Before Extreme Coatings, 3 months processing glass filled nylon.

If abrasive wear is your problem, we guarantee at least 2X life improvement with our carbide encapsulation.

After encapsulation with carbide, 10 months in the same process.

The ASTM G-65 wear test simulates low-stress sliding abrasion and provides a comparison between wear resistant materials. Volume loss is calculated and used to compare these materials. Our tungsten carbide is more than three times more wear resistant than the next best material tested. These test results give us the confidence to guarantee AT LEAST double the wear life of our carbide encapsulation over your current feed screw. See Wear Data

In response to market demand, Extreme Coatings has developed the ability to apply our long lasting tungsten carbide to just the screw flight land. FliteGuard® is an ideal option for applications where outside diameter (OD) adhesive wear shortens service life and where root erosion/wear is not an issue. Technological advances allow the root of the screw to be completely masked coating just the wearing portion of the feed screw, the flight land.

FliteGuard® can be applied to new or rebuilt feed screws and the carbide application can be carried out before or after a feed screw is chrome plated.

Improvement in masking materials and technique allows us to apply twice as much long lasting tungsten carbide as before. We now offer up to .010” (0,25 mm) per side (.020”, 0,5 mm overall) for a significant gain in wear life and improved productivity.

Productivity in an extrusion processes is especially sensitive to screw OD wear. Doubling the screw to barrel clearance can reduce output and melt rates by as much as 25% in low viscosity resins. In a high fill, highly abrasive extrusion process our carbide coating tripled feedscrew service life and, more significantly, resulted in 15% more production output compared with the previous feed screw! (Case History 2005-2 Extrusion Severe Abrasion) This is a solid example of the value that minimizing wear can have on a close-tolerance system.

FliteGuard PDF Data Sheet (425k)

Extreme Coatings does not make or repair feed screws, we encapsulate screws to make them last longer. All you need do is ask for Extreme Coatings and we will take care of the details with your supplier of choice. Be sure to ask about the Purchase Encouragement Program (PEP) which allows you to evaluate our carbide encapsulation at no charge for six months. Furthermore, our Rebuild Certificate states that we will return your feed screw to its pre-encapsulation condition if you are not completely satisfied with the screw performance.

Tool steels such as D2, CPM-9V or 420V are often used as substrate material for feedscrews processing abrasive materials. These steels provide improved wear resistance compared to an unprotected feedscrew and are often available from stock. The unique alloy chemistries that give tool steels their wear resistance also make these feedscrews difficult or impossible to repair once they are worn.

FliteGuard® offers great value for repair of tool steel feedscrews. Tool steel screws that are worn up to .025” (0,6 mm) overall can be refurbished with a thermal spray application of tungsten carbide. This is a very economical alternative to screw replacement. Not only will a screw be returned like new, tungsten carbide will wear as much as three times longer than the original material!

It’s easy to get a FliteGuard® quote. Your screw supplier can quickly determine if a feedscrew is a good candidate for repair. Send them your worn tool steel screw and request the FliteGuard® option. There is nothing to lose and much to gain from a longer lasting repaired feedscrew.

How much longer will my feedscrew last?

Our standard guarantee is double life.  In an abrasive process like glass filled nylon, the ASTM G-65 test (Abrasive Wear Test ASTM G65) shows that carbide encapsulation will be three times better than the next best material.  From experience we have learned that wear life can improve by three to five times compared to the feedscrew being replaced.

How much wear is too much for a typical feedscrew

This depends on many factors. SPI guidelines suggest .0015” (.04 mm) per inch of screw diameter starting clearance between screw and barrel. For a 50 mm screw this is .003” (.08 mm) clearance per side or .006” (.13 mm) overall. Depending on resin viscosity, output can be reduced 25% with a doubling of this beginning clearance (.012”, .25 mm). Factors that should be considered are what affect screw wear has on production and part quality. An extrusion system can be especially sensitive to adhesive wear of the feedscrew outside diameter.

