The world’s energy demand has increased dramatically throughout modern history and today, the energy consumption is about 25 times the amount used 200 years ago. According to recent demographic research, the global population is expected to reach nine billion by 2050, an increase of approximately 25 percent compared to today’s population levels.
The International Energy Agency (IEA) estimates that an unprecedented level of investment — US$1.6 trillion per year on average — will be necessary to meet energy demand through 2035. Large investments in R&D and manufacturing technology are crucial to maintain a long term competitive advantage.
Going Deeper
Exploration and Production companies, known as E&P companies, are driven by continuous demand from international governments and are very much focused on the exploration of deep-water and ultra-deep water reservoirs. These deep and ultra-deep water projects continue to push technology to the edge. Potential investors and multinational energy companies foresee a long term investments in the upstream sector.
Deep waters are among the most important and challenging exploration and production frontiers today, the success of which offers a unique opportunity for adding significantly to the world’s oil reserves. As the exploration expands to deeper waters, they reveal ever more technically and economically challenging environments, with minimal local support infrastructure.
Going deeper into the sea means unprecedented technological challenges. The equipment involved in this hostile environment must be carefully designed using advanced technology and modern engineering.
The Exotic Venture
According to Iscar’s cutting tool engineers, there is a fast growing demand for machining exotic materials, such as stainless steel, duplex and super-duplex, Inconel and titanium.
These exotic and expensive materials are widely utilised in offshore projects due to their mechanical and corrosion resistant properties in most acid-alkaline solutions, and chlorine bearing environments.
However, for metal cutting tool suppliers, these non-standard materials are normally categorised as high temperature resistant alloys. In general terms, medium carbon steel is easier to cut compared to heat resistant alloy; so serious thoughts must be given to the cutting tool technology and cutting conditions applied to the cutting tool for these alloys.
Aiming to optimise cutting conditions and tooling technology, it is important to consider material properties of the workpiece and how they can affect machining. In general terms, there are four main properties to evaluate before choosing the right cutting conditions and tool: tensile strength, hardness, ductility and thermal conductivity.
Dealing With Inconel
In order to keep in line with the tight security and environmental regulations in deep water projects, E&P companies will choose equipment suitable to withstand corrosive environments, which is often accompanied with high pressure and high temperature conditions.
For example, Inconel 718 has become very popular among the companies related to the upstream exploration sector due to its excellent corrosion-resistant properties. The austenitic microstructure of this nickel-based super alloy provides high tensile and yield strength.
However, machining Inconel 718 presents major problems to be addressed which are characterised by the very high temperatures on the cutting edge of the insert, due to the abrasive elements in the material composition (high nickel content of 50 to 55 percent and chrome 17 to 21 percent) resulting in high wear rates, chipping, notching and insert breakage.
Inconel 718’s metallurgical sensitivity to residual stresses and self-hardening during the cutting operation may reduce drastically the expected tool life due to high deformation of the cutting edge, even at low cutting speeds.
Carbide grades are being developed to help counter the challenges posed by this material. One grade for example (IC806 by Iscar), has a coating that combines hard submicron substrate with thin PVD coating and a special post coating treatment, which provides improved tool life and better reliability.
Getting The Shape Right
Machining high temperature alloys is not only a question of choosing the right substrate and coating; it also means choosing the correct cutting tool and geometry.
Take for example, the Inconel cladding machining process, which is normally found in tubing hangers (a component used in the completion of oil and gas production wells).
The relatively thin Inconel layer welded in the inner walls of this component must be machined with carbide cutting tools. This process is normally called rough boring and involves critical machining setup, the necessity for long tool overhang, unsteady material stock to be removed and interrupted cutting.
All these disadvantages frequently lead to chattering and as a consequence, poor carbide tool life. As a result, the Inconel cladding machining operation becomes a bottleneck in the manufacturing process and eventually causes high manufacturing expenses.
