WO2016178663A1

WO2016178663A1 - Sintering a multi-lobed helical rotor

Info

Publication number: WO2016178663A1
Application number: PCT/US2015/029070
Authority: WO
Inventors: Richard David Peer
Original assignee: Halliburton Energy Services, Inc.
Priority date: 2015-05-04
Filing date: 2015-05-04
Publication date: 2016-11-10
Also published as: US20180079005A1; SG11201707688SA; CA2981001A1; GB201715453D0; DE112015006512T5; GB2552912A

Abstract

The present disclosure relates to a method and system for manufacturing a multi- lobed helical rotor. The method for manufacturing a multi-lobed helical rotor may comprise mixing one or more powdered metals, compacting a mixture of one or more powdered metals to form a solid metal piece, sintering the solid metal piece, and polishing the solid metal piece. The system may comprise a positive displacement pump, which may comprise a casing, a multi-lobed helical rotor disposed in the casing, wherein the multi-lobed helical rotor comprise sintered powdered metals, an inlet to the casing, and an outlet leading from the easing.

Description

SINTERING A MULTI-LOBED HELICAL ROTOR

BACKGROUND

[0001] The present disclosure rela tes to a method and process for manufacturing parts and tools used in the oiifieid. More particularly, the present disclosure relates to the manufacturing of multi-lobed helical rotors with sintered powdered metals.

[0002] Various types of parts and tools are currently used in the oilfield. Current methods of manufacturing rotors may take forty or more hours to produce a finished product. Milling a multi-lobed helical rotor may require removal of large amounts of materia! from a metai block. This generates large amounts of waste materia! and significant consumption of milling bits and tools. Additionally, after the milling process, a milled multi-lobed helical rotor and/or other oilfield tools may need polishing, grinding, and/or additional finishing steps. Polishing may take as much as fifteen hours to complete and may require the use of sanding disks and/or belts. This makes the current manufacturing process of oilfield parts and tools expensive, wasteful, and time intensive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] These drawings illustrate certain aspects of some of the examples of the present invention, and should not be used to limit or define the invention.

[0004] Fig. 1 is an illustration of an example of a multi-lobed helical rotor within a pump;

[0005] Fig. 2 is a schematic illustration of an example multi-lobed helical rotor manufacturing process;

[0006] Fig. 3 is an illustration of an example of muiti-iobed heiicai rotor die; and [0007] Fig. 4 is an illustration of an example of a drilling system using a positive displacement pump.

DETAILED DESCRIPTION

[0008] The present disclosure relates generally to a method and process for manufacturing parts and tools used in the o ilfield. More particularly, a method and process for manufacturing a multi-lobed helical rotor. The disclosure describes a method and process that manufactures parts and tools used in the oilfield through sintering powdered metai. Specifically, a process may comprise mixing powdered metals, compacting the powdered metals, sintering the powdered metals, and polishing the resultant product.

Many oilfield tools and parts are specially manufactured to meet stringent requirements for oilfield use. Sintering powdered metals may drastically cut the time it. takes to produce oilfield tools and pans while retaining stringent specifications,

[0009] Certain examples of the present disclosure may be implemented, at least to part with an information handling system. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, iiitel.lige.nce, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resoyrces such as a centra! processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communication with external devices as well as various input and output (1/0) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.

[0010] An example of a method for manufacturing a multi-lobed helical rotor may comprise mixing one or more powdered metals, compacting a mixture of the one or more powdered metals to form a solid metal piece, sintering the solid metal piece, and polishing the solid metal piece. The method, may further comprise choosing one or more powdered metals as the base material for the multi-lobed helical rotor. The method may comprise choosing the one or more powdered metals and at least one additive as the base material for the multi-lobed helical rotor. The step of mixing may comprise combining the one or more powdered metals with at least one additive and the step of compacting may comprise adding the at least one powdered metal and at least one additive to a die. The step of compacting may comprise compacting at least one powdered metal and at least one additive with a hydraulic rani. The step of compacting at least one powdered metai and at least one additive with a hydraulic ram may form the multi-lobed helical rotor. The step of sintering may comprise placing the multi-lobed helical rotor in a furnace, wherein the furnace may be a multi-belt furnace. The step of polishing may be performed by an abrasive -flow machine. The step of compacting and the step of sintering may be combined into a single step in which the compacting may be performed at elevated temperatures.

