TPT November 2015

Article

Quaker Chemical Corporation

Achieving threading efficiencies for pipe applications – new thread cutting fluid technology By Glen May, Quaker Chemical Corporation, global MTM manager/tube and pipe product manager; Robert Evans, Quaker Chemical Corporation research scientist; and Edward Platt, Quaker Chemical Corporation, machining specialist

operation. The degree and type of wear are largely influenced by the fluid’s lubrication and heat removal properties as well as its ability to facilitate chip removal during and after the cutting process. To effectively assess the performance capabilities of a thread cutting fluid for high strength pipe connections, various machining methods can be utilised. One method involves the machining of AISI 4140 steel, whereby over extended drilling, the effects of a given thread cutting fluid on cutting edge wear and cutting forces are measured. Such a test can serve as a useful approach for evaluating the performance capabilities of cutting fluids used for P110 and L80 grade pipe connections. The utility and application of this method can be seen in a recent test study conducted using two commercially available fluids (designated MB 365 and AE 208) along with Quaker’s high performance thread cutting fluid, Quakercool ® 750 TP. In this test, each fluid was used at eight per cent concentration in water of 130ppm hardness. Machining for each fluid involved drilling, in succession, 143 holes in AISI 4140 steel, using a titanium nitride coated high speed cobalt drill. The axial cutting forces were measured over the 143 holes and were utilised for assessing fluid performance. In addition, measurement of flank wear on the drill cutting edge was made following machining and also provided additional measure of performance for the thread cutting fluids. The machining conditions used are detailed in Figure 1.

Introduction With its wide range of metalworking fluids and complementary fluid solutions, Quaker Chemical Corporation (“Quaker”) offers a unique “Front to Back” product portfolio to the tube and pipe industry. An important component of this offering is pipe threading fluids. Quaker has focused considerable research effort on gaining a better understanding of the mechanisms of lubrication and wear occurring in the thread cutting process, and to define the physical and chemical properties of the metalworking fluid required to obtain the highest level of effectiveness with regard to tool life, energy consumption and finished part quality. A combination of chemistry, process knowledge and extensive in-house machining capabilities enables the study of the real-life effects of cutting fluid properties in the machining of high strength steel alloys. Prior to the recent global drop in crude oil prices, the demand for OCTG pipe continued to increase due to the need for deeper wells and the rising production of shale oil in the United States. Drilling pipe is manufactured from a very high quality alloy, while the couplings that link pipe sections together needed to be produced from high quality, high strength steels. The cutting of deep course threads, necessary for enabling fast, clean coupling of pipes and fittings, can be very demanding on the cutting tools used. To ensure that the highest possible thread quality and tool life are obtained, highly engineered, wear-resistant and often expensive cutting insert materials are used. For this reason, it is important to have an optimised thread cutting process in order to gain the maximum number of parts per tool (tool life), while maintaining acceptable thread quality and productivity. Along with other process factors such as cutting speeds and chip loads, the metalworking fluid utilised can have a dramatic influence on tool life and the overall optimisation of the cutting process.

Machining Conditions

Machine

Bridgeport V2XT

Workpiece

AISI 4140 Steel C:.38-.43, Mn: .75-1.0, Cr: .98, P: .035 max., S: .04 max, Si: 0.25

Drilling

Tool Gehring M35 (HSC) TiN Coated GT 100 Point 130 Type A Drill 6.35mm diameter (0.25" dia.) DIN 338 R-GT1, Parabolic Flute

Hole Depth 1.0" through hole Speed 770 RPM 50.4 SFM Feed 2.5 IPM .0032 ipr

Fluid effects on lubrication and wear

In a pipe thread cutting operation, wear of the cutting insert is a significant factor influencing the quality of the thread cutting

Figure 1

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N ovember 2015