TUNGSTEN FEED SCREW COATINGS BY EXTREME COATINGS.
A revolution in feed screw wear reistance technology!
A revolution in wear resistance technology for the plastic and rubber industries!
Excellellent for extrusion, compounding, injection and blow molding.
Reduce Downtime by 50%!
Reduce Rebuild Costs by 30%!
Improve Production Efficiency!
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- The Concept
- The Process
- Component Preparation
- Wear Mode
- Abrasion Resistance Data
- The Coatings
The Concept
Surface Engineering's Extreme Coatings™ process utilizes emerging Thermal Spray technologies to apply to feedscrews extremely wear resistant coatings to virtually any size injection molding or extrusion feed screw. This process provides crack free coatings with hardness values ranging from 55-75 on the Rockwell "C" scale in thickness from 0.003"-0.050". Proprietary compositions of various Carbides, Ceramics, and Alloys are incorporated to achieve abrasion resistant characteristics unmatched by any of the conventional hardfacing alloys popular today! This process completely eliminates the necessity for Chrome Plating, Flame Hardening, or Nitriding, as the entire feed screw surface is coated, including the root and flite sides. The coatings are much more wear resistant than any of the three aforementioned processes, which makes the process excellent for feedscrews exposed to fiber filled compounds. Furthermore, the process requires no preheat of postheat procedure, and during application, components rarely exceed temperatures of 350°F. The low heat input helps prevent distortion, minimizing costly straightening and/or machining time. It also allows for the repair of D-2 Tool Steel components, typically scrapped when completely worn. Preparation for screw rebuilding requires only touch up work and the removal of old Chrome before the coating application. Another unique aspect of the process is the "Dualcoat" concept. This targets those who require extreme wear resistance through the root of a feed screw, but whose barrels may not be compatible with the hardness of the root coating. In this case, the flights may be coated with a more traditional product, but will be masked during application of the harder root coating, thus eliminating compatibility issues and maximizing feed screw life. It also must be noted that today’s popular hardfacing alloys can be applied via the Extreme Coatings process with an improvement in feed screw life. This is due to the elimination of base metal dilution inherent to welded overlays. Other applications where this process is currently utilized includes Turbine Components, Bushings, Shafting, Mixer Blades, Augers, Conveyor Screws, Chutes, Fan Blades, Conveyors, Slurry Pumps, and many other applications where extreme conditions of wear exist.
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The Process
As the gas mixture burns, the powder particles are melted and accelerated down the barrel. Temperatures above 6000 ºF are attained with the combustion chamber while the substrate temperature is maintained below 350 ºF by a gas cooling system. Particle velocities of approximately 2,500 ft/s are produced. The kinetic energy released by impingement upon the substrate contributes additional heat and promotes bonding, high density, and appreciable hardness values. The coating is built up to the specified thickness while the workpiece is rotated or passed in front of the gun.
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Component Preparation
Surface Preparation is the most critical step in a thermal spraying operation. Coating adhesion quality is directly related to the cleanliness and roughness of the substrate surface. The coating material and the substrate type are the major factors in determining what surface preparation is necessary to achieve consistent bonding. Sprayed deposits do not add to the strength of the substrate. The purposes of surface roughening are as follows:
provide compressive surface stresses
provide interlocking laminations (layers)
increase the bond area
decontamination of the surface
Internal stresses from shrinkage develop in coatings and these stresses increase with increased coating thickness. The stresses are more severe in hard metals or ceramics. Roughening is a method of reducing these stresses by dividing the internal stresses into smaller components which will cancel each other out. As the layers are folded up and down, the coating strength is improved.
Wear Mode
Surfaces subjected to low stress abrasion show that material has been removed by hard, sharp particles or other hard, sharp surfaces plowing material out in the furrows. Grinding with a surface grinder can be a controlled from of low stress abrasion. The low stress qualifier means that the abradant is imposed on the surface with relatively low normal forces. The operating forces must be low enough to prevent crushing the abradant. Low stress abrasion rates are directly proportional to the sliding distance and the load on the particles or protuberances and are significantly reduced by hard microconstituents within the surface microstructure.
