Tech Front: Oil Field Threading Demand on the Rise
Demand for oil field equipment technology for oil and gas industry applications like pipe and casing threading grew by 33% in the US in 2012 according to estimates cited by EMAG LLC (Farmington Hills, MI and Leipzig, Germany). Production in the Gulf of Mexico is projected to rise from 1.3 million to 1.7 million bbl/day during the next decade, and growth in global oil reserves will continue at a high level globally in countries like Russia, Brazil and Vietnam, where capital investment today is measured in the billions of dollars.
EMAG Leipzig Maschinenfabrik specializes in the sophisticated turning equipment required to meet the demand for machining oil field delivery pipes and casings. "We are talking about a gigantic production output," said Frank Schiffler of EMAG Leipzig. "One steel mill produces up to 2 million metric tons of pipes per annum. Component quality is paramount for these because the pipe threads have to be totally leakproof and must carry the enormous total weight of pipe and oil during the delivery."
EMAG’s USC series of turning machines features sizes for complete machining of different sizes of pipes with external and internal threads to API and GOST standards, as well as cutting all proprietary threads of the larger oil field technology producers. Depending on the machine used, the max pipe diameter that can be threaded ranges from 2 to 20
" (60–508 mm). "All workholding and centering equipment are configured to suit individual requirements," said Schiffler. "The same applies to all automation components. As a result, the customer has a fast production solution that automatically loads and unloads the components in 12–20 seconds, depending on pipe size and thread type." The three-part threading process from facing to chamfering and finally thread cutting is said to increase output substantially compared with traditional turning machines.
"There are two important factors that must be taken into account when machining threads on delivery pipes and casings: processing quality and process integrity," said Schiffler. "The whole process benefits from important EMAG design details: The machine base is made with Mineralit, a polymer concrete, and guaranteeing the stability and the vibration-resistance of all machine components. The main drive forms an integral part of the spindle unit. Its frequency-controlled, maintenance-free AC asynchronous motor provides a high torque rate, which allows for the simultaneous machining of both ends of the pipe.
The pipes are securely clamped in front and rear chucks that, depending on workpiece requirements, can be actuated pneumatically, hydraulically or mechanically. The pipe ends are stabilized during the machining process by the insertion of vibration-reducing mandrels, resulting in the highest possible precision.
When faced with high production rates, fast machining processes and expensive pipe blanks, machine downtime is particularly costly for the manufacturer. Process integrity of these machines is essential and a key development area for EMAG. "We design complete solutions for our customers," said Schiffler. "In addition, we integrate, for instance, measuring stations, crack detection equipment, embossing and plating units and, of course, a monitoring system that covers all components in the production system. In the end, what we supply is a production system that is designed to guarantee the greatest possible degree of process integrity," said Schiffler. EMAG also supports its equipment globally with service specialists so that both user and maintenance staffs are fully trained. "A 24/7/365-day telephone service is available, ensuring that machine downtimes are reduced to an absolute minimum," said Schiffler. ME
For more information from EMAG, go to www.emag.com, or phone 248-447-7440.
Tooling for Aerospace
With the dramatic increase in the use of composites in the form of carbon fiber reinforced polymers (CFRP) in the aerospace industry as well as for automotive and defense industry applications, holemaking is challenging cutting tool development and process technology. According to Sandvik Coromant (Fair Lawn, NJ), drilling the CFRP material involves different material-specific issues like delamination, splintering and dust of the CFRP, and machinability issues like chip formation and evacuation that aluminum and titanium present in CFRP/metal stacked components. The following discussion is an edited version of a report by Sandvik Coromant on the CFRP drilling process and cutting tools required for quality holemaking.
Production planning begins with the usual assessment of drilling requirements, including the number of holes, the hole size, depth and quality, the manufacturing equipment or machine type available, stability of the setup, and the mix of CFRP and stacked metal properties. Machines are normally automated, power-fed or hand-held in the form of CNC machine, robot, portable power-feed machine or an operator’s hand tool. Machine technology available and the demands of the operation and experience of the operator can vary to the extent that these have to be compensated for by tool selection.
The amount of machining needed on CFRP and CFRP/metal stacked components is typically less than that required for conventional metal components, but due to the material properties, holemaking can be more demanding to machine to critical specifications. CFRP machining involves fracturing the fiber part of the material. CFRP is a poor heat conductor and with no chips being formed, the heat generated during machining composites is a risk to the resin part of composites at elevated temperatures.
