Thermoplastic & Silicone Injection Molding

A silicone injection molding company with over two decades of custom injection molding experience, Casco Bay Molding is an American leader in ISO 13485:2016 Certified medical, consumer, and industrial manufacturing. We’re pleased to offer advanced plastic and silicone injection molding capabilities, precision tooling, and product design all under one roof at our factory in Sanford, Maine.

Experts in silicone injection molding, our engineering team is here to help you through the product design, machining, manufacturing, and fulfillment processes.

Have a custom plastic or silicone molding project? Request a quote from our design team.

Streamlined Silicone Injection Molding: Our Approach

At Casco, all stages in the product development process occur under one roof, including product design, precision tooling, manufacturing, and fulfillment.

By involving our in-house tooling team from the start, we’ll help you develop an elegant product design that prioritizes use, manufacturability, and material conservation. Some of the many benefits of our one-roof approach include:

1. We understand the unique properties of different types of silicone and thermoplastic. With decades of medical, industrial, and consumer product design experience, our unique team of OEM engineers will work with you to create the best, most cost-effective version of your product.

2. We take manufacturability—the ease at which a product can be injection molded at scale—into account from Day 1. From the drawing board, our production team is involved to help us optimize your product design for production.

3. Unlike other factories that send your mold out for initial precision tooling and any future adjustments, Casco has an in-house tool shop. This means that potential mold adjustments are more affordable and have higher turnaround times.

Medical Silicone Injection Molding Experience

Casco Bay Molding is pleased to offer expert medical device manufacturing for class I and class II devices. In addition to ISO 13485:2016 certification, Casco Bay Molding is the manufacturer on record for many FDA-registered products.

Current and past medical industry silicone injection molding projects include menstrual health products, surgical instruments, labware, respiratory equipment, micro-filtration technology, and personal protective equipment.

Menstrual Product Silicone Injection Molding 

Casco Bay Molding is a global leader in menstrual cup and menstrual disc manufacturing. We offer both private labeling services—use one of our existing comfortable menstrual cup designs for your brand—and menstrual cup design services.

From the drawing board to FDA regulations to fulfillment, Casco Bay Molding will help you establish and scale your menstrual cup business.

Surgical Instruments and Labware

Manufacturing surgical technology is another specialty of ours. Current and past projects include catheter components, sterilization trays, surgical device handles, medical device cases, surgical fiber optic light strain reliefs, laparoscopic trocar technology, and more.

Respiratory Equipment Injection Molding

Casco offers significant expertise in respiratory equipment silicone injection molding and overmolding. Recent projects include sleep apnea mask components and pediatric and adult ventilator valves.

Microfiltration Technology Injection Molding

Examples of recent microfiltration jobs include in-line IV set filter and air vent components, filtration gasket overmolding, 0.2-micron pleated cartridge technology, and reverse osmosis ultra-filtration technology components.

Industrial and Consumer Silicone Injection Molding 

Casco Bay Molding brings the same attention to detail to our industrial and consumer product projects. Injection molding silicone products for babies and mothers is one of our areas of expertise.

Many of our customers in the baby care space appreciate the material traceability, quality control, and design protection that come from working with silicone injection molding companies in the U.S.

Current and past products in the newborn and toddler space include nipple shields, baby bottle nipples, healthcare application components, and toys.

What Is Injection Molding?

Injection molding is a cost-effective way to mass-produce a silicone or thermoplastic product.

It involves the creation of an aluminum tool, also called a mold, that is inserted into an injection molding machine. The mold has two halves, called a core and a cavity, respectively. Our machines exert enormous pressure on these halves to bring them together. Thermoplastic or silicone is then melted and injected into the mold through its gates.

Production and fulfillment is only part of what we offer. We are pleased to work with medical device OEM engineers and creative product developers who understand the unique physical properties of silicone rubber and thermoplastic. This allows us to design a product suitable for injection molding and cost-effective for you.

