Micro Molding Services

HYmoldplastic offers the highest quality micro molding services and can assist in the production of parts with intricate and complex geometries and excellent surface finishes.

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The Micro Injection Molding Process

The micro molding process is nearly identical to the standard plastic injection molding process but requires more careful control to ensure high-quality parts. Before micro injection molding can actually begin, molds and die sets must be fabricated. Precise and advanced manufacturing methods such as electric discharge machining (EDM), micro EDM, and micro-machining are used to create extremely precise molds with tolerances as small as a few micrometers. Once fabricated, molds can be mounted in a micro injection machine. Then, a thermoplastic or liquid silicone rubber is melted and maintained at a consistent temperature. The molten material is forced into the micro mold with a controlled flow rate and held at a particular pressure while it cools. Advanced programming and controls within micro injection molding machines ensure molding parameters are stable and consistent. Once sufficiently cooled, the micro injection molded parts are ejected from the mold and inspected to ensure dimensional tolerances are met.

Types of Micro Molding Processes

There are various types of micro molding, each with its own sets of advantages and disadvantages and special use cases. The different types of micro molding processes are listed and described below:

Insert Molding

Insert molding is a type of injection molding in which a metal component is placed into a mold cavity before molten plastic fills the mold. Insert molding is also possible with micro molding. In the insert micro molding process, a metal insert is positioned either manually or automatically by a robotic arm in the mold. Then, the mold closes, the plastic resin is injected in a single shot, and the molten plastic forms around the insert to create a single part. Finally, the part is ejected, the metal insert is removed, and the process repeats. Insert micro molding is a great way to enhance product durability and functionality. It is commonly used in the medical manufacturing industry to make components like catheters or in the electronics industry for micro-optic and integrated circuit components.

Overmolding

Overmolding is another subset of injection molding. It is the process of molding different materials or different colors of the same material in the same mold to create complex multi-material or multi-color parts. As with typical injection molding, the overmolding process begins with the injection of a substrate material into a mold. Then, a second injection is made using a different material or the same material with a different color into the same mold. The material from the second injection is layered directly on top of the first layer. This results in a single solid piece composed of different materials or colors. The process is great for enhancing grip characteristics for consumer products and attractive, multi-color products. Micro overmolding is often used to create small parts like: multi-color buttons or housings for electronics and seals and gaskets in automotive.

Material for Micro Molding

Material selection is highly important in micro molding projects as thermoplastic polymers and other specialized resins must be carefully vetted for suitability for particular applications, particularly in medical applications. The different materials used in micro molding are listed and described below:

Polyethylene (PE)

Polyethylene is one of the most commonly used thermoplastics in the world. Polyethylene is an FDA-compliant material, which makes it suitable for food and beverage applications. Additionally, it has great chemical and thermal resistance, as well as high tensile strength. Common applications of PE include: packaging, consumer goods, and textiles.

Polypropylene (PP)

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Nylon (Polyamide)

Nylon is a popular thermoplastic lauded for its chemical resistance, strength, and dimensional stability across a wide temperature range. Nylon has many uses including: textiles, electrical housings, and mechanical components like bearings, bushings, and sprockets.

Polycarbonate (PC)

Polycarbonate is a thermoplastic known for its transparency, optical clarity, tensile and impact strength, recyclability, and chemical and fire resistance. These properties make polycarbonate great for electrical housings, switches, machine guards, and more.

Delrin(Acetal / Polyoxymethylene / POM)

Delrin is DuPont’s trademarked polyoxymethylene (POM or acetal) resin. Delrin® is known for its strength, toughness, elasticity, rigidity, chemical and flame resistance, machinability, dimensional stability, and low friction coefficient. POM is used for mechanical components such as: gears, pulleys, and rollers.

Polysulfone (PSU)

PSU is a translucent thermoplastic known for its biocompatibility, food compatibility, good mechanical properties, and wide operating temperature range. PSU is commonly used in food preparation and medical industries due to its bio-friendliness.

Polybutylene Terephthalate (PBT)

PBT is a thermoplastic that has great dimensional stability, high strength, good chemical, UV, and thermal resistance, and low moisture absorption characteristics. PBT is often used in the automotive and electronics industries for automotive fenders, electrical enclosures, and power-tool housings.

Acrylic (Polymethylmethacrylate / PMMA)

Acrylic is a widely used thermoplastic due to its optical clarity and transparency, high tensile and impact strength, light weight, and durability. PMMA is often used as a substitute for glass and is commonly used in applications like: signage, windows, machine guards, and more.

PEEK (Polyether Ether Ketone)

PEEK is a special thermoplastic that is known for its wide operating temperature range up to 489 °F or 250 °C. Not only that, but it also has high strength, great chemical resistance, and high stiffness. PEEK is used in a variety of applications, from mechanical components like: bushings, bearings, and seals to fluidic components like valves and fittings, electrical housings, and connectors.

ULTEM (Polyetherimide / PEI)

ULTEM is a popular brand name for the thermoplastic PEI. PEI is known for its rigidity, high mechanical strength, and creep resistance over a broad range of temperatures. Additionally, PEI is a great electrical insulator, which makes it commonly used for applications like coils and fuses in electronics and interior trim pieces in aircraft.

LCP (Liquid Crystal Polymer)

LCPs are advanced polymer materials that maintain an ordered microstructure in both liquid and solid phases. The ordered microstructure results in exceptional mechanical strength and great temperature and flame resistance. Uses of LCP include: electrical connectors, catheters, surgical and dental instruments, and coatings on cookware.

Micro Molding Advantages

Lightweight
Micro molding creates parts that are lightweight and small. This is particularly useful for creating small and comfortable medical implants. Additionally, lightweight micro molded parts are also important in the creation of small, lightweight electronics or microfluidic components like small valves and fittings.

Size
Not only are the parts made by micro molding lightweight, but they are also exceptionally small in size. Advanced machining processes like micro-machining and EDM are used to create small, precise mold cavities and cores. As a result, micro-molded parts can easily fit into small and confined spaces. Micro molding has become a popular process for creating small parts in electronics, medical implants for orthopedics, pacemakers, and micro-optics.

Less Energy and Time
Micro molding offers significant cost savings compared to conventional injection molding. The cost savings are a result of the smaller tools and machinery needed to complete the micro molding process. Tools and molds are often smaller in size and thus cheaper to manufacture. Additionally, because parts are smaller, clamping forces are smaller, and consequently, power requirements are smaller. Finally, since parts are smaller, cycle times are often shorter since parts do not require as long a time to cool compared to parts made from conventional injection molding. All these traits of micro molding enable significant cost savings.

Tight Tolerances
Creating parts that satisfy tight tolerances is something the micro molding injection molding technique excels at. Micro molding enables the production of exceptionally small, detailed, and complex components with tolerances as small as 0.005” to 0.015”. Advanced manufacturing methods like micro-machining and EDM allow micro-sized cavities, cores, and other features to be made with great accuracy. The process is often used in the fabrication of electronics, medical devices, and micro-optics because of its ability to produce parts that satisfy tight tolerances.

Chemical Resistance
Thermoplastics used in the micro molding process often exhibit great chemical resistance. Therefore, the miniature parts created by the process can be used in applications with high exposure to various chemicals or in corrosive environments. This is particularly useful in the medical industry for implants, instruments, and diagnostic equipment, as well as in fluidic control components like valves and fittings. Additionally, various consumer goods and electronics may benefit from the chemical resistance offered by micro molded parts.

Micro Molding Applications

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