Injection molding is a manufacturing technique in which the molten material is injected into a hot mold cavity under high pressure. The material then cures and solidifies within the mold, taking its shape. This process is widely used in mass production for creating silicone parts and products. An injection molding prototype is a sample or model of a product made using the injection molding process.
Prototype versions often focus on rapid production and quick turnaround times. They also serve as functional and visual representations of the final products, allowing engineers to evaluate their designs and test their functionality.
The following are several reasons why injection molding prototype might be a better option than traditional prototyping methods:
1. Accurate Representation of the Final Product’s Characteristics
Injection molding prototypes closely mimic the intended product’s material properties, surface finish, and dimensional accuracy. This fidelity level enables designers and engineers to thoroughly evaluate and validate the design, ensuring it performs as intended. They can also be used to fine-tune the strategy before proceeding to full-scale production, ultimately leading to a higher-quality end product.
2. Reliable Testing of Product Functionality
Engineers and designers can subject the prototypes to rigorous testing scenarios to assess various factors. These may include the product’s mechanical performance, structural integrity, ergonomic suitability, and overall user experience. Businesses can also identify performance issues or design flaws early in development and before market launch by conducting these tests.
3. Faster Iterations and Time to Market
Unlike time-consuming conventional prototyping methods, injection molding enables the rapid production of prototypes. They also have no limitations regarding the number of iterations within a given timeframe. This expedites the product development cycle and enables businesses to promptly address market demands.
4. Cost-Effective Production
The injection molding process allows for efficient and streamlined production of prototypes, enabling businesses to create multiple replicas cost-effectively. They can also benefit from reduced per-unit costs by leveraging economies of scale. Moreover, an injection molding prototype typically utilizes production-grade materials.
5. Streamlined Transition to Mass Production
Injection molding prototypes offer a streamlined transition to mass production by closely resembling the final product and minimizing the need for adjustments. This ensures efficiency and consistency throughout the production process. As a result, businesses can scale up production seamlessly and maintain high product quality.
6. Optimized Product Development Processes
Prototyping is instrumental in optimizing product development processes by enabling the rapid production of functional models. Since the prototypes resemble the final product, they facilitate efficient design validation, reliable testing, and iterative improvements. Furthermore, iterating quickly based on feedback and testing outcomes enables businesses to minimize errors.
7. Stakeholder Collaboration and Feedback
The prototypes provide tangible models to share with stakeholders, including clients, investors, and marketing teams. These physical models also allow for better communication and collaboration, as stakeholders can visualize and interact with the product. Their feedback and input can then be incorporated into the design, ensuring the final product meets their expectations and requirements.
8. Customization and Personalization
Businesses can gauge customer preferences and market demand by creating prototypes with different variations, finishes, or features. This information can help manufacturers tailor the final product to target audiences, enhancing customer satisfaction and market competitiveness.
Trust ETI for High-Quality Molding Services!
Elastomer Technologies is a trusted provider of customized molding solutions and part production services tailored to our customers’ needs! We have established a solid reputation for delivering outstanding results in the industry with our commitment to quality and meticulous attention to detail. Aside from silicone injection molding, we also offer die-cutting, transfer molding, and rubber molding.
Reach out to us with any inquiries or to request a quote. Partner with ETI and experience excellence in molding solutions!
Rubber molding is a versatile and cost-effective manufacturing process used in many industries for decades. It involves heating a rubber material and then pressing it into a mold to create a product with precise dimensions and intricate details. Moreover, it offers several advantages, including enhanced durability, flexibility, and affordability.
However, the technique may not be suitable for every product or application. Therefore, determining when to use rubber molding requires an evaluation of the project’s specific needs. This article will explore the key factors to help you decide whether this method is appropriate for your requirements.
Key Considerations for the Effective Utilization of Rubber Molding
One important factor to consider when using rubber molding is the type of material. Using silicone in the molding process is prevalent due to its multiple benefits. For instance, silicone rubber is known for its tolerance to high temperatures, electrical insulating capabilities, and resistance to harsh environmental conditions.
Here are five additional considerations:
Physical Properties
Rubber molding provides the ability to create products with various physical properties. For example, the elasticity of rubber materials is beneficial for products that require a high degree of flexibility. This includes industrial gaskets, seals, and flexible hoses. Rubber’s durability also makes it an ideal choice for products and applications subjected to repetitive stress.
Hardness is another crucial physical feature that can be modified in molding. The material’s rigidity is advantageous for applications requiring a high degree of stiffness, like structural components and machine parts. As a result, the ability to control and modify the product’s hardness enables manufacturers to create pieces that fulfill unique performance specifications.