[0011] A system may comprise a positive displacement pump which may further comprise a casing, a multi-lobed helical rotor disposed in the casing, wherein the multi- lobed helical rotor may comprise sintered powdered metals, an inlet, to the casing, and an outlet leading from the casing. The sintered powdered metals may be formed from powdered metals having a particle size of about 0.5 microns to about. 100 microns. The multi-lobed helical rotor may comprise i 7-4 stainless steel, wherein, die multi-lobed helical rotor may further comprise at least one additive selected from a group which may consist of plastic, carbon, copper, wax, and/or combinations thereof. The system may further comprise a second multi-lobed helical rotor disposed in the casing, wherein the second multi-lobed helical rotor may comprise sintered powdered metal The system may further comprise feed conduit coupled to the positive displacement pump, and a drill string coupled to the feed conduit, wherein the drill string may be at least partially disposed in a wellbore. The system may further comprise a derrick comprising a traveling block for raising and lowering the drill string, wherein the positive displacement pump may be connected to a solids control system. The solids control system may be connected to a retention pit.

[0012] Fig. 1 illustrates an example of a positive displacement pump 2. Positi ve displacement pump 2 may comprise a multi-lobed helical rotor 4, a casing 6, an inlet 8, and an outlet 1.0. It should be noted that positive displacement, pump 2 may comprise more than a single and/or a plurality of multi-lobed helical, rotors 4. in examples, a positive displacement pump may produce the same flow at any given, speed, no matter what the discharge pressure may be. Positive displacement pumps may be considered constant flow machines. Benefits of using positive displacement pumps, for example a lobe pump, within the chemical industry' may be the sanitary qualities, high efficiency, reliability, corrosion resistance, and good clean-in-place and steam-in-place characteristics.. Additionally, positive displacement pumps may be able to handle solids, slurries, pastes, and a variety of liquids.

[0013] The manufacturing process of a multi-lobed helical rotor 4, and an associated method, may embody principles of this disclosure. However, it should be dearly understood thai the process and method, of manufacturing a multi-lobed helical rotor 4 maybe one example of an application, of the principles of ibis disclosure in practice. A wide variety of manufactured oilfield tools and parts may be possible with the disclosed process and methods. Therefore, the application of this disclosure is not limited to the details of a. manufacturing process for a multi-lobed helical rotor 4 and method as described herein and/or illustrated in the drawings.

[0014] As illustrated in Fig. 1, a multi-lobed helical rotor 4 may comprise a plurality of lobes 12. Multi-lobed helical rotor 4 and lobes 1.2 may be made of any suitable material to withstand the pressures and chemicals that they may contact. This may make the material makeup of multi-lobed helical rotor 4 an important factor during manufacturing. Additionally, individual lobes 12 may be of any suitable diameter, shape, angle, twist rate, and/or orientation to satisfy pumping requirements. Manufacturing a multi-lobed helical rotor 4 and lobes 12 may be complex, require precision, and be time intensive, tit some known methods, milling machines may be used to produce multi-lobed hel ical rotors 4, Milling times may take forty hours before completion and may require an additional, fifteen hours of polishing before a multi-lobed helical, rotor 4 may be ready for service. The high demand, for these complex, parts may make the forty to fifty-five hour manufacturing time an inefficient and cosily process.

[0015] Fig. 2 illustrates a manufacturing process that may be used to cut the production time of multi-lobed helical rotor 4. The process may use powdered metals and a sintering process to manufacture multi-lobed helical rotor 4. The process may comprise mixing 1.4 powdered metals, compaction 16 of the powdered metals, sintering 18 the powdered metals, and polishing 20 the final product.

[0016] Mixing 14 of powdered metals may be used to control the strength, toughness, and/or other characteristics a multi-lobed helical rotor 4 may require when in use. Typical materials may be .17-4 stainless steel, iron, tungsten carbide, cobalt chromium, aluminum, copper, carbon, and/or any combination thereof Selection of powder size may control density and consistency of the finished part. For example, powder size may range may be about 0.5 microns to about 100 microns, which may produce the best die .fill with ninety nine percent or greater finished part density. Additional additives add to the powdered metal may also improve and/or add special characteristics to multi-lobed helical rotor 4. Characteristics such, as lubricity, conductivity, and others may be beneficial during the lifetime use of multi-lobed helical rotor 4, For examples, fillers may be plastic, carbon, copper and wax can be used to enhance the manufacturing process (plastics and wax may aid in the compaction process and die fill) while carbon, copper and other elements may be added to modify the physical characteristics of the part (copper may be added for lubricity and enhanced thermal/electrical conductivity). Mixing 14 powdered metals and additives may be accomplished using a dry powder blender. These blenders can be the tumble type and/or rotary blenders. In examples, powdered metals and additives may be added in stages during compaction 16, providing different metal characteristics throughout multi-lobed helical rotor 4.

