Category Archive: Silicone Injection Molding
ProMed Pharma announces a preclinical rat study to assess pharmacokinetics of a novel long-acting contraceptive implant
Bioresorbable implant aims to address key unmet needs for
family planning at an affordable price in low and middle
income (LMIC) settings
PLYMOUTH, MINNESOTA, UNITED STATES, April 19, 2022
/EINPresswire.com/ — ProMed Pharma is pleased to
announce the initiation of preclinical evaluation of a novel
fully resorbable contraceptive implant. The implant,
developed in a project funded by the Bill & Melinda Gates
Foundation, aims to address key unmet needs for family
planning at an affordable price in low and middle income
(LMIC) settings.
Commercially available contraceptive implants, while safe
and highly effective, require removal by trained health care
providers any time the user wants to discontinue the
method, including when pregnancy is desired, or when the
implant reaches the end of its effectiveness. This
requirement imposes a strain on resources in LMIC
settings.
The implant being developed by ProMed is specifically designed to address the needs of LMIC settings.
• First, it aims to expand women’s contraceptive options by providing 18 months of contraception by long-term release of levonogestrel. This duration fills the gap between that offered by existing injectables and longer-acting methods such as non-erodible implants.
• Second, the implant is fully biodegradable, eliminating the need for women to return to medical clinics for removal at the end of the period of effectiveness.
• Finally, the implant, which comprises a levonogestrel-releasing outer sheath surrounding a drug-free polymer core, is designed to retain sufficient mechanical integrity to allow removal if or when desired. Removability is important to respond to women’s needs, such as in cases where pregnancy is desired prior to exhaustion of the contraceptive.
The preclinical evaluation of the implants follows selection of four lead formulations combining levonogestrel with cost-effective, commercially available biopolymers that yield near-linear release without the need of a rate controlling membrane. The preclinical study will evaluate the pharmacokinetics of levonogestrel, establish duration of removability, and track length of biodegradation of the designs. The results will allow further narrowing of formulations for clinical evaluation.
Dr. James Arps, Director of Business Development at ProMed, noted “the implant designs have shown promising mechanical integrity and drug release profiles based on in vitro tests to date and have a form factor which is similar if not superior to other implants on the market.” The study will be carried on for a minimum of 6 months with the option of gathering drug release and polymer degradation data up to 1.5 years.
About ProMed Pharma:
ProMed Pharma specializes in the molding and extrusion of drug-loaded silicones, thermoplastics, and bioresorbable materials, leveraging this expertise to manufacture long-term implants and combination devices under cGMP. Working with both established and early stage companies, we utilize robust manufacturing processes for controlled release of APIs utilizing a variety of materials. From clinical trial materials to commercial products, ProMed supports
pharmaceutical and medical device companies developing controlled release formulations including subcutaneous, orthopedic, cardiovacular, and ophthalmic implants, intravaginal rings, and steroid-eluting combination components. The company has facilities in Plymouth and Maple Grove, Minnesota. Please visit www.promedpharmallc.com for more information.
James Arps
Promed Pharma
+1 763-331-3800
email us here
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Injection molding and other medical manufacturing processes are often complex and peppered with potential pitfalls. Fortunately, nearly all of these potential issues can be resolved with a highly competent design. Achieving the best design the first time around is crucial as there is a lot at stake. If OEMs do not get the design right, product rejection rates will increase, productivity will decline, and a host of other issues will ensue – all negatively impacting the bottom line. Additionally, modifying a product or mold design during the production stage can be very costly – so it is worth the time to get the design phase right.
One approach used in medical manufacturing to ensure the best design is Design for Manufacturing, or DFM. This is the process of designing products for ease of manufacturing as well as creating a better, more cost-effective product. DFM is a vital product development step that looks to simplify and optimize the design to ensure high quality and efficiency during production.
One apThe DFM process should occur early in the design phase of any molding project and should engage key parties including designers, tool fabricators, raw material suppliers, manufacturers, and other stakeholders. The goal is to tap into the experience of each of these experts. The team will scrutinize the current design from many angles with the goal of identifying a more cost-effective solution that maintains excellent quality.
How does the DFM Process Add Value?
Simply stated, OEMs need to ensure the part is as easy to manufacture as possible. This will result in more efficient production, better quality, and lower cycle times. Below are some ways OEMs gain value from the Design for Manufacturing process.
· Save Significant Cost and Time: OEMs are often in a rush to get a new product to market so it is tempting to shorten – or even skip – the DFM process. However, it is important to keep in mind that changes to the design become exponentially more expensive and timely to implement as the product advances through the life cycle. A thorough DFM upfront will allow any optimizations to be made or issues to be resolved before the changes significantly impact the project timeline or budget.
· Optimize Functionality and Aesthetics: tooling for molding projects is often expensive to fabricate and costly to modify; thus, it is imperative to get the tool design right the first time. If the design is off even by a small margin, the product aesthetics and functionality will be altered. The DFM process often includes computer simulations of the design as well as rapid prototyping so the team can fully visualize the product. Oftentimes, these steps yield valuable insights and design optimizations that would have been lost if the DFM process was not performed – resulting in a more functional and aesthetically-pleasing product.
