Extrusion screws serve as the backbone of the extrusion process, fulfilling multiple critical functions such as conveying, compressing, and blending plastic compounds. The design of these screws represents a refined scientific discipline, with specialized configurations continually evolving to enhance output rates, promote thorough mixing, and expand processing parameters. Tailored screw designs are crafted to align with the specific characteristics of the plastic compound, the desired output capacity, and the physical properties sought in the final product

A single-screw extruder, as the name suggests, operates with a single screw. It was the pioneering type of extruder, originating around 1935 in Hamburg, Germany. Even today, single-screw extruders remain prevalent and indispensable in the realm of plastic processing. They are renowned for their versatility and robust performance, making them the go-to choice for custom profile extrusion across diverse industries.

Twin-screw extruders emerged following the development of single-screw machines, with their origins traced back to Italy. Custom plastic extrusions commonly utilize counter-rotating twin-screw machines, which offer superior mixing capabilities and precise control over the extrusion process. On the other hand, co-rotating twin-screw extruders are primarily employed for compounding plastic materials, blending various additives and components to achieve desired properties.

Counter-rotating extruders feature screws that rotate towards each other, with one turning clockwise and the other counter-clockwise. These intermeshed screws effectively mix and convey the material down the extruder. There are two main types of counter-rotating extruders:

Parallel Twin-Screw Extruder: This configuration comprises two screws that run parallel to each other and maintain the same diameter from the beginning to the end of the screw. They provide consistent mixing and conveyance throughout the extrusion process.

Conical Twin-Screw Extruder: In contrast, conical twin-screw extruders have larger screw diameters at the back of the machine, gradually tapering as material flows towards the die. This design facilitates enhanced mixing and compression of materials as they progress through the extruder.

Both types of twin-screw extruders offer significant advantages in terms of mixing and conveying materials, catering to various requirements across industries and applications.

We provide a diverse range of single-screw machines tailored to various needs, with sizes spanning from ¾” to 3 ½”. These machines can handle profiles ranging from as small as 1/8” to over 8” in width. Generally, the larger the diameter of the extruder, the higher the hourly output capacity in pounds. Twin-screw extruders, typically measured in millimeters, offer versatility in size to accommodate specific plastic profiles. Our selection includes machines ranging from mid-sized to large, capable of handling profiles as small as under 1” and as large as 12” wide. Some of these profiles weigh over 7 pounds per foot.

The barrel of the extruder serves as a hardened steel cylindrical cavity, specifically crafted to accommodate the extruder screw(s). It withstands substantial pressure generated by the compression of plastic compounds during extrusion. Depending on the application’s demands, the barrel may be solely hardened or, for high-volume operations, lined with tougher materials like tungsten carbide to enhance durability and longevity.

Plastic compounds are introduced to the extruder via a hopper, essentially functioning as a funnel to contain the material as it is fed to the machine, either through gravity or force. Typically, as the extruder size and output capacity increase, larger hoppers become necessary to serve as a reservoir for the plastic compound. Our main extruders are outfitted with vacuum loaders, enabling our operators to prioritize the quality of the custom extrusion without needing to allocate valuable time to manually filling the hoppers.

Plastic materials exiting the barrel and screw end are directed into the extrusion die through the adapter. This component not only facilitates the mounting of extrusion tooling onto the extruder but also transitions the material flow from the barrel and screw to the desired shape. Adapters can come in two main configurations: slide-in or bolt-on.

Slide-in adapters offer convenience during changeover between different extrusion dies but are susceptible to leakage issues. Conversely, bolt-on adapters require more time for changeover but provide better control over pressure distribution, resulting in reduced gate leakage and more uniform product quality.

To enhance efficiency and flexibility while minimizing costs, many custom profile extruders employ a series of standard adapters that can be utilized across various extrusion tooling setups. This approach reduces tooling expenses and increases manufacturing adaptability, ensuring optimal production performance.

Visualize the extrusion die as the gateway leading to your final profile. It’s the extrusion tool that dictates the shape of the finished product. Typically composed of multiple die plates, a custom profile die transitions the initial shape from the adapter to the ultimate form of the extruded profile. This process, known as streamlining, is crucial in controlling tolerances throughout the extrusion process.