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Abrasion Resistance Data
Coating/Alloy Chemical Composition Application Process Average Hardness Volume Loss mm³
DPH 300g Est.Rc
XC1000 88% Wc 12% Co HVOF 1100 68-71 3.0
XC1000 83% Wc 17% Co HVOF 1000 67-70 4.7
XC4000 75% Cr2C3 25% NiCr HVOF 650 62-64 3.2
XC6000 50% NiCrB 50% Wc HVOF 750 64 5.9
XC7000 Nickel-Cr-Boron HVOF 60 11
XC8000 Co-Cr-W HVOF 57 18
Stellite 6 Co-Cr-W TIG Actual 40 64
Stellite 12 Co-Cr-W TIG Actual 47 57
Stellite 1 Co-Cr-W TIG Actual 54 52
56 Nickel-Cr-Boron TIG Actual 49 15
D2 Tool Steel WROUGHT 60 12
316 Stainless Steel TIG N/A 83
"C" Nickel-Cr-Mo TIG 16 105
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The Coatings
Type Rc Descriptions
XC1000 68-70 A composition of Cobalt saturated with 80-90% Sub-Micron sized Tungsten Carbide with a particulate hardness average of Rc 82, providing ultimate abrasion resistance.
XC2000 70-74 An Oxide of Chromium combined with an Oxide of Silicon providing extreme abrasion resistance and hardness.
XC3000 65 An Oxide of Aluminum producing very hard, dense, and smooth coatings. Resists very fine particulate abrasion. Corrosion resistant.
XC4000 55-65 A composition of Nickel, Chromium, and Chromium Carbide producing an abrasion resistant. Coating with extreme corrosion resistance and excellent ductility, relative to hardness.
XC5000 60 A proprietary composition of Molybdenum and Tungsten Carbide producing unique antigalling and abrasion resistance.
XC6000 55-60 A Nickel-Chrome-Boron alloy system combined with 50-60% Tungsten Carbide providing extreme abrasion and corrosion resistance.
XC7000 60 A Nickel-Chrome-Boron alloy system similar to "56" only much more abrasion resistant.
XC8000 58 A Cobalt base alloy system similar to Stellite 12™, only much more abrasion resistant.
XC-RD 75-80 Tungsten Carbide / Cobalt; A Unique sub-micron manufacturing process providing improved wear resistance over the traditional Wc/Co coating.
What is a feedscrew or barrel wear problem?
A wear problem occurs when any feed screw or barrel, that due to any amount of wear, and without operating parameter modifications(1), will no longer deliver QUALITY(2), plasticized resin to the die or mold at the desired out-put rate, within the desired recovery/cycle time, or at the proper head pressure.
Operating Parameter Modifications
Compensating for screw/barrel wear through machine parameter modifications can cause excessive shear, burning, and polymer degradation!
Modifications are typically made to maintain out-put rates or decrease scrap rates
Costs of wear!
Quality - Resin of quality may be defined as resin that is free of unmelt, was exposed to minimal shear, has seen standardresidence time, and is therefore free of degradation.
Degradation - Loss of polymeric physical properties such as compression strength, tensile strength, impact strength, torsional strength, or other tangible or intangible engineered properties
Production Efficiency Advantage Factor! (PEAF)
Defined as the quantified cost of inefficiency on a per machine, per month basis, and in most cases factors in as a reduction to feedscrew and barrel expense.
NiBoride: Wear Resistance for ID Surfaces from .0005” to .005” Thickness
Our “NiBoride” coating is a proprietary composition of Nickel and Boron with a Knoop hardness of 1000-1100 HK (70-74 HRC). Post heat treatment produces a dense, crystalline structure of wear resistant Nickel Boride (Ni3B) with excellent abrasion resistance. The coating has a low coefficient of friction, high bond strength and can withstand high temperatures. Similar to the Electroless Nickel plating process, NiBoride can be deposited uniformly from .0005” up to .005” (12½ to 125 micron) thickness on virtually any metallic substrate. Complex shapes and inside diameters are candidates for our NiBoride coating. The as-plated surface finish is approximately 32 RMS (0,8 mm Ra). Polishing can meet almost any surface finish requirement including a mirror finish. This plating technology has value in any application where a small wear tolerance and adhesive or low stress abrasive wear shorten component life.
NiBoride PDF Data Sheet (125k)
Cushion Master: Long Life Non-return Valve for Severe Abrasive Wear
Extreme Coatings™ Cushion Master Series© check rings and seats are designed to compliment the wear resistance of a feed screw encapsulated with one of our coatings. Tip components are commonly replaced two to three times during the life of a feed screw. We have engineered these components to provide the necessary toughness, corrosion, and wear resistance to potentially reduce this ratio to 1:1, eliminating downtime and inefficiency caused by worn components. If replacing check rings and seats is a frequent burden then consider the Extreme Coatings™ Cushion Master© as your solution. (Case History PDF 3-PC Non-return Valve)
Cushion Master PDF Data Sheet (95k)
Through-Put Calculator: How our Carbide Coating Can Pay For Itself in Weeks?
