September 18, 2024

Micro Injection Molding: Precision in the Smallest Details

Micro molding is a highly specialized manufacturing process that focuses on creating extremely small components, often with complex geometries and tight tolerances. A common misunderstanding arises when distinguishing between micro-molded parts and small precision parts.

While both involve creating parts on a small scale, a true micro part is defined not merely by its size but by the complexity of its features, often involving intricate details in the micrometer range. In contrast, small precision parts may be tiny, but they do not necessarily require the same level of feature resolution or tolerances that micro molding demands. This difference in complexity and scale often leads to confusion in terms of classification, with many assuming that small size alone makes a part “micro.”

Classification of Micro Injection Molding

Micro Components

• Part size: A few millimeters or less
• Part weight: In milligram range
• Details: In micron range

Micro Structural Components

• Part size: A few centimeters
• Part weight: Several grams
• Surface textures: In micron range

Micro Precision Parts

• Part size: Arbitrary
• Part weight: Arbitrary
• Tolerances: In micron range

Applications of Micro Injection Molding

Micro injection molding is used in a variety of industries where precision and miniaturization are essential:

• Medical Devices: Micro molded parts are crucial in medical devices such as surgical instruments, catheters, and implants. These components often require biocompatible materials and precise tolerances to ensure safety and functionality.
• Microfluidics: In diagnostics and lab-on-a-chip applications, microfluidic devices rely on micro-injection-molded components to channel small volumes of fluids accurately.
• Consumer Electronics: As electronic devices continue to shrink in size, micro-injection-molded parts such as connectors, gears, and housings are increasingly in demand.
• Automotive: The automotive industry uses micro injection molding to produce miniature sensors, switches, and connectors, contributing to the growing trend of vehicle electrification and advanced driver assistance systems (ADAS).

The Smaller, The More Complex

Micro molding aims to produce a molded part from a homogeneous melt produced from a grain or a few grains of granulate.

The injection molding process has high demands in terms of machine technology:

• Reproducible dosage and injection of extremely small shot weights
• Precise screw movements
• Homogeneous melt preparation
• Short dwell times for the melt
• Reliable removal with a robotic system

Maintaining control over the injection molding machine, mold, robotics, and peripheral equipment calls for smart technology that offers extensive data integration options, and monitors and adaptively controls the process.

High Precision and Tolerance: Micro molding’s defining feature is its ability to achieve ultra-fine tolerances, often within a few microns. This level of precision is essential for critical applications, particularly in the medical, electronics, and automotive sectors, where tight tolerances ensure component reliability and functionality. 

Micro Injection Module

The ARBURG E5 micro injection unit combines an 8 mm injection screw for tiny shot weights of less than one gram with a second plasticizing screw for melting. The plastic is processed according to the first-in, first-out principle.

Micro Tooling: Micro molding molds are typically highly specialized and feature intricate details at a microscopic level. They are custom-engineered for the specific part and require advanced manufacturing techniques like laser machining or electrical discharge machining.

Micro structural components require special, high-precision mold technology for the creation of structured cavity surfaces.

Material Developments: New materials are making micro molding even more versatile. Advanced polymers, including biodegradable and biocompatible materials, are being used to create medical implants that dissolve in the body, eliminating the need for removal surgeries. Nanocomposites and smart materials are being integrated into molded parts, enhancing their functionality for applications like medical implants and sensors.

Choosing the Right Partner for Micro Injection Molding

Given the complexities involved, it is essential to choose an experienced partner when embarking on a micro injection molding project. Look for a manufacturer with a deep understanding of the entire process, from mold design and material selection to process optimization and quality control.

The ideal partner should have a track record of success in producing micro components and offer capabilities such as in-house tooling, advanced simulation software, and precision molding equipment. They should also provide a collaborative approach, working closely with you from concept to production to ensure the success of your project.