Whether you’re an amateur mold designer or a professional, there are several things you should be aware of when designing an injection mold. In this article, you’ll find ten essential tips to help you build better molds.
Rounded corners
Using rounded corners in injection mold design & manufacturing improves the strength and durability of the parts. Rounded corners help keep the wall thickness consistent throughout the domain. This increases load-bearing strength and improves its handling. In addition, rounded corners prevent voids from occurring.
Rounded corners also prevent fractures in the molding process. They also help keep the part from warping. Rounded corners are also helpful because they improve the melt flow around the corner.
Rounded corners in injection mold design are usually created by using a chamfer. However, they may also be made by combining a chamfer with a corner radius.
Uniform wall thickness
Keeping the wall thickness of a plastic injection molded part consistent is vital for many reasons. Among the most important is how it affects the overall cost and quality of the finished piece. Therefore, it is a crucial consideration during the early design stages of a part.
Keeping the wall thickness consistent also allows for optimal processing and filling of the mold. Variations in wall thickness can result in an unbalanced filling pattern, air trapping, and weld lines. In addition to aesthetics, this can also harm part functionality.
In general, a wall should be no more than about 5mm thick. Thinner sections are easier to handle, quicker to manufacture, and less expensive to ship. However, thin walls also have a greater chance of breaking during handling.
Side-action cores
During injection molding, the cores are held by a hydraulic cylinder. Alternatively, pneumatic actuation may be used. These auxiliary actuation methods are cheaper and can be used for trim moldings.
It is possible to achieve full hydraulic pressure during injection. Compressed air above 80 psi is rarely used. This causes performance issues. A high-force side-action system should be used. This ensures an increase in cycle speed and improved setup.
The primary source of opening power for side-action cores is the pull block “3”. The pull block is a wedge-shaped cylinder inserted into the corresponding angled hole in the sliding insert block. It is then moved towards the core shut-off by the cam pin.
Ejector pins
During injection molding, ejector pins push a part out of a mold. They usually are located on the B-side of a mold half. The B-side half of the mold remains intact while the A-side half is lifted and ejected.
Injection molding involves injecting a liquified plastic into a steel mold. When the plastic cools, it assumes the shape of a metal mold. The part can then be ejected from the mold. In addition to ejector pins, the mold can have a gate, an access point for the molten plastic to enter the mold.
The ejection pin is positioned in a position that will provide consistent force to the part. In addition, the ejection pins must be placed on a flat surface. Ejector pin marks can occur if the nails are not placed on a flat surface.
Cleanout slots under the leader-pin bushings
Whether you’re building an injection mold, stamping die, or jig, you’ll need to use the appropriate components. Choosing the right parts is essential, as they can save you time and money. Here are some common mold parts and their purpose:
There are many different mold parts, some quite different from others. These include sleeves, interlocks, pins, and bushings. But before you begin your mold build, make sure you know what each of these components is and what purpose they serve. If you do, you’ll be satisfied and save time.
In addition to the components listed above, you should also take note of a few design tips. One of the more critical features to consider is the design of the leader-pin bushings. Using these correctly will help you maintain an airtight seal and prevent your parts from being glued together.
Surface finish
Choosing a surface finish for your injection mold design is an important design consideration. The right choice can make a big difference in your long-term success.
A surface finish can be added for aesthetic or functional purposes. For instance, a nice finish will improve the perceived value of your product. It also has the potential to mask imperfections in your product.
Several different types of surface finishes are available to you. The best way to choose a finish is to consider the intended use.
For example, a textured finish will hide imperfections and increase paint adhesion. It will also improve grip.
The best way to decide on a surface finish for your injection mold design depends on the material of your mold. For example, steel molds offer a more comprehensive selection of surface finishes than aluminum molds.
