Servtek Services Injection Units and Feed Screws

BARR VBET Solid/Melt Mixing Screw

SERVTEK is your exclusive supplier of the BARR VBET Solid/Melt Mixing Screw. The BARR VBET Mixing Screw is superior to typical barrier screws because it maximizes conductive melting to provide:

• Higher Production Rates
• Lower Melt Temperatures
• Uniform Melt Temperatures
• Improved Mixing
• Reduced Shear Energy Input
• Improved Energy Efficiency
• Increased Conductive Melting
• No Hot Spots and No Splay Due To Excellent Melt Quality

The VBET screw channel is divided into tow sub-channels. The particles continuously change their positions as they flow from one sub-channel into another sub-channel along the screw. A particle in the surface layer of one sub-channel ends up in the center layer of the other sub-channel. This Solid/Melt Flow mechanism gives uniform melt quality and uniform melt temperature by continuously mixing the melt. Undesirable hot spots inside the screw channel are eliminated.

• Distributive Mixing Properties
• Without the Shear
• Without Material Separation Without Sacrificing Recovery or Cycle Time

Servtek Services Injection Units and Feed Screws

High Speed, High Throughput, Superior Mixing Without Shear

With SERVTEK’s MELTSTAR II feed screw you don’t have to sacrifice recovery or cycle time to achieve high speed, high throughput, superior mixing without shear.

If you're processing Rigid Polyvinyl Chloride (RPVC), Polycarbonate (PC), Acrylonitride-Butadiene-Styrene (ABS), or any shear-sensitive materials, you know the problems.

With gentle mixing sections, the material doesn't mix.  With aggressive mixing sections, your material may shear and burn.  Shear and restriction from a mixing section hurts recovery, which hurts productivity and profitability.

MELTSTAR II is the proven performance feed screw for all these applications.

Many mixing screws are designed for "dispersive" mixing, in which the size of the ultimate particles is reduced and the particle positions are randomized.  This exposed the particles to unusually high shear stresses in order to break them down.

To eliminate high shear and stress the MELTSTAR II creates "distributive" mixing, achieving a true "homogeneous" blend of the polymer - with uniformity in temperature and material - but without adding excessive work or shear.

The MELTSTAR II mixing feed screw incorporates a moderate shear mixing device to split the melt flow into several streams, passing through parallel channels.  This flow causes a "kneading" effect on the melt pool as it splits and recombines.  The spiral grooves in the mixing device enhance the forward flow of material.

Servtek Services Injection Units and Feed Screws

Process Polycarbonate without Black Specks

SERVTEK’s KLEARSTAR feed screw has lubricity properties and corrosion resistance for optimal processing of polycarbonate without black specks.

The KLEARSTAR package for processing polycarbonate includes:

• Bi-Metallic Barrel
• Feed Screw
• Tip Assembly
• Barrel Adapter

In a polycarbonate application, volatile by-products (gases) are released during melting of the resin pellets. These gases attack the metallic component surface of the conventional nitrided surfaces. This corrosive wear results in pitting and erosion at the screw root diameter and the barrel surface. The pitting that occurs as a result of this corrosive wear provides an area for the plasticized material to adhere. This material degrades resulting in black specks, and ultimately is injected into the mold, consequently increasing the amount of reject parts.

SERVTEK’s KLEARSTAR feed screws provide corrosion resistance and the lubricity properties necessary to process polycarbonate, especially in the molding of lenses. This results in the total absence of black specks.  The corrosion resistance and lubricity properties of this base material improve the flow of material to a degree that prevents sticking. You will increase productivity through the elimination of black specks and inferior product and decreasing down time for maintenance. 

Servtek Services Injection Units and Feed Screws

Anti-Corrosion Package for PVC and CPVC Processing

SERVTEK’s PVCSTAR anti-corrosive package of feed screw, smear-head tip and end cap eliminates all corrosive effects of PVC/CPVC.

Processors of PVC and CPVC are often forced to shut down the process, pull the feed screw, tip and end cap which are “cooked” with burned, degraded or baked on PVC or CPVC.  PVCSTAR protects against the chlorine in the PVC, which attacks the substrate material of the typical feed screws with multiple plating layers of chrome.  Prior to PVCSTAR, re-chroming, repair and expense were the only alternatives.

PVCSTAR ceramic coating completely fills micro-cracks of chrome plate with chromium oxide (Cr203).  PVCSTAR’s ceramic coating prevents blistering of plating caused by penetration of chlorides through the chrome plate. PVCSTAR lowers friction and stops polymers from wedging into micro-cracks, making cleaning of components easier and faster.

Servtek Services Injection Units and Feed Screws

SERVTEK SERVICES offers complete screw refurbishing, repairs and modifications services for any make or model of injection molding feed screw.

Your feed screw’s optimum performance and long life are vital to dependable and productive part production. Maximize your equipment investment with SERVTEK’s proven, reliable feed screw rebuilding services.

• Workmanship and materials will be of the highest quality and reliability in the industry
• All root channel damage, pilot damage, thread damage, and bearing areas are repaired at no extra cost
• All rebuilds are warranted as new to be free of manufacturing and/or material defects
• SERVTEK can upgrade your feed screws with PVCSTAR for highly corrosive applications.
• Various options are available for coating the feedscrew, such as STARGUARD encapsulation and WEARSTAR.
• Refer to the Wear Chart table for the recommended minimum and maximum clearances for several sizes of injection feed screws to determine if your feed screw needs to be rebuilt or replaced.