Familiarity with the specialized materials likely to be required is also important. To minimize the potential for counterfeiting, some resin manufacturers will only sell product to a limited number of injection molding facilities. For example, Forefront Medical is the only contract manufacturer within Asia approved by Solvay to purchase its PEEK materials. Additionally, Forefront Medical maintains a database of approved materials which includes a full range of medical-grade polymers. While the best material will vary depending on application, cost considerations and desired functionality, Forefront Medical’s team is often able to recommend pre-approved materials choices to remove the variable of regulatory materials approval lead-time from the product development process.

No one ever said that designing and manufacturing molded parts was easy. Our goal is to get you through it quickly and with quality parts. A good starting point is our Design for Moldability Toolkit.

Our digital factories create prototypes and low-volume parts fast, while our manufacturing network, offers advanced capabilities and volume pricing.

Steel Core Pins: A steel pin is strong enough to handle the stress of ejection and its surface is smooth enough to release cleanly from the part without draft. There shouldn’t be any cosmetic effect on the resulting part; if there is, it will be inside the hole where it won’t be seen.

When choosing a material for your part, relevant properties might include mechanical, physical, chemical resistance, heat, electrical, flammability or UV resistance. Resin manufacturers, compounders and independent resin search engines have data online. Here is a quick look at some common commodity and engineering resins.

Part handling after molding was also a challenge. A de-ionizer was added to remove the electrostatic charge which otherwise would cause the small parts to stick to the mold. A standard handling robot could not be utilized because of the part size. Forefront was able to deliver first articles for customer functional testing in less than six months from project start.

UndercutsA portion of the part that shadows another portion of the part, creating an interlock between the part and one or both of the mold halves. An example is a hole perpendicular to the mold opening direction bored into the side of a part. An undercut prevents the part from being ejected, or the mold from opening, or both.

Short glass fibers are used to strengthen a composite and reduce creep, especially at higher temperatures. They make the resin stronger, stiffer, and more brittle. They can cause warp due to the difference in cooling shrink between the resin and the fibers.

Stock colors from the resin vendor are typically black and natural. Natural might be white, beige, amber or another color. Semi-custom colors are created when colorant pellets are added to natural resins. For available colors, visit our materials page. There is no added charge for our inventory colors. They may not be an exact match and may create streaks or swirls in parts.

ABS: ABS is a great choice for a vast majority of parts. It’s reasonably priced, strong, relatively tough, has a decent appearance and is forgiving even if you don’t follow all the standard design rules for plastic parts.

The micro size of component was the major challenge. Forefront chose to modify their smallest machine to support this effort and this required significant work on the screw system to more precisely control the discharge of plastic on the screw. This part involved one third the volume of material compared to that of normal resin screw interface.

Forefront Medical’s project engineering team utilized Cimatron software for the tool, hot runner and cooling system design. They were able to use Moldflow software for DoEs to optimize the design and molding parameters plus moldflow analysis once those parameters were established. Moldex3D software was utilized for molding process simulations to test their assumptions prior to tool fabrication.

Thermoplastic injection molding: Thermoplastic injection molding is the most common type of molding. It injects thermoplastic resin into the mold where the material cools to form the final part.

Glass beads and mica flakes are used to stiffen a composite and reduce warping and shrinkage. With high loading, they can be challenging to inject.

Insert Molding: Insert molding is process that begins with an insert component placed into the mold before resin enters. The material is then injected and flows around the insert, typically metal, to form the final part. This is frequently used for parts that require metal threads.

Introduction It’s no secret that medical devices are getting smaller. Implants, tubing and drug delivery systems now often require injection molders capable of fabricating parts at a micro level. The smaller the part; the more complex the injection molding process since material behaves differently in smaller shot sizes. Forefront Medical Technology, a specialty contract manufacturer with a focus in disposable diagnostic, drug delivery systems and medical device systems, has experience with both standard and micro molded products. This white paper describes the product development and process complexities found in micro molding in greater detail, plus looks at how these capabilities were successfully applied in a recent micro molding project.

Material cost and size drive a need for a mold to deliver superior quality parts with minimal waste and without secondary finishing operations. Specialized materials requirements may also limit regional supplier choices. A supplier experienced with medical plastics can eliminate or reduce regulatory materials approval lead-time. Longer tooling fabrication lead-times can be mitigated with additional engineering and in-house machining resources. Choosing a supplier with a strong engineering team and scalable resources helps ensure a smooth product development process and superior quality product.

Our quoting platform identifies undercut features require side actions with solid arrows and faces with corresponding colors.

BossesA raised stud feature that is used to engage fasteners or support features of other parts passing through them. There can be a tendency to design thick bosses which will increase the likelihood of sink and voids in a part. Consider reinforcing bosses with ribs or gussets for extra strength

RibsA rib is a thin, wall-like feature parallel to the mold opening direction, its used to add strength and support to features like bosses and walls. To prevent sink, ribs should be no more than 60% of the wall’s thickness.

Part production: The actual production of plastic parts begins by loading resin pellets into a barrel. The temperature of the barrel is raised until the resin pellets reach a molten state and are then compressed. Next, the molten plastic is injected into the metal tool through a runner system, which then feed into the mold cavity through gates. The part then cools down, solidifies, and is ejected from the tool with ejector pins.

Since companies rely on injection molding to produce thousands, sometimes millions, of parts, quality control is critical.

Injection molding is process tailored for producing large volumes of parts. Compared to other manufacturing technologies—like CNC machining and 3D printing—it requires an upfront, capital investment into tooling. But individual piece-part price will be substantially less when compared to other means of manufacturing plastic parts. This cost structure makes it an affordable solution for production runs.

Long glass fibers are used like short glass fibers to strengthen and reduce creep, but make the resin much stronger and stiffer. The downside is that they can be particularly challenging to mold parts with thin walls and/or long resin flows.

ISO 13485: ISO 13485 is the standard for medical industry. This includes design qualification (DQ), operational qualification (OQ), and performance qualification (PQ).

Surface finish is another important consideration for injection molding since parts are typically cosmetic and intended for end-use production. Keep in mind that textured surface will require more draft than a more polished finish. This is to ensure the part releases from the mold and so that the bead blast can be properly applied to the tool.

Polycarbonate (PC): Can tolerate higher temperatures and more durable than a typical ABS but less forgiving when it comes to moldability.

Pickouts: Pickouts are inserts that are machined separately from the tooling and placed in the mold before material is injected. They are used to achieve undercuts on interior surfaces. Pickouts are ejected along with the plastic part and placed back in the mold. Using a pickout overcomes many shape and positioning restrictions, but is more costly than sliding shutoffs, or using a side-action.

Minerals such as talc and clay are often used as fillers to reduce the cost or increase the hardness of finished parts. Since they do not shrink as much as resins do when cooled, they can reduce warping.

Get machined parts anodized and chromate plated with our quick-turn finishing option. Eligible materials include aluminum 6061/6082 and 7075.

Core GeometryCore out parts to eliminate thick walls. You get the same functionality in a good molded part. Unnecessary thickness can alter part dimensions, reduce strength, and necessitate post-process machining.

Lead-time for mold fabrication and validation can also be longer. A standard mold can be built and validated in 8-10 weeks. A micro mold tool typically takes three-to-four times the machining duration and resources. At Forefront Medical Technology, lead-times have been equalized by increasing technical resources applied to the tool fabrication. For example, while a standard tool might be fabricated by one person; a micro molded tool might require a team of ten people to fabricate and validate within an 8-10 week window.

Ultrasonic welding: uses a high frequency vibration to generate heat and drive an insert into a part. In more complex molding applications it can also be used to fuse parts together.

Side ActionsA portion of the mold that is pushed into place as the mold closes, using a cam-actuated slide. Typically, side-actions are used to resolve an undercut, or sometimes to allow an undrafted outside wall. As the mold opens, the side action pulls away from the part, allowing the part to be ejected. Also called a “cam.”

Developing optimized injection parameters can also involve a lengthy development process. With standard molds and resins, developing injection parameters typically takes two hours. With micro molding, DoEs on injection pressure, injection speed and other variables must all be performed to determine the best mix of optimized parameters. This process typically takes a week, followed by three-to-four weeks for process validation.

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Production Part Approval Process (PPAP): PPAP is a quality inspection process typically used in the automotive industry. The method is used to verify that a production process can reliably produce a quality part repeatedly. There are 18 components to a PPAP inspection that range from customer approval to sample part production.

TolerancesWith our injection molding process, we can hold about ±0.003 in. machining accuracy. Shrink tolerance depends mainly on part design and resin choice. It varies from 0.002 in./in. for stable resins like ABS and polycarbonate to 0.025 in./in. for unstable resins like TPE.Wall ThicknessWall thickness is important because it can lead to defects such as sink and warp. It is best practice to maintain a uniform thickness throughout an injection-molded part. We recommend walls to be no less than 40 to 60 percent of adjacent wall thickness, and all should fit within recommended thickness ranges for the selected resin.