Think of making pasta: uneven strands may result from improper streamlining. Similarly, in plastic extrusion, smooth flow within the die is essential to prevent material degradation caused by heat. Streamlining ensures consistent material flow and helps maintain product integrity.

Within the die, the streamlined portion leads into the die land—a section of the tool where material flows consistently without further streamlining. This land stabilizes material flow and improves the surface finish of the extruded shape by smoothing its outer surface.

The point where the plastic compound exits the extrusion die is known as the die lip. Maintaining a flat and sharp die lip is crucial, as any damage can lead to irregularities in surface finish and appearance. At our manufacturing facilities, we prioritize proper inspection, handling, and care of extrusion tooling, including die maintenance. Additionally, we produce many of our own extrusion dies and collaborate with a global network of top-tier tooling vendors for additional support.

Precise temperature control is paramount in plastic extrusion. As the plastic material resides in the barrel and screw of the extruder, temperature regulation is achieved through a combination of friction heat and barrel heaters. This meticulous control ensures the optimal temperature of the extrudate.

Upon entering the adapter and die, the plastic compounds necessitate external heaters to maintain uniform temperature until exiting the die lip. Die heaters come in various forms, ranging from simple strip heaters affixed to the extrusion die to sophisticated solutions like custom-made plates with flexible heater cords or specialized die inserts tailored for the extrusion tool. These heaters play a critical role in ensuring consistent material temperature throughout the extrusion process, contributing to the quality and integrity of the final product.

The hopper, as mentioned earlier, serves as the receptacle for material fed into an extruder. These hoppers can range from simple steel funnel configurations to highly precise feeding systems that rely on gravimetric measurement for accuracy. In applications requiring tight tolerances, many extrusion lines are equipped with such advanced equipment.

Consider a scenario involving the production of a custom color-matched, single durometer extruded profile. This process typically involves a natural color base compound and a color concentrate. A gravimetric feeding system can be utilized to simultaneously feed these two materials into the extruder, ensuring precise blending for color consistency.

Moreover, in environmentally conscious settings, a three-station unit may be employed to introduce reprocessed plastic into the mix, further reducing waste and promoting sustainability throughout the manufacturing process. This approach aligns with the goal of manufacturing the finished extruded profile in the most eco-friendly manner possible.

The comparison between plastic extrusion and pasta making underscores the fundamental similarities in their processes. Both involve feeding ingredients into an extruder, conveying them down the barrel with a screw, and forcing them out through a die to create a specific shape. However, a key distinction lies in the role of heat.

While pasta making generates minimal heat, the plastic extrusion process relies on both frictional heat within the extruder and external heat to shape the material. This heat is essential for pushing the material through the extrusion die, forming the desired profile.

After exiting the die, it’s crucial for the manufacturer to capture the profile to maintain its shape and integrity during the cooling process. Various cooling methods, such as water, other liquid coolants, or air, can be employed for this purpose. In cases where tight tolerance requirements are essential, vacuum calibration (or vacuum sizers) may be utilized. These devices use vacuum to hold the extruded profile in place during cooling, ensuring precise dimensions and geometry. Many modern vacuum sizers incorporate water for efficient heat removal during the cooling process

Cooling methods in plastic extrusion are tailored to the specific design of the profile being produced. For simpler profiles like screen splines and extruded gaskets, a basic water-pan setup may suffice, holding water or other coolants to facilitate cooling. This equipment is commonly used for flexible profiles and smaller extrusions.

However, for more intricate products such as window lineal profiles or office partition base raceways, a calibration table is often employed. This sturdy structure allows for the mounting of vacuum sizing and water cooling tanks to facilitate precise sizing and cooling of the extruded profiles. Calibration tables come in varying lengths to accommodate a wide range of profiles, and they typically feature self-contained vacuum pumps, as well as water and air supplies equipped with quick-change couplings. These features help reduce setup time during tooling changeovers, enhancing efficiency and productivity in the extrusion process.

Numerous extruded profiles feature textured or embossed patterns on their exposed surfaces, enhancing both their visual appeal and functional performance. Take a moment to observe handrails and corner guards in commercial buildings during your next visit. Many of these products boast a pebble grain embossed pattern, combining aesthetic allure with the protective and durable qualities inherent in high-impact, rigid plastic materials.