How much does it cost to encapsulate my feedscrew?

We provide the Extreme Coatings encapsulation service through your feedscrew manufacturer. Your screw supplier is our direct customer. We do not set the price that you will pay, however, experience has shown that a carbide encapsulated feedscrew will cost about twice as much as a screw protected with hardfacing and chrome plate. Compared with tool steels, carbide encapsulation will cost about fifty to sixty percent more. Remember, in all cases, we guarantee at least double the life.

Does Extreme Coatings make new feedscrews?

Extreme Coatings does not make new screws or rebuild worn feedscrews. We encapsulate screws to make them last longer. We work with your present feedscrew supplier to provide this service.

Do I send my worn feedscrew to Extreme Coatings to be repaired?

Not directly. We supply this coating service through your present feedscrew supplier or original equipment manufacturer. A worn feedscrew should be sent to your screw supplier for any necessary repairs and then prepared for carbide encapsulation. Your supplier will send the coating ready feedscrew to Extreme Coatings to complete the process.

Will a coating ever come off the feedscrew?

It can happen. The carbide coating has a mechanical bond to the screw surface. If the screw surface moves or flexes, the bond can be weakened which may lead to a release of coating. What can cause this movement? Excess heat such as a torch or cleaning oven can expand the screw surface. A cold start can result from operating equipment before sufficient heat input (soak) to soften any remaining polymer in the system. Non-compressible tramp material will gouge the screw surface and remove coating at the contact point.

Will a hard tungsten carbide coating wear my “soft” barrel?

This is a common concern among processors.  We commissioned an ASTM G-77 test procedure to address this issue.  In brief, tungsten carbide spinning against a bimetallic (FeB) liner shows no difference in liner wear than standard alloy materials such as Stellite and Colmonoy. Follow this link for more details (Adhesive Wear Test ASTM G77).  A hard coated feedscrew contacting a less hard barrel liner is not a source of wear.  In extrusion, system alignment, auxiliary die and barrel support, temperature profile, and proper screw design are much more critical to reducing wear. 

What if I need to remove the coating to re-cut my screw?

Extreme Coatings has the capability to “strip” the coating from a worn feedscrew. This feature is especially beneficial for large, complex, expensive feedscrews. A screw will eventually wear through the coating at the outside diameter (OD). When that happens simply remove the screw and coordinate with you screw supplier to have Extreme Coatings strip and re-apply a fresh layer of tungsten carbide.

My feedscrews last a long time, can a coating benefit me?

We believe that any injection molding feedscrew that is replaced or rebuilt at 24 months or less will benefit significantly from encapsulation with carbide. Extrusion feedscrew that are rebuilt or replaced within five years will likewise see great benefit from carbide. Obvious gains are longer screw life, however intangible benefits such as consistent quality, through-put, lower energy and maintenance costs, as well as higher capacity utilization offer cost savings and competitive advantage.

Can Extreme Coatings apply this same material to my barrel?

We get asked this question a lot. The answer is no. Our process is line-of-sight and we cannot fit the spray apparatus inside a barrel. Spin cast barrel liners of tungsten carbide are available from all the major barrel suppliers.

Can Extreme Coatings coat my mold/die/calibrator/widget?

This is also a common question.  After we improve feedscrew life, processors find a downstream component, profile die, calibrator, non-return valve, or other part that wears “quickly”.  We have tried to solve a lot of these issues with thermal spray coatings and have learned that some respond well, others not.  For inside diameter surfaces we offer our NiBoride nickel boride material.  Follow this link for more details.  (NiBoride see case history / document page).  For non-return valves – tip assemblies, we have developed the Cushion Master.  This is a solid tungsten carbide check ring and rear seat that provides from six to eight times the life of standard tip assemblies.  Follow this link for more details (Cushion Master)

Does Extreme Coatings have references? Who works with Extreme Coatings?