[0017] Compaction 16, may include placing mixed powdered metal within a die 22. Die 22, best illustrated in Fig. 3, may be used to form the structure and shape of multi- !obed helical rotor 4. Additionally, die 22 may be used to form intricate twisting, angles, and/or shapes of lobe 6. Compaction 16 may be performed by traditional means, cold iso- static pressing, and/or hot iso-static pressing.

[0018] Traditional compaction 16 may include placing a predetermined amount of powder into a die 22, Die 22 may be sealed and pressure may be applied to the powdered metal (and additives) by a hydraulic and/or mechanical rams/actaators. Actuation of hydraulic and/or mechanical rams/actuators may be performed and monitored by an information handling system. In examples, the pressure applied may be as low as 20 kst and as high as 60 ksi. A target or desired compaction pressure may depend on a specific part size, powder content, and/or required density. A hold time (which may be defined as the time that the powdered metal may be compacted under the compaction pressure) may also be dependent on the size and shape of the part Compaction times may range from about ten to about one hundred and twenty minutes.

[0019] Pressure applied to powdered metals (and additives) may cause the molecular structure of a powdered metal to merge with the mokcular structure of adjacent powdered metals and/or additives. Sensors may be used within dies 16 which may provide information to the information handling system relating to the compression and formation between powdered metals and additives. The traditional process may not require heat due to the large amount of pressure applied to the powdered metal. After compaction 16, the powdered metal and/or additives may have formed a solid metal piece. The solid metal piece may then be removed from, die 22 and moved to a sintering process 18. In examples, compaction 16 may be repeated any number of times, which may allow for the addition of different powdered metal mixtures and/or additives to die 22. This may allow an operator to manipulate the strengths, toughness, properties, and chatacteristics in different areas of muUi-lobed helical rotor 4. Compaction 16 may also be performed by cold iso~stat.ic pressing.

[0020] Cold iso-static pressing may be performed at room temperature with water and/or oil . Powdered material and/or additives may be placed within a die 22. Cold iso- static pressing may use a die 22 which may be flexible. Die 22 may be flexible from material such as elastomer, urethane, and/or any combination which may be used to create die 22. The fluid (e.g., oil, water, and/or any other suitable liquid for compression) may place pressure upon the powdered material and/or additives within die 22, Pressures applied may he between 60 ksi and 150 ksi. Compaction pressure may usually be determined by a specific part size, powder content, and/or required density. A hold time (which may be defined as the time that the powdered metal may be compacted under the compaction pressure) may also be dependent on the size and shape of the part. Compaction times may range from about ten to about one hundred and twenty minutes. The amount of fluid used and amount of pressure applied may be monitored by an information handling system. The information handling system may further monitor and alert an operator as to the merging between the powdered metals and/or additives. Additional machining may be required due to the flexibility of die 22. After compaction 16, the powdered metal and/or additives may have formed a solid metal piece. The solid metal piece may then be removed from die 22 and moved to a sintering process 18. In examples, compaction 16 may be repeated any number of times which may allow for the addition of different powdered mixtures and/or additives to die 22. This may allow an operator to manipulate the strengths, toughness, properties, and characteristics in different areas of mu!fi-lobed helical rotor 4.