Volume
The molding process allows for the production of identical, highly consistent components. This decreases the likelihood of manufacturing faults and boosts overall production efficiency. In addition, the low cost of raw materials — silicone and natural rubber — makes it a cost-effective option for high-volume runs.
For small production runs, this technique is not optimal. The cost of forming the mold can be a significant fraction of the total expenses, making this process less cost-effective. Similarly, the lead time can be lengthy, with some molds requiring several weeks to complete. This can be troublesome for runs needing a rapid turnaround time.
Quality
Rubber molding is widely known for its ability to create products with accurate dimensions and detailed features. It also allows for the production of intricate shapes and designs, making it suitable for products where appearance and quality are primary concerns. Moreover, the molded rubber parts can be made to precise specifications, ensuring they will fit well and perform as intended.
Environment
This technique is a good choice for products that need to be resistant to harsh environmental conditions. Rubber is highly resistant to weathering, ozone, and UV rays. Thus, it ensures that your product will retain its shape, strength, and appearance. This makes rubber molding ideal for outdoor products, including garden hoses, patio furniture, and weather stripping.
Budget
While rubber molding is known for being a cost-effective manufacturing technique, it is not necessarily the most economical solution for every application.
Considering initial and ongoing costs is important when deciding when to use the method. Initial costs can be high, as it typically involves the creation of custom molds. These molds must be precisely created and constructed, which can be time-consuming and costly. Meanwhile, the ongoing expenditures include materials, labor, and mold maintenance.
ETI: Your Trusted Partner for Your Molding Needs
For over 45 years, Elastomer Technologies has offered customized molding solutions and part production services to meet the specific needs of our customers! With a focus on quality and attention to detail, we have built a reputation for delivering outstanding results in the molding industry.
Aside from rubber and injection molding, we also offer die-cutting, transfer molding, prototype molding, and other services. You can visit our Services & Capabilities page for more information. You may also contact us if you have any inquiries or request a quote to partner with us!
Injection molding is a versatile manufacturing technique used in the silicone industry for over a century. In particular, liquid injection molding (LIM) is a medical device manufacturing process with several advantages over other methods. For instance, it allows for increased product strength and weight. It also produces a final product within the parameters set by the device and regulatory bodies while remaining more economically efficient than other alternatives.
The underlying principle of the process is to create medical equipment and devices from specially formulated silicone materials that are strong, dependable, and FDA-compliant. This article will examine the benefits of medical device injection molding and the factors to consider when selecting materials.
Benefits of Medical Device Injection Molding
Liquid injection molding offers numerous advantages to medical device manufacturers, making it one of the most effective methods for producing rubber components. Some of the benefits that medical injection molding companies provide include the following:
Improved Ergonomics
Silicone liquid injection molding works well with moving parts devices. It extends the life of complex features that rely on buffers and materials to keep parts running without imposing undue wear and tear. Furthermore, silicone rubber is a safer and less allergenic alternative to other medical device materials due to its biocompatibility.
Flexible Design Options
Manufacturers have a wide range of design options with medical injection molding. It enables the integration of multiple components into a single fully bonded solution, which is ideal for medical applications. A single piece is also more substantial than an assembly of individual parts and thus lighter.
Increased Functionality
Silicone molding components are strong and flexible and can be stretched up to six times before breaking. This increases durability while also broadening the potential medical applications. Moreover, the parts perform as expected because the liquid injection molding process is so precise.
Lower Cost
The design of the medical silicone injection process aids in the reduction of unnecessary costs. As a result, when a large volume of medical injection parts is produced, the manufacturing method can reduce the expenditure per part. This makes medical injection molding more cost-effective than transfer molding and compression molding.
Decreased Burden of Sterilization
The materials commonly used in this manufacturing process are contaminant-resistant; they do not require a lot of sterilization to stay bacteria-free. Because of this feature, the material easily fulfills FDA standards and other prerequisites.
Considerations in Choosing Silicone Materials for Medical Injection Molding
Several silicone grades are suitable for medical device injection molding. Each material has characteristics that influence how it performs in the application and operating environment for which it was designed. When deciding on the best medical-grade silicone material for your application, keep the following factors in mind:
FDA Requirements
Tubing, medical instruments, and other external applications have different requirements than implanted medical devices. Thus, examining your application’s FDA requirements is critical before deciding on the material.
Strength and Resistance
Silicone resins have varying degrees of strength, so make sure the medical-grade silicone material you choose has the strength properties required for your application. Moreover, chemical and heat resistance are crucial when selecting a medical-grade material, especially if your finished components must be sterilized through autoclave, gamma ray, or chemical methods.