· Confirm Manufacturability: last but certainly not least, the DFM process ensures the part can be manufactured. This may seem obvious but there are many instances of products reaching production only to realize the part cannot actually be manufactured per its current design – costing OEMs valuable time, money, and resources
ProMed’s Approach to DFM
To avoid this situation, OEMS should team up with an experienced medical manufacturing partner, like ProMed, that has DFM expertise. ProMed’s design and manufacturing teams are integrated to allow manufacturability issues to be identified and addressed during the design process instead of after the tooling is fabricated – saving customers significant development time and cost as well as innumerable headaches. At ProMed, we works with our customers throughout the product life cycle, providing a cost-effective solution that meets the customer’s needs.
LSR is a versatile silicone that has a wide range of end-uses from medical devices to consumer goods to electronics to automotive. There are several types of LSR that can be manufactured such as medical, self-lubricating, conductive, flame-retardant, and radio opaque. The type of LSR produced is determined by the additives incorporated during the manufacturing process. Additionally, LSR is available in different grades, namely medical, food, and industrial. Given its versatility, it is not surprising that the worldwide demand for LSR continues to grow.
LSR has excellent properties, such as a low viscosity and low shrink rate, that make it a great choice for silicone injection molding and the manufacturing of complex products and intricate parts. One of the benefits of LSR is that it cures faster than most other rubber materials; additionally, due to the highly automated nature of silicone injection molding and the potential for 24/7 manufacturing, high volumes of LSR products can be produced in a short period of time – adding to its popularity.
A key benefit of LSR’s lower viscosity is that it is easier to mix additives into. Additives that can readily be incorporated into a batch of LSR include colorants, desiccants, barium, and pharmaceuticals such as hormones or steroids. For these reasons, LSR is a great option for medical devices such as combination products. The low viscosity of LSR and the temperatures needed to vulcanize LSR are usually low enough that significant degradation of compounded substances, like Active Pharmaceutical Ingredients (APIs) that are used in combination products, can be avoided.
While LSR has many attractive properties, its biocompatibility is outstanding. LSR has demonstrated superb compatibility with human tissue and body fluids, and is resistant to bacteria growth. Medical grades of LSR are temperature resistance and can easily sterilize, which makes them compatible with various medical devices and accessories such as implantable devices, liquid feeding bottles, dialysis filters, and oxygen mask instruments.
Looking for a proven and reliable medical manufacturing partner for your next silicone injection molding project?
Contact the professionals at ProMed to learn more about our range of medical manufacturing solutions and the various silicone materials we utilize.
DFM Checklist for Medical Manufacturing
There are many factors to consider when designing a molded product for the healthcare sector. Below is an example of a DFM checklist that lists key design consideration for an injection molding project. These are topics that OEMs should discuss with their medical manufacturing partner to ensure each of these items is considered in the product design. This is not a comprehensive list but these are some of the most common design parameters that will help ensure a robust design and a successfully molded product. The DFM checklist for your project can be customized to meet the specifics of your application. Visit our website for more medical manufacturing design considerations regarding material selection and part functionality.
· Simplification:
- Can the product size or geometry be simplified or standardized?
- Can complex features such as undercuts or sharp corners be simplified or removed?
- Are all specified tolerances necessary, and which dimensions/tolerances are critical?
· Part thickness:
- Can the part be made to have a uniform thickness throughout?
- Check for thick areas of the part that could result in sinks and voids
- Check for thin areas of the part that could result non-fill
· Part Draft:
- Does sufficient draft exist? Is draft in the right direction and location for a good parting line?
- If texture is being used, is there enough draft to release the part?
· Gate location:
- Can the gate be located in a thick area of the part?
- Will the gate seal at the right time?
- Are multiple gates needed?
· Material considerations:
- Will the material have flow concerns such as excessive shear?
- If the resin does not flow well, are long or thin flow lengths needed?
- Is the fiber orientation correct?
· Operating conditions to consider:
- Maximum pressure during filling and packing
- Clamp force profile
- Fill pattern – is there a potential for material solidification, voids, or hot spots?
- Temperature profile
- Venting temperature – is there a potential for air traps?
· Defects:
- Consider the potential for flash, weld lines, sink marks, short shots, burn marks, shrinkage, warpage, etc.
· Tooling: potential for tool integrity concerns such as thin steel?
About ProMed
ProMed was founded in 1989 to address an industry need for cleanroom manufacturing of silicone components, specifically those having a medical application. Over time, we broadened our product offerings to include assembly, micro-molding of highly engineered plastics, and combination products. We have garnered a reputation as the world benchmark of implantable silicone components and assemblies – and are one of few companies in the world to provide contract manufacturing of drug-eluting products.
ProMed has expertise in working with the full spectrum of silicones covering a wide range of properties and characteristics. We will assist in your material selection to help ensure all design requirements are met. Our manufacturing facilities and equipment are designed for a single purpose—to mold medical and implantable silicone, combination components, and bio-material grade plastics with uncompromising quality and service. We currently have four divisions that are located within two manufacturing sites. All are certified class 10,000 / ISO Class 7 cleanrooms.