[0021] Compaction 16 may additionally be performed by hot iso-static pressing. Hot iso-static pressing may be used to produce a more uniform grain structure over multi- lobed helical rotor 4. This form of pressing may be performed at elevated temperatures. Temperatures are typically near 65-70% of the melt temperature of the target metal powder. Ex: 1.7-4 SS has a green bar melt temperature of 2560-2625F so a typical process range may be S 792-1837F, Powdered metal and/or additives may be placed within die 22. Die 22 may be made of metals that may be able to resist the high temperatures and pressures exerted upon the powdered metals and. additives. For example, suitable metals may be, but. are not limited to, tungsten carbide and/or high strength tool steels. Pressure may be applied to the powdered metal and/or additives using a gas. The application of gas and pressure may be monitored, by an information handling system. The information handling system may further monitor the temperature and formation between the powdered metals arid/or additives. Pressure applied to powdered metals and/or additives may be about 15 ksi at 2000 F°. Compaction pressure may usually be determined by a specific part size, powder content, and/or required density. A hold time (which may be defined as the time that, the powdered metal may be compacted under the compaction pressure) may also be dependent on the size and. shape of the part. Compaction times may range from about ten to about one hundred and twenty minutes. Application of pressure at these temperatures may produce more uniform grain structure over multi-lobed helical rotor 4 and/or lobes 12. After completion of a hot iso-static pressing, the metal product produced may not: need to be sent to a sintering 18 process and may only require a polishing process 20.

[0022] A sintering process 18 may be described as heating a solid mass of material by heat and/or pressure without melting it. to the point ofliquefaction. Atoms in a material, may diffuse across boundaries of adjacent particles, fusing the particles together and creating one solid object. As described above, the powdered metals and additives may have been pressed together hi a process of compaction 16. The solid metal objects formed may be placed, onto a. conveyor system and/or placed into a furnace.. A furnace and/or the conveyor system may be controlled by an information handling system. The furnace may be a batch furnace and/or a continuous furnace. Additive gases such as, but not limited to, nitrogen, hydrogen, and/or other inert gases, and/or any combination thereof may control the cleanliness and material properties of the solid metal object placed within the furnace. Temperatures within the furnace, controlled by an information handling system, may heat the sol id metal object to between se venty and ninety percent of the melting temperature. Temperatures may range from 2000 to 2100 F°, which may depend on melting temperatures of the base metal powders. Traditional furnaces may heat the solid metal object at the same temperature throughout the furnace. In examples, a mesh-belt furnace may be used to heat the solid metal object in three different zones. There may be a preheat zone, a hot zone, and/or a cooling zone. Each zone may be heated to different temperatures, in examples, after heating the solid metal object, the process may control the temperature at which the solid metal object cools. The rate of cooling may he dependent on the type of base material . For examples, base materials such, as martensile and ausenite may be cooled at a rate which may be determined by the part size and/or configuration (e.g. thin wall versus (hick wall or solid bar, etc.). Heating and cooling the solid metal object may require as little as three hours in the sintering 18 process. After completion, the solid metal object may be a "near net" multi -Iobed helical rotor 4 and/or any oilfield tool or part. A "near net" multi-lobed helical rotor 4 may be described as a multi-lobed helical rotor 4 that may only need minimal amounts of polishing process 20.

[0023] Polishing process 20 may be a final step in a process before multi-lobed helical rotor 4 may be ready for service. Polishing may be performed using electropolishing, mechanical polishing, and/or an abrasive flow machine, Electrapolishing may immerse mu!ti-Iobed helical rotor 4 in a temperature-controlled bath of electrolyte, serving as an anode. The tempera ture of the bath may be control led by an information handling system. Multi-lobed helical rotor 4 may be connected to a positive terminal of a DC power supply and a cathode may be attached to the negative terminal. The cathode may further be placed within the temperature-controlled bath. A current may pass from multi-lobed helical rotor 4 to the cathode. The metal on the surface of multi- lobed helical, rotor 4 may oxidize and dissolve in the electrolyte. This type of polishing may passivate the material but may also work as final polish due to the smoothing of multi- lobed helical rotor's 4 surface.

[0024] In some embodiments of the polishing process 20, mechanical polishing may be performed using blasters and/or standard mechanical disks and/or belt sanders. A blasting method may use powders and/or any combination of mediums comprising, but not limited to, baking soda, walnut shells, and/or glass bead. A wand blasting device may^¬ be used for polishing the inner diameter of multi-lobed helical rotor 4 (more relevant to a stator. ID of rotor can be machined or left in as manufactured state provided tolerances are met). Blasting within a cabinet may be used for polishing the outer diameter of multi- lobed helical rotor 4. Grit may be a medium comprising, but not limited to, baking soda, walnut shells, and/or glass bead. In an example, grit may surface harden multi-lobed helical rotor 4 and "dimple" the surface, providing a roughness for additional bonding strength and/or a final polish. Mechanical polishing may be labor intensive and require specialized personnel to perform the polishing. An additional polishing process of abrasive flow machining may be used as an alternate to mechanical polishing.

