Since July of 2022 we have pushed the limits of our new Mantle Beta additive manufacturing machine, worked with Mantle to improve the machine’s quality and efficiency, and completed numerous trials to identify ways to add value using this technology.
One of our greatest success stories is utilizing Mantle’s technology to quickly deliver production-representative parts for a medical OEM to complete biocompatibility and functional testing. This included molding over 7,000 pieces for development trials. We were then able to implement the lessons learned from our prototype mold build into a production tool, allowing us to save over 30% in design costs. Most of all, this tool had over 40 swipe-by shut off conditions, something we were concerned a printed technology wouldn’t be able to handle. Traditionally, this project would have required at least 8 weeks for manufacturing, requiring over 30 electrode shapes alone.
The project required over 40 swipe-by shut offs, a testament to its complexity. And with traditional means, it would have required over 30 electrode shapes for EDM with traditional methods.
THE CHALLENGE
A large medical device OEM needed production-representative parts quickly in order to complete biocompatibility and functional testing. Development trials needed to be completed before large-scale production could begin. Secondly, the complex part design included over 40 swipe-by shut off conditions, posing major risks to quality.
THE SOLUTION
Westminster Tool used metal additive manufacturing to quickly produce H13-equivalent, production-level cavities in a fraction of the time compared to traditional machining methods. By spending more time on risk mitigation upfront with the printed prototype mold, the customer was able to save over 30% in design costs for production tooling.
PHASE ONE: Production-Quality Prototype Parts in Under 4 Weeks
The first step was designing a prototype mold using MUD frame inserts and H13-equivalent printed cavities to replicate a production environment as quickly as possible. To do this, Westminster Tool used Mantle’s Trueshape Technology to print a top and bottom cavity. While the cavities were printed and sintered over 8 days, our team finalized a post-print machining strategy, ordered MUD inserts and began the insert modifications.
The cavities required 55 hours of post machining including the following:
- Grinding the bottom of the blocks to have a flat base to start from.
- Squaring the blocks to bring molding geometry to center using hardmill.
- EDM wiring ejector pin holes.
- Tapping water lines and bolt holes.
- Hard-milling and EDMing difficult swipe by areas (6 areas total).
These operations took an additional 1.5 weeks before we were ready for final assembly and molding: resulting in molded parts within 4 weeks. The parts had minimal flash, and all critical dimensions were within +/- 0.003”. The parts were then molded in batches for development and biocompatibility testing in two different materials. The first was an ABS and the second was a PC/ABS blend. Ultimately over 7,000 pieces were produced for the customers development needs.
PHASE TWO: Reviewing Lessons Learned
The first of several lessons learned involved warp and sink challenges. We were able to improve some of these by adjusting process parameters but not all. Despite achieving success for development testing, these remaining defects needed to be addressed in a production tool. While we waited for feedback from the customer, we began identifying root causes and mitigation strategies such as surface finish, ejection, and gating strategies for the production mold.
The prototype tools also gave a better understanding of how the material performed during molding. In particular, the part length shrank more than anticipated, thus moving a dimension out of tolerance. Traditionally, we would have suggested staying steel safe in this area to hit the tolerance adding additional cost and time. But based on the successful fitment of the prototype part into the assembly, Westminster Tool and the customer could confidently move forward with the current length.
CONCLUSION: Real Saving Opportunities for Production Molds
At Westminster Tool we complete a thorough design for manufacturing process for every production mold we build. This is heavily focused on risk identification and mitigation and accounts for about 20-30% of our design costs. By learning and understanding the prototype tool and the risk related to the part, we were able to remove most of these costs from our production tool build. In addition, we already had majority of the cavity stacks designed which saved an additional 10% of design time.
During the process of building tools, our pride comes from working towards real savings on the back end of the project. Most of the time, projects get hung up on the qualification phase of tools. Whether it’s learning the hard way, for example, that a material is shrinking differently than expected or dealing with a mechanical challenge, troubleshooting can unnecessarily add weeks to a timeline.
Our ultimate goal is that by getting involved sooner in part development, we can seamlessly transition a mold from qualification to production.
