Design for Manufacturability (DFM) in plastic injection molding is a strategy that ensures efficient, cost-effective, and high-quality manufacturing by addressing potential design issues early on. It minimizes common errors like inconsistent wall thickness, inadequate cooling channels, and poor material selection.
In plastic injection manufacturing, the quality and effectiveness of the final product rely on various elements of its design. There are countless variables that one must take into consideration to design for manufacturability (DFM). These include the viscosity of the plastic resin, the de-molding process, or a specific surface finish for the product.
Only hands-on industry experience can shave off valuable time from the early design stages and resolve quality issues that could complicate the manufacturing process. But what is DFM manufacturing and how can an expert plastic manufacturer help
There are countless benefits to dedicating adequate time and resources to a thorough design and simulation phase. In order for plastic molding manufacturing to be as efficient as possible, you’ll need to have strict guidelines in place. Otherwise, potential issues could pile up down the line, each requiring its own time and effort to properly resolve.
The role of injection molding experts and their extensive knowledge in the field is to predict and mitigate problems that are likely to occur. That’s because, at a later point in production, delays are much more costly to resolve with less time to spare to the agreed-upon manufacturing deadline.
With decades of experience designing custom plastic injection molds, Kurt is an expert mold designer at Crescent Industries. He has coordinated with manufacturing personnel on mold design, and worked with research and development personnel to execute and implement new injection molding processes.
In our constant pursuit of industry excellence, we’ve interviewed Anderson to explain some of the injection molding issues that can be identified and solved with DFM.
"One issue that we see over and over again is the thick areas of the part. Injection molding requires a part that has a nominal wall thickness. If there are localized thick areas of the part, during DFM we can see the problems that would result from that thickness. One such problem is sink marks. Another is longer cycle times, as it takes longer to cool those areas. And in severe cases, we can have deformed parts that end up failing our quality inspection," said Anderson.
Draft angles are also a highly sensitive and crucial part of the mold. If made improperly, you risk causing damage to the part of the mold during the ejection process.
"Sometimes it’s a requirement that there be texture on the part, and the texture also could be damaged if we don't have the proper draft."
Fortunately, there are plenty of tools for testing part design during DFM that help cut down on potential issues, including prototyping and mold-filling simulation software.
"We take existing parts that have been manufactured, load them directly into the software, and we can simulate the entire injection molding cycle. In doing that, we can see any potential issues through the simulation, such as sink marks, voids, high pressures, and high temperatures. We can even see ahead of time if there's going to be excessive warpage on the part."
The simulation can also be used to develop a robust process that your injection molding partner can use when setting up the mold for first-time use in the press. DFM covers many injection molding manufacturing needs and helps identify numerous issues and possible solutions before the mold goes into production.
Plastic molding injection design is part of a sequential manufacturing process where each step depends on the ones preceding it. A simple error in the early design stages can result in a plethora of quality and functionality issues.
Working with injection molding experts can help you evade some of the most common DFM pitfalls, such as:
An ideal mold would result in uniform wall thickness throughout the plastic material. However, inconsistent wall thickness can increase risks of other plastic defects such as flow lines and warping of the material.
Any intentional change in thickness should be smooth and gradual, with the thicker parts set closest to where the plastic resin passes into the mold cavity. The use of a fillet or chamfer in the injection process can also help eliminate the risk of inconsistent wall thickness.
Drafts are necessary for properly aligning the walls of the mold, allowing for easier separation and removal of the product after curing. With shallow and insufficient draft angles, you risk the part being stuck in the mold or damaged during ejection.
"For any injection molded part to work properly, we need to have a proper draft, so that the part can be ejected from the mold. If that’s not present, we could have damage as the part is being ejected."
Mold design should depend on the type of plastic material you’re going to be using. That’s because some polymers are more likely to "stick" to the mold, especially with designs like internal threads with feathered edges. This is especially the case for glass-filled and high-temperature plastic materials.
Cooling channels facilitate uniform and efficient cooling of the molten plastic material while inside the mold. Poorly designed or inadequate cooling channels could lead to shrinkage or deformations throughout the part. Not to mention, cooling takes up around 75% of the cycle time and can disrupt the production line if not properly controlled.
Some plastic parts need to be cast separately and then assembled post-ejection. The design can greatly simplify this process by including fastener holes and self-mating features in the mold itself. DFM can also minimize the overall number of parts, making assembly as efficient and waste-free as possible.
When designing for multi-part products, it’s crucial that all the parts are made with consistent tolerance all over. Otherwise, you risk designing parts that may fit too tight or too loose together, further complicating the assembly process. This can also possibly affect the quality and functionality of the final product.
Neglecting to collaborate with other departments relevant to the manufacturing process could result in parts that are over-budget or designs that aren’t made with the target client in mind. Early and continuous collaboration helps identify potential issues before they become costly problems, ensuring a smoother path to production.
The first step towards successful manufacturing is working with a partner that understands your injection molding manufacturing needs: from early design to finishing touches. As one of the leading plastic injection manufacturers in the US, Crescent Industries can help you implement DFM into your production pipeline.
We’re an employee-owned plastic injection molding company, proud to be a single-source solution for all your custom-molded components. Our expert engineers put their knowledge to work as they design for manufacturing a wide range of commodity-grade resins and plastics for the medical, pharmaceutical, dental, defense, and industrial markets.
You can learn more about DFM’s use cases for Original Equipment Manufacturers (OEMs) in our ABCs of DFM user guide.
DFM optimizes product design to ensure efficient and cost-effective manufacturing processes.
DFM helps prevent costly production issues down the line. It also ensures high-quality and easily manufacturable designs.
DFM involves identifying potential manufacturing issues, optimizing design for efficiency, and ensuring the final product meets quality standards.