[0025] Abrasive flow machining may be used for polishing both, inner features and. outer features of muit.i~l.obed helical rotor 4. Polishing the inner features of multi-lobed helical rotor 4, an abrasive flow machine may comprise two media chambers (in examples there may be more than two media chambers) and a hydraulic ram within each chamber. Hydraulic rams may be connect at the ends of a tubular (stator). Within the chambers may be a polishing medium. Polishing mediums may be, but are not limited to, silicon carbide, aluminum oxide, and/or boron carbide with sixes ranging from about fourteen grans to about two thousand grains. The viscosity of the medium selected may depend on how fine a finish is required (e.g., low viscosity medium for minimal material removal and high viscosity medium for maximum material removal-per cycle). The harder the surface of the finished pari may require a more aggressive polishing medium and process pressure,

[0026] During polishing, polishing media may be forced through the inner features of multi-!obed helical rotor 4. Contacting the surface of multi-lobed heiical rotor 4, the polishing media may slowly polish and/or remove the surface roughness. This may be repeated until the desired dimensions are produced. The dimensions may be routinely monitored by an information handling system as polishing mediums are pushed through the inner features of multi-lobed helical rotor 4. in examples, the polishing may be done within a one-way flow loop and/or a two way flow loop. Using a flow system, the polishing medium may be constantly reused, reducing waste and cost. Additionally, a flow system may keep reused polishing media in contact with the surface of multi-lobed helical rotor 4, reducing the time it may take to polish the surface. The abrasive flow machine may then be reset, or an extra abrasive flow machine may be used, to poiish the outer features of multi-lobed helical rotor 4.

[0027] Polishing the outer features of multi-lobed helical rotor 4 with, an abrasive flow machine may be accomplished with polishing media that may comprise, but are not limited to, a belt type, a one-way flow loop, a two way flow loop, and/or any combination thereof. Multi-lobed helical rotor 4 may be placed within a tubular comprising polishing media. The polishing media may be forced around the outside dimensions of multi-lobed helical rotor 4 through hydraulic and/or tumbling means. As described above, the polishing media may he reused and recycled. This may allow polishing media to stay in direct, contact with multi-lobed helical rotor 4. reducing the polishing time. During the process of polishing 14, an. abrasive flow machine may reduce the time and waste when polishing multi-lobed helical rotor 4, allowing multi-lobed heiical rotor 4 (or any type of oilfield tool and/or part) to be ready for use in. a shorter amount of time. [0028] Referring now to Fig. 4, a drilling system 24 is illustrated thai may use a positive displacement pump 2. In examples, there may be more than one positive displacement pump 2 used on drilling system 24. As illustrated, a positive displacement pump 2 may be used to move wellbore fluids through the wellbore and/or throughout drilling system 24. It should, be noted that while Fig. 4 generally depicts a land-based drilling system, those skilled in the art will readily recognize that the principles describe herein are equally applicable to subsea drilling operations that employ floating or sea- based platforms and rigs, without departing form the scope of the disclosure.

[0029] As illustrated, drilling system 24 may include a drilling platform 26 that supports a derrick 28 having a traveling block 30 for raising and lowering a drill string 32. Drill string 32 may include, but is not limited to, drill pipe and coil tubing, as generally known to those skilled in the art. A kelly 34 may support, drill string 32 as it may be lowered through a rotary table 36, A drill bit 38 may be attached to the distal end of drill sting 32 and may be driven either by a downhole motor and/or via rotation of drill string 32 from the well, surface. Without limitation, drill bit 38 may include, roller cone bits, FIX^' bits, natural diamond bits, any hole openers, reamers, coring bits, and the like. As drill bit 38 rotates, it may create a wellbore 40 that penetrate various subterranean formations 42.

[0030] Drilling system 24 may further include a. positive displacement pump 2, one or more solids control system 44, and a retention pit 46. Positive displacement pump 2 .representatively may include any conduits, pipelines, trucks, lobulars, and/or pipes used to fluidically convey drilling fluid 48 downhole, any pumps, compressors, or motors (e.g., topside or downhole) used to drive the drilling fluid 48 into motion, any valves or related joints used to regulate the pressure or flow rate of drilling fluid 48, any sensors (e.g., pressure, temperature, How rate, etc.), gauges, and/or combinations thereof, and the like.