Similarly, consider baseboards or wire raceway covers found on open office partitions. These panels endure considerable wear from foot traffic and cleaning equipment. Textured patterns, such as pebble grain or custom designs, serve to mitigate scuff marks and scratches, ensuring longevity and maintaining aesthetics.

We operate embossing equipment at our warehouse offering a range of patterns from traditional pebble grain to custom designs and wood grain textures that closely resemble real wood.

Plastic extrusions often benefit from the addition of double-sided adhesive tapes or magnetic strips, enhancing their functionality across various applications. These additions extend the versatility of extruded plastic profiles, serving purposes such as point-of-purchase display tags, Velcro® attachments, automobile body side moldings, wall protection corner guards, and weather stripping. The term ‘peel and stick’ signifies the convenience and utility provided by pressure-sensitive adhesive tapes when applied to extrusions.

Require a vinyl extrusion to adhere to steel? Our services include custom application of magnetic tape to the extrusion, facilitating attachment to metal surfaces. If steel attachment isn’t necessary, we offer the application of double-sided foam and non-foam adhesive tapes, engineered to adhere effectively to a wide range of surfaces. These tapes are applied inline during the extrusion process, optimizing functionality while minimizing costs.

With our extensive experience in tape application, coupled with specially designed tape applicators, we can accommodate a variety of custom extruded shapes with precision and efficiency.

In extrusion terminology, various terms are used to describe the equipment responsible for pulling and conveying extruded profiles down the production line. This equipment is commonly referred to as a puller, conveyor, or haul-off. As seen in the picture below, top and bottom cleats or belts are utilized to apply pressure on the extruded profile as it moves downstream. These belts can be fabricated from a range of materials, including foam, silicone, or rubber.

Achieving optimal performance requires careful adjustment to maintain the integrity of the plastic extruded profile without distorting its shape as it passes through the unit. In many instances, an additional speed controller is situated near the extruder, allowing the line operator to adjust the speed of the haul-off. This feature enables precise control over the size and dimensions of the extruded profile during production.

Plastic extruded profiles, being linear products, require cutting to length before they are removed from the extrusion line and packaged. For medium to large profiles, a traveling saw is commonly employed. Also known as a progressive saw, this equipment clamps onto the profile to move the cut-off saw downstream with the product until the cut is completed.

A progressive saw features a blade contained within the bottom of the unit, which travels upward through the plastic part during cutting. This design helps to effectively control dust and saw chips, enhancing the overall cleanliness of the cutting process. When applicable, the use of a progressive saw can contribute to a more efficient and controlled cutting operation.

The traveling saw, while effective for square cuts at 90° angles or consistent angles for shaping trapezoid profiles, does have its limitations. It’s primarily utilized when extruded profiles require straightforward cuts, which suffice for applications where mill lengths are produced or no further fabrication is needed. However, our commitment to excellence lies in our capacity for both inline and offline fabrication.

A significant portion of the extruded products we manufacture serves as components in OEM products. To streamline processes and enhance efficiency, we endeavor to deliver fully finished extruded profiles whenever feasible. This includes more intricate end cuts, hole drilling, punch-outs, and other fabrication techniques, thereby reducing labor and handling requirements at your facility. Our aim is to provide you with ready-to-use extrusions that seamlessly integrate into your production processes.

The manufacturing process of drinking straws is a fascinating one. These tiny tubes are produced through extrusion, with extrusion lines capable of running at speeds exceeding 180,000 straws per hour. To achieve such high production rates, a specialized cutting method known as a fly knife cutter is commonly employed.

As the name suggests, a fly knife cutter features one or more knives mounted on a rotating wheel. These knives cut through the plastic extrusion as the wheel rotates. Many of these units are servo-driven, allowing the blade to extend for cutting and retract at incredibly high speeds. Additionally, the blade (or blades) can be fixed in an extended position to provide one or multiple cuts per revolution of the flywheel on the cutter.

Fly knife cutters are typically utilized for small to medium-sized extruded profiles and can include cutter guides to ensure clean end cuts on the final product. This advanced cutting technology enables efficient and precise production of drinking straws at high speeds, meeting the demands of the market for this ubiquitous product.

Ensuring precise dimensions in extrusion is paramount, often requiring measurements accurate to thousandths of an inch. To meet this need, we equip our teams with sophisticated equipment capable of such precise measurement, such as digital length gauges.

