expansion. Kunststoff Institut Luedenscheid did the runner designs and the mold flow simulations with the actual solid melt and not just the part surface grids. The new solution reduced scrap rate to almost zero, required less injection pressure, allowed a smaller machine and resulted in a 100% naturally balanced fill.

It's All About Time and Talent

Kuemmerle also introduced new innovative processes and standards that enable the company to deliver tools in less than half a typical build. To accomplish this, Formula Tooling performs standardized design for manufacturing (DFM) studies and feasibility studies with a 24-hour turnaround time. The same applies to 3D mold designs, as the company has a comprehensive library of standard template designs used as a starting point. As a result, full multi-cavity production molds that might typically take 16-20 weeks in production can now be delivered in only six to eight weeks. In addition, single-cavity pilot tools are made for complete process testing and melt flow analysis for part quality.

Formula’s in-house engineering staff and tooling partners both have teams of high-level engineers and university graduates. This engineering expertise helps develop the company’s advanced mold design standards that solve customer challenges such as eliminating springs within a design, interchangeable cavity and core blocks on high-cavitation molds and a fail-safe system on their valve gated hot runner systems to protect the needles.

The Result of Coming Together

Formula Tooling recently built 13 molds for COVID-19 test plates in just 4.5 weeks—from the initial kick-off to the first mold trials—and achieved full validation in only eight weeks. These test plates contributed to more than 500 million COVID-19 tests.

“We did something nobody else thought was possible,” Kuemmerle says. “It included some very long days and nights and could only happen with a group of dedicated partners and preferred suppliers who we have worked with for over 15 years. All of them went the extra mile for this project in the fight against COVID-19. We used Microsoft Teams for constant communication and collaboration. We threw as much labor into it as we could. We had almost 30 engineers and CNC programmers working in three shifts around the clock on the manufacturing drawings and machining programs in the first days. But, once we completed the design, we put the full power of our machining capacity to work.

“The 13 molds required 2,496 individual cores that were manufactured on five CNC lathes and at the same time, 26 cavity blocks and 26 core blocks were machined on six three-axis high-speed milling machines. We did all of the EDM on 14 high-quality mirror EDM machines from Switzerland, Japan and Taiwan.”

According to Kuemmerle, these EDM machines employ special technology and additives in the dielectric fluid, helping to create highly polished surfaces that resemble a mirror, eliminating the need for additional polishing.

“One of the huge advantages of our long-lasting relationships with partners around the globe is that we can upscale almost immediately and unlimitedly. This is a perfect example of what can be done when people come together,” he concludes.