CFRP materials are abrasive when machined because of the fiber hardness. When bonded in the weaker resins, there are tendencies for fibers to be pulled out, for elastic mismatch to occur, and also for interlayer fracture to take place. This makes hole entry, exit, and walls of holes prone to damage that puts them outside quality limits. Also, when stacked with a metal such as titanium or aluminum, the tool has to have the right capability of penetration. There are no chips and conventional surface finish is usually not an indicator of hole quality. Hole quality is normally based on the degree of any separation of the bottom layer in the material (delamination) as well as any residual, frayed fibers in the hole (splintering). These are not directly detectable, and hole quality often deteriorates before there are signs that the tool is worn out.
The principal tool solutions today are based on diamond-coated cemented carbide drills and diamond-veined drills. Polycrystalline diamond (PCD) is the hardest of tool materials and therefore the most wear-resistant and well-suited for machining CFRPs and stacked materials. A drill with carbide as the core tool material with a PCD edge is an ideal tool for composite holemaking today.
The carbide tool can be strengthened through its geometry as well as through the drill shank, in this way providing the best cutting action while maximizing clearance and material evacuation. Drills based on carbide are especially suitable for many unstable operations, when hand tools are used and thrust may be uneven from operators and when there are clearance variations between drill and drill bushing. They are also ideal for many power-fed operations and in machines involving single passes in stacked materials. The best result is achieved when the two tool materials are combined in a tool making use of the fact that carbide and PCD have different advantages and limitations as tool materials. Carbide is very strong but wears quickly in abrasive materials; PCD is very wear-resistant but brittle.
The modern standard, semi-standard and engineered drills with a diamond-coating are available in different geometries and grades for different material and machining conditions. These drills have also been developed to drill holes optimally in CFRPs that vary from fiber-rich to resin-rich as well as being all around alternatives and suited for stacked materials. Two standard drills offer a choice to optimize operations in machines and power-feed setups. One drill is best for fiber-rich materials with extra capability to minimize tendencies for fraying in holes. It has spurs at the drill periphery to cut fibers, to avoid splintering and is also good for CFRP/aluminum stacked materials. Another standard drill specializes in drilling resin-rich CFRPs. It has a double-angled cutting geometry which gives it soft entry and exit capability and so minimizes delamination. Further dedication is available through tailor-made options. A diamond-like coating is an alternative on carbide drills to make available a versatile, low-cost tool which is regrindable.
A more recent drill type for CFRPs and stacked materials is based on vein technology. This integrates the PCD edge in the carbide drill body. It is an advanced high-tech method, based on a patented process developed during the past couple of decades and makes the best use of the hard, wear-resistant PCD edge in a tougher carbide shank. The PCD edge is made part of the drill at a sufficient distance away from the drill tip to allow the application of a high-strength braze joint. The tool geometry is ground, leaving the edge shielded to a variable extent by the carbide part of the drill.
Vein technology allows for a large variation in tool geometry that was impossible to achieve with the conventional PCD-bit process. The PCD-vein drill is typically engineered for a solution which is part of an automated setup for optimizing performance and hole-quality consistency when drilling a CFRP. Part of its unique edge may include strengthened tool corners for higher cutting speeds, combined with the ability to maintain tight entry and exit limits.
The PCD-vein drill can also be engineered for CFRP stacked with metals. It can then be provided with micro-grinds placed to cope with concentrated areas of high stress. This provides the drill with even more ability to remain sharp and exact throughout a long tool life. The edge of the drill cuts CFRP fibers at low thrust, resulting in minimal fiber breakout, delamination and burrs when exiting the stacked metal. ME
For more information from Sandvik Coromant, go to www.sandvik.coromant.com/us, or phone 201-794-5000.
Smooths HSM Motion
Hurco’s VMXHSi series high-speed machining centers are equipped with UltiMotion motion control system that uses complex software algorithms for motion planning instead of conventional hardware. The software is more efficient in how it processes motion so there is less chatter, less vibration, and less machine jerk, which results in better surface finish and reduces cycle time by as much as 35%. The software-based motion control system has rapid cornering capabilities, allowing it to travel through blended corners at high speed with negligible deviation.
With UltiMotion, the software evaluates each section of the motion profile and shifts the look-ahead to the maximum number of blocks to optimize maneuvers. For example, with drilling and tapping, instead of the jolting down/up/stop motion of conventional motion controls systems that use hardware, UltiMotion keeps the motion smooth and is able to use a spherical motion to move to the next set of holes. The Hurco integrated control has the memory and processing power to handle the advanced toolpaths generated by CAM systems. The control is optimized for HSM with a 64 GB solid-state drive, 2 GB of memory, a 2-GHz Dual Core Intel Processor, processing speed to 2277 bps and Dynamic Variable Look-Ahead capable of up to 10,000 blocks. ME
For more information from Hurco Companies Inc., go to www.hurco.com, or phone 800-634-2416.
This article was first published in the March 2013 edition of Manufacturing Engineering magazne. Click here for PDF.