Operating a digital length gauge is straightforward. The measurement device is securely mounted on a highly accurate set of linear rails. The plastic extrusion to be measured is then inserted onto the unit for assessment. One end of the extrusion is positioned against a fixed stop, while the rail on the opposite end smoothly slides along the linear rails until it reaches the other end of the profile.

The actual length of the part being measured is displayed on a digital readout, providing measurements with precision to three or more decimal places. This level of accuracy ensures that extruded profiles meet the exact specifications required for their intended application, contributing to product quality and consistency.

The versatility of materials like Polyethylene, PVC, and ABS lies in their ability to be re-melted and reprocessed without significant loss of properties or scrap. Both post-industrial and post-consumer scrap materials can be recycled and repurposed into new products. This stands in contrast to thermoset materials, such as fiberglass, which permanently set during the curing process and cannot be ground and reprocessed.

It’s worth noting that we prioritize sustainability in our operations. As a net consumer of reprocessed materials, we utilize more recycled materials than we generate during our manufacturing processes. Embracing green manufacturing practices, we actively reduce scrap and seek out opportunities in products and industries that enable us to exercise environmental stewardship. By incorporating recycled materials into our production processes, we contribute to the circular economy and minimize our environmental footprint.

Resin serves as the quintessential raw material in plastic manufacturing, primed for subsequent processes such as extrusion and molding. Compounding, a pivotal step in plastic production, involves blending plastic resins with various additives and subjecting them to a heating or melting process. Through this method, the physical, thermal, electrical, or aesthetic properties of the plastic are modified to suit specific requirements.

Compounds are meticulously tailored to meet the demands of particular applications. By incorporating an array of additives and fillers, specific performance parameters can be achieved. This versatility enables the creation of plastics with diverse characteristics, ensuring suitability for a wide range of industrial and commercial applications.

A dry blend refers to a free-flowing mixture of compound or resin along with other ingredients, prepared specifically for extrusion processes. These dry blend materials hold significance for processors equipped with twin-screw extrusion equipment capable of handling powder materials directly, without the need for pelletization.

At our manufacturing facility in Fort Myers, Florida, we utilize various twin-screw extrusion lines specifically designed to handle dry blend compounds. By employing the powder form of the material, we eliminate the need for the additional step of pelletizing. This streamlined process enhances efficiency and reduces production time, allowing us to more effectively meet our customers’ demands.

In the plastics industry, the spectrum of possibilities extends far beyond black and white. It’s a vibrant world where colors like red, blue, green, yellow, and a myriad of others are commonly found. At our facilities, we harness the versatility of a diverse range of color concentrates to create a veritable rainbow of hues, tailored to suit specific applications. Whether it’s for aesthetic appeal, branding requirements, or functional differentiation, we’re equipped to deliver precisely the color you envision for your plastic products.

Resins or mixtures of resins, along with compounding additives, are extruded or chopped into short segments to prepare them for molding operations. These segments, typically similar in shape or size, are commonly referred to as pellets. Pellets serve as the raw material for molding processes, where they are melted and shaped into the desired final product.

Pellets offer several advantages in molding operations, including ease of handling, uniformity in size and shape, and efficient melting characteristics. They enable precise control over material distribution and facilitate consistent molding results. Additionally, pellets can be customized with specific additives or properties to meet the requirements of various molding applications.

An additive or component incorporated into a compound to facilitate processing is commonly referred to as a processing aid. In certain cases, raw resins such as PVC require processing aids and other ingredients to enable extrusion, as these materials may lack inherent properties necessary for the extrusion process.

Processing aids play a crucial role in binding the material together during melting and extrusion, ensuring smooth and consistent flow through the equipment. Additionally, they can enhance the surface aesthetics of the finished part by improving the material’s ability to flow through the tooling, resulting in a smoother and more uniform appearance. Overall, processing aids contribute to improved processability and quality of extruded products.

In its essence, a composite is characterized by its composition of multiple materials. Typically, this entails the integration of a strengthening agent alongside a thermoplastic resin or compound. We specialize in the production of a diverse array of composite products, employing wood fiber as the strengthening agent and PVC as the thermoplastic material. This strategic combination allows us to enhance stiffness while simultaneously mitigating thermal expansion and contraction.

