Micro Injection Molding Service and its use in Medical equipment

Micro Injection Molding Service and its use in Medical equipment makenica.com/micro-injection-molding-service-and-its-use-in-medical-equipment March 12, 2021

Micro Injection molding service is an advanced molding process being employed by several injection molding companies that creates lightweight, high-precision and highprecision bits. These pieces are tiny—usually less than 4 millimetres in diameter or less than 1 gramme in weight.

The method starts with the mould, sometimes referred to as the tooling. The mould has tiny cavities in the form of the required component. During the LIM (liquid injection molding) process, LSR is rapidly pumped in to the heated cavity, vulcanising and shaping the part. Some micro injection molding processes use a runner, a channel used to guide the cavity material.

Alternatively, by using direct gating methods, the material is pumped directly into the component, removing the runner and the waste material.

Tremendous precision and accuracy are required in the manufacture of the tool (mould) and the components' production. Since the pieces are so fragile, even slight misalignment may have a significant impact on production.

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Micro molding LSR often needs extra precision when combining A and B components of the material, applying color (if applicable) and dosing to allow consistency and repeatability of the operation. The mould, feed system and molding unit must regulate mixing, dosing and closure with the utmost accuracy.

Then the actual challenge begins, controlled demolding, handling and inspection of tiny tacky components. Cavity separation is recommended for containment and traceability as well as for magnifying devices for inspection. All of this involves a team with strong skills and experience. It helps to innovate in a space where every micrometre is vital.

Why injection molding companies use a micro injection molding service?

Some of the advantages that the use of micro-molded products can realize include: Reducing the weight of the part: If weight is of extreme significance in your application, consider the use of micro-moulded products. For example, in the aerospace and medical industry, each part's weight may make a significant difference in the efficiency of the application.

Increased confidence in essential components: Injection molding companies use Micro Injection molding service in specialized applications where the part's size plays a vital role in the assembly or unit's performance and function.

Why is LSR beneficial for micro injection molding service?

One of the critical reasons why injection molding companies use LSR for micro injection molding service is because of its low viscosity, which makes it suitable for filling small micro features. The lightweight characteristics of LSR make it ideal for applications requiring high elasticity and sealing comprehensibility in injection molding companies.

Product miniaturization in injection molding companies raises many problems for product developers, and LSR will help engineers develop their lightweight applications.

As the pieces are so small, the weight of the shot is also small. The material will remain in the barrel for a long time, exposed to heat. This heat allows thermoplastic polymers to degrade if the remaining time in the molding barrel is too long. However, LSRs are held at a cool temperature in the barrel and typically do not degrade or cure in the barrel prematurely.

The low viscosity of LSR is also helpful as it allows for easier filling of small cavities.

What kinds of items are widely made by injection molding companies using LSR micro injection molding service?

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Medical components: Micro Injection molding service is beneficial for medical LSR parts engineered to provide high efficiencies in a small room – such as hearing aids, septum, pressure sensing diaphragms, surgical instruments, and portable drug delivery devices.

Automotive components: Micro processes of automotive injection molding service help produce small automotive parts constrained by weight constraints—small seals, micro switches, sealed housings, and micro connectors.

What is shot weight, and why is it essential for micro injection molding service?

What is shot weight? In injection molding service, a shot is a material that is inserted into the mould for each cycle. Shot weight is the weight of this material. The part weight, the runner weight and the number of cavities in the mould all contribute to calculating the optimum shot weight.

Shot weight is significant for the Micro Injection molding process because the small parts have unique specifications. Smaller shot weights require smaller injection barrels or lower tonnage stuffer boxes to meet the mould dimensions.

Challenges in the mould construction In injection molding companies, the mould construction for micro injection molding service faces a variety of technical challenges: Accuracy and precision: Micro Injection moulds need extremely reliable and precise electrical discharge machining (EDM) to obtain the required micro-details and avoid inconsistency when the mould is closing.

Assembly and disassembly: due to their thin, fragile, easily disassembled components and the need for correct alignment, Micro Injection moulds require deliberate, delicate assembly and disassembly methods.

Design: Much of the problems of mould construction are the design of moulds. The mould design must include necessary details to ensure consistent alignment of the mould halves to allow for proper demolishing (parts removal).

The mould design must also promote consistent reliability and durability for highcapacity production—a standard Micro Injection mould must produce millions of parts over its lifetime.

Balancing Pressures: It is essential to control cavity pressures on the cold deck with Micro Injection moulds. Doing this makes for a more reliable filling. i.e. a well-balanced cold deck and robust valve gate technologies ensure a synchronous needle closing that prevents short shots or incomplete filling of the component.

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Temperature management: The cavity temperature directly influences the curing of the material and the forming of the component. Nozzle technology, with strong cooling through the tip/beginning of the cavity, helps transition from cooling during filling to heating during vulcanization. It is also beneficial to produce the correct fill.

Gating: Direct gating is usually done if the part has sufficient landing space for the gate.

Since parts geometry cannot enable the use of very small direct gates, engineers must create alternative in-direct gate solutions such as film, edge or tunnel gates. Overflows may also be used to ensure the complete filling of the part.

Optimizing overflows: using overflows will reduce the chance of trapped air, which hinders the mould's proper functioning. Runners can also be useful for encouraging the handling of parts during multi-step processes, including in-line slitting, laser marking, pad printing, packaging and assembly.

Challenges in LSR molding LSR molding also poses a complex range of problems for engineers of Injection molding companies: Detection of fluctuations: control of inputs and outputs is essential for detecting fluctuations in the process. Detecting and mitigating fluctuations is vital since even the slightest variation will impact the micro-moulded pieces' small features.

