Extreme Coatings - Breaking News

New Products / Highlights

Tungsten Carbide: Superior Adhesive Wear Resistance Creates the Forever Feedscrew

There is a common misconception that a hard coated feedscrew will wear a softer barrel liner.
Extreme Coatings commissioned the ASTM G77 test to answer this question.

Adhesive wear is the result of surfaces contacting one another under load. For adhesive wear to occur, micro-welding between contacting surfaces must occur. When two surfaces contact, they initially touch only at a few high points and friction and wear originate there. When surfaces are subjected to a compressive load, the points are plastically deformed and eventually welded together by high local pressure. As sliding continues, these bonds are broken, producing cavities on one surface, projections on the second surface, and small, micro-fracture particles are created which contribute to abrasive wear.

Tungsten is a refractory metal with a very high melting point (>3200°C) and cannot weld under friction heat below this threshold. The test results show that a rotating tungsten carbide ring contacting a nitrided steel block resulted in no discernable wear.

What does this mean for a feedscrew and barrel?

With no abrasive additive, a carbide protected feedscrew will likely last more than ten times as long as an unprotected nitrided steel feedscrew. An added benefit from minimum adhesive wear, a nitrided steel barrel may now last twice as long as before!

Tungsten carbide protection of the screw outside diameter creates the Forever Feedscrew! This feedscrew can actually improve the life of the barrel.

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)

Cushion Master II: Repaired Tip Assemblies Last 3X to 5X Longer Than Original

Extreme Coatings has developed the technology to apply our thermal spray tungsten carbide coating to the outside diameter of a worn check ring and both the front and rear seat faces. We can replace up to about .007” of wear. The material is metallurgically bonded to the coated surface which ensures chipping will not occur. After coating, the parts are ground to the correct dimension and the surfaces polished. This process results in a high percentage of carbide at the point of wear which can provide triple the wear life or better. Contact Extreme Coatings to learn more about this option.

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. Screw speed is increased to compensate which increases screw wear rate and thermal input to the polymer. By not allowing the 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 Encapsulation?

The estimated Return on Investment (ROI) in Extreme Coatings carbide encapsulation is calculated using a few basic inputs. Present feedscrew cost, screw substrate material, service life in months and an estimate of total OD wear are all that is required. From this we estimate a new carbide encapsulated feedscrew service life to the same wear point and compare total cost over the life of each feedscrew.
This total cost divided by service life gives a monthly operating cost for each option. With few exceptions, the monthly cost of an encapsulated feedscrew will be less than the cost of the current feedscrew. Carbide encapsulation is the least costly option over the life of an encapsulated feedscrew.

Intangible costs resulting from feedscrew wear such as shot and melt inconsistency, heating / cooling expense, maintenance labor, downtime and finished part quality are difficult to estimate. Overall production consistency and repeatability are the benefits from a feedscrew in like-new condition over a long service life.