Barrier Screws for Extrusion and Injection Molding
High-Performance Extrusion Barrier Screw & Injection Molding Barrier Screw Technology
What is a Barrier Screw?
A barrier screw design is characterized as a feed screw that incorporates a secondary flight, or barrier flight, into the transition section. The barrier flight generates two separate channels: the primary channel and an auxiliary or barrier channel. As the solid bed is conveyed forward, it will remain in the original primary channel. The barrier flight is undercut at some clearance that is great enough for molten material to flow over the flight into the auxiliary channel, but not great enough for unmelted solids to pass over. As the solid bed melts and a melt pool is generated, the melt pool continually flows into the new auxiliary channel.
Generally, the primary channel continually decreases in cross-sectional area, much the same as a conventional screw’s transition section. Meanwhile, the auxiliary channel’s cross-sectional area generally increases, allowing for more and more melt to accumulate within the channel. This melt separation action in barrier screws eliminates solid-bed-break-up and significantly increases melting capacity compared to conventional square pitch screw designs.
Barrier Screws: Reduce Cycle Times & Increase Throughput
Barrier screws have been widely used in the extrusion industry for decades and have been increasingly common in the injection molding industry. Barrier screws should be thought of as a category of screw design with many different individual barrier screw designs that have varying levels of performance and success. Not all barrier screw designs are alike! When appropriately used for the proper application, barrier screw designs can significantly increase output and melt quality in both plastic extrusion and injection molding applications.Â
SpiraMelt MVP Barrier Screw Family: Maximum Viscosity Performance
The SpiraMelt MVP barrier screw family is a modern, high-performance approach to barrier screw technology. The MVP barrier screw family consists of the base MVP Barrier Screw, the MVP HS (high shear variation), and the MVP LS (low shear variation). The flexibility and variety of the MVP barrier screw family allows injection molders and extrusion firms to maximize their production on a wide range of resins and processing demands. At SpiraMelt, we specialize in custom-designed, high-performance screw technology. Let us manufacture a tailored barrier screw for your application! The MVP barrier screw family is designed to accommodate a wide range of applications to meet your rigorous production requirements. Whether you require and injection molding barrier screw or an extrusion barrier screw, the MVP barrier family is the right choice!
The Standard MVP Barrier Screw: A Modern Barrier Screw with Maximum Output & Stability
The standard MVP Barrier Screw is a high output barrier screw design that provides excellent melt quality at superior throughputs. The MVP barrier screw typically delivers 20% more output than conventional screw designs. With optimized primary flight lead changes, the MVP barrier screw maintains the primary channel width – even with the introduction of the auxiliary channel. This unique channel geometry maximizes the area available for melting, significantly improving viscous heat dissipation. When compared to other screws, the area available for melting is typically 1.5x that of conventional screws, due to efficient melt separation and maintained primary channel width. This means more output, higher part quality, and better stability!
Let our team of screw design experts design a solution for you!
The MVP Barrier Screw Improves Throughput on Injection Molding and Extrusion Applications
The SpiraMelt MVP Barrier Screw is perfect for both extrusion and injection molding applications that demand high quality and high output. Eliminate solid-bed-break-up and other downfalls of conventional or “GP” screw designs with improved melt capacity and melt separation.Â
It is common to see gels and un-melts in final molded parts in both extrusion and injection molding applications when outputs exceed the melting capacity of a given screw design. The MVP Barrier Screw allows for higher output, stability, and melt quality at low melt temperatures. Let our team design a screw for you!
Pressure Stability
The SpiraMelt MVP Barrier Screw maximizes pressure development to achieve optimum output at lower melt temperatures. Eliminate solid bed break up and instability with improved screw designs today!
Melt Quality
The SpiraMelt MVP Barrier Screw improves overall throughput while supplying a high quality isothermal melt. Lower melt temperatures at higher outputs can be achieved!
The Advantages of Melt Separation
- The MVP barrier screw eliminates solid-bed-break-up through melt pool separation. The unique channel geometry of the MVP barrier section allows for much more area available for melting when compared to other barrier screw designs. When compared to conventional or "GP" screw designs, the area available for melting is significantly higher. In conventional designs, the melting area is continually decreased because of the ever increasing melt pool that occludes the channel.
- Enhances melt uniformity from moderate shear rates introduced by the barrier flight during melt separation. Agglomerates cannot pass from the primary channel to the auxiliary channel without shearing over the undercut barrier flight. The clearance and geometry of the section is optimized to best fit the resin(s) being processed.
- Provides a high quality isothermal melt at low melt temperature through maximum pressure development within the melting area of the screw. This leads to major gains in output without sacrificing melt quality! By eliminating solid bed break up, the MVP barrier screw provides better quality, stability, and uniformity, even at higher outputs.
