A Whole Lot of Shakin's Not Goin' On
Tool dampening has evolved to become a means of boosting productivity in the oil & gas industry
By Brent Godfrey
Industry and Applications Specialist
Fair Lawn, NJ
Machined components used in the oil & gas industry are unique, notorious for their width and depth. These components tend to have tucked-away features that require long, slender tools just to reach, meaning large length-to-diameter ratios that make the tool susceptible to vibration problems. What’s more, because of the deep-sea or deep-mine environments to which oil and gas components are often exposed, they are increasingly made of difficult-to-machine materials.
Going back 50 years, tool chatter in these types of components led to compromised machining performance, component-quality issues, excessive noise levels, poor tool life and even scrapped components. In many cases, operations were impossible to perform, and therefore presented potential for improvement—a new means waiting to be recognized and developed.
What we today know as modern antivibration tooling originated in a nail-making factory in Trondheim, Norway. The company named Teeness—now a part of Sandvik Coromant—started manufacturing during the nineteenth century, and after many years of making nails and associated products dramatically changed direction in 1967.
A young engineer presented a prototype of a damped boring bar, a result of the work he did in earning his university diploma. His idea sparked the imagination of engineers at Teeness who, well aware of vibration problems (particularly in internal turning), set about trying to put the idea into practice.
A chain of innovations followed, in collaboration with Sandvik Coromant, to establish the unique Silent Tools program. Ever since, Silent Tools has been the trademark for toolholders designed to minimize vibration with a dampening system inside the tool body. The majority of Silent Tools customers use them for long overhangs and poor accessibility. However, great productivity increases and surface quality improvements are to be gained, even for overhangs as short as 4 × D.
Dampened Tools Today
Vibrations can occur from a number of sources during metalcutting operations, and there are various ways of reducing them. Vibration is often the limiting parameter in gaining high output in the machine; e.g., turn down speed, feed and depth of cut. By using Silent Tools you can increase the cutting parameters and at the same time get a more secure and vibration-free process with close tolerances, good surface and much higher metal removal rate, which provides a lower cost per component.
Today`s Silent Tools have solutions for most machine types, including lathes, machining centers (boring mills), and multitasking machines when long tool-overhangs are needed. For internal turning applications, a range of boring bars in various lengths, with exchangeable heads, have been specially developed for overhangs ranging from 7 to 14 × D, where ordinary tooling is prone to fail. In milling and boring applications, tool assemblies that incorporate a Silent Tool adapter are part of solutions where the milling cutter or boring head can perform to higher cutting data, provide better results and provide longer, more secure tool life. In milling, for smaller diameters, the dampening system is built directly into the shank of the end mill, providing excellent accessibility for machining hard-to-reach features.
Dampened tools of different sizes and reaches are also becoming an increasingly important part of tooling in multitask and mill-turn machines. Development of dampened tooling, as standard tooling or advanced engineered products, for solving complicated applications in various industries has been ongoing since the start in the ’70s and has also included solutions with machine tool builders.
The energy industry contains some of the most difficult features in some of the most demanding materials. Silent Tools have a long track record in this industry.
There’s often a requirement in oil and gas production for materials to last longer in increasingly extreme environments featuring elevated temperatures or abrasive/corrosive conditions. Oil and gas drilling operations require corrosive resistance. A primary offender is sour oil—a frequently found but corrosive, sulfur-rich crude oil. Even seawater can be a threat over time in deepwater drilling operations, both in its constant pressure and wave action and its briny corrosiveness.
Corrosion-resistant, superalloy materials are a boon to the industry in this sense, as they perform much better and last much longer. Their physical properties allow them to withstand pressures not just when drilling straight down, but also drilling horizontally or branching off at angles from the initial vertical hole to hit intermittent gas pockets. And these types of horizontal holes expose materials to ever-increasing vertical pressures from the sea bed or bedrock pushing down from above. Superalloys are the only way to ensure safe removal of mined material without collapse or other catastrophic failure. But superalloys’ notoriety in machining difficulty precedes them. Silent Tools’ removal of chatter and vibration assists in keeping tolerances precise and scraps to a minimum, even in difficult materials.
Now, the Silent Tools program for internal turning includes standard tools with diameters up to 10" (250 mm), well suited for those large oil & gas industry components. The largest boring bar delivered had a 450-mm diameter, was designed for a 10 × D overhang and weighed almost seven tons. Dampened tools are on the increase for rotating-tool applications, including CoroBore products for rough and finish boring. Quick-change of Silent Tools is being applied increasingly on turning centers. Especially in larger machines, when Coromant Capto C10 couplings are used, the quick-change facility is an advantage when boring bars stick out so far that it is hard for other operations to be carried out with the bar in the turret. The quick-change takes a few minutes; rigging the large boring bar every time would take an average of 40 minutes. Also, automatic tool change can be installed, such as in the case where a robot (which also changes components) changes a 100-mm Silent Tool boring bar with an overhang of 14 × D.
A recent example of a state-of-the-art solution for large dampened boring bars was handled together with the maker of large multitasking machines. The application in question was the internal turning of long titanium components. The bar was engineered and made to have a reach of 13 × D—6.93" (176-mm) diameter with an unsupported reach of 90.55" (2300 mm). The bar also had to have automatic tool change at the front of the bar. Good chip evacuation was required for operational security, and the bar was equipped to deliver an ultra-high-pressure coolant supply (5075 psi or 35 MPa) for a jet at the cutting edge to form chips.
Silent Tools is currently the leading global brand in vibration-dampened tooling. Sandvik Teeness in Norway has made a long journey in the development of the original vibration-dampening idea for machining to today’s position. Since 2008, Sandvik Teeness has been the global competence center for antivibration machining within Sandvik Coromant, with research, concept-development, design of engineered and standard tools and application support.
The innovative, patented system of dampened tooling is seen globally as state-of-the-art technology. Although different when compared to the original concept at the outset, tool-dampening can still be said to be based on the principle of a heavy mass, supported by specially designed rubber springs in a special fluid. It is the result of R&D into the nature of dynamic vibrations, and decades of experience from solving long tool-reach applications. Such efforts have resulted in Sandvik Coromant Silent Tools moving dampened tooling forward from being just a means to solve a problem to a means of boosting productivity in the oil & gas industry.
This article is a digital exclusive feature for the 2013 edition of the Energy Manufacturing Yearbook. Click here for PDF.