Medical-Grade Liquid Silicone Rubber

The Value of DFM (Design for Manufacturing)

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!

Liquid Silicone Rubber vs High Consistency Rubber for Medical Device Components

Silicone elastomers have long been a popular material for medical devices and medical device components due to their durability, ease of molding by many methods, 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 implants due to its excellent biocompatibility.

Silicone elastomers are available in two commercial forms: Liquid Silicone Rubber (LSR) and High Consistency Rubber (HCR). HCR is known for its gummy consistency and mostly comes in partially vulcanized sheets. LSR is a newer 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.

Medical device OEMs often face a tough decision: should we use HCR or LSR for our medical device component manufacturing? LSR and HCR are both used to manufacture medical device products; however, there are some key differences. The following compares LSR and HCR to shed some light on their differences and when each should be utilized.

Viscosity Difference Leads to Different LSR and HCR Manufacturing Techniques

The performance characteristics of HCR and LSR are relatively similar; however, viscosity is a key differentiator between LSR and HCR, and has a significant impact on the equipment and processes used to manufacture each of these elastomers.

Simply put, viscosity is a measure of a material’s ability to flow. A low viscosity indicates a material is less viscous and more readily flows where a high viscosity indicates a material is more viscous and less apt to flow well. For reference, water has a relatively low viscosity and easily flows whereas molasses has a higher viscosity and is more resistant to flow.

LSR has a lower viscosity than HCR. Due to the lower viscosity, LSR is most often processed via injection molding. LSR’s desirable handling properties and lower shrink rate make it an excellent choice for manufacturing highly complex geometries and intricate products. Additionally, due to the automated nature of injection molding, LSR can produce high volumes of components in a short period of time. For this reason, deciding whether HCR or LSR injection molding is the better choice for your project largely depends on the production volume required.

A lower viscosity makes it easier for manufacturers to mix additives into LSR. 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.

Due to its higher viscosity and more challenging handling properties, HCR is typically processed using compression and transfer molding methods, which are more labor-intensive. In some cases, HCR is used in injection molding projects.

OEMs Often Prefer LSR

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, however, LSR is often the best choice given the lower capital costs and labor associated with processing this elastomer. Due to its lower manufacturing cost and versatility with formulations, companies often prefer LSR over HCR – but the decision is on a case-by-case basis.

ProMed’s Silicone Manufacturing Capabilities

At ProMed, we combine industry-leading medical-grade LSR and HCR expertise with the latest developments in silicone materials and technology. We have garnered a reputation as the world benchmark of implantable silicone components and assemblies. From helping OEMs incorporate the latest medical-grade silicone formulations into their designs to delivering rapid silicone prototypes, we serve as a premier silicone molding contract manufacturer for medical device OEMs.

ProMed has expertise in working with the full spectrum of silicones covering a wide range of properties and characteristics. Our wide range of materials include: Liquid Silicone Rubber (LSR) 5 to 80 Durometer, High-consistency Rubber (HCR): 20 to 80 Durometer, Room Temperature Vulcanizing silicone (RTV). 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.

Contact ProMed today at 763-331-3800 to discuss your next medical device project.

Liquid Silicone Rubber

2019 & Beyond - What the LSR Material Market is Predicting

What is LSR?

Liquid Silicone Rubber (LSR) is aplatinum-cured elastomer that can be injected into a mold cavity to manufacture a part. LSR starts out as a 2-part liquid that cures into a solid form when mixed together. LSR is a versatile rubber in the elastomer industry and has a wide range of end-uses from medical devices to consumer goods to electronics to automotive. For example, LSR can be found in catheters, stents, windshield wiper blades, LED headlights, adhesives, microwaves, seals, and grommets.

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.

LSR has many attractive properties such as durability, low viscosity, chemical and temperature resistance, and flexibility, but 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.

LSR MarketPredictions through 2026

The LSR market is forecasted to steadily grow over the next 5-10 years and some sources estimate the global market for LSR will reach a valuation of US$ 7.9 billion by 2026. Additionally, the global LSR market is forecasted to have a Compound Annual Growth Rate, or CAGR, of 4.5% through 2026 which is considered moderate growth. (Note: CAGR is considered a good measure of an investment’s return over time compared to annual return figures that do not account for compounding).

This growth is attributed to several factors. First, enhancements to the physical properties of LSR is expected to allow LSR to continue to replace traditional rubber materials in various applications. Additionally, injection molding of LSR produces consistent parts, cycle to cycle, and is a low-cost option for part manufacturing; for these reasons, LSR injection molding continues to expand into new markets, driving the continued demand for LSR.

LSR growth is also attributed to several societal factors such as growing demand for LSR in equipment and surgical tools necessary to treat the rising geriatric population and the growing awareness about health concerns, accelerated demand within the electronics industry due to continued innovation and technology advancements, as well as global urbanization and standard of living increases.  The industries that are expected to demonstrate the highest demand for LSR are medical and automotive.

Among the various grades of LSR, medical grade is expected to continue to hold the largest global market share. Moreover, stricter regulations and compliances of many specifications for use in medical products are further projected to drive the overall market growth. In addition, replacement of latex with LSR in impactable devices is expected to provide new opportunities for LSR applications.

The LSR market is segmented across five regions: Asia Pacific, North America, Europe, Latin America, and the Middle East & Africa (MEA). Among these, Asia Pacific is expected to continue as the largest marketplace for LSR, estimated at 35% of global market share, due to demand for the product in electrical & electronics and medical applications. Other factors contributing to the market growth are the easy access to raw material and favorable government policies. China and India are the strongest country-based markets in the Asia-Pacific region since distribution networks are well established and many LSR players have a strong presence in these countries.