We can identify the right manufacturing solution for any project. We have extensive experience in a wide range of injection molding techniques including:
· Automated Silicone Injection Molding
· Multi-cavity tooling
· Micro molds and micro molding
· Servo-controlled de-molding capabilities
· Insert molds, overmolds, and automation integration
· Transfer molding
· Compression molding
Click here to see why ProMed is your silicone injection molding partner. Contact ProMed today at 763-331-3800 to discuss your next silicone injection molding project.
MediSilicone injection molding is a cost-effective manufacturing solution that many OEMs rely on for high-quality, efficient production. This method of manufacturing is very common within the medical sector and has several benefits compared to other molding processes. For example, silicone injection molding is a good choice for a wide range of part sizes, materials, and colors – including highly intricate and complex parts. This method produces products that are virtually identical from part to part which provides excellent brand consistency and part reliability during high volume runs, which is especially crucial for products used in the medical industry. The high reproducibility of silicone injection molding also allows for production to be scaled up to very large volumes, resulting in low costs per unit.
Common Silicones for Injection Molding: LSR and HCR
Silicone elastomers have long been a popular material for silicone injection molding due to their highly desirable mechanical and physical properties. Silicones have excellent durability, chemical inertness, high tensile strength, vast range of available durometers, low toxicity, a wide temperature range, and compatibility with many sterilization methods. Furthermore, silicone is compatible with human tissue and body fluids, has a very low tissue response when implanted, and does not support bacteria growth – making it a perfect option for implants due to its excellent biocompatibility.
Silicone elastomers are primarily available in two forms for medical manufacturing: Liquid Silicone Rubber (LSR) and High Consistency Rubber (HCR). LSR and HCR are both used in medical manufacturing. While HCR and LSR have several similarities, viscosity is a key differentiator and often impacts the decision on which material is utilized for a given silicone injection molding project. The following provides an overview of both elastomers and when each should be utilized.
What is Liquid Silicone Rubber (LSR)?
Liquid Silicone Rubber (LSR) is a platinum-cured elastomer. LSR is a newer silicone technology and starts out as a 2-part liquid that cures into a solid form when mixed. LSR generally comes in buckets and has a longer shelf life than HCR.
LSR is a versatile silicone that has a wide range of end-uses from medical devices to consumer goods to electronics to automotive. There are several types of LSR that can be manufactured such as medical, self-lubricating, conductive, flame-retardant, and radio opaque. The type of LSR produced is determined by the additives incorporated during the manufacturing process. Additionally, LSR is available in different grades, namely medical, food, and industrial. Given its versatility, it is not surprising that the worldwide demand for LSR continues to grow.
LSR has excellent properties, such as a low viscosity and low shrink rate, that make it a great choice for silicone injection molding and the manufacturing of complex products and intricate parts. One of the benefits of LSR is that it cures faster than most other rubber materials; additionally, due to the highly automated nature of silicone injection molding and the potential for 24/7 manufacturing, high volumes of LSR products can be produced in a short period of time – adding to its popularity.
A key benefit of LSR’s lower viscosity is that it is easier to mix additives into. Additives that can readily be incorporated into a batch of LSR include colorants, desiccants, barium, and pharmaceuticals such as hormones or steroids. For these reasons, LSR is a great option for medical devices such as combination products. The low viscosity of LSR and the temperatures needed to vulcanize LSR are usually low enough that significant degradation of compounded substances, like Active Pharmaceutical Ingredients (APIs) that are used in combination products, can be avoided.
While LSR has many attractive properties, its biocompatibility is outstanding. LSR has demonstrated superb compatibility with human tissue and body fluids, and is resistant to bacteria growth. Medical grades of LSR are temperature resistance and can easily sterilize, which makes them compatible with various medical devices and accessories such as implantable devices, liquid feeding bottles, dialysis filters, and oxygen mask instruments.
Looking for a proven and reliable medical manufacturing partner for your next silicone injection molding project?
Contact the professionals at ProMed to learn more about our range of medical manufacturing solutions and the various silicone materials we utilize.
What is High-Consistency Rubber (HCR)?
Another common elastomer for silicone injection molding is High-Consistency Rubber, or HCR. It should be noted that the terms HCR and HTV, which stands for High Temperature Vulcanization, are often used interchangeably and refer to the same silicone material; for the purpose of this article, we will use the acronym HCR.
HCR is a type of silicone elastomer comprised of long polymer chains with a very high molecular weight. It is cured at high temperatures with a platinum catalyst or peroxides. HCR is known for its gummy consistency that is similar to peanut butter, and mostly comes in partially vulcanized sheets.
HCR has many desirable properties such as excellent aging resistance, thermal stability, electrical properties, mechanical strength, elongation, and hardness. For these reasons, HCR is a good material for a broad range of applications within medical manufacturing. Due to its higher viscosity compared to other elastomers such as LSR, HCR is typically processed using compression and transfer molding methods, but is also utilized for silicone injection molding projects.
HCR takes longer to cure than many other molding materials. A longer cure time results in a longer silicone injection molding cycle time. To improve project economics, HCR molds often have a large number of
cavities in order to accommodate the longer cycles and still achieve the desired production volume for each cycle – resulting in a more cost-effective solution on a per unit basis.
Which Silicone is Best for My Injection Molding Project?