As an extrusion screw wears, pumping efficiency decreases and output rate drops. Feed screw speed is increased to compensate which increases screw wear rate and thermal input to the polymer. By not allowing the feed screw OD to wear as quickly, a carbide coating maintains pumping efficiency and higher output rate is achieved. Our through-put rate worksheet estimates this gain in productive output from a carbide coating. Basic inputs are hours of operation, new and worn output rate, estimated total OD wear, months to this wear point and the sell price of output. A straight-line wear curve is calculated for the present case and for our carbide coating using standard ASTM G-65 wear test comparative data. The difference between old and new production is compared and the difference multiplied by the product sell price. This dollar value is usually quite large and provides a very quick payback period on our carbide coating.
PDF Example Low Rate 20 LB hr (45k)
PDF Example High Rate 3000 LB hr (50k)
Return on Investment: What Return Can You Expect for Your Investment in our Carbide Coating?
The estimated Return on Investment (ROI) in an Extreme Coatings carbide coating is calculated using a few basic inputs. Present feed screw cost, feed screw substrate material, service life in months and an estimate of total OD wear are all that is required. With this information we calculate a new feed screw service life to the same wear dimension and compare purchase cost for a carbide coating with the present feed screw cost. This difference in cost is the investment for a carbide coating. The increased wear life multiplied by the previous feed screw monthly cost represents the gain from a carbide coating. ROI is the ratio of money gained or lost on an investment relative to the amount of money invested. In all cases, the gain from Extreme Coatings is far greater than the investment.
FliteGuard: Long Life and Productivity for Extrusion Feed Screws
19/06/2007
In response to market demand, Extreme Coatings can apply our long lasting tungsten carbide to just the screw flight land. FliteGuard is an ideal option for applications where adhesive wear (outside diameter flight wear) shortens service life. Technological advances allow the root of the feed screw to be completely masked coating just the wearing portion of the feed screw, the flight land.
FliteGuard is appropriate for new or rebuilt feed screws and the carbide can be applied either before or after a feed screw is chrome plated.
The carbide coating thickness is limited to .005” (0,125 mm) per side or .010” (0.25 mm) overall.
Extrusion productivity is especially sensitive to adhesive screw outside diameter wear. Doubling the screw to barrel clearance can reduce output and melt rates by as much as 25% in low viscosity resins.
Visit www.extremecoating.com/breaking-news/throughput calculator for examples of productivity gains resulting from our coaitng. Contact Flite Technology or Extreme Coatings to create a throughput estimate for your process.
Tough economic times call for creative solutions. We are here to help you provide cost effective solutions to your customers.
Full Encapsulation
Our flagship product full encapsulation of any feedscrew with .005”, .010” even .012” of hard wear resistant tungsten or chromium carbide. Virtually eliminates screw wear and provides a high level of corrosion resistance. We have coated thousands of screws like this.
FliteGuard OD Only
Metal to metal adhesive wear reduces the feedscrew OD. Protecting this surface with highly wear resistant tungsten carbide extends equipment life and can add a 10 to 15% boost to production output in extrusion processes. Selective coating on a high wear portion of any feedscrew also makes good economic sense. FliteGuard is ideal for applications where root wear is not a problem.
Tool Steel Feedscrew Repair
This same FliteGuard option can make a worn screw new again. We can apply .010” per side or .020” overall (sometimes up to .030” overall) of tungsten carbide to the worn OD of a feedscrew. In these tight economic times you can offer your customer a solid solution that helps keep them processing. CPM-9V, D2, nitrided steel or virtually any screw material can be repaired using this method.
Cushion Master Tip Assemblies
Once a feedscrew is protected the weak link becomes the tip assembly. We offer this same tungsten carbide protection for non-return valves which provides 3 to 5 times longer service life in the most demanding applications. This service is available to improve the performance of new parts or to repair worn tip assembly parts and make them longer lasting. Most substrate materials can benefit from this process.
It’s Elemental – Segmented Twin Screw Wear Protection
We are developing the capability to apply our wear resistant materials to segmented elements with high bond strength to take the punishment. A metallurgical bond of our coatings to most substrate materials provides superior wear resistance for hard to replace elements. Help your customer alleviate the headache of changing out worn elements with this service.
Emergency feed screw and barrel repairing, rebuilding, repairs. Rush jobs
welcome for worn out and broken feed screws and barrels. Losing production, check your wear today.