[0031] Positive displacement pump 2 may circulate drilling fluid.48 through a feed conduit 50 and to kelly 34, which may convey drilling fluid 48 downhole through the interior of drill string 32 and through one or more orifices in drill bit 38. Drilling fluid 48 may then be circulated back to the surface via an annulus 52 defined between drill string 36 and the walls of wellbore 40, A t the surface, the recirculated or spent drilling fluid 48 may be exit the annulus 52 and may be conveyed to one or more solids control system 44 via an interconnecting flow line 54. The solids control system 44 may include, but is not limited to, one or more of a shaker (e.g., a shale shaker), a centrifuge, a hydrocyclone, a separator (including magnetic and electrical separators), a desi!ler, a desander, a separator, a filter (e.g., diatomaceous earth filters), a beat exchanger, and/or any fluid reclamation equipment. The solids control system 44 may further include one or more sensors, gauges, pumps, compressors, and the like used store, monitor, regulate, and/or recondition the drilling fluid 48.

[0032] Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples disclosed above are illustrative only, as the present invention may he modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual examples are discussed, the invention covers all. combinations of all those examples. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below, it is therefore evident that the particular illustrative examples disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. Moreover, the indefinite articles "a" or "an," as used in the claims, are defined herein to mean one or more than one of the element that it introduces. Also, the terras in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should he adopted for the purposes of understanding this invention.

Claims

CLAIMS What is claimed is:

1. A method for manufacturing a multi-lobed helical rotor comprising:

mixing one or more powdered metals;

compacting a mixture of th e one or more powdered metals to form a solid metal piece;

sintering the solid metal piece; and

polishing the solid metal piece.

2. The method of claim 1, further comprising choosing the one or more powdered metals as the base material for the multi-lobed helical rotor.

3. The method of claim 1, further comprising choosing the one or more powdered metals and at least one additive as the base material for the multi-lobed helical rotor.

4. The method of claim 1, wherein the step of mixing comprises combining the one or more powdered metals with at least one additive.

5. The method of claims 1 , wherein the step of compacting comprises adding the at least one powdered metal and at least one additive to a die.

6. The method of claim 5, wherein the step of compacting comprises compacting the at least one powdered metal and at least one additive with a hydraulic ram.

7. The method of claim 6, wherein the step of compacting the at least one powdered metal and the at least one additive with a hydraulic ram forms the multi-lobed helical rotor.

8. The method of claim 7, wherein the step of sintering comprises placing the multi-lobed helical rotor in a furnace.

The method of claim 8, wherein the furnace is a multi-belt furnace.

10. The method of claim 9, wherein the step of polishing is performed by an abrasive flow machine.

1 1 . The method of claim J , wherein the step of compacting and the step of sintering are combined into a single step in which the compacting is perfomied at elevated temperatures.

12. A system comprising:

a positive displacement pump comprising:

a casing;

a multi-lobed helical rotor disposed in the casing, wherein the muiti- lobed helical rotor comprises sintered po wdered metals;

an inlet to the casing; and

an outlet leading from the easing.

13. The system of claim 12, wherein the sintered powdered metals were formed from powdered tnetais Slaving a particle size of from about 0.5 microns to about 100 microns.

14. The system of claim 12, wherein the multi-lobed helical rotor comprises 17-4 stainless steel.

15. The system of claim 1 2, wherein the mulii-Iobed helical rotor further comprises at least one additive selected from the group consisting of plastic, carbon, copper, wax, and combinations thereof.

16. The system of claim 12, wherein the system further comprises a second multi-lobed helical rotor disposed in the casing, wherein the second muiti-lobed helical rotor comprises sintered powdered metal.

17. The system of claim 12, wherein the system further comprises feed conduit coupled to the positive displacement pomp, and a drill string coupled to the feed conduit, wherein the drill string is at least partially disposed in a wellbore.

18. The system of claim. 1 7, further comprising a derrick comprising a traveling block for raising and lowering the drill string.

19. The system of claim 17, wherein the positive displacement pump is connected to a solids control system.

20. The system of claim 17, wherein the solids control system is connected to a retention pit.