Making quality products requires a proper understanding of the processes. This statement applies to all the processes encompas in rapid prototyping, such as CNC machining, injection molding, 3D printing, etc.
Injection molding is a process with unique mechanisms. We will break it down and talk about it. This time we say it’s about some mold design and therefore requires a good understanding of injection molding design guidelines. Injection Molding Design Guidelines That You Can Use in Your ProjectBelow are some injection molding guidelines that you can use in your project.
1.The Importance of Uniform Wall Thickness in Injection Molded Parts
With wall thickness changes, there can be a sudden change in the direction and flow rate of molding, which can cause defects like sink marks and flow lines. If the molding process is done with the wrong gate, it is almost impossible to correct the resulting consequences during the forming process. Also, regardless of the position of the mold gate, it is possible to cause poor molding.
The design of the injection molded parts should be appropriately considered as rounded corners ensure even wall thickness that improves the melt flow around a corner. It also increases the strength of the molded part.
Plastic parts should consider uniform wall thickness when designing injection mold parts. Ribs are also ideal for improving plastic parts’ wall thickness and durability. The uniform wall thickness of a mold vastly affects its structural design.
2.Reasonable design of Ribs
In injection molding design, the cross structure is the best because it can handle many load arrangement changes. Therefore, a properly designed cross structure that can withstand everyday stress ensures a uniform distribution of stress across the article.
The nodes formed at the intersection represent the accumulation of material. However, you can hollow out the node’s center to prevent problems. You must note that material accumulation does not occur where the intersection intersects the edges of the component.
3.Types of Injection Molds
Below is an extensive discussion of the various types of plastic injection mold you can use.
Single Cavity Injection Mold
A single-cavity injection mold has only one cavity. Therefore, it can only produce a single component per injection cycle. You should incorporate the single cavity injection mold into your plastic molding guidelines if you deal with small production.
Advantages
1.It has a lesser cost than a multi-cavity injection mold
2.The mold is easy to design and manufacture
3.There is better control of the injection cycle which improves the parts’ quality
Disadvantages
It has lower productivity.
Multi Cavity Injection Mold
A multi-cavity injection mold has more than one cavity. Therefore, it can only produce multiple components per injection cycle. You should incorporate the single cavity injection mold into your plastic molding guidelines dealing with large production.
Advantages
It has a lesser cost per unit.
It has higher productivity.
Disadvantages
The mold is hard to design and manufacture, which increases lead time
Higher cost of manufacturing a multi-cavity mold
Family Mold
A family mold has more than one core and cavities for producing different parts. Therefore, you can mold separate components in one injection cycle.
Advantages
It has a lesser cost of manufacturing parts
It has a high productivity
Disadvantages
The mold is hard to design and manufacture, which increases lead time
Higher cost of manufacturing a multi-cavity mold
Male and Female Injection Molds
Molds that you can utilize in injection plastic mold design can also be of two types, male molds and female molds. In male molds, the thermoplastic sheet is located over the mold; in female molds, the thermoplastic sheet is inside the mold.
Male molds are generally applicable when the inner dimension of the plastic part is a priority, and Female molds are appropriate when the part’s outer dimensions are more critical.
Male Molds
Less expensive than female molds
Parts formed over a male mold retain the color and texture of the extruded sheet better.
Require greater draft angles than female molds
Male (concave, fixed) mold (exhaust groove)
Female Molds
More expensive than male molds
Can produce highly detailed parts
Used for production of the exterior surface of the finished parts
The inside corners of a female mold could be tight
Female (convex, moving) mold
Two Plate Mold
The components of a two-plate mold include movable side mounting, a backing plate, a support plate, movable side formwork, fixed side formwork, a fixed side mounting plate, a positioning ring, a runner bushing, guide bushing, guidepost, a return lever, and an ejector bottom plate.
Three Plate Mold
The components of a three-plate mold include movable side mounting, a backing plate, a support plate, movable side formwork, fixed side formwork, a spore splitter plate, a fixed side mounting plate, a positioning ring, a runner, a runner bushing, a guide bushing, guidepost, a return lever, and an ejector bottom plate.
Conclusion
Mold design is a critical production process, indicating the beginning of injection molding. Hence, it is essential to understand what you need and how to proceed with the process.