Medical device OEMs often face a tough decision: should we use HCR or LSR for our silicone injection molding project? For companies already using HCR to manufacture medical components, it may make sense to continue using this elastomer especially since the initial capital equipment costs have already been made. For new product development, however, LSR is often the best choice given the lower capital costs and labor associated with processing this silicone. Due to its lower cost and versatility with formulations, companies often prefer LSR over HCR – but the decision should be made on a case-by-case basis. This is why it is important to team up with an experienced partner, such as ProMed, who will guide you through the selection process to ensure the right material is chosen for your silicone injection molding project.
About ProMed
ProMed was founded in 1989 to address an industry need for cleanroom manufacturing of silicone components, specifically those having a medical application. Over time, we broadened our product offerings to include assembly, micro-molding of highly engineered plastics, and combination products. We have garnered a reputation as the world benchmark of implantable silicone components and assemblies – and are one of few companies in the world to provide contract manufacturing of drug-eluting products.
ProMed has expertise in working with the full spectrum of silicones covering a wide range of properties and characteristics. We will assist in your material selection to help ensure all design requirements are met. Our manufacturing facilities and equipment are designed for a single purpose—to mold medical and implantable silicone, combination components, and bio-material grade plastics with uncompromising quality and service. We currently have four divisions that are located within two manufacturing sites. All are certified class 10,000 / ISO Class 7 cleanrooms.
We can identify the right manufacturing solution for any project. We have extensive experience in a wide range of injection molding techniques including:
· Automated Silicone Injection Molding
· Multi-cavity tooling
· Micro molds and micro molding
· Servo-controlled de-molding capabilities
· Insert molds, overmolds, and automation integration
· Transfer molding
· Compression molding
Click here to see why ProMed is your silicone injection molding partner. Contact ProMed today at 763-331-3800 to discuss your next silicone injection molding project.
Design for Manufacturing, or DFM, is the process of designing products for ease of manufacturing as well as creating a better, more cost-effective product. DFM is a vital product-development step that looks to simplify and optimize the design to ensure high quality and efficiency during production.
Successful silicone molded parts must be designed from the beginning to be manufacturable. The DFM process should occur early in the design phase of any injection molding project and should engage key parties including designers, tool fabricators, raw material suppliers, manufacturers, and other stakeholders. The goal is to tap into the experience of each of these experts. The team will scrutinize the current design from many angles with the goal of identifying a more cost-effective solution that maintains quality!
Part design should be focused on the ease of manufacturing because it can help reduce cost and lead to a robust and reliable process. Several aspects of the design will be considered during the DFM process: part geometry, location and shape of critical surfaces, size, and among others. Additionally, the DFM process should consider material selection, dimensioning/tolerancing, and the selection of critical dimensions as all of these factors impact manufacturability. By making the right material, color, durometer, dimension, and tolerance choices, OEMs can develop molded devices and components that can be reliably manufactured in large volume—while minimizing scrap rates and losses.
The Value of DFM
OEMs need to ensure the part is as easy to manufacture as possible! This will result in more efficient production, better quality, and lower cycle times. Below are some ways OEMs gain value from the Design for Manufacturing process.
- Save Significant Cost and Time: OEMs are often in a rush to get a new product to market so it is tempting to shorten – or even skip – the DFM process. However, it is important to keep in mind that changes to the design become exponentially more expensive and timely to implement as the product advances through the life-cycle. A thorough DFM upfront will allow any optimizations to be made or issues to be resolved before the changes significantly impact the project timeline or budget! When it comes to DFM, the old adage “an ounce of prevention is worth a pound of cure” is very true!
- Optimize Functionality and Aesthetics: tooling for injection molds is often expensive to fabricate and costly to modify; thus, it is imperative to get the tool design right the first time! If the design is off even by a small margin, the product aesthetics and functionality will be altered. The DFM process typically includes computer simulations of the design so the team can fully visualize the product. Oftentimes, this step yields additional insights and optimizations that would have been lost if the DFM process was not performed – resulting in a more functional and aesthetically-pleasing product.
- Confirm Manufacturability: last but certainly not least, the DFM process ensures the part can be manufactured! This may seem obvious but there are more instances of products reaching production only to realize the product cannot actually be manufactured per its current design – what a nightmare! To avoid this situation, OEMS should partner with an experienced injection molder, like ProMed, that has DFM expertise. ProMed’s design and manufacturing teams are integrated to allow manufacturability issues to be identified and addressed during the design process instead of after the tooling is fabricated – saving customers significant development time and cost as well as innumerable headaches! ProMed works with customers throughout the product life-cycle, providing a cost-effective solution that meets the customer’s needs!
ProMed’s DFM Approach
Over the years, ProMed has evolved into a full-service provider of molded parts and assembled products, including molded silicone components, biomaterial grade plastic components, combination components (pharmaceuticals into silicone) and value-added assemblies. We have garnered a reputation as the world benchmark of implantable silicone components and assemblies – and are one of few companies in the world to provide contract manufacturing of drug-eluting products. Through multiple media platforms, ProMed’s collaborative DFM meetings include a diverse group of engineering experience that work to provide you with the best path that will meet your requirements, budget and timeline.
Our innovative processes range from simply molding components to automated assembly to providing complete devices. We utilize state-of-the art technology, draw from an experienced technical community, and take a creative systematic approach to provide you with a dependable, high-quality and overall cost-effective solution to your manufacturing needs. Let our team of experts take you all the way from concept to completion – or jump in anywhere in between. We offer complete in-house production and technical services such as:
- Design, tooling, molding and assembly
- Transfer, liquid injection, RTV, insert and compression molding capabilities
- Standardized tooling platforms
- IQ/OQ/PQ activities
Contact ProMed today at 763-331-3800 to discuss how we can help with your next silicone injection molding project!
For companies seeking high-quality and cost-effective parts and devices for the medical sector, silicone injection molding is an ideal solution. Below are the basics of medical silicone injection molding including the process, materials, advantages, and how it differs from other silicone molding techniques.
Common Silicone Molding Methods
To better understand the basics of silicone injection molding it will be useful to understand how this process compares to other silicone molding techniques. Below are the most common methods used to manufacture silicone into a final product.
- Compression Molding: silicone is compressed between two heated mold cavities to force the material to fill the desired mold shape.
- Transfer Molding: silicone is pushed into the heated mold using a plunger, where it takes the shape of the cavity.
- Extrusion: melted silicone is pushed out of a die to form the shape of the desired finished product.
- Injection Molding: melted silicone is injected into a mold cavity to form the shape of the mold.
It is important to note that each of the primary molding techniques above may have variations of the basic process. For example, rotational molding is an extension of the techniques above where silicone is inserted into the mold at the desired temperature while the mold continuously rotates to form hollow parts with uniform wall thickness. Additionally, blow molding is another variation where heated silicone is blown into a mold along with air and as the silicone expands, it presses against the walls of the mold forming a thin-walled, hollow shape.
Materials Used in Medical Silicone Injection Molding
Silicone elastomers have long been a popular material for medical devices and components due to their durability, wide temperature range, chemical inertness, high tensile strength, vast range of available durometers, low toxicity, and compatibility with many sterilization methods. Furthermore, silicone is compatible with human tissue and body fluids, has a very low tissue response when implanted, and does not support bacteria growth – making it a perfect option for medical implants!
Silicone elastomers are available in two commercial forms: Liquid Silicone Rubber (LSR) and High Consistency Rubber (HCR). LSR and HCR are both used to manufacture medical device products. For companies already using HCR to manufacture medical device components, it may make sense to continue using this elastomer especially since the initial capital equipment costs have already been made. For new product development, LSR is often the best choice given the lower capital costs and labor associated with processing this elastomer. However, the decision to use LSR or HCR should be made on a case-by-case basis and OEMs should consult their molding partner.
Silicone Injection Molding Process and Equipment
There are also variations within medical silicone injection molding, however, the main equipment and process are generally the same. Below are examples of injection molding equipment. The process begins when silicone is fed into a heated barrel. In the picture below, solid raw material is stored in a hopper and then fed into the barrel. In the case of LSR manufacturing, the two liquids LSR components are stored in separate containers and then fed simultaneously into the barrel.
Next, a screw is used to mix, heat, and transport the silicone toward to the mold. The melted material is then injected through a nozzle into the mold and travels via a gate and runner system into the mold cavity; the proper design of the gate and runner system is essential to ensuring the mold is filled properly. As the silicone enters the mold, excess air can be released via vents. The pressure and temperature of the mold are maintained to allow the silicone to conform to the desired shape and harden quickly. Once the part is adequately cooled, the mold opens and the part is ejected, sometimes with the help of ejector pins. The mold is then ready to receive the next charge of silicone. The injection molding process is a continuous operation with minimal downtime, resulting in high output rates.
(photo credit: Wikipedia)
Advantages of Medical Silicone Injection Molding
Silicone injection molding has several benefits compared to other molding processes, and below are some of its key advantages.
- High Quality & Very Reproducible: Silicone injection molding produces products that are virtually identical from part to part which provides excellent brand consistency and part reliability during high volume runs – this is especially crucial for parts and devices used in the medical industry! High reproducibility also allows for production to be scaled up to very large volumes, resulting in low costs per unit after the upfront equipment set-up costs are paid.
- Excellent Versatility: silicone injection molding is a good choice for a wide range of part sizes, materials, and colors. Additionally, injection molding allows for the use of multiple materials simultaneously, allowing for a high degree of customization.
- Able to Produce Complex Parts: silicone injection molding is typically performed at high pressure which forces the silicone into small crevices in the mold (that other molding processes are unable to reach), enabling the production of intricate and complex parts.
- Efficient Production: silicone injection molding is a very fast process that generates high-output production compared to other molding methods, making injection molding a more efficient and cost-effective solution.
- Automation Reduces Cost: silicone injection molding is highly automated via the use of machines and robotics, requiring less oversight by operations personnel. Automation reduces labor costs which decreases the manufacturing costs per unit.
- Low Waste Generation: silicone injection molding manufactures smooth products that have minimal finishing requirements after removal from the mold – resulting in less waste generation compared to other molding techniques. Oftentimes, injection molding waste is able to be reused, resulting in a more environmentally-friendly and lower cost process.
