Images courtesy of MTD Micro Molding
Molding projects sometimes don’t go as planned. Design-to-manufacture transitions might take longer than expected, projects may exceed budgets, production parts may fail testing (or worse, in the field), and sometimes a design simply can’t be molded and you’ve got to go back and redesign.
Lindsay Mann, director of sales and marketing for MTD Micro Molding, tells MD+DI that a common request over the years has been to figure out why another molder couldn’t execute a customer’s design successfully. This can be particularly troublesome for startups with limited funding.
“Most pitfalls and roadblocks can be overcome by fully understanding the edges of success and failure for your design, knowing what specific technology expertise is required to bring your design to life, and consulting your selected molder early in the process,” she added.
Transparency is important for successful collaboration, especially for startups. “They are looking for manufacturing experts to get it right the first time,” said Mann. “Medical device companies are looking for a manufacturer who is not learning on their dime or their watch, so experience is key. Molders need to show evidence of their experience molding the desired material and molding complex geometries like theirs (i.e. thin walls, sharp points, small thru holes, exotic materials).”
There are some steps startups can take before giving up on molding a particular design. Mann shared the following:
- Get a second opinion. “Bring your grand ideas to your molding partner and discuss your wish list for your design(s). if you are told your design is ‘impossible,’ it may not be you, it might be your molder.”
- Consider a different material. “Allow your molder to help reduce costs by assisting in the process of material selection and creating a customized plan for achieving validated production.”
- Ask to view part samples from prospective molders. “When requesting quotes for a micromolding project, ask molders to show similar examples of parts they have created that are similar to your design.”
There can be some challenges with micromolding to keep in mind when re-evaluating a design or looking for a new partner. “The challenge lies in the ability to hold tight tolerances and provide to them the most 3D-CAD-file-like product possible,” she said. “The key to being successful in doing this starts with the tooling design and ends with the molding equipment configuration.
“At the scale and level of complexity we work in, the tool construction needs to be broken down into building multiple inserts like a jigsaw puzzle to give us the ability to vent all of the thin features,” she continued. “The molding equipment is not off-the-shelf equipment. Extensive updates to the injection units are made in-house to achieve higher injection speeds and pressures that allow micro features to fill more effectively.”
Another challenge is that a lack of data is a big deal in micromolding. “It is important to understand this challenge—with a shortage of accurate information available, micromolding companies like MTD are forced to create our own rule book to be successful in micromolding,” Mann said. “The reality is that challenges that are experienced in the macromolding world are amplified in the micro world, and issues can be much more difficult to solve and can be far more detrimental to a project. It is crucial to partner with a molder that fully understands these challenges.”
So when should a company ask a mechanical engineer or designer to take a second look at a design?
“Reducing or refining the overall geometry is an obvious way to reduce manufacturing costs. For a micro part design, the molder can point out costly areas on a drawing to help facilitate a conversation about what changes can reduce manufacturing and piece part costs immediately or long-term,” Mann explained. “Basic changes on a drawing can usually result in a 5-10% overall cost reduction. Examples of small changes include changing a wall thickness, radius, draft, or small features in order to make the design less difficult and costly to manufacture.”
Along with such design refinements, molders can “help reduce costs by assisting in the process of material selection, creating a customized plan for achieving validated production, and offering solutions for minimizing material waste with tools like runner optimization,” she said.
However, Mann advises against approaching a molder with the following request for a critical part design: “’Can you redesign my part to reduce cost by x%?’ While this type of request will typically result in a revised quote, the molded product likely won’t resemble the intended design,” she explained. “The molder or manufacturer does not look at your design in the same lens as you do; they are assessing it from the manufacturability point of view. Your molder doesn’t have a comprehensive understanding of how this product is designed to perform, how it should function, or how it needs to mate and/or interact with other components in a device.”
There are a few complications that could sink a design. “Are you requesting ‘no flash’? Requiring extremely tight or challenging tolerances? Assigning a challenging gate location? If so, you may be causing your supplier to chase their tail to solve the problem – or you may be incurring a huge increase to budget and lead time.” Mann said. “Is it worth it? Sometimes simple drawing concessions can help. Inadequate material choice also frequently leads to manufacturing issues. There are polymers that demonstrate high compressibility, poor fill properties, poor long-term dimensional stability. Tight tolerances like +/- 0.001 in. may be difficult to achieve with these materials. Your design and drawing will dictate what materials can be used.”
In the end, you need a molder you can trust. “Go with the ‘true positive,’” Mann advised. “A molder that is open with concerns and can present options for manufacturing success should be more comforting than a molder that has zero concerns.”
But “don’t make assumptions.,” she added. “If you allow the molder to evaluate what is possible and realistic as a long-term molding solution, they can listen to your expectations and provide substantive feedback. Extremely difficult geometries typically require some kind of unconventional approach to the project in order to be successful. Having an understanding of the technology, experience, and knowledge required to create these complex geometries in plastic will help you save you time in your supplier qualification process.”
And don’t give up on injection molding, which Mann calls the most cost-effective process for higher-volume programs. “It is all about quantity. [It is a] cost-effective process for supporting higher volumes compared with processes like plastic machining and 3D printing. If you need a few to a few thousand parts, machining or 3D printing would be the most cost-effective way to achieve this. When a project demands volumes in the hundreds of thousands to millions of parts per year, injection molding is the most cost-effective manufacturing solution. The investment in a hardened steel production quality mold is high, but once this step is complete, a manufacturing process is established that can produce millions of parts every year, quickly and inexpensively.”
MTD Micro Molding had worked with a customer to calculate what it costs to have a project rescued. “This OEM had developed a concept for a bioabsorbable fixation device that generated excitement and positive comments from reviewing surgeons. Although the company worked with a reputable molder, after five years of labor the molder had limited success and could not produce the part represented in its drawing with sufficient quality,” Mann said.
So “after the five years, the OEM decided to cut its losses and start fresh with a different molder. When the OEM tallied its losses, the results were staggering. Factoring in an estimated one-year delayed market entry, the loss of potential product sales, the time unnecessarily spent in process development, and the cost of restarting their project with a new molder, the sum came to about $1.5 million.”
To help customers, MTD Micro Molding launched the Quick Launch program for companies that are “struggling with quality issues with a current molder or simply have a need to get a product to market very quickly,” she said. If they are “unhappy with their current vendor performance but worried they don’t have the capital to change vendors, this program can be a great help to keep the project moving forward.”
Mann said that if a project qualifies for the Quick Launch Program, there is no additional cost, and the program includes:
- Discounted tooling with volume commitments
- Lifetime tooling maintenance
For more details on molding, consult this whitepaper: https://mtdmicromolding.com/white-papers/design-for-manufacturing-breakthroughs/
Mann also provided the below checklist for further guidance: