When it comes to rapidly manufacturing injection molded parts, there are several key factors to consider. Here are a few of the top considerations to start off on the right track:

Design


All successful injection molding programs begin with proper design for the process, and in this case for rapid production. When designing your part for rapid injection molding, the most important factors that contribute to lead time are part size and complexity. Whenever a larger part can be broken down into smaller pieces and then assembled, you will potentially shorten lead time. This is because simple, shallow cavity designs are produced quicker via the CNC machining process. Designing parts that are moldable with a “Straight Pull Mold” is a great place to start. This requires that all the part’s features be designed so that when the two halves of the mold are pulled from each other and the part is ejected, there are no secondary processes required.  This is due to mold material’s tendency to pull through part plastic (this is referred to as an ‘undercut’.) Undercuts require mold pieces to pull out sideways, perpendicular to the direction of the pull. These ‘side actions’ as they are called can require ‘hand loads’ for lower volume projects or automatic/mechanical loads for higher runs.

Material


Ideal quick turn projects should utilize standard, off the shelf materials and colors that are either already on hand or can be quickly sourced from a material distributor. Generally, lack of need for name brand material does not cause issues, but this is not the case for all projects.  When a precise brand and type of material is required, the material can be ordered and shipped while tool cutting occurs simultaneously. Should the material not arrive within the allotted window, a substitute material can sometimes be used in place of the production material to, at the very least, confirm basic design and function of the part. Once production material arrives, a second sample run can take place before proceeding with higher production runs.

Cost


Of course when there is a lead time requirement for parts quicker than the standard, there are cost considerations. These considerations are driven by additional man hours required by the project up front and often result in overtime and extended shop hours to achieve the desired ship date. Those items that can be sped up? Things such as tool design, steel or aluminum delivery to the shop, part material ordering, and scheduling sample production runs.

It is important to remember that in many cases, all the money in the world cannot speed up certain processes. Cutting of the core and cavity, for example, is at the mercy of the almighty CNC machine. So while there are things within a tooling shop’s control, other things will always have a fixed lead time. This is why those factors mentioned become even more important to reduce the number of days to the finish line.