ProMed’s Medical Silicone Injection Molding Capabilities
ProMed was founded in 1989 to address an industry need for cleanroom manufacturing of silicone components, specifically those having a medical application. We have garnered a reputation as the world benchmark of implantable silicone components and assemblies – and are one of few companies in the world to provide contract manufacturing of drug-eluting products.
ProMed has expertise in working with the full spectrum of silicones covering a wide range of properties and characteristics. We will assist in your material selection to help ensure all design requirements are met. Our manufacturing facilities and equipment are designed for a single purpose—to mold medical and implantable silicone, combination components, and bio-material grade plastics with uncompromising quality and service. We currently have four divisions that are located within two manufacturing sites. All are certified class 10,000 / ISO Class 7 cleanrooms.
We can identify the right manufacturing solution for any project. We have extensive experience in a wide range of injection molding techniques including:
- Automated Injection Molding
- Multi-cavity tooling
- Micro molds and micro molding
- Servo-controlled de-molding capabilities
- Insert molds, overmolds, and automation integration
- Transfer molding
- Compression molding
Contact ProMed today at 763-331-3800 to discuss your next medical molding project.
For medical device OEMs, the design phase is when a general concept and a list of requirements becomes a detailed plan for creating a potentially life-saving product. While there are several fabrication methods available for making medical devices, injection molding continues to be the dominant method. Its advantages of low price per part, high production volumes, compatibility with many different FDA-approved materials, and its ability to maintain tight tolerances, produces consistent results.
Injection molding is a supremely flexible process, but there are a few constraints and requirements that need to be incorporated into the design of any parts made by that process. For medical injection molded parts in particular, we’ve identified the five most important of these design considerations, which we’ve listed below along with our advice for part design success.
Part Function: What is it Supposed to Do?
All five of these design considerations are interrelated—design choices in one area constrain your options in the other four—but the primary driver of the part design process is ultimately the intended end-use of the medical injection molded part.
Are you designing a device meant to remain implanted in a patient for several years, or is the part a knob or button on a monitoring device or life-supporting equipment? Perhaps it’s a patient connected device that is disposable? Each of those uses implies specific operating temperatures, chemical exposure, and applied stresses over the lifetime of a product. Everything from material choice to the shape of the part is determined by this, so having a well-defined list of requirements at the beginning of the design process will not only help your team, but also assist your medical injection molding contract manufacturer with their DFM review and subsequent mold design.
Will the Part Need to be Repeatedly Sterilized or will it be Disposable?
Single-use products meant to be incinerated give you more leeway with material choice than those that will need to repeatedly withstand the abuse from the sterilization method(s) chosen. Devices that will be steam sterilized will need to be made out of materials that not only have a high melting temperature, but are also highly resistant to both heat and hydrolysis. On the other hand, ethylene oxide (EtO) sterilization requires excellent chemical resistance. UV, gamma, and e-beam methods limit your choices to other materials. Finally, only a handful of niche materials are suitable for devices which could potentially be sterilized by multiple methods over their lifetime.
What will it be Made of?
From liquid silicone rubber (LSR) and thermoplastic elastomers (TPEs) to polysulfone and PEEK, the choices of rubbers and resins are almost endless. With that wide selection of materials come wide ranges of durometers, opacities, biocompatibilities, lubricities, and resistances to heat, steam, radiation, chemicals, tearing, and wear.
With overmolding, design engineers aren’t restricted to just one material. A stiff thermoplastic component can be overmolded with soft silicone rubber grip, a popular combination for the product to be mechanically strong yet comfortable to hold.
How Easy is the Part to Actually Mold?
In order to consistently make high quality parts without exorbitantly expensive revisions, your part design needs to incorporate features such as adequate draft angles, consistent wall thicknesses, and generous radii for perpendicular features such as walls, bosses, and ribs.
Furthermore, for parts made with thermoplastics, really thick walls should be eliminated via core-outs. This not only helps prevent sink marks and warping, but also reduces the cost per part since less cycle time is required to fill and cool large volumes, not to mention the material cost savings from the reduction in resin used to pack the mold.
Price of the Finished Part
Ultimately, medical injection molded parts must be price competitive with competing products already on the market, and affordable enough to provide compelling value over the lifetime of the product.
Closely tied to the price per part, is the production volume expected for the tooling. If you are making millions of parts with a single mold, it’s easier to justify more expensive mold materials (like hardened steel) and features like hot runners for thermoplastic molds and cold decks for LSR. Multi-cavity molds may require a larger upfront investment, but also pay for themselves in the long run due to time and material savings.
Having processed many medical injection molded parts from initial concept to finished product, ProMed’s medical device design expertise can help your engineering team avoid common pitfalls, improve your product, and ensure consistent, high quality results.
From surgical instrument handles and catheters, to drug-eluting implants and stents, different jobs require different devices to be made. Different devices in turn, require different fabrication processes. In this article, we’ll discuss five different molding processes within our expertise here at ProMed, and explain the niches that each of them fill.