These advantageous physical properties hold significant importance across various industries, including construction, transportation, and numerous other markets. By leveraging our expertise in composite manufacturing, we provide solutions that meet the stringent performance requirements of our clients across diverse applications.

The visible line that occurs at areas where intersection legs occur in a plastic extruded profile is typically caused by differential cooling rates during the extrusion process. When you closely examine a drawing of a plastic profile with intersection legs, you’ll notice that there is more mass in the area of the intersection. As thermoplastic materials cool, they undergo some degree of shrinkage. However, the intersection of two legs cools at a slower rate than the rest of the profile due to the increased mass, causing it to shrink more significantly.

To mitigate this issue during the design of extrusion tooling, several techniques are employed to minimize or eliminate the visible line, also known as a sink mark, in the final part. One common approach is to separate the flow of the two legs within the die and then allow them to merge back together as the extrudate is compressed toward the front of the extrusion die. This can sometimes create a weld line where the two melt streams reunite, so careful tuning of the extrusion tooling is crucial to minimize this line.

Alternatively, the potential issue can be turned into a deliberate design feature by incorporating indentations on the side opposite the intersection leg. These indentations help to disguise or distract from the visible line, enhancing the aesthetic appeal of the final product. The provided drawing illustrates some options for designers to consider when addressing this challenge in custom profile extrusions with intersecting legs.

As extruded profiles progress down the extrusion line, the cooling process initiates, crucial for ensuring the final product’s quality. Common cooling methods for plastic extrusions include water, air, or a combination of both, depending on the specific product requirements. In instances of high-speed extrusion, warm water may be employed to prevent shocking the surface of the product, which could lead to undesirable physical property issues.

For multi-hollow extruded plastic profiles, cryogenic cooling utilizing nitrogen may be utilized to rapidly cool the inner legs of the extruded product. This method helps maintain profile integrity and enables increased line rates. Consistent and even cooling during the conveying period is essential to preserving the straightness of the extruded profile.

Plastic profile extrusion companies often use two terms to describe lack of straightness: bow and camber. Bow refers to side-to-side warping of the part, while camber describes up-and-down warping. Tolerances for straightness are typically established during the design and tooling development phases and are subsequently monitored as part of ongoing quality assurance checks throughout the production of the plastic profile extrusion. Ensuring straightness is critical for meeting product specifications and ensuring the performance and functionality of the final product.

Defining the cross-section of an extruded profile involves examining the end of the product in a two-dimensional view. In the illustrations provided above (under “weld line”), the cross-sections of four different examples demonstrating ways to design around sink marks are depicted. Each of these drawings showcases a distinct cross-section of the extruded profiles, highlighting the varying shapes and features of the profiles. By analyzing these cross-sections, one can gain a better understanding of the geometric characteristics and design elements of the extruded profiles.

In the overall extrusion process, thermoplastic materials undergo compression from the moment they enter the hopper on the machine until they exit the front of the extrusion die. The compression area just before the extrusion die and flowing through the die is typically measured in pounds per square inch (PSI). Maintaining the appropriate backpressure during this process is crucial for ensuring the integrity of the extruded profile and preserving its physical properties.

Insufficient backpressure can lead to loss of profile integrity and compromised physical properties of the extruded product. Conversely, excessive backpressure can pose safety concerns and potentially cause damage to the equipment. Therefore, it is essential for the extrusion operator to monitor back pressure throughout the process using pressure gauges installed on the extruder and inserted into the die. By closely monitoring and adjusting backpressure as needed, operators can optimize the extrusion process and ensure the production of high-quality extruded profiles while minimizing the risk of equipment damage or safety hazards.

The custom plastic extrusion process encompasses several key steps: melting plastic, extruding it through a die, and then controlling the shape and size of the plastic profile as it cools. Like any manufacturing process, slight variations can occur during extrusion, necessitating tolerances on key dimensions.

Tolerances on plastic extrusions are crucial as they directly impact fit and function. It’s essential to consider tolerance requirements early in the design phase. We can provide design-for-manufacturing assistance, including tolerance specifications tailored to your project’s needs. Typically, our quality assurance team will develop a control print detailing dimensions and tolerances for critical features, along with a control plan for use by our manufacturing and quality assurance teams. This proactive approach ensures that the final extruded profiles meet your specifications and quality standards.