The solution is clear for this type of application. A carbide insert specially designed for machining high temperature alloys should be used. One of the most important features of such inserts (SNMG 432-EM-R in this case) is actually the lack of radius. Its 45 deg approaching angle reduces notch wear and allows increasing both cutting speed and feed, yet achieving long-lasting tool life. (See figure 1)
A sharp cutting edge reinforced by a tiny edge preparation is followed by a 13 deg rake angle, allowing a considerable 6 mm depth of cut in these hard-to-cut materials. However, neither the coating nor the geometry of the insert can assure efficiency during machining high temperature alloys, since good chip control is hard to achieve.
Turning Up The Pressure
As mentioned previously, high temperature alloys produce a very high temperature as they are being cut. By effectively removing the heat by applying coolant, the chips become less ductile and therefore easier to break.
Today’s standard CNC machines are normally equipped with traditional coolant systems, which deliver coolant at low pressures. But when machining high temperature alloys, the heat rate generated is beyond the coolant’s boiling point, which turns to vapour and prevents the coolant from reaching the machined cutting zone, causing thermal shock on cutting edges and eventually a negative impact on the insert life.
Able to overcome this thermodynamic barrier, high pressure coolant systems pressurise the coolant and deliver enough liquid volume through small outlet nozzles.
At atmospheric pressure, the coolant flowing through the nozzle can reach a very high velocity. As a result, a considerable force is generated on the chips, lowering temperature and protecting the cutting edge from thermal shock, assuring better carbide insert tool life and part surface finish.
One example of an effective high-pressure coolant tooling system for turning centres, vertical turning lathes and multi-task machines is the JHP system from Iscar. (See figure 2)
By implementing this high-pressure coolant tooling system, smaller chips can also be easily managed — they do not tangle around the workpiece or machine parts, so there is no need to stop the process frequently. This additional feature/advantage enhances the productivity and cut expensive manufacturing costs.
It has been proven that by applying high pressure coolant, both tool life and chip control can be considerably improved when machining stainless and high temperature alloys.
All In One
For machining deep cavities in oil & gas deep drilling parts, it is always recommended to use a reliable tool that guarantees rigidity, tool life, repeatability, accuracy and optimal tool life performance.
In this case, there is one machining technology by Iscar called the ‘all-in-one’ solid EFP carbide cutter. Its design provides an advantage in cavity milling, featuring a combination of the company’s three endmills.
The Feedmill EFP solid carbide endmills utilise a large radius cutting edge configuration that allows for high feed rates up to 0.5 mm/tooth, at 0.3 to 1.0 mm depth of cut. As a result, the cutter delivers a reduction in cycle time, which increases productivity. (See figure 3)
The cutting edge geometry axially directs the cutting loads towards the spindle, providing high stability during cutting and enabling high feed rates, even with long tooling overhang. This feature allows for high metal removal rates when machining pockets and cavities in high temperature alloys.
After penetration into the cavity, the serrated cutting edge features flat peaks, which leave a better surface finish, in comparison to other rougher endmills.
The Road Forward
There is no doubt that the oil and natural gas industries touch our lives in countless ways everyday. They fuel our cars, heat our homes and cook our food. The oil and gas industries provide the world’s 6.9 billion people with 60 percent of their daily energy needs.
The other 40 percent comes from coal, nuclear, hydroelectric power, and ‘renewables’ like wind, solar, tidal power, and biomass products. Global demand for energy continues to grow, especially in developing countries such as China and India. Increasingly, oil and gas are found in challenging areas, such as deep water, and arctic regions of the world.
To meet the fast growing energy demand worldwide, governments are approving more deep water drilling permits. E&P companies foresee a strong growth in offshore activity whereas the oil & gas deep-water exploration and extraction is expected to reach unprecedented rates.
Deepwater surface-to-seabed projects today are typically at depths of 1,500 to 2,000 m and the number of drilled wells at depths of up to 7,000 m is continuously increasing.
At these depths the hostile environment requires special equipment and exotic materials to meet the tough safety regulations which involve enormous investments. In order to meet these challenges, innovative and advanced cutting tools are needed.