Silicone Injection Molding
Liquid Injection Molding (LIM) is a process in which liquid silicone rubber (LSR) is injected into a heated mold under pressure, completely filling the cavity before curing into a solid part which is then ejected from the mold. This process is virtually identical to the injection molding of thermoplastic polymers, except for the fact that LSR is a thermoset polymer. This means that the mold must be heated (not cooled as with thermoplastic resins) so that the mold permanently cures the silicone in a process called vulcanization. Once cured, the part will not melt back into a liquid. This flipping of temperature zones also means that LIM utilizes “cold decks”, not “hot runners” in order to conserve material and reduce cycle times.
Injection molding is a natural fit for making medical devices out of silicone because LSR’s low viscosity allows the mold cavities to be filled quicker and at lower pressures. LIM’s short molding cycles produce cost-effective parts in medium- or high-volume production runs, making it a popular choice for our OEM customers.
Transfer molding
Transfer molding is a process that’s similar to injection molding, and uses many of the same elements: a heated mold cavity, sprue channels, and an external actuator that pushes the molten material into the mold. In transfer molding, an open chamber (called the pot) is filled with the material to be molded (which can start as either a solid or liquid). Then, a plunger pushes on this material and squeezes it into the mold, which is connected to the pot via channels.
Transfer molding typically uses higher pressures than injection molding does to fill the mold. Another difference is the fact that the mold casting material may begin the process as a solid, in contrast to both LIM and thermoplastic injection molding.
Whereas LIM is the preferred process for LSR, transfer molding (along with compression molding, explained below) is commonly used for a different type of silicone called high consistency rubber (HCR). HCR’s higher viscosity makes that particular silicone unsuitable for injection molding.
Compression molding
If the pot in the transfer molding process were removed, and the top half of the heated mold took the place of the plunger, the result would be compression molding. Unlike both injection molding and transfer molding where the molded material is forced into the cavity, compression molding forces the heated cavity onto the material.
Like transfer molding and LIM, thermoset elastomers like silicone are used as the molding material. The heat for the vulcanization is provided by the mold and usually a preheating of the material as well.
Suitable for high-volume production, compression molding excels at fabricating large parts at low cost and with less waste compared to other methods (as there is no runner system or gates to trim off). One disadvantage of compression molding is that the process doesn’t accommodate undercuts in the parts, as any undercuts make ejecting the cured part very difficult.
Insert Molding & Overmolding
Parts made by the three molding processes described above need not be a single material all the way through. It’s often very desirable to make a composite product which has a plastic or silicone layer molded over some or all of a piece of a different material. Silicone gripping surfaces on steel surgical instruments are just one example of such overmolding.
Creating overmolded parts is typically a two-shot (or more) process—essentially a separate molding process for each layer. OEMs must carefully check the material compatibility of the materials they wish to combine because not all combinations of elastomers, thermoplastics, and metals are possible. On the whole, though there are few obstacles, leaving the OEM’s design team’s creativity as the limiting factor.
Insert molding also involves combining premade parts with molded rubber or plastics, but is a one-shot process. This is because the inserts are usually metal parts like threaded studs, which are machined rather than molded.
Both overmolding and insert molding are great for joining parts to moldable materials without using adhesives or mechanical fasteners.
RTV Casting
The last molding process on our list is actually an indirect molding (i.e. casting) process, since it’s a method to make molds that then make the actual parts. With that aside, room temperature vulcanizing (RTV) silicone casting definitely deserves to be on any list of processes applicable to silicone molded medical devices.
A cost-effective way to produce small volumes of parts, RTV casting reproduces surface textures and other fine details. Furthermore, since silicones feature great chemical and heat resistance, RTV molds can be used to cast materials like low melting point metals (e.g. zinc and pewter), epoxies, waxes, and gypsum—all without needing a mold release agent.
The team at ProMed specializes in molding medical devices, including the five methods we touched on here. Whether you’re in the market for micro-molded implantable devices, or an RTV casting for new design concept, the professionals at ProMed have you covered.
Injection molding, a manufacturing method used for making everything from car parts to kids’ toys, is also utilized to make life-saving medical devices, including those inserted or implanted into patients’ bodies. Catheters, balloons, and feeding tubes are all made possible and affordable when biocompatible materials combine with injection molding.
As we have discussed before in an earlier article, the material of choice for implantable medical devices is often medical grade silicone. Its range of available durometers, extreme chemical inertness and biocompatibility, excellent tear and heat resistance make it ideal for parts that need to remain in the human body for extended periods of time.
Furthermore, the low viscosity of liquid silicone rubber (LSR) make that elastomer ideal for injection molding (and therefore mass producing) implantable medical devices, making life-saving advances in medical technology more affordable for patients.
Polymers Delivering Doses: Drug-Eluting Implantable Devices
But those advances don’t stop with opening up arteries or providing ports into and out of the body. Increasingly, injection molded implantable medical devices are being used to deliver steady, long-term doses of hormones, cancer drugs and other active pharmaceutical agents (APIs). Injection molding of medical devices is extending its impact into drug delivery.
Drug-eluting medical implants offer several advantages over both pills and injections when it comes to drug delivery. Perhaps the most important clinical benefit is the larger amount of time the API dose is within therapeutic window—the range of concentrations within the body low enough not to be toxic, but high enough to be effective. Both pills and injections produce API concentrations that rapidly rise and then exponentially decay as the body dilutes, metabolizes, and/or excretes the pharmaceutical compounds. By contrast, drug-eluting implants can slowly and steadily release the API at a controllable, optimal rate within the therapeutic window.
