For the past 15 years, Extreme Coatings, Inc. has had tremendous success using thermal spray carbide coatings to significantly increase the life of the feed screws used in plastic injection molding and extrusion equipment. The same technology and expertise is now being used on downhole mud motor rotors for the oil and gas drilling industry.
For Extreme Coatings, the move was a natural one. The geometry and actions of mud rotors are very similar to those of feed screws, so existing technology and working methods were directly applicable.
Mud motors are a type of displacement pump used in drilling for gas and oil. The most expensive part to replace is the power section, consisting of a rotor and a stator. Historically, stainless steel rotors have been chrome plated. When the drilling fluid, or mud, is fouled, the chrome plating can rapidly wear away in places and build up in others. When that occurs, the incorrect fit can cause a loss of power to the drill and eventual motor failure. With increased exploration into corrosive environments such as shale formations, the demand for more corrosion- and wear-resistant coatings has grown.
Through new coating development like their CPR (Chrome Plating Replacement) coating and refined polishing techniques, Extreme Coatings is not only repairing the mud rotors, they are making them run better. Extreme Coatings strips away worn chrome plating and replace it with a more corrosion resistant high velocity oxy-fuel (HVOF) thermal spray coating. The tungsten carbide used in these coatings is harder than chrome, and the method of application and polishing results in a high finish that reduces friction. This can increase the life of a rotor by six to ten times.