Feeding A and B material components: LSR consists of an A&B component – one containing a cross-linker and an inhibitor, while the other includes a platinum catalyst.

Managing the correct feeding of the components A and B of the materials and ensuring an accurate 1:1 ratio is essential for the product's consistency. It causes a proper curing reaction and a thorough mixing to take place.

Controlling colour: for LSRs with colour pigments, controlling the third-stream flow of colour pigment is essential, even at low dosing rates.

Demolding and handling of parts: Removing parts from the cavities can pose a challenge, as the LSR parts are tacky. The problem is rising with higher cavitation moulds.

Robotic handling: efficient robotic handling is vital for the handling and execution of in-line secondary operations. LSR components' handling poses increased difficulties due to its static and tacky properties and the microparts limited scale.

Inspection of components: Micro moulded parts are very small in scale. The orientation and examination of delicate dimensional features can pose a challenge.

Micro Injection Molding service in medical parts There's no wonder that medical instruments are getting smaller. Implants, tubing and drug delivery devices now also need injection moulders capable of manufacturing parts at a micro stage. The smaller the part, the more complicated the injection molding service as 4/7

the material reacts differently in smaller shot sizes.

How is the medical micro injection molding service different?

Medical micro injection molding service requires much more advanced equipment than conventional micro injection molding.

In traditional micro-injection molding machines, the screw performs four simple actions: melt, feed, convey and inject the polymer. Sophisticated medical micro injection molding devices use a screw-over-plunger configuration where the screw just heats, feeds and conveys the polymer to the plunger cavity.

As you can see in the comparison below, this has several benefits. Still, the most basic thing is that we can monitor the time of residence at high temperatures and not shear all the barrel material. The benefits translate to our customers' very real outcomes: cost savings with less resource use and shorter time frames for product development.

Advanced Medical Micro Injection Molding service Optimized runner systems [Unrecoverable] minimal material waste, by volume Violent molding process (fast, high temp, high shear rates) Tight/stringent process windows Macro Molding guidelines do not apply Without EOAT, robots, and cameras, there is a high risk of mould and cell damage Tightly married tooling and molding processes – the key to success Cold runner systems more common No material regrind option Good fit for Engineering/Exotic/Bioabsorbable materials Highly complex detail achievable Conventional Injection Molding service Long/larger runners Increased material waste Less-violent molding process More latitude in process window development Macro- molding guidelines do apply Robotic part removal does not always add value Less shear sensitivity Hot runner systems more common Material regrind is common Bad fit for Engineering/Exotic/Bioabsorbable materials – regular material waste too expensive to justify Highly complex detail not achievable

Keys to effectiveness in medical micro-molding

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Equipment and Mold Equation Injection molding machines must inject at higher pressures and speeds because micro molding pieces are limited in dimension. Suppose special material such as polyether ketone (PEEK) is used. In that case, the mould and the screw material must be reinforced to tolerate a melting point of at least one hundred degrees above the standard resins' melting point.

The moulds are usually built to take advantage of the smallest shot weight, which is often less than 0.010 grammes in micro injection molding service. While the hot runner system is the safest option, the runner system and gating mechanisms must be carefully engineered because if the material does not flow correctly, it will degrade.

The mould requires a heating and cooling system to monitor temperature variations in the process.

Mould Design/Fabrication and Process Development Challenges Automated mould flows analysis software is the secret to maintaining proper mould construction and robust process control. However, there is not as extensive a library detailing the material variety effect on the mould as can be seen with regular size items for micro moulded parts. Engineering study could therefore be needed before a mould flow analysis is carried out.

Developing optimized injection parameters by injection molding companies may also entail a lengthy process of development. With traditional moulds and resins, the production of injection parameters takes typically two hours.

Micro molding, injection pressure DoEs, injection speed and other factors must all be done to assess the right combination of tailored parameters. This procedure usually takes one week, followed by three to four weeks for validation of the process.

Lead time for the manufacture and validation of moulds can also be longer. Standard moulds can be produced and tested in 8-10 weeks. Usually, a micro mould tool requires three-to-four times the machining duration and resources.

Critical contract manufacturing capabilities A contract manufacturer engaged in micro injection molding service requires an excellent technical team and outstanding design equipment to face these challenges successfully.

Given the amount of fine-tuning needed during mould design, production and validation processes, there is also value in vertically integrated tool manufacturing facilities with precision machining capability.

It is also necessary to have experience with the advanced materials that are likely to be needed. To reduce the risk for counterfeit products, only a small range of injection molding plants would be sold by certain resin suppliers.

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Finally, the potential to minimize lead times by making more resources available is often essential to the progress of many design efforts.

Conclusion Successfully micro molding medical components need technical skills, state-of-the-art software and facilities, strong collaboration with the mould production team and a concentration on creating a specification that meets both the customer's practical requirements manufacturable.

The added complexity of the micro molding brings lead-time to the process relative to standard molding. Selecting injection molding companies with the best combination of skills will help minimize this extra lead time.

Material expense and scale drive a mould's need to produce superior quality parts with minimum waste with no secondary finishing operations. Specialized material specifications can also restrict the preference of regional suppliers.

Injection molding companies with expertise in medical plastics can eliminate or minimize the approval of regulatory materials over time. Longer tooling production lead times can be mitigated with additional technical and in-house machining tools.

Choosing injection molding companies like Makenica with extensive technical staff and scalable tools helps ensure a seamless product production process and superior product output.

Read More: Know about the Dental 3D Printing in India

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