Injection molding is a widely adopted manufacturing process for producing different parts by injecting molten material into the mold. Most of the time, thermoplastics or thermosetting plastics are used as raw material heated in the barrel unless converted into a molten form. Then the molten material is injected into the mold. Concurrently, micro injection molding is also a manufacturing process that uses the same procedure. The products formed with this method weigh from 1g to 0.1g with tolerances ranging 10-100 microns. Micro molding is typically mainstreamed to accomplish the manufacturing of complex and microscopic geometries. 

Why Is Mold Design the Key in Injection Molding?

Amid several other portions of the injection molding process, the design of the mold carries primary importance. From the quality of the final product to the costs incurred in the process, everything is related to the mold design. To ascertain the veracity of mold design, here are some of the points that relate to its importance and demonstrate how a perfect mold design reduces the cost of injection molding: 

1. Shape of the Molded Parts

The shape of mold directly influences the final product in an injection molding process. The barrel injects molten material into the mold, and the molten material gets cooled and adopts the shape of the mold. If the mold shape offers malfunctioning at some point, the molded part will also have flopped as a waste part adding to the costs of the process. Thus, an accurate and perfect mold shape can significantly reduce the chances of wastage. The manufacturing process may remain free from extra costs that needed to be acquired to balance the waste products. 

2. Angles 

Angles of the molded products are key factors determining their quality. In case of any setback with the angles of the mold, the final molded part might go unexploited. Typically, the angles of mold design are related to the designing and manufacturing of the mold at CNC. Consequently, if angles are correctly designed and shaped in these two steps, the final molded part will also be fine to use; otherwise, it might need to be squandered, leaving the process uneconomical.

For example, when the draft can get angled toward the core/cavity, affecting parting lines, fits between parts, tool configuration, and cost. Considering these subtleties during the development phase ensures the design is optimized for minimum expense and ideal performance.

3. Surface Finish 

The final molded part is an accurate depiction of the quality of the mold design. Whether it is the shape of a molded part or the surface finishing of the final product, each factor is associated with the mold design. If the surface of the mold is rough, the molded part might not be able to be sold in the market. Meanwhile, generating a texture on the mold surfaces makes the surface of the molded part consistent and has implications on part design. To generate mold surfaces and different textures, they can be CNC machined, EDM’d, or turned.

4. Weight, Surface Area, and Thickness 

The molded parts are readily defined for their weight, surface area, and thickness. All these factors are associated with the mold design. While the mold design is under the designing process on modeling software, the weight, surface area, and thickness of the final molded parts are defined.

If any of these factors mentioned above are not adequately met in the mold design, the final molded part might not match the calculated amount spent to achieve the final product. E.g., if the thickness increases in mold design, the consumption of molten material will also increase. Likewise, consistent wall thicknesses will offer the best flow. The minimum recommended wall thickness is 1 mm, reaching a maximum of 4 mm for conventional molding processes.

5. Number of Cavities

The number of cavities defines the number of molded parts attained in a single shot. It is directly associated with the mold design. For instance, if the size of the molded part is small, the number of cavities will be more significant. The reported number of cavities is from 1 to 216, which is the highest number. The greater the number of cavities, the more economical the process will be. However, the angles, surface finish, and shape of final molded parts must get ensured. 

6. Location of Gates 

The location of injection molding gates directly affects the quality of the finished product. That is why in the final mold design, the gates should be away from pins, cores, and other internal obstructions; otherwise, it may cause weld marks on the surface of the molded piece. Inarguably, if the location of the gates is not accurate, the consumption can increase. 

Conclusion

The global market size of the injection molding industry was $139 billion by 2018, expected to reach $233 billion by 2023 with a CAGR of 10.9%. In the interim, the injection molding industry directly relies on mold design. If the design is up to the mark, the product will prevail in the market. Similarly, mold design is a leading factor that defines the quality of the final molded part.

The perfect mold design also ensures the proper investment of money while bringing the wastage to the lowest level. Existing prototyping techniques such as 3D printing consider early testing of design ideas where the whole part can be modeled before constructing costly tooling.