Operating Environment
Operating conditions influence strength, temperature resistance, chemical resistance, corrosion resistance, radiation exposure, and other factors. Hence, it is vital to ensure that the medical-grade silicone you choose can withstand the demands of your working environment.
Molding Method
Although medical injection molding and medical insert molding are both viable methods for prototyping medical devices, not all silicone grades are compatible with both. Therefore, you must determine what approach to take before deciding on medical-grade silicone material.
ISO Certification
A manufacturing company’s ISO certifications reflect its dedication to quality control and proven capacity to meet and surpass client expectations. Albeit a quick and easy procedure, examining your provider’s certification is essential to ensuring that you are getting the standard you require.
Choosing the best manufacturing company is undoubtedly the key to success in terms of best solutions, extended life, hygienic design, meeting standards, and cost-effectiveness over the entire product life. However, analysis and expert opinions are equally important in the medical industry before the manufacturing process, as not all machine capabilities can work on specific requirements.
ETI Is Your ISO-Certified Expert In Liquid Injection Molding
Elastomer Technologies Inc. is an ISO 13845:2016 certified company for comprehensive quality assurance management in medical device manufacturing.
At ETI, we ensure the safety and affordability of some of the most critical medical equipment in cardiology, general surgery, oncology, neurosurgery, orthopedics, and other fields. We employ a wide range of high-quality materials to ensure product durability, strength, and resistance to the inherent stressors of the healthcare industry — such as chemicals, bacteria, and extreme temperatures.
For more information about liquid injection molding and other services offered by ETI, visit our website or request a quote today.
Rubber is a very versatile material. It is used to manufacture a wide range of parts and products, from seals and gaskets to tubes and hoses to bumpers and grommets. As part of this, rubber can be subjected to a variety of manufacturing processes. Each process entails different techniques to turn the raw material into the desired component.
Below, we focus on two of the most commonly-employed rubber manufacturing processes: rubber molding and rubber extruding. We highlight each of their steps, the advantages they offer, and the typical parts and products they produce in order to help readers understand which method is best suited for their needs.
What is Rubber Molding?
The rubber molding process encompasses three key components:
The custom-designed mold to make the desired part or product
The raw material which is placed or injected into the mold
The molding machine to hold the mold and place/inject the material
Together, these three elements enable rubber molding companies to manufacture various components in different shapes and sizes.
Steps in the Rubber Molding Process
The steps in the rubber molding process are as follows:
Creating the mold for the component
Installing the mold within the molding machine
Placing or injecting the material into the mold
Applying heat and pressure to cure (vulcanize) the material
Removing the finished component from the machine
These steps may vary slightly depending on the type of rubber molding method used for the project. The three most commonly utilized are:
Injection molding: rubber is injected at high pressures into a closed mold and then heated
Compression molding: rubber is placed into a mold, which is then closed and subjected to heat and pressure
Transfer molding: pre-formed rubber is inserted into a pot, forced through a runner and gate system into molding cavity, and then cured
Advantages of Rubber Molding
There are many advantages that rubber molding can bring to a production. For example, molding rubber products is one way to produce highly detailed three-dimensional shapes. Some of the other reasons manufacturers use it include:
It is fast. The rubber molding process offers fast cycle times, which helps reduce overall production time for projects.
It is efficient. Manufacturers can utilize the same molding machine to create a variety of parts and products by simply changing out the mold. As a result, rubber molding offers high machine efficiency rates.
It is economical. Rubber molding can be amenable to automation, which enables manufacturers to lower operational costs.
It is precise and accurate. Molded rubber components can be made to a high degree of precision and accuracy, depending on the method and material. This allows manufacturers to achieve high dimensional tolerances and good surface finishes.
Applications of Rubber Molding
Molded rubber parts and products find application in a wide range of industries. Typical components produced include:
Backflow preventers
Elastomeric check valves
Electrical enclosures
Seal and gaskets
Surgical instruments and devices
What is Rubber Extruding?
Similar to the rubber molding process, the rubber extrusion process relies on three key components:
The custom-designed die to make the desired part or product
The raw material which is forced through the die
The extrusion machine to hold the die and press the material through it
Together, these three elements allow rubber extrusion companies to create a wide range of parts and products in various shapes and sizes.
Steps in the Rubber Extrusion Process
The rubber extrusion process involves forcing soft, unvulcanized rubber through a die with an opening in the profile/shape of the desired component, curing the formed material, and then cutting it to the proper length as a post molding process. The steps in the process are as follows:
Raw material is loaded into the extruder’s feed hopper
The extruder’s heated shearing screw pushes the material forward into the die
The material is pushed through the die opening at high pressures and elevated temperatures
The material exits the die in the shape of the die opening
The material is vulcanized to ensure it maintains its shape
The material is cut to the proper length
Advantages of Rubber Extrusion
Some of the key advantages of the rubber extrusion process are:
It is efficient. Minimal material waste is produced during rubber extrusion operations. As a result, rubber extrusion offers high material efficiency rates.