These implants are able to do so because the matrix of the device is loaded with the API before they are molded. Silicones, because of the relatively low temperatures at which they can be injection molded and vulcanized and their ability to be compounded with various APIs, are optimal for this application because the injection molding process is less likely to degrade the drug.
Molded medical implants can also provide site specific administration of a drug, and therefore achieve local concentrations of an API that would be above the therapeutic window if present systematically. This enables lower total doses, reduces side effects, and has a greater therapeutic effect.
A third benefit of drug delivery via an implantable device is much greater patient compliance. Since the implant can continually release the drug within the body for several months, there are no daily doses for the patient to forget.
Peering Beyond Silicone
Even as medical grade silicone finds wide use in drug-eluting implantable devices, an exciting new frontier is opening up: expanding beyond silicone into synthetic biodegradable polymers. Such polymers open the door to drug-eluting implants which slowly and safely dissolve away inside the patient’s body, releasing the loaded therapeutic as they do so. These implants don’t need to be removed at the end of the treatment period. Another benefit is the potential to slowly release difficult to deliver API’s, because the therapeutic is released as the polymer encasing the API particles dissolves away, much like an oral pill. This results in steady release rate over time even for these difficult molecules.
Although this new breed of drug-eluting implants won’t be made with silicone, they in all likelihood will still be made via injection molding. Although technical questions still remain—like which polymers in this class have low enough melting points to be molded without significantly degrading any compounded API—injection molding’s ability to produce high volumes at low price per part while at the same time maintaining tight dimensional tolerances, will surely play a key role in this new drug delivery technology.
High quality medical components—whether for implants, instruments, or IV bags—must be safe and durable, because lives literally depend on them. Low toxicity, high biocompatibility, chemical inertness, and the ability to repeatedly withstand sterilization environments (like gamma rays, steam, or EtO) are all requirements of the materials that long-life medical components are made of. The ability to safely reuse the same medical devices reduces the cost of medical care, while re-use procedures put in place protect not only the healthcare professional, but also the patient’s health and safety.
For disposable, single-use medical parts where repeated sterilization isn’t a requirement, the toxicity and biocompatibility requirements, however, still apply. In addition, those single-use parts must be cost-effective for the manufacturer and affordable for the consumer.
For both categories of medical components, plastics and elastomers (rubbers) are the materials of choice. Since medical grade thermoplastics (which harden when cooled down to near ambient temperature) and silicones (like LSR which permanently sets when heated) have a lot to offer designers of new molded medical components, we’ll be discussing them in this post.
Silicone: Safe and Versatile
Let’s begin with silicone, which has many chemical and mechanical properties well suited for medical molded components:
Very chemically inert: Medical grade silicone resists attack from disinfecting chemicals and biochemical interaction. Medical grade silicones have excellent biocompatibility.
Strong, flexible, and durable: Silicones have high tear and tensile strength, great elongation, and low compression set, even over a wide temperature range. They’re high elasticity and flexibility is a great match for applications such as feeding tubes and seals for peristaltic IV drug delivery pumps.
Sticky when it needs to be: Although silicone has a low surface energy (and is thus used in applications that need to repel liquids), there are formulations of Liquid Silicone Rubber (LSR) that are self-adhesive and can stick to other plastics without priming. Overmolding silicone to specific thermoplastics is a common occurrence for durable medical devices that need extra grip capabilities for the doctor/nurse.
Silicone is permeable and thus makes a great matrix for pharmaceutical delivery in drug-eluting implants.
Wide range of available durometers: from 0 Shore A to 80 Shore A. This customizability makes it great for applications like clinical and surgical instrument grips, gaskets and o-ring seals.
There’s a Great (Medical) Future in Plastics
All of these features are why medical grade silicones have been widely used for decades, and will continue to be considered, in spite of LSR’s higher cost compared to some other resins.
But they are not the only game in town when it comes to molded medical components. Thermoplastics are also popular choices, especially for niche use. With so many different polymers (and varying molecular weights of each polymer), this family of plastics exhibits a wide gamut of thermal, chemical, and mechanical properties. A few of these are worth mentioning here:
Polysulfone (PS): This thermoplastic elastomer (TPE) has excellent resistance to both hydrolysis and heat, and thus can be sterilized by steam and autoclaving. PS has great biocompatibility, and can be thermoformed by injection molding and extruding.
Polyether ether ketone (PEEK): PEEK maintains its excellent chemical resistance and mechanical stability at high temperatures (and thus can be sterilized by heat and disinfected by chemical agents). Like both silicone and PS, PEEK can be molded, albeit at very high temperatures (PEEK melts at about 343°C). Since PEEK resists biodegradation, it’s a good candidate for implantable medical devices.
Medical device OEM’s can choose from many polymers for their next innovative, life-saving product. Although silicones continue to dominate (particularly in implantable devices), some thermoplastics have long been chosen for use in healthcare.
ProMed’s extensive LSR and thermoplastic expertise and manufacturing capabilities can take your molded medical product from concept to completion, just as we have for so many other global OEMs.