Unlike other manufacturers, we offer our in-house precision machine shop services. Not only do our experienced machinists offer unparalleled insight into a mold design, but adjusting a mold once created is more cost and time-effective with our in-house time. Additionally, we are able to reduce mistakes and lead times through our partnership with our in-house machine shop.

6 Advantages of Injection Molding Silicone & Thermoplastic

There are many reasons to go injection mold your product with Casco Bay Molding. Here are a few to keep in mind:

1. Experience: We have the unique ability to design, prototype, create the mold for, produce, and fulfill your product to scale right here in Maine, USA.

2. Time: Our team has a breadth of experience troubleshooting tooling complications and a quick turn-around time given our in-house tooling shop. This means getting your machine running — and your product to market — as soon as possible.

3. Cost: Though plastic or silicone injection molding may require an up-front tooling investment, the price per unit can be extremely low. The more parts are produced, the further that price drops.

4. Quality: Casco Bay Molding is an ISO Certified manufacturer and an FDA-registered menstrual cup producer. We used medical-grade silicone in our silicone projects and have experience with a variety of polymers as well. We are pleased to offer high-quality parts no matter the project.

5. Consistency: The beauty of our injection molding process is creating millions of identical parts. Whether we are developing a medical application part or, scuba diving equipment, consistency and quality are key.

6. Efficiency: Depending on the project, injection molding can produce a low rate of scrap, This diminishes both the financial and environmental cost of production.

3 Types of Injection Molding: Silicone, Thermoplastic & Overmolding

III. Overmolding Silicone and Thermoplastic

At Casco, we offer overmolding and two-component manufacturing capabilities. Leveraging the benefits of our one-roof approach to manufacturing, we’re able to over-mold LSR onto thermoplastic, metal, and other materials—all while cutting down on costs for our customers.

Injection Molding & Overmolding process

The LSR product development cycle starts by understanding the application and part’s environment. Below please find a few tips for a successful two-component / over-molding project outcome.

1. Part Design: Understanding the LSR and the thermoplastics processes, and both materials’ capabilities. The simplest designs are the most elegant.

2. Material Selection: Work with Casco Bay Molding to define which thermoplastic can handle the heat of an LSR injection mold. A few acceptable thermoplastic examples are injection-molded Nylon, SPS — Syndiotactic Polystyrene: Valox — PBT, Polycarbonate, Radel & Polysulfone. Glass-filled versions of these resins aid in silicone’s chemical bond.

3. Bonding Type: The most reliable results are achieved with both a mechanical and chemical bond. Mechanical design is dictated by a good part design. Chemical bonding is facilitated with a priming agent and/or a surface treatment with an ample amount of surface area.

4. Tooling: We frequently get our silicone molding team and precision machine shop engineers involved early in the process once an order is received. Care must be taken to address potential variation in shrinkage in the X-Y-Z directions.

5. Production: High or Low volume? The answer can dictate the approach. High volumes can permit a fully automatic production with a two-component molding machine, while with a low volume approach, most frequently, machine operators insert plastic or metal parts manually.

6. Prototyping: If a project is of a technical nature and high volume, it behooves the customer to invest in a single cavity silicone short run/prototype injection mold. Casco Bay frequently builds a single cavity in a four cavity mold base, enabling us to adjust the customer part design on a single cavity before blindly investing in high volume production.

7. Manufacturability & Tolerances: Design a part with real-world tolerances, define non-critical areas where silicone and plastic can be gated, and vented.