It is economical. The production costs for rubber extrusion operations are much lower than many other production methods.
It is versatile. The rubber extrusion process can be used to create virtually any two-dimensional shape in continuous or set lengths. Additionally, the components produced can be durable, flexible, and lightweight, depending on their design and construction material.
Applications of Rubber Extrusion
Like the rubber molding process, the rubber extrusion process is utilized to produce components for many industries and applications. Typical parts and products include:
Connectors
Gaskets
Seals
Trim
Tubing
Vibration reducers
Rubber Molding at Elastomer Technologies, Inc.
Rubber molding and rubber extrusion both play a critical role in the production of many rubber parts and products.
Whether your next project requires rubber molding or rubber extrusion, it is important to partner with an experienced and knowledgeable part fabricator, as they are better equipped to ensure the success of your project.
Looking for a rubber molding company you can rely on? Turn to the experts at Elastomer Technologies, Inc. We are an ISO 9001:2015 certified rubber molding company, and we have specialized in the design and manufacture of rubber molded parts and products for over 30 years. This extensive experience, knowledge, and skills enable us to deliver quality molded rubber solutions for nearly any part or product needs.
To learn more about the differences between rubber molding and rubber extrusion or our services and capabilities, contact us or request a quote today.
Compression molding is a molding method that utilizes custom machined molds to form parts and products from uncured rubber or plastic. The process involves placing the material into the open mold cavity, closing the mold, and applying heat and pressure to shape and solidify the material into the desired component. It can be used to turn a variety of designs into tangible objects for a wide range of industries and applications. However, while it is an ideal production solution for many projects, it is not suitable for all of them.
Below, we highlight the key advantages and disadvantages of the compression molding process to help you understand if this is the right solution for your needs.
Advantages of Compression Molding
There are many advantages to choosing compression molding for a rubber or plastic component manufacturing project, including, but not limited to, the following:
It is a simpler process.
The compression molding process is relatively simple and straightforward compared to other molding and manufacturing processes. For some part designs this makes it easier for operators to perform, which translates to lower overall production costs.
It involves lower tooling costs.
Compared to injection molding, compression molding does not require special equipment and expensive complex tooling. As a result, the equipment and tools required for the operation are much simpler, which typically means less capital investment. Although it is a labor intensive process, when handled correctly, the wear and tear sustained by the molds during operations is relatively small, which can mean less maintenance needed over time, resulting in lower cost quotes for customers.
It is great for producing large items and thicker parts.
As the compression molding process involves loading the material directly into the mold cavity, it is not subject to part weight limitations except for those imposed by the part design, and equipment (e.g., size and pressure capacities). As a result, it can usually handle the larger amounts of raw material needed to create bigger parts and products.
It can be a good choice for insert molding and multi color molding.
Done in a vertical compression press with the right approach to tooling this process lends itself to some types of insert molding and dual color molding without the high cost of special equipment, very expensive tooling, high set-up and material costs used in liquid injection molding of silicone
It is cost-effective for short production runs.
Due to its lower tooling and setup costs, compression molding is ideal for small to medium production runs. It is often used to create prototypes or samples of designs before proceeding to large-scale production.
Disadvantages of Compression Molding
While the compression molding process carries many advantages for customers looking to start a new part production, it also has a few disadvantages, such as:
It has a higher chance of post molding costs.
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The size (projected area) of the part and its weight must be carefully calculated in relation to the force available from the press used to shut and hold the mold closed during a molding cycle. Even if this is optimal expect more parting line flash and and parting line control issues that may need to be dealt with by hand trimming or nitrogen de-flash of the parts adding cost.
It has slower processing times.
Compared to injection molding, compression molding requires more time to bring materials to cured state. These slower processing times can affect production rates and costs in higher volume projects.
It is not suitable for all complex designs.
The material used in compression molding operations may be subject to some limitations of flow within the mold cavity. As such, it may not reach into more intricate portions of the mold and tooling revisions may be needed to fill some parts. This quality makes the process unsuitable for some complex part and product designs.
Elastomer Technologies, Inc.: Your Partner for Compression Molding Needs
Compression molding can be an effective and efficient manufacturing solution for many projects. By understanding the unique advantages and disadvantages it carries compared to other available solutions, you may find that it is the ideal solution for your project.
Equipped with over 30 years of experience providing precision molded and die cut components to customers in a wide range of industries, the team at Elastomer Technologies, Inc. has extensive knowledge on compression molding and tailoring the process for each project. Check out our compression molding page to find out how we can benefit your next project.