The North America market, the United States in particular, is also forecasted to grow due to increasing usage of LSR in the electronics industry as well asincreased expenditures on, and technological advances of, medical devices. Europe is also forecasted to grow LSR demand due to growing demand for lightweight material in the automobile sector. Additionally, multinational companies are focusing on collaboration,and perhaps even joint ventures, with distributors to achieve sustainable growth. The Latin America and MEA regions are also expected to observe LSR market growth due to increasing demand for growing usage of LSR in consumer goods and healthcare industries.

The LSR market faces a couple key challenges including minimization of the carbon footprint associated with LSR production, and improvement of LSR’s reusability and disposability. But even with these challenges, the LSR market is forecasted to have moderate growth across all 5 regions as LSR usage expands to even more markets.

Contact ProMed today at 763-331-3800 to find a solution to your medical molding needs.

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The Importance of Medical-Grade Liquid Silicone Rubber

Medical-grade Liquid Silicone Rubber (LSR) is becoming increasingly crucial to the medical device industry, as the combination of the general benefits of medical-grade silicones combine with LSR’s unique advantages for medical device OEMs. As new medical-grade LSR materials become commercially available, more reliable, better performing, and more affordable medical devices will be within reach of patients.

Medical-Grade Silicones

Silicone has long been a popular material for medical device manufacturers due to its durability, ease of molding by many methods, wide useful temperature range, chemical inertness, high tensile strength, vast range of available durometers, biocompatibility, and compatibility with many sterilization methods.

Medical-grade silicones add the benefits of stringent purity and biocompatibility testing, making them suitable for use in long-term implants.

One application where medical-grade silicones really shine is drug-eluting implantable devices. Before molding, silicones can be compounded with active pharmaceutical ingredients (APIs) such as cancer drugs or hormones which can can then be steadily released into a targeted area of the patient’s body over time once that molded implant is inserted.

Drug-eluting implants are able to maintain the desired level of the API in the patient much more consistently and over a longer period of time than both pills and injections. Also, since the implant can usually be inserted near the targeted organ or tissue, lower total amounts of API are needed because that API doesn’t need to spread throughout the entire body before reaching the targeted area.

As a result, the level of the API in the patient’s body remains inside the therapeutic window (the range of concentrations between too low to be effective and high enough to be toxic) for a much longer duration.

As we’ll see shortly, medical-grade LSR is a great material for making drug-eluting implants, due to its processing advantages.

The Advantages of LSR

LSR is a type of silicone material which starts out as two separate liquid components which are then precisely mixed together before injection into a heated mold, where the silicone elastomer becomes solid (i.e. vulcanizes).

The low viscosity of LSR makes it a great silicone material for making parts via injection molding, since the LSR can easily flow into and completely fill molds with relatively low injection pressures, even those with intricate and small features.

LSR’s inherent compatibility with injection molding results in the cost-effective, repeatable, and scalable manufacture of silicone parts—including medical devices and their components.

Furthermore, the temperatures needed to vulcanize LSR are usually low enough that significant degradation of compounded substances like APIs can be avoided. Thus, medical-grade LSR an excellent material for drug-eluting implants.

Implantables aren’t the only medical device application suitable for medical-grade LSR. Wearables (such as heart rate and activity monitors), respiratory products, linings for prosthetic limbs, and other devices which must stay in prolonged physical contact with a patient all benefit from medical-grade LSR’s outstanding biocompatibility and purity.

The Future of Medical-Grade LSRs

New and improved medical devices originate from innovations in both design and materials. As new medical-grade LSRs continue to be released on the market, the medical device industry as a whole will make steady advances and improve the length and quality of life of patients around the world.

Dow Corning’s release earlier this year of two new LSRs is a prime example. These new LSR materials cure quickly at low temperatures, don’t require a primer for binding to many substrates (including polyester), need low injection pressures, and boast broad process windows.

These are all significant features for the medical device industry for the following reasons:

  • Fast cure times at low vulcanizing temperatures enable silicone injection molders to shorten the total molding cycle time (which in turn can greatly reduce the cost per molded part), and consume less energy for each silicone part since the mold will not need to heated as much as other LSRs may require. Both of these result in reduce production costs for medical-grade LSR products, and consequently, lower costs for the patients and insurance companies to purchase these products.
  • The lower injection pressures of these LSRs will allow silicone medical device manufacturers to utilize more economical, lower tonnage injection presses. These LSRs’ broad process windows can enable lower defect and scrap rates, due to a more forgiving molding process.

New medical-grade LSRs, like these from Dow Corning, will help the whole medical device supply chain ramp up production capacity to meet global demand.

At ProMed, we combine industry-leading medical-grade LSR expertise with the latest developments in silicone materials and technology. From helping OEMs incorporate the latest medical-grade LSR formulations into their designs to delivering rapid silicone prototypes, we serve as a premier silicone molding contract manufacturer for medical device OEMs. Contact us to find out how we can help you.

Thermoplastic & Silicone Use for Medical Molded Components

Thermoplastic & Silicone Use for Medical Molded Components

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.

Rubber & Plastics News Article “ProMed Succeeds with Rapid Prototyping”

Promed Prototypes

"ProMed has recently added rapid prototyping capabilities, fulfilling an industry need for fast turnaround of sample parts made from specified material." Read Article

Plastics Today Article "ProMed Prototypes Offer Fast Turnaround on Silicone Molded Parts"

ProMed Prototypes has been published in a national article which can be found at Plastics Today.

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