Silicone Injection Molding Project Examples

Medical Device Components (Class I & Class II)

• Surgical: Catheter technology, injection assist device components, sterilization trays, laparoscopic trocar technology

• Medical/Dental Instruments: muscle stimulation device, over-molded dental and medical instrument handles, fiber optic light strain reliefs

• Labware: Plastic wells for gene sequencing application, sliding glass cover gasket, sanitary gasket

• Micro-Filtration: Reverse osmosis equipment components, air vents, filtration gaskets, sterilizing 0.2-micron pleated cartridges

• Intravenous: Pressure activated valves, needleless valves, injectable drug-device components, Luer activated valves

• Respiratory: Sleep apnea flapper valve, adult and pediatric ventilator valve

• Menstrual: Menstrual cup, menstrual disc

Consumer:

• Kitchen & Bath: Two-part drinking water faucet spray face, hot-cold drinking cap

• COVID-19: Face shield, face mask

• Recreational: ExerTies sleeve straps, scuba diving equipment

Food Processing Equipment:

• Frozen food handling suction cup

• Ice cube tray

• Food formation components

Overmolding Product Examples

Our team’s liquid silicone rubber (LSR) over-molding / two-component experience includes the following projects:

• Silicone over-molded onto a plastic handle

• Two-component military products

• Silicone molded onto a precision metal plate for diode fabrication

• Food processing parts

• Kitchen equipment (ex: spatulas)

• Silicone seal on a polysulfone base

• Labware applications with silicone rubber gaskets over-molded onto Ultem and Valox parts

• Medical and dental handles with silicone over-molded onto a stainless steel tube

• Filtration applications with silicone gaskets molded to a plastic screen

• Silicone over-molded onto a glass slide

Types of Thermoplastic & Silicone Injection Molding Jobs

We offer an ISO 13485:2016 certified custom silicone injection molding and decades of experience. Whether your product requires medical-grade silicone such as a menstrual cup or you want the quality and attention to detail of an award-winning manufacturer, Casco Bay Molding can assist you during the product development process and mass-production.

Not sure which category applies to your project? Our silicone injection molding processes can be divided into two main categories: high and low volume. We are happy to help you determine the best solution for your needs.

I. High Volume Thermoplastic & Silicone Injection Molding

Casco Bay Molding is a leading silicone injection molding company thanks to decades of engineering and manufacturing experience. Specifically, we offer cold runner LSR injection molding solutions for Class VI, healthcare grade liquid silicone rubber parts. This approach is generally used for higher volume applications where the cost of materials represents a large part of overall production costs. We employ removal robots and special mold designs to fully automate machine run-time for silicone parts, reducing costs.

II. Low-Volume (or Short-Run) Custom Injection Molding

Short-run silicone injection molding and part production require a tool steel core and cavity designed to fit into a mold base. In these cases, liquid silicone rubber core and cavity sets are fabricated under our direction. Generally, these parts are manually extracted until the unit part volume increases enough to justify a higher volume approach.

We work hard to make silicone part and mold design changes quickly, thereby reducing turnaround times. From Day 1, we will work with you to shorten the product development cycle.

Interested in developing a product or seeking the advice of a leading injection molding company? We offer comprehensive product development services specializing in medical applications.

III. Prototype Creation

Our prototype liquid silicone rubber parts are also produced on steel core and cavity (C&C) sets. Yes, aluminum C&C sets can be cost-effective in the short term, but our experience shows that this cost is negligible compared to the cost of re-cutting a C&C set once the aluminum becomes warped after repeated thermal cycling.

We aim to turn simple core & cavity sets around in 3 to 8 weeks depending on our production schedule and complexity. Occasionally, our prototype steel core and cavity sets can be hand injected but are generally fit into one of our standard tool steel LSR mold bases. Frequently, we quote tooling fees and mold test fees for small volume jobs requiring LSR parts.

No matter your design, it is important we understand how a part will be used and its critical dimensions. Locating gates and vents in non-critical part regions facilitates good mold cavity filling while allowing for proper shrinkage in areas of critical dimensions.

High Volume Plastic Injection Molding

Current high-volume jobs include technically challenging faucet spray components, made up of a glass-filled plastic substrate over-molded with silicone rubber. Our customer requirements and ISO procedures include spray testing, PPAP qualification, and Statistical Process Control. Other current high-volume production includes ABS jobs and medical/dental glass-loaded Nylon parts that require post-molding assembly.