To learn more about compression molding and if it’s right for your needs, contact the experts at ETI today.
“Molding” is an umbrella term encompassing all of the processes that utilize molds to shape material (typically rubber or plastic) into the desired parts and products. Manufacturers are able to employ a variety of molding methods to suit different product and production requirements. One of the most commonly used methods is compression molding.
What Is Compression Molding?
Compression molding of rubber compounds is a technique that involves the compression of pre-formed and/or pre-heated raw material in a heated mold cavity (sort of like making a waffle in a waffle iron). The material experiences high pressures within the closed mold, forcing it to conform to and, once cooled, retain the shape of the die cavity. Below, we provide a more comprehensive overview of the process as well as highlight some of the advantages it has over other manufacturing methods.
An Overview of the Compression Molding Process
While all molding methods operate under the same basic principles, they differ in the exact steps taken to create a molded part or product. Compression molding operations typically follow these steps:
Designing and creating/sourcing the mold. Before the compression molding process can begin, the manufacturer must first obtain an appropriate two-part compression mold to create the desired component.
Creating the pre-forms. At the start of the compression molding process, the manufacturer must form the molding material into a pre-form. The carefully weighed pre-form might have the general shape of the desired component but be larger to ensure the material reaches and fills all areas of the mold cavity during the molding process.
Heating the mold. Before the pre-forms are placed in the mold cavity, the mold must be heated to facilitate the curing of the material that has a heat sensitive catalyst milled into it
Placing the pre–forms. The pre-forms are placed into the cavity of the heated mold, and then the mold is closed.
Applying heat and pressure. Heat and pressure is applied to the mold and, consequently, the pre-form. This causes the material to fill and conform to the shape of the mold cavity. Any excess material is free to leak out of the mold cavity.
Ejecting the molded component. Once the component has been formed, it is released from the mold.
Removing excess material. If the molded component has excess material (i.e., flash), it is removed.
Advantages of Compression Molding
Compared to other molding and manufacturing methods, compression molding offers a number of advantages, including the following:
Broad design flexibility. The compression molding process is highly versatile. It can be used to produce a wide range of components in various shapes, sizes, and complexities.
Strong parts. Compression-molded parts generally have little to no residual stress.
Less waste generation. Compared to injection molding and transfer molding, compression can generate less material waste. This quality makes it ideal for molding operations involving expensive materials.
Low tooling costs. The compression molding process requires tooling that is much simpler and, consequently, less expensive than the tooling used in the injection molding or transfer molding processes.
Suitability for large parts. Since material is loaded directly to the mold cavity, the part has less weight limitations except for those imposed by the size and pressure capacities of the press and the way the mold is designed.
Partner with the Experts at ETI for Your Compression Molding Needs
If you’re looking for the right partner for your next compression molding project, turn to the experts at Elastomer Technologies, Inc. (ETI). We are an industry-leading contract molding provider. One of our core service offerings is compression molding. We can compression mold a variety of materials, including butyl, EPDM, nitrile, polyisoprene, silicone, and Viton®, into parts of a wide range of sizes and complexities.
Compression molding uses a heated mold in combination with precise amounts of material and applied pressure to create solid components from a wide range of available and custom formulated materials. In this blog, we offer a concise overview of the compression molding process, its benefits, and its uses for various industries.
What is Compression Molding?
Compression moldingis a highly specialized manufacturing process that uses heated reusable molds and melted thermoset materials to create highly accurate and exceptionally strong components. The process applies intense pressure to force the molten material firmly into all mold cavities, which makes it ideal for producing components with complex geometries or fine details. Compression-molded materials also exhibit an exceptionally high level of strength due to the permanent cross-linking of molecules in the material during the molding process.
The Compression Molding Process
The compression molding process can be broken down as follows:
Design and fabricate a mold around the exact specifications of the desired component.
Heat the mold and and place the specified material into the preheated mold, and close the mold.
Apply extremely high pressure to the material in the mold to remove air and fill all available space, so that even the most detailed components are completed to a high degree of accuracy.
Allow the material to cure and solidify, then remove from the mold cavity.
Compression Molding Uses and Applications
Thermoset materials used in the compression molding process exhibit a favorable strength-to-weight ratio, which facilitates the production of parts that are precise, strong, and low weight. This makes compression molded components ideal for a variety of applications, touching every market segment including:
Automotive parts
Aerospace components
Material handling tools
Industrial equipment
Medical components
Construction and architectural components
Advantages and Disadvantages of Compression Molding
Compression molding offers some unique advantages over other molding processes:
Enhanced component material strength. The combination of heat and pressure result in exceptionally strong components.