Extreme Coatings has a solid reputation as the premier supplier of carbide encapsulation of feedscrews to the plastics and rubber processing industries. Extreme Coatings is a service mark of Surface Engineering & Alloy Company, a wear resistance company with 30 years experience solving wear problems. Since 1997, we have carbide encapsulated over 5500 feedscrews worldwide with great success. We work with all feedscrew and equipment manufacturers. It is likely we have supplied our service through your present feedscrew source. We encourage you to ask about our reputation for quality and after sales service with your supplier.

How much extra time does it take to get my screw coated?

Our quoted lead time is ten business days. We average six to seven days. Depending on feedscrew diameter, we can meet a “rush” delivery if given prior notice.

I have a technical question about a coating, can I contact Extreme Coatings directly?

Absolutely. Our toll free number is 888-367-2569. Ask for John, Tom or Greg.

The importance of maintaining a tight tolerance between the feed screw and barrel in plastic extrusion machinery is observed by a measurable reduction in the out-put of the machine, either in pounds per hour or feet per minute. It has been determined in lab testing that a doubling of feed screw/barrel clearance may reduce the output of an extruder by as much as 20-25% in low viscosity resins and 10-13% in higher viscosity resins. Furthermore, as the outside diameter of the screw wears, the flight to barrel scraping or wiping action decreases which, with some polymers, leaves a thin residue of molten plastic on barrel that may burn or retard thermal conductivity. Additionally, back flow increases potentially causing excess shear and subsequent polymer degradation. Scrap or reject rates may increase, but more importantly, the physical properties of the polymer may be jeopardized. Even a small percentage of abrasive filler may cause unacceptable wear to occur 3-4 times quicker. Processing non-abrasive polymers such as clear LDPE have little to no effect on screw wear, but for those running 24-7, adhesive wear will be obvious in as little as 2 years.

Maintaining a tight tolerance between the feed screw and barrel in a plastic injection molding machine is of vital importance to the production efficiency of the machine and the quality of the parts being produced. The principles of plasticizing in an injection molding machine are almost identical to those of an extruder. The main difference is that the injection screw is extruding plastic into the barrel to create a shot rather than through a die to form a product. As this is the case, wear on the O.D. of the screw may be observable as an increase in the feed screw recovery time or maybe even the cycle time. In applications where the cycle time maybe much greater than the recovery time, it may be misinterpreted to be acceptable to continue with production if the cycle time is not affected. In contradiction, an increase in residence time may cause polymer degradation or burning. In the case of glass filled resins, back flow may cause excessive shear affecting the integrity of the fibers. Both, if not held to a minimum, will adversely affect the physical properties of an engineered polymer. Further to this, especially in the case of low viscosity resins without a new check ring, it may be difficult to hold a cushion and short shots may be evident. With respect to machinery down-time, one can expect an encapsulated feed screw to last at least twice as long as any feed screw on the market today, even CPM9V* tool steel, thus, eliminating the time associated with numerous maintenance inspections.

Extreme Coatings: Encapsulating a plastic injection molding or extrusion feed screw with a wear and corrosion resistant tungsten or chromium carbide coating will reduce your average amortized monthly feed screw costs by up to 50% regardless of the type of polymer being processed. There are two primary modes of wear that cause processing problems in plastic injection molding machines and extruders.

1.) Adhesive wear (metal to metal) is caused as the feed screw flight lands rub against the barrel I.D.

2.) Abrasive wear occurs when hard fillers such as fiberglass or Titanium Dioxide are compressed against the screw flight and barrel surfaces causing material removal. The high concentration of extremely hard tungsten or chromium carbides in our coatings provides adhesive and abrasive wear characteristics unmatched by common hard facing alloys or tool steels. In most cases, one can expect an encapsulated feed screw to last at least twice as long as any other feed screw on the market. This is backed by our Double Life Guarantee and also a component of our Purchase Encouragement Program (PEP).