DURABLE MOLDS & MINDFUL MODIFICATIONS
What Is Mold Design and How Does It Work?
In an era of unprecedented change for businesses, there is now a wide range of design techniques available for small scale and mass productions.
You can design projects in 3D modeling software to get a physical model within a short time. Several connections need to be made between mass production and prototyping techniques.
Understanding the process and requirements can save time and resources.
What Is Mold Design?
Mold design is the refinement, analysis, and the design of molten polymer materials for industrial manufacturing. These designs have a significant impact on the quality of your product.
When considering the production of a new plastic injection mold, the design is a critical part of your decision making. Here are some of the key considerations:
- The Shape:
The shape of the molded parts determines the time cycle of the process. For instance, deep screw threads and undercuts require extra moving parts. During the molding process, the cycle time increases.
- Angles:
On the sidewalls, angles have to be included to make the parts easy to remove from the mold.
- The Surface Finish:
You can boost the aesthetic qualities of your design by etching, embossing, and introducing other finishes.
- Cavities:
The number of cavities is a function of the number of units produced per annum. In turn, the unit cost of the mold is affected. The cooling system should cool the inner and outer cavities at the same rate to prevent the occurrence of molds with differing dimensions.
- Weight:
The thickness and the surface area of the mold influence the cycle time. If your plastic injection mold has varying thickness, ensure that the cooling is carefully controlled to prevent the formation of depressions. Sinking marks on the outer surface of the design results from excessive shrinkage of the thick areas.
- Points:
Every plastic injection mold requires a point where the plastic is introduced into it. Should you fail to consider this at the start of the process, the surfaces may have blemishes requiring a different removal process and extra cost.
How Does Mold Design Work?
Before designing your part, you must have the following items:
- A fully developed component drawing
- Material specifications in terms of color and grade
- Estimating details specifications of the tool, including the number of impressions, type of mold, runner system, gate, de-gating method, estimated cycle time, and the use of robotics.
Do not be tempted to start a design before specifying important details. Should your established design work, you do not have to design a new one. Base your new design on the established one. If you have molded a similar shape before, did the tool run satisfactorily? If it did, use the design as your basis. Things you need to consider are the parting line, the gate, part to eject, and if venting will be necessary.
The Parting Line
If in your design process you get the parting line stage wrong, the whole design will be negatively affected. The majority of the part should be on the ejection side.
If there is too much component in the ejection half, it may remain on the side of the tool whenever it opens. In order to be ejected, the component should stay on the side of the tool each time it opens.
Gating
The resistance at the gate may be high if the gate is small, which would then result in defects. This is because there would be an increase in the resin's shear heating. If the relationship between diameters and the hole are important, a two-plate tool may not work for you.
The reason is; trying to gate from the side may lead to differential warpage and shrinkage as a result of the uneven length of melt flow. A hot runner or three-plate tool may be more viable in that case.
Ejection
Ejection can be done using a stripper plate, pins, or sleeve ejectors. If there are the options of sleeve ejection or stripper plate, avoid using pin gating. If the area to be ejected is small, then better ejection support would be achieved with sleeve ejection or stripping. Slender pins may deflect in the tool leading to premature breakage or wear.
So, how should you choose between the other two options in your project? The primary factor should be the size and shape of the part of the tool to be stripped.
Venting
If air enters the cavity, it will be forced to escape through the parting line. Should the melt go beyond this point, it means that there is no exit path for air to escape. The air may then be trapped, causing the part to burn.
Understand that the pattern will depend on the injection speed, the size of the gate, the tool pressure, among others. Be sure to provide a route where air can escape.
The Basics
Designing plastic parts can be complex and involves many factors in the application process. First, determine how the parts are to be used, how it fits other parts during assembly, and the processing issues involved.
How the molten plastic fills and cools influences the form the features must take. Molding is used to create many things including containers, automotive interiors, and electronic housing, among other things. During the manufacturing of plastic parts, plastic injection molding is often preferred.
At Bennett Plastics we focus on developing customer partnerships to solve all your plastic injection molding needs. We are a 3rd generation family-owned plastic injection mold company and experienced staff. We understand that the accuracy and success of a molding project boils down to the use of quality products. For this reason, we offer you competitive pricing, utmost quality, sustainability, safety, and partnership. From the basic concepts to the final project, Bennett Plastics strives to manage your design, molding, and tooling requirements to achieve optimal solutions.
Please do not hesitate to contact Bennett Plastics to learn about our plastic injection mold manufacturing services!
Please do not hesitate to contact
Bennet Plastics to learn about any of our manufacturing services!