Bulk density refers to the weight per unit volume of plastics used in custom extrusion applications. It plays a significant role in extrusion processes as it directly impacts flow and feed rates on the extruder. Variations in bulk density can lead to fluctuations in the size of the extruded product, making it a critical consideration for custom extrusion manufacturing operations.

Maintaining consistent bulk density ensures uniform flow of the plastic material through the extruder, resulting in consistent product dimensions. This consistency is essential for meeting quality standards and ensuring that extruded profiles meet the desired specifications. Therefore, monitoring and controlling bulk density throughout the manufacturing process is essential to achieving reliable and high-quality extrusion results.

As discussed previously, back pressure is crucial for controlling the physical properties of the extruded product during the extrusion process. This pressure is generated by compression inside the extruder and extrusion tooling. However, once the plastic compound exits the extrusion die in a compressed form, it undergoes a phenomenon known as die swell.

Die swell refers to the tendency of the extruded material to relax or expand slightly after exiting the die. This expansion can affect the final dimensions of the extruded profile. Importantly, die swell is material-specific, meaning that different types of plastics will exhibit varying degrees of die swell. For instance, PVC may experience a different level of die swell compared to Polyethylene or Polypropylene compounds.

Our tooling engineers rely on their experience and knowledge of die swell characteristics for different materials when designing extrusion tooling. Understanding and accounting for die swell is critical in tooling design to ensure that the final extruded profiles meet the desired specifications and dimensional accuracy. By factoring in die swell during the design phase, we can optimize tooling performance and achieve consistent extrusion results across different materials and applications.

In the extrusion process, cleaning materials from barrels, screws, and plastic extrusion tooling is a time-consuming task that can add to production costs. For instance, when transitioning between jobs on the production line, this may involve removing and cleaning the die, pulling the screw on the machine for cleaning, and brushing out the barrel while the screws are removed.

To address this challenge, ultra-stabilized compounds have been developed to facilitate cleaning of these components and flushing the system using purging compounds. These purging materials are exceptionally stable, allowing them to effectively clean all items, including the die, screws, and tooling. Remarkably, they can be left in the extrusion die during storage and reused without the need for extensive cleaning before starting the next job. When the regular compound is introduced, it pushes the purge material out of the die as it exits.

Purge compounds also find utility during shutdowns for weekends or holidays. Our extrusion technicians utilize purge materials when shutting down certain lines during these periods to clean and safeguard the extruder and die. While materials like Polyethylene and Polypropylene may not require this step, it is essential for materials like PVC. If PVC is left to cool and then reheated for start-up without proper cleaning, it can degrade within the tool. Therefore, using purge materials helps prevent degradation and ensures smooth start-ups and consistent production.

When operating an extruder, materials are fed to the extrusion screws and barrel to create the plastic extrusion. There are two primary methods for accomplishing this feeding process.

Firstly, the material can be contained in a hopper positioned directly above the feed-throat of the extruder and fed by gravity. In this approach, known as flood feeding, the screws take in the maximum amount of material they can with every revolution of the machine.

Alternatively, a metering device can be added at the feed-throat to regulate the amount of material introduced to the screws. This method, known as starve feeding of the extruder, entails the flights of the screw not being completely filled with material during every revolution. Starve feeding offers advantages to the extrusion technician in certain situations. By not completely filling the screw channel, it provides more control to the technician and reduces some variables that can occur with flood feeding. This controlled feeding method can lead to more precise processing and improved consistency in the extruded product.

Surging is a common issue in the extrusion process and is generally considered undesirable. It occurs frequently in single-screw extruders, where there is slippage back over the flights of the screw during each revolution. While this slippage aids in mixing materials and colorants, it also introduces the potential for surging and variation in the extruded product.

Differences in pressure as material exits the screw can exacerbate this issue, leading to inconsistent processing. Surging, characterized by fluctuations or variations in the extrusion process, can negatively impact size and tolerance control of the final product.

To mitigate surging, proper screw design tailored to the specific characteristics of the plastic compound being extruded is crucial. By optimizing the screw design, extrusion technicians can minimize surging and achieve more consistent and precise extruded profiles. This underscores the importance of careful consideration and customization in extrusion equipment and processes to ensure high-quality output.