Superior detail and accuracy. The application of pressure ensures that every detailed cavity of the mold is filled, resulting in components with a high degree of detail and precision.
Cost-effectiveness. Compression molding creates exceptionally durable, accurate components at a lower overall cost than other production methods. Because the mold is reusable, the process can be used for production runs at relatively low costs.
Metal replacement. Due to their high strength and lightweight nature, compression molded thermosets are often used to replace metal components in various aerospace, industrial, and automotive assemblies and medical components are molded with this method as well.
Although compression molding offers a wide range of benefits, it is not necessarily the best option for all parts. The cycle times are often longer than comparable molding processes, and the cost offset by additional cavities in a mold to make more parts per process cycle which will increase the cost of tooling.
Common Rubber Materials in Compression Molding
Compression molding can be used to create components from a wide range of polymers, including:
Fiber-reinforced materials
Neoprene
SBR
Silicone
Fluorosilicone
FKM
Natural Rubber
Nitrile
Butyl
What is the Difference Between Injection Molding and Compression Molding?
Although injection molding and compression molding are similar, they exhibit some distinct differences:
Injection molding is ideal for small parts, while compression molding can be used for much larger components.
Injection molding is faster, as it does not require the same amount of finishing work.
Compression molding equipment has excellent production capacity and gains economies of scale through multi cavity tooling, which makes it better for high-volume production runs.
Compression molding equipment is easier to repair and maintain than injection molding.
Compression Molding Services at Elastomer Technologies
With more than 40 years of experience, Elastomer Technologies is a leading expert in compression molding and fabrication services. We pride ourselves on providing quality manufactured products using equipment and processes that meet and exceed even the most stringent industry standards.
Contact us todayfor more information about our compression molding services!
Rubber molding is a manufacturing process that uses pre-shaped molds to create parts and components from uncured rubber. Depending on the product and specifications, there are several different rubber molding method options—such as compression molding, transfer molding, and injection molding—each of which comes with unique considerations and best use cases.
In the following blog post, we offer an overview of the above three methods, outlining their process steps, tooling considerations, design and material considerations, and applications.
Overview of Liquid Injection Molding
Liquid injection molding (LIM) is a highly versatile and cost-effective rubber fabrication method that involves injecting liquid silicone rubber (LSR) compounds into a high quality injection mold. Once injected into the heated mold and cured, the material maintains the shape of the mold, thereby producing a detailed component. The process readily accommodates automation, enabling it to be used to complete large production runs in a short period of time.
Tooling Considerations for LIM
Although LIM is quick and efficient, it is not ideal for all applications. For example, the process may not be suitable for producing prototypes for manufacturing operations. The upfront cost of creating the mold, lead times, set-up cost, process validation cost and material costs can be limiting factors.
Design and Material Considerations for LIM
Liquid injection molding operations utilize liquid silicone rubber. The material is particularly useful because it is consistently produced and has a useful range of temperature and mechanical properties. Its shrink rate is fairly predictable but as it cures after ejection may continue to shrink so it is important to consider shrinkage when designing a liquid injection molded part.
Silicone likes to move into spaces in a mold so its flow characteristics can be of benefit when filling very thin walls and other complex geometry. However, this same characteristic can create flash issues at parting lines of molds. It is also important to note that when variable geometry in a part is required it can create pressure variations as the liquid silicone moves through a mold. It is important for LSR molding that gate locations, gate sizes and venting in molds be used to optimize the process.
There are many suppliers and distributors of liquid silicone rubber to be found and they all have many pre-designed and manufactured compounds that can be employed. Custom compounding of liquid silicone material is rare, but in the right application it can be done. However the cost is usually quite high and the lead time can be very long.
Be aware that the cost, availability and use of liquid silicone should be part of the research done by a designer or customer. Molders can be of great assistance in narrowing the field of available materials and suppliers and all have preferences based on experience but picking a material for a product and process is ultimately the customer’s decision.
Applications and Uses of LIM
By altering injection pressure and speed, process temperatures, and clamp pressures, industry professionals can easily tailor the LIM process to suit a wide range of part and production needs. They can also integrate automation components to increase the level of precision and accuracy achievable and decrease the need for post-molding operations, saving manufacturers both time and money.
The LIM process can be a cost effective method of manufacturing high volumes of simple geometry and complex products. Typical parts produced include electronic components, isolators, O-rings, and seals for use in the aerospace, medical, consumer and automotive industries.
Liquid silicone rubber is a versatile material that has low surface energy and a broad temperature range. This along with other properties makes it an excellent choice for medical device components. It can be formulated to be both conductive and non-conductive allowing it to be useful in electrical applications. Silicone can be colored and this along with its finish gives it aesthetic appeal. Its elasticity provides an avenue for designing specific mechanical applications.
