November 8, 2022

As advancements are made across sophisticated industries, like medicine and aerospace, the requirements for tighter tolerances on plastic components have become increasingly necessary. Tight tolerance can mean something different depending on the molder, but it is generally recognized as ± 0.002 inches, and very tight tolerance is ± 0.001 inches.

Part complexity, material, manufacturing processes, and tooling all impact the tolerances that can be achieved. High-performance plastics offer many valuable benefits for complex and critical products that face harsh environments. Many of these resins excel at maintaining tight tolerances, even at high temperatures. High-performance plastics are excellent candidates for machining after molding, which allows the tightest tolerances to be achieved.

Quite simply, parts with proper tolerances will fit as they should, whether snapping, sliding, or pressing the parts together. Not all parts require tight tolerances, and finding the tolerance best suited for your application is important.

Tight tolerances are usually required for complex or critical parts, especially those used in higher-risk applications, such as for the medical or aerospace industries. Underperformance or part failure may occur if the tolerance is not met, which could have catastrophic results. For these parts, tight tolerance means fewer rejects and failures, and problems with mating during assembly can be avoided. In the long run, achieving the tolerances required for your part saves you time and money.

The tight tolerances that can be achieved with high-performance plastics have allowed parts to be transitioned from metal. This has been crucial in the aerospace industry as engineers look to reduce weight to increase fuel efficiency and reduce emissions. In the oil and gas industry, components like bearings that generally experience extreme wear hold their tolerances because of the high-performance plastics’ low coefficient of friction.

Achieving tight tolerances involves using advanced tooling and sometimes secondary operations that can add costs to the project. Requiring tight tolerances for every project doesn’t make sense, but it is worth the extra investment for those where tight tolerance is critical.

Injection molding automation systems add repeatability to tasks that deliver 100% accuracy every time — increasing and maintaining the quality of the production line. This is difficult for a human worker, who is more effective in other, more complex areas of the operation. With automation, exacting detail can be achieved on parts and processes in an infinitely repeatable manner.

Automated processes create high volumes of products with minuscule error rates; this means there are fewer deformed parts and less waste because fewer parts are rejected. This not only helps reduce costs — less wasted materials for instance — but also aids in creating faster turnaround and fulfillment times, and leads to more sustainable manufacturing processes.

We touched on the reduced material expenses that come with injection molding automation systems, but such solutions typically lower the labor costs associated with manufacturing and fabrication as well. Robotic systems can handle work that previously needed multiple employees. They can fulfill the most repetitive and potentially dangerous tasks, allowing labor resources to be directed elsewhere to drive value.

Automation systems can continue operating without interruption and properly maintained systems could run 24/7. This results in better per-unit production and quick order completion. Interconnected automated systems also generate analytical data that allows users to immediately notice problems, or identify areas for improvement.

Injection molding automation systems provide benefits outside the direct molding process as well. They can be used to handle newly molded parts, which may be delicate and vulnerable to deforming under pressure. Finely-tuned robotic tools can handle parts that need overmolding or further processing. Systems can be devised to feed plastic machining processes, pad printing, packaging, and more.

Loading and Unloading — Automated machinery uses the same amount of shot material per cycle, so products remain uniform. Robots can load or unload machines without error.

Visual Inspection — Robotic systems can orient the parts and use sensors to determine if their dimensional errors, and much more. Humans can oversee several cells at once.

Assembly/Sorting — Robotics can be used for complex tasks after the mold stage as well, such as welding assemblies, sorting parts for kits, and more.

Secondary Processes — Smart systems can use side-entry injection molding robots to perform tasks such as decorating and labeling quickly and accurately. Also, robotics are essential in consistent, efficient CNC machining processes.