There are a few features that will be commonplace in most or even all parts created through the process of plastic injection molding, and one great example here is known as the parting line. This line, which is created by two halves of a mold coming together, will be present in some form on all plastic injection molded products — but there are several other factors that help determine where the parting line will go and how prominently it will appear.
At EnviroTech Custom Injection Molders, we’re proud to produce high-quality plastic injection molding products for a wide range of industries, from medical equipment to food processing, electrochemical, defense and many others. What exactly is the parting line on such products, why is it necessary, and what are some of the unique part shapes or other challenges that may be at play here? Let’s look at a simple primer.
Parting Line Basics and Meaning
As we alluded to above, the parting line is simply the line on a plastic injection molded product where two halves of the mold come together during production. In other words, it’s the line that indicates where your mold was “cut in half” so that the two halves could be removed from one another and your finished product could be ejected.
While this line may seem like a fairly minor thing, it’s actually an important indicator of both the functionality and quality of your product. First, a parting line that’s not properly aligned or managed can cause issues with how your product functions. If the two halves of your mold aren’t lined up correctly, for example, you may end up with a product that doesn’t fit together as intended or that doesn’t function properly.
Conversely, a well-managed parting line can actually help improve the overall quality of your finished product. A cleaner parting line, for example, can indicate that your mold was machined more accurately and that your production process is running more smoothly. It can also make it easier to produce products with tighter tolerances, as there’s less potential for error when everything is lined up correctly.
There are a few other factors that play into the placement and appearance of your parting line, as well. The type of mold you’re using, for example, can have an impact – some molds are designed in such a way that the parting line is barely visible, while others may place it in a more prominent position. Additionally, the type of material you’re using can also be a factor, as some materials are more difficult to mold than others and may require a different molding process altogether.
Finally, it’s worth noting that the parting line isn’t the only line that will appear on your finished product. There are a few other types of lines that may be present, as well, such as mold flash or gate lines. These lines serve different purposes and aren’t necessarily indicative of any issues with your product – but we’ll leave those for another day.
Determining Parting Line Location
For many plastic projects, a key element will be determining precisely where the parting line should go. This decision will be impacted by a few different elements, including both the mold function and the part function.
For instance, some molds are designed in such a way that the parting line is barely visible, while others may place it in a more prominent position. Additionally, the type of material you’re using can also be a factor, as some materials are more difficult to mold than others and may require a different molding process altogether.
Part geometry will also come into play when determining parting line location. Some part shapes may lend themselves more easily to a certain parting line placement – and in some cases, multiple parting lines may be necessary to produce the desired shape.
Finally, the injection molding process itself can also play a role in where the parting line is located. Some processes, like insert molding, will require a specific mold design that takes the parting line into account.
Possible Parting Line Challenges
There are certain projects where the parting line will be a bit of a tougher consideration than others. A couple examples:
- Complex shapes: When the part being manufactured is complex in shape, it can be difficult to find a single parting line that will work for the entire mold. In some cases, multiple parting lines may be necessary – or, alternatively, a more complex mold design may be required.
- Tight tolerances: If the finished product needs to have tight tolerances, it’s important to ensure that the parting line is accurately placed. Any misalignment can potentially cause issues with the finished product.
- Specialty materials: Some materials – including certain types of glass or metal – can be more difficult to mold than others. In these cases, it’s often necessary to use a different molding process altogether, which may impact the parting line placement.
With the right injection molding professionals on your team, however, even the most complex parting line challenges can be overcome. If you’re having trouble finding a solution that works for your project, reach out to an expert – they’ll be able to offer guidance and help you find the perfect solution for your needs.
For more on this, or to learn about any of our quality injection molding or related plastic services, speak to the pros at EnviroTech Custom Injection Molders today.