Overview of Compression Molding
Compression molding involves the compression of specific compounds of catalyzed rubber between two halves of a heated mold while applying tremendous pressure. Once released from the mold by hand, the cured material holds the internal shape of the mold producing a specific part.
Tooling Considerations for Compression Molding
The tooling for compression molding typically consists of two pieces of steel or sometimes aluminum that, when put together, form an enclosed space that creates a part. One side of the mold may be machined to create the outside geometry of a desired part and the other side might contain the details of the inside of a part.
The costs associated with building the mold are directly related to the amount of complexity required to be machined into the mold to make the desired design. The more complex or the larger the part, the number of cavities that are requested to be made that make individual parts in a mold, the time and type of material used to make the mold all go into the cost.
Additionally there is a cost to set-up and test new molds that is usually folded into the mold cost. This would include press time, material cost and any additional cost estimated by a molder.
Material and Design Considerations for Compression Molding
Compression molding can be used to manufacture a startlingly wide variety of products. The diversity of compounds within the types of material is nearly limitless allowing it to be designed to make parts that can perform with specific mechanical requirements, chemical resistance properties, and environmental qualifications.
The compression molding process may not display the same level of accuracy and precision, which makes it less suitable for products where tight dimensional tolerance is critical and where flash and parting line shift may cause issues. This makes trimming of parts, and nitrogen de-flashing of parts a go–to solution for some of these issues.
Applications and Uses of Compression Molding
The compression process is useful for the production of large or small parts with varying degrees of complexity usually lending itself better to smaller quantities of parts as it is slower and more labor intensive than injection molding of rubber. Designers and engineers often employ it for prototyping and sample production operations to test out new part or product designs. However, this process can be used successfully to make high quantities of parts.
Any industry can benefit in the use of compression molding rubber parts. Medical, oil and gas, aerospace, electronics, automotive and other consumer products companies all use products made with compression molding.
Overview of Transfer Molding
Similar to compression molding, the transfer molding process requires the use of pre-measured and positioned material. However, it offers greater precision and is less prone to flash on parting lines as the two halves of the mold that contain the part geometry are closed together before material enters the part detail in the mold. Compared to injection molding, it is much slower since the material is placed by hand in the mold and the part removed by hand forms the mold once molded.
Tooling Considerations for Transfer Molding
While tooling is similar to compression molding it has some advantages for specific parts. The pot and piston design allows better efficiency and precise distribution of material in the mold. This can be beneficial for parts where gate location may be critical to effectively fill a thin wall or in a larger part that might require a pressurized distribution of material to fill more effectively or a multiple cavity mold saving time in loading many individual cavities with material.
Choosing the right material can be very important. Aluminum molds can have problems with parting lines when molding some materials and the constant opening and closing of molds can create wear and tear. Steel is preferred for production tooling and different types of steel including pre-hardened alloy, hardened material, stainless steel and even more exotic material such as titanium can be employed in specific applications.
Design and Material Considerations Transfer Molding
Compared to both compression molding and injection molding, transfer molding usually generates less material waste because overflows in the mold are usually not needed. It does produce waste in the form of leftover material in the transfer pot and sprues leading to the gates where the material enters the cavity in the mold. After the molded product solidifies, this material must be removed and discarded as it is a thermoset material and cannot be reused.
When designing a transfer mold, it is important to consider the above. Ideally, the mold should produce the highest quality part in the shortest cycle time with the least amount of scrap. Partnering with an experienced mold maker can help achieve this goal.
Material used in transfer molding is usually the same range of materials used in compression molding.
Applications and Uses of Transfer Molding
Transfer molding is faster than compression molding and less expensive than injection molding, qualities that make it ideal for use in the manufacture of parts in small production runs. However, like compression molding it produces an amount of waste, and this has to be measured against the cost of the material being employed.
As with compression molding, any industry can benefit in the use of transfer molding of rubber parts. Medical, oil and gas, aerospace, electronics, automotive and other consumer products companies all use products made with compression molding.
Molding Services at Elastomer Technologies, Inc.
Liquid injection molding, compression molding, and transfer molding are three commonly employed rubber production methods. Each offers unique benefits and limitations that suit them for different applications.
At Elastomer Technologies, Inc. (ETI), we are well-versed in all three methods, enabling us to meet a wide range of rubber molding needs. Our customer base is highly diverse, ranging from aerospace and automotive to food processing and medical. By partnering with us, they benefit from our:
Over 35 years of industry experience
Commitment to superior customer service
Continuous improvements to our molding techniques and technologies
To learn more about rubber molding or our services and capabilities, reach out to us today.
