Cycle time directly influences part cost and capacities, so keeping it as low as possible is generally the overarching goal of engineers and project managers. In getting quotes from various injection molders they may be confronted with divergent cycle time estimates, calling accuracy and the molder’s capabilities into question.

Customers count on their injection molders for expert advice. “Tight tolerance” is a term that is often tossed around loosely in the industry—however, if it’s not done right, parts and products will underperform or possibly fail, resulting in a tooling and/or process overhaul. Therefore tight tolerance is serious business, especially for complex, mission-critical parts.

Geometric dimensioning and tolerancing (GD&T) is a symbolic language that is used on engineering drawings and computer-generated models to communicate geometric dimensions and allowable tolerance for various parts. Not only is this a useful exercise for product design, it’s also helpful on the manufacturing floor because engineers and operators can quickly see the degree of tolerance that is required for each part.

While the injection molding process is a mainstay for many industries, it isn’t static. Molders are continually challenged with evolving their knowledge and use of emerging tooling technologies, materials and trends to make products that are competitively advantageous and profitable for manufacturers.

Critical-use medical devices are essential in the performance of important and often life-saving tasks. As such, they often boast complicated designs and functionality that require the expertise of a complex injection molder to produce. However, that’s only part of the equation.

Each new injection molding project has three inherent goals: performance for the customer; production efficiency for the manufacturer; and reliability for the end user. These goals are reasonable. The challenge lies in accomplishing all three within a desired timeframe and budget. To do so, plastics engineers at complex injection molders turn to Design of Experiments (DOE) to identify flaws that would otherwise derail project success.

The exact strength and flexibility of plastics can be easily determined with finite element analysis (FEA) techniques. The FEA process subdivides the product or part into finite-sized units of simple shape. Mathematical equations are used to test each unit for displacement, from which the stresses and strains can be calculated.

In broadest terms, Design for Manufacturability (DfM) — also known as Design for Manufacturing — is the process of consciously and proactively designing products to optimize all facets of manufacturing, including injection molding. DfM simultaneously helps ensure cost and time efficiencies, superior quality, regulatory compliance and end user satisfaction. Since manufacturing processes vary, there are set guidelines for DfM practices that define tolerances, rules and best practices.

The safety and welfare of military personnel is always a top priority, but sometimes that goal puts manufacturing focus on the end product instead of the process. In the case of engineering critical-use, injection-molded parts for military applications, the design holds the key to many benefits the end product will deliver.