Tough lathes put teeth in oil-field equipment shop

Cougar Tool Inc. manufacturing manager Gary Spencer says some innovative lathes opened his eyes “way back when” to the true potential of what can be done on a CNC machine designed for manual-operation lovers. As a result, 14 of Mag’s VDF DUS lathes today play a lead role in the company’s shops, where they are used to manufacture Cougar’s line of specialized downhole tools, as well as refurbish rented tools and produce prototype designs.

Boring holes to 32 in. (813 mm) depth, profiling internally and externally, or cutting/re-cutting threads, the conversationally programmed machines are critical in meeting Cougar’s requirements for speed and precision in producing short runs of heavy, large parts.

“We compete with the best in every corner of the globe from our 100,000-sq-ft Edmonton facility, so the cost-efficient manufacture of turned parts is a core competency,” Spencer said. “Our shop is also key to our R&D capability, and the ability to add one-off R&D parts into our work flow, with programming by the operator on the floor, has been a big plus for us.”

Based in Edmonton, AB, Cougar Tool is a family-owned, global business with facilities in Canada, the US, Iraq, Saudi Arabia, Dubai and Abu Dhabi. Most manufacturing takes place at the ISO-certified Edmonton facility. All of the company’s machinists are apprenticed and go through a program at NAIT (Northern Alberta Institute of Technology) to become journeymen.

Cougar product lines include single and double-acting drilling jars, shock tools, Mech-Thrusters, mud motors, drill bit protection devices, stabilizers/reamers, and a range of support tools. About 80% of the company’s approximately $50 million in annual sales is derived from rental business, so the shop is constantly refurbishing worn and damaged tools to ensure availability. “We are also developing new lines all the time, always looking for new points of entry into the market,” Spencer added.

The downhole tool business is all about cylindrical, turned parts, he emphasized. “We make the whole tool when it comes to hydraulically or mechanically acting drilling jars and shock tools, which consist of about 15 external and 10 internal parts, all screwed or fitted together to make a functioning tool,” Spencer explained.

Drilling jars ‘jar’ stuck drilling tools to free them up, while shock tools and Mech-Thrusters protect drill strings and bits from transient shock loads, ensuring optimum weight-on-bit, penetration and bit life. These tools commonly operate in deep, hot wells, and are subjected to high torques and corrosive environments. As a result, the company is a heavy user of high-carbon steels, such as 4330 VMod and 4145, heat treated and stress relieved.

Regarding manufacturing tolerances for turned parts, Spencer understates somewhat when he says the company’s downhole drilling tools “are not Rolls-Royce engines.” Cougar’s processes are quite stringent, utilizing computer-aided design, finite element analysis and CAM. Sliding and sealing interfaces require tolerances to 0.001 in. (0.025 mm), often followed by honing and chrome finishing of some bore surfaces.

Lathes are backbone
of manufacturing

“We put the biggest pieces of steel into our VDF DUS machines that we can – often 72-in. (1,829-mm) long and 10-12 in. (254-304 mm) in diameter,” said Cougar production manager Dave Hemmerling.

“We standardized on these machines because the Siemens control is easy to use, the machines hold excellent accuracy over long cuts, they are built for heavy use, and it’s easy to cut/re-cut taper or straight threads on them. Just about every part we machine has a thread at one end or both, and at least 50% are taper threads. The Siemens control makes it easy to cut new – and re-cut old – threads. The programming is fast, and the spindle rpm can be changed in cycle to control vibration.

“Our tooling is relatively basic, involving no turret and no probing capability. We do a lot of deep boring to produce the long housings required for drilling jars.” Parts are chucked, utilizing a tailstock and steady rest for support, if needed.

To take some of the heavyweight work off its 12 VDF 560 DUS machines, Cougar moved up to a VDF 800 DUS in July 2008. The 560’s handle part lengths of 40-315 in. (1,000-8,000 mm) and virtually any weight, with chuck capacity of 11 in. (280 mm), swing over the bed of 22.4 in. (570 mm) and a spindle motor rated 33 hp (25 kW).

Cougar’s VDF 800 DUS machine, by contrast, takes part weights up to 8,816 lb (4 metric tonnes), and lengths to 110 in. (2,794 mm), with an 18-in. (457-mm) chuck and swing over the bed of 32 in. (820 mm). Its 62-hp (46-kW) spindle motor provides speeds of 6-1,600 rpm through a two-speed gear box. Z-axis feed force is 2,800 lb (12.5 kN).

Designed for constant duty, VDF DUS lathes have the transmission mounted behind the headstock to eliminate thermal effects caused by the gearing, with a backlash-free overload coupling to protect the gearbox.

The VDF 800 DUS machine’s A-11 spindle is supported with a thermally optimized arrangement of lifetime-lubricated bearings. The Meehanite cast iron bed retains its core sand to enhance vibration damping, while hardened double-V guideways distribute high axial cutting forces and prevent skewing. Larger models of the machine handle part lengths up to 787 in. (20,000 mm).

Although Cougar relies heavily on conversational programming through the CNC, the VDF DUS machine is true to its heritage as an ‘operator’s machine’ for one-off parts, and features a patented, ergonomic operator panel and handwheels.

“Standardization on these machines has been very helpful, allowing us to transfer part programs from one facility to another over our Predator network,” Hemmerling added.

“All our drawings are generated in our CAD/CAM system. The majority of our programs are already produced and stored in our DNC system, but we can produce part programs on the lathes by programming off our drawings. All programs made by the machinists are double checked by the shop foreman before running. By repeating this process, the machinists get trained, and only proven programs go to the DNC system for storage.

“Manual mode is used quite often, too, for simple operations, such as facing, turning steady pads and test cuts for measuring tooling. This feature makes the machine more versatile, and simple operations are completed quickly,” said Hemmerling.

“We work these machines hard, and they have proven themselves oil-field tough, with excellent longevity, backed by excellent service here in Canada,” Spencer concluded. “We recently sold our first VDF DUS machine on the used market after years of double-shift work. The bedways were still in great shape and we received about 30% of the machine’s original price.”

MRO

For more information on Cougar Tool, visit www.cougartool.com. Mag is a machine tool and systems company serving the durable goods industry worldwide with manufacturing solutions for metal cutting and composites applications. Its equipment and technologies include turning, milling, hobbing, grinding, honing, systems integration, composites processing, maintenance, automation and software, tooling and fluids, and core components. For more information, visit: www.mag-ias.com.