Liquid injection molding, compression molding, and transfer molding are characterized by a number of both shared and unique qualities. The following blog post explores each of these three molding techniques, outlining their similarities and differences, pros and cons, and applications.
Liquid Injection Molding (LIM)
Liquid injection molding (LIM) utilizes liquid silicone rubber (LSR) or similar elastomeric material to create a range of products that demonstrate excellent durability and flexibility. Some of the typical products produced by LIM are:
Seals and sealing membranes
Electrical and electronic components, such as connectors and cables
Medical and sterile devices
Kitchen goods
Infant care products
Due to its use of LSR, liquid injection molding relies on a more streamlined and consistent mechanical mixing process rather than a labor-intensive one (such as is used in compression molding). The closed-loop process employs a pump and mixing unit to mix and dispense the liquid material into a molding press. Once the curing stage is complete, the press opens and ejects the finished component, allowing it to be manually or robotically removed.
Liquid injection molding is one of the most cost-effective and versatile manufacturing methods currently available. It is applied towards any industry or market, including:
Aerospace and aviation
Automotive
Electronics
Food and beverage
Medical and dental
When implemented correctly, LIM consistently produces high-quality molded components in large quantities. However, it is not always the most optimal choice. For example, it is important to consider whether silicone would be the best material to choose. Silicone tends to react with certain environmental and chemical conditions, such as pressurized steam at temperatures above 150°C, which breaks down the material’s siloxane polymer and degrades its material properties.
For a more detailed explanation of when you should and should not choose the liquid injection molding process, download our new eBook, “5 Common Liquid Injection Molding Mistakes (And How to Avoid Them)”.
Compression Molding
Compression molding involves placing thermosetting resins into a heated mold cavity and applying pressure to force it down and compress it in the mold. Throughout the entire process—from distribution to curing—the material is regulated for temperature and pressure level to facilitate accurate part production.
Compression molding is highly flexible and versatile. It is suitable for producing parts with a variety of sizes, thicknesses, and complexities and addresses certain manufacturing challenges, such as production operations that require special materials, difficult-to-manage inserts, or unique part shapes.
Due to its flexibility and versatility, compression molding is advantageous for any industry that requires:
Versatile compound requirements to meet part performance criteria.
Parts with difficult to mold geometry.
Prototype parts that require the material of choice.
Insert molding.
Dual material molding.
Compression molded parts can exhibit environmental versatility and high chemical resistance. Parts that can be produced by compression molding process include buttons, gaskets, respirator masks, spatulas, and syringe stoppers.
Although compression molding is suitable for high volume production, liquid injection molding offers faster processing and is more repetitive and consistent requiring little if any labor. Compression molding offer faster production changeover times, in some cases less expensive tooling, lower up front material costs and greater production flexibility (as tooling and materials can be relatively quickly changed to meet production demands).
With these considerations in mind, before deciding on a molding process for your application, consult with your molding service provider to make sure that compression molding is most suitable for your production needs.
Transfer Molding
Despite its similarity to compression molding, the key distinctions of transfer molding lie in its specific tools and unique benefits.
Similarly to injection molding, transfer molding pushes the material into a mold through a sprue. However, a plunger—rather than a screw, barrel and complex injection system—is also employed to transfer the material.
Both injection and transfer molding are efficient methods of producing high-quality, durable, and lightweight products in large volumes. However, injection molding generally allows for faster production cycles than transfer molding, making it more suitable for certain projects.
Transfer molding offers several advantages over other molding processes, such as:
Minimal flash formation at parting lines of molds.
Faster setup times.
Lower tooling costs.
Greater part design flexibility (and capacity for part complexity).
Any industrial application can employ transfer molding.
LIM, Compression Molding, and Transfer Molding Services at ETI
As outlined above, the ideal molding process largely depends on your production specifications and requirements. For assistance determining the optimal material and molding process to use for your part, fill out and submit our Design analysis form.
For over 30 years, ETI has stood by the same guiding principle: create a way to achieve every customer’s goal. To help deliver on this promise, we are always looking for ways to improve the quality of our service. Most recently, we invested in a new and larger facility that allows us to have better material control and improved workflow while allowing for future technological improvements.
To learn more about the liquid injection molding, compression molding, or transfer molding services we offer at ETI, reach out to us today.
Contact Our Team
Whether your project is in the initial stages of development or set for production, ETI is ready to help you select the right material and process for your project. Our team manufactures parts that meet your specific requirements regarding performance, delivery, and price.
Take a moment to fill out our brief contact form, and one of our representatives will respond as soon as possible.