The MVP barrier screw is best suited for semi-crystalline and other shear tolerant materials. High output and quality can be achieved in both extrusion and injection molding applications where cycle time and overall throughput is a priority.
HDPE
LDPE
LLDPE
XLPE
MDPE
PP
Blended Polyolefins
PET
PETG
FPVC
Nylon
And more.
The MVP HS Barrier Mixing Screw: Maximum Output and Uniform Shear History
The SpiraMelt MVP hs barrier screw offers maximum output with superior melt uniformity on shear tolerant resins and additive packages. When paired with the spiral mixing chamber of the MVP hs barrier screw, maximum melt quality is achieved with superior dispersive mixing, breaking up agglomerates and un-melts, reducing in-molded stresses in parts. The spiral mixing chamber breaks up agglomerates and gels, imparting high shear rates on the extrudate to homogenize the melt. Controlled geometry (flight width, clearance, etc.) enables use with a wide range of shear-tolerant resins to maximize output and quality. The undercut barrier flights and inlet/outlet channels of the MVP hs mixing design provide not only optimal dispersive mixing but also high levels of distributive mixing, increasing output at low melt temperatures.
Mixing Screw Technology Combined with Barrier Screw Technology: All in the Same Package!
The MVP hs barrier screw combines the high-performance MVP barrier section with improved melt quality and dispersive mixing. In both extrusion and injection molding applications where high output and high melt quality are critical, the MVP hs barrier screw is a great option to maximize production! Contact us today to learn how improved screw technology can improve your production!
Let our team of screw design experts design a solution for you!
Advantages and Benefits
- The MVP hs mixing section eliminates marbling and color swirls on injection molded and extruded parts
- Lower melt temperatures and higher outputs on most crystalline resins or additives that demand optimum dispersive mixing
- Highest plasticating rates for semi-crystalline resins, improving cycle times and pph performance while reducing scrap rates
- Wider application and processing window with less downtime during changeovers
- Better physical properties in final molded parts
- Faster cycle times with the advantage of lower melt temperatures and uniform shear history
- Superior color saturation at lower let down ratios
The MVP hs is best suited for semi-crystalline and other shear tolerant materials. High output and quality can be achieved in both extrusion and injection molding applications where cycle time and overall throughput is a priority.Â
HDPE
LDPE
LLDPE
XLPE
MDPE
PP
Blended Polyolefins
PET
PETG
FPVC
Nylon
And more.
Let our team of screw design experts design a solution for you!
The MVP LS Barrier Mixing Screw: Superior Color Mixing and Melt Uniformity
The SpiraMelt MVP ls barrier screw is a high output barrier screw that provides superior melt uniformity at lower shear rates. When the SpiraMelt MVP barrier section is paired with the unique mixing geometry of the MVP ls, maximum melt quality is achieved with superior distributive mixing through turbulent reorientation of the melt stream. This MVP ls mixing section unifies the melt without excessive shear rates and no areas of low flow for degradation. Exceptional color saturation can be achieved at lower LDR, saving you time and money. Change colors on-the-fly without special purging compounds or shutting down to clean for color changes. Spend more time making product!
Eliminate Color Swirls and Save Money on Expensive Colorants!
The SpiraMelt MVP ls barrier mixing screw offers superior color mixing and melt uniformity on more shear sensitive and stiff viscosity resins. The unique flow geometry in the low shear mixing element provides exponential mixing action and turbulent reorientation. The continual converging and diverging flow paths promotes a high-quality isothermal melt without excessive shear rates or dead spots for material hang-up and degradation. This makes the SpiraMelt MVP ls a perfect choice for molders and resin processors that run colorants, high viscosity, or more shear sensitive resins. You can now achieve rich, fully color saturated parts at lower LDR. Change colors on-the-fly without all the headaches!
Let our team of screw design experts design a solution for you!
Advantages and Benefits of the MVP LS Barrier Screw
- Wider application and processing window with less downtime during changeovers
- Change colors on-the-fly with no shutdowns or cleaning. Spend more time processing
- Eliminates burning and over-shearing when processing high viscosity resins while delivering high outputs
- Faster cycle times with the advantage of lower melt temperatures and shear rates
- Better physical properties in final molded parts
- Faster cycle times with the advantage of lower melt temperatures and uniform shear history
- Superior color saturation at lower let down ratios
The MVP ls barrier screw is excellent for high viscosity materials or color mixing applications with no marbling. Speeds up material/color changeover, thanks to self-cleaning action. Achieve better physical properties and superior cosmetic appearances in your molded parts!
HDPE
LDPE
LLDPE
XLPE
MDPE
PP
PET
And other stiff viscosity resins, in both extrusion and injection molding applications
Let our team of screw design experts design a solution for you!