Additionally, we have invested in a Keyence camera GO/NG monitoring vision system which has been installed mold-side to 100% inspect critical dimensions on all parts as they come off the press.

INJECTION MOLDING PROJECT EXAMPLES

Past long-run jobs included technically challenging energy extraction industry Syndiotactic Polystyrene (SPS) parts, requiring a far-field Ultrasonic weld. SPS is known for its chemical resistance and high strength vs. weight ratio. We molded (20 to 40%) glass-loaded SPS in 16 cavity hot tip molds. Glass loading adds to the challenge of ultrasonically welding a part consistently, and wearing the Titanium welding horn throughout the process. As defined in our ISO work instructions, both the molding and welding processes were monitored to stay within an acceptable range during fully automated production.

MEDIUM PRODUCTION RUNS

Medium run experience includes engineering polymers, for example- Polysulfone water: chemical filter stack backing plates, Valox & Ultem medical lab-ware parts, ABS military parts, and components used in medical instrument sterilization. Casco Bay Molding has the necessary material drying and hot oil mold heating equipment to run these technical engineering resins.

To minimize our thermoplastic customers’ tooling investment, we frequently use small dedicated mold bases, RoundMate Pods, or MUD set inserts that fit one of our MUD set or RoundMate mold bases.

POST-MOLDING CAPABILITIES

Post molding assembly, Ultrasonic welding, spin welding, printing, and decoration services are included within our capabilities.

As mentioned our team enjoys developing two-component silicone parts, also referred to as over-molded silicone rubber and plastic parts. We are pleased to offer our customers the ability to have your silicone rubber and thermoplastic parts injection molded under the same roof.

PLASTIC AND SILICONE Tool Creation 

We have a wealth of experience with 2-component parts or over-molding silicone onto various plastic or metal parts. Per standard LSR parts, we start with a core & cavity set and evolve the project into a full-blown silicone injection mold as the project dictates.

Casco Bay Molding’s internal mold shop allows us to have our mold makers involved in a final part review before mold design and production. Our ISO 13485:2016 certified process and product development team is based on understanding the important aspects of a component’s function within the final application. We are pleased to have a part and tool design review meeting prior to beginning a project.

Plastic & Silicone Injection Molding FAQs

The following are the most commonly asked questions about our manufacturing processes. Have more questions? When you submit a quote, feel free to include them in the notes section.

CAN WE TRY INJECTION MOLDING DIFFERENT Silicone DUROMETERS?

Yes. Once the core & cavity set or mold is completed Casco Bay Molding can run various durometers in the same mold. Liquid silicone rubber is delivered in a closed “sheetrock bucket” or 55-gallon drum sets. Each durometer has its A & B sides that are pumped into the injection molding machine.

CAN WE PROTOTYPE SILICONE RUBBER?

Yes and No. If you build a plaster or silicone mold, you can hand inject RTV (room temperature vulcanization silicone). It is more difficult to inject LSR (liquid silicone rubber) into anything but a metal mold because you need to elevate the temperature of the mold to get the LSR to cure. Casco Bay Molding builds tool steel Short Run –prototype silicone rubber core and cavity sets for customers who want to have LSR Silicone parts

CAN I USE A CHINESE MOLD?

We do not find Chinese molds (especially those from Asia) to be a viable option for our injection molding processes. The tighter LSR (liquid silicone rubber) tooling tolerances and ability to adjust the LSR tool’s vents, gates, and part geometry negate the cost advantage of sourcing overseas tooling. In our opinion, plastic molds can offer some pricing advantages as long as a U.S. tool-making partner stands behind the mold.

A Leader Among Silicone Injection Molding Companies

Casco Bay Molding sets the gold standard for American manufacturing due to our attention to detail, extensive molding experience, and talented engineering team. We specialize in medical manufacturing, and also manufacture consumer and industrial products for companies around the world. Interested in working with us? Submit a quote and a member of our team will be in touch shortly.