GatesA gate is an opening in the injection mold tool that allows resin to enter and fill the cavity. There are three common types of injection molding gates.

Overmolding: Overmolding is a process used to manufacturing plastic parts with two or more materials. You’ll often find this on parts to improve grip by adding rubber to the handle.

Ejector PinsEjector pins are installed in the B-side of the mold and help to release the plastic part from the tool after the part has cooled sufficiently. Designing in sufficient draft can help reduce the need for ejector pins on a part.

Finally, the ability to shorten lead-times by making a larger number of resources available is also critical to the success of many design efforts. Forefront Medical’s vertically integrated tooling design capabilities, plus precision machining resources in its Singapore and Jiangsu facilities provide the resource scalability needed to support the added complexity of micro molding tooling. Rapid prototyping capability is also important. Forefront Medical uses its rapid prototyping (SLA) system to generate prototype parts for customers while the mold is in the development phase.

Carbon fiber is used to strengthen and/or stiffen a composite and also to aid in static dissipation. It has the same limitations as glass fibers. Carbon fiber can make plastic very stiff.

Liquid silicone rubber molding: Liquid silicone rubber uses thermoset materials and a chemical reaction creates the plastic part.

The term injection molding encompasses a handful of processes that inject liquid resin into a tool to form plastic parts. Here are four common types:

About Forefront Medical Technology Forefront Medical Technology is a global medical device contract manufacturer with five locations. Singapore is Forefront’s headquarters, as well as home to our Design Engineering Center and specialty manufacturing. JiangSu and Xiamen, China, are additional manufacturing locations and are also China FDA Registered. Shanghai, China, Farmington, CT USA are regional Business Development offices which assure our technical sales teams are close to our customers for local, responsive assistance. We have developed extensive capabilities with laryngeal mask airways, diagnostic devices, drug delivery systems, enteral feeding catheters, infusion sets, wire reinforced tubes, optically clear components, patient monitoring devices and other specialty products. Each of our locations has state of the art manufacturing capabilities that include class 100K clean rooms for extrusion and injection molding, complimented by class 10K clean rooms for assembly and packaging. Forefront Medical’s integrated technical approach provides customers the total manufacturing solution and global supply chain. Our facilities are TUV ISO 13485:2016, ISO 9001 and FDA Registered. Forefront is a wholly owned subsidiary of VicPlas International Ltd, who is listed on the SGX Main Board, Singapore stock exchange. Visit www.forefrontmedical.com to learn more about our capabilities. For a confidential review of your project, please complete our enquiry form here, or email us at: info@forefrontmedical.com.

We have developed extensive capabilities with laryngeal mask airways, diagnostic devices, drug delivery systems, enteral feeding catheters, infusion sets, wire reinforced tubes, optically clear components, patient monitoring devices and other specialty products. Each of our locations has state of the art manufacturing capabilities that include class 100K clean rooms for extrusion and injection molding, complimented by class 10K clean rooms for assembly and packaging. Forefront Medical’s integrated technical approach provides customers the total manufacturing solution and global supply chain. Our facilities are TUV ISO 13485:2016, ISO 9001 and FDA Registered. Forefront is a wholly owned subsidiary of VicPlas International Ltd, who is listed on the SGX Main Board, Singapore stock exchange.

Critical Contract Manufacturing Capabilities To successfully meet these challenges, a contract manufacturer engaged in micro-molding needs a strong engineering team and excellent design tools. Given the amount of fine tuning that may be necessary during the mold design, fabrication and validation processes, there is also value in vertically-integrated tooling fabrication facilities with precision machining capabilities.

Nylon: Affordable cost, strong, and wear resistant. Can be susceptible to shrink and warp, particularly glass-filled nylon.

A Case Study: Micro Molding an Implantable Device The team at Forefront Medical recently helped a medical device manufacturer with a micro molding challenge. A small part was needed for a product used in implantable tissue grafting. Forefront Medical’s dedicated project engineering team worked with the customer to design a part that had the functional characteristics required for the application and was also manufacturable. PEEK was selected as the material.

Our helpful design aid demonstrates part features that are too thin or too thick, bad bosses, right and wrong ribs, and other considerations to be mindful of while designing parts for injection molding.

Molds are typically designed to take advantage of the smallest shot weight, which in micro molding is often under 0.010 grams. While a hot runner system is the optimum choice, the runner system and gating systems must be carefully designed, because if the material does not flow properly it will degrade. The mold needs both a heating and cooling system to control temperature changes precisely throughout the process.

Laser Engraving uses a laser to burn a 2D image onto a part or mold cavity. While color is not an option for laser engraving it is a more cost-effective, faster way to mark plastic parts when compared to pad printing.

Forefront Medical Technology is a global medical device contract manufacturer with five locations. Singapore is Forefront’s headquarters, as well as home to our Design Engineering Center and specialty manufacturing. JiangSu and Xiamen, China, are additional manufacturing locations and are also China FDA Registered. Shanghai, China, Farmington, CT USA are regional Business Development offices which assure our technical sales teams are close to our customers for local, responsive assistance.

Conclusion Successfully micro molding medical parts requires engineering expertise, state-of-the-art tools and equipment, close coordination with the mold fabrication team and a focus on developing a design that addresses both the customer’s functional goals and is manufacturable. The added complexity of micro molding adds lead-time to the process compared with standard molding. Selecting a supplier with the right mix of capabilities can help reduce this added lead-time.

Mold Design/Fabrication and Process Development Challenges Automated mold flow analysis software is key to ensuring a correctly designed mold and tight process control. However, with micro molded parts there is not as comprehensive a library outlining material selection impact on the mold, as is found with standard size parts. Consequently, there may be engineering research required prior to performing mold flow analysis.

First Article Inspection (FAI): FAI is a method used to verify that parts are to specification. We take a critical-to-quality approach to injection molding FAIs. Using GD&T, customers can call out the most critical dimensions of their part.

Logos and TextSans serif fonts will be the easiest to mill into a mold with text. We recommend font larger than 20 pt. and no deeper than 0.010 in to 0.015 in.

Pad Printing allows for the addition of color graphics to molded parts at scale. This can be used for adding logos, graphics, and instructions on parts. We offer pad printing for ABS, PC, and ABS/PC resins.

It's most often used for the manufacturing plastic parts at scale due to its low material waste and low cost per part. It’s an ideal manufacturing process for industries like medical devices, consumer products, and automotive to name a few.

Scientific Molding: Scientific molding describes a standard process used to develop, optimize, and document the ideal set up process for each injection molding project so that the same process and parameters are followed for every single run. This ensures part consistent for each run of parts.

In addition to our standard surface finish options, we also offer industry-standard Mold Tech finishes for more complex textures. These can be used to improve grip on a part’s handle or hide cosmetic defects like parting lines. Mold Tech textures can be used to achieve the following effects:

The Equipment and Mold Equation Injection molding machines must be capable of injecting at higher pressure and speed when micro molding parts with small shot sizes. If a specialized material such as Polyetheretherketone (PEEK) is used the mold and screw material must be hardened to withstand a melting point at least one hundred degrees over the melting point of normal resins.

Tooling fabrication: Once an injection molding design is finalized the first step in the manufacturing process is to mill the tooling, which is typically fabricated from steel or aluminum. In most cases, the metal block of material is placed in a CNC mill, which then carves out a negative of the final plastic part. Additional treatments like polishing or laser etching can then be applied to the tooling to achieve specific surface finishes.

Visit www.forefrontmedical.com to learn more about our capabilities. For a confidential review of your project, please complete our enquiry form here, or email us at: info@forefrontmedical.com.

Stainless steel fibers are used to control EMI (electromagnetic interference) and RFI (radio frequency interference) typically in housings for electronic components. They are more conductive than carbon fiber.

Tough Black (Loctite Henkel 3843) and Ceramic-Filled (BASF 3280) are two new advanced photopolymer materials now available for 3D printing.

The thin wall of the part drove a strong focus on temperature and process control. Heaters needed to be added to the mold to reach an equilibrium state.

Standard Injection Molding or Micro Molding—What’s the Difference? From a non-technical perspective, the logical assumption is that micro molded parts simply require a mold with smaller cavities. The reality is that there are significant differences between the processes including:

Polypropylene (PP): PP is a cheap material and good when cosmetics and rigidity aren’t a priority. Chemical resistant and good for living hinge designs.

DraftApplying draft to molded parts is critical to ensure parts do not warp during the cool down process and it helps the part easily eject from the mold. Applying 1 to 2 degrees works well in most scenarios. If there are vertical faces, we advise incorporating .5 degrees of draft.