Improve Tool Performance Research Articles

Effectiveness of deep cryogenic treatment in improving mechanical and wear properties of cold work tool steels

In recent years, deep cryogenic treatment (DCT) is getting increased attention in many tooling applications as a mean to improve tool performance. However, contradictory results are reported indicating improved as well as deteriorated wear resistance. The goal of this work was to investigate effect of DCT on wear properties of tool steel and how they change depending on the tool steel type, and hardness and fracture toughness obtained. Results show that steel composition considerably affects the way how cryogenic treatment changes steel properties. For low carbon tool steel toughness properties can be improved for up to 70% at only minor hardness drop, but are quite limited in the case of high-speed steel, while at high carbon content both hardness and toughness are deteriorated. In general, DCT was found to result in reduced abrasive wear resistance except for cases of combined hardness and fracture toughness improvement.

Tools for Assessing the Impacts of Climate Variability and Change on Wildfire Regimes in Forests

Fire is an intrinsic element of many forest ecosystems; it shapes their ecological processes, determines species composition and influences landscape structure. However, wildfires may: have undesirable effects on biodiversity and vegetation coverage; produce carbon emissions to the atmosphere; release smoke affecting human health; and cause loss of lives and property. There have been increasing concerns about the potential impacts of climate variability and change on forest fires. Climate change can alter factors that influence the occurrence of fire ignitions, fuel availability and fuel flammability. This review paper aims to identify tools and methods used for gathering information about the impacts of climate variability and change on forest fires, forest fuels and the probability of fires. Tools to assess the impacts of climate variability and change on forest fires include: remote sensing, dynamic global vegetation and landscape models, integrated fire-vegetation models, fire danger rating systems, empirical models and fire behavior models. This review outlines each tool in terms of its characteristics, spatial and temporal resolution, limitations and applicability of the results. To enhance and improve tool performance, each must be continuously tested in all types of forest ecosystems.

Effect of Tool Pin Thread Forms on Friction Stir Weldability of Different Aluminum Alloys

The primary objective of this study is to investigate parametric effects of pin features on material flow and friction stir weldability of two different aluminum alloys. A series of bead on plate friction stir welds were made on two different aluminum alloys (AA 7050 and AA6061) with cylindrical tool pin having four thread pitches (1.02mm, 1.41mm, 2.12mm & 3.18mm) including smooth/unthreaded pin attached to an unvarying single scrolled shoulder geometry. Welds were performed under a range of process parameters (welding & rotational speed). It was observed that thread forms are obviously beneficial for improving tool performance and reducing in-plane reactions (X & Y forces) forces on tool. Wormhole defects in the weld nugget were eliminated or minimized by employing threaded pins as a consequence of effective material transportation near the weld root. Tool pins having intermediate thread pitches (1.41mm and 2.12mm) perform better than either extreme over the range of attempted parameters. Defects are far more prevalent in 7050 welds than in 6061. In-plane reaction forces on pin are significantly larger in AA7050 welds than in AA 6061 and torque- peak temperature values are of similar order in both welded materials.

Optimizing the composition and properties of nanostructural coatings for cutting tools on the basis of the electron-density functional

Nanostructural coatings for cutting tools are optimized on the basis of the electron-density functional. Means of modifying the coating composition so as to improve tool performance are outlined.

Control of tool performance by means of coatings

If highstrength and lowwear coatings are used in machining structural materials, the performance of cutting tools made from highspeed steel or hard alloys may be significantly improved. However, standard coatings are inadequate when machining special materials (titanium alloys, lowmagnetic steel, high� strength cast iron, etc.) or in complex loading condi� tions (for example, discontinuous cutting, alternating loads). To select the best means of improving tool perfor� mance, we need a large range of options. In particular, it is helpful to have a range of manufacturing technol� ogies for tool materials. Effective technologies may be selected on the basis of the hardening mechanisms in the tool materials. The structure of the cutting system may also be taken into account in regulating the loss of perfor� mance of the tool and the machine tool's elastic sys� tem. The cutting system includes three types of links: a mechanical link between the tool, the blank, and the machine tool; a direct link between the machine tool (the dynamic characteristics), the cutting zone (the processes in this zone), and the cutting tool (its work� ing life); and an inverse link between the tool, the cut� ting zone, and the machine tool. This cutting system may be regarded as consisting of interrelated objects, where the state of each one affects the other objects and the output parameters. In this approach, the tool performance is an integral parameter, corresponding to a set of processes and phenomena characterized by interaction of the objects within the cutting system. Consequently, it is impor� tant to know which processes and phenomena deter� mine the tool performance in ensuring the reliability of the cutting system. They are shown in general form in Fig. 1. primarily the processes at the frictional surfaces; the mechanisms of chip formation and tool wear and fail� ure; and the static and dynamic stability of the equip� ment. The block diagram in Fig. 2 illustrates output� parameter control of the cutting system by means of the input parameters. Most of the available means of control involve hardening of the cutting tool. We now consider individual means of improving tool performance by modification of the tool mate� rial—for example, by preparing the surface for coating application. Improvement in tool performance involves selecting the coating structure, the coating material, its method of application, and its treatment so as to eliminate defects. We will confine our analysis to three stages: selec� tion of the treatment of the basic tool; selection of the material, structure, and method of application of the coating; and selection of the coating treatment. Treatment of the tool base must be regarded as a means of improving the initial state of the tool mate�

Multicomponent nitride coatings for improving tool performance

Multicomponent nitride coatings for improving tool performance

Tool life enhancement in cold forging by locally optimized surfaces

Cold forging tools are exposed to extremely high loads. Depending on the most critical combination of the dominant factors characterizing the load which can be different even within the same tool, different damaging mechanisms will be initiated at least one of which is finally limiting tool life by either wear or fatigue. Since these failure mechanisms are mostly initiated on the tool surface, the adjustment of surface properties to the local effective load combination might improve tool performance and increase tool life. In this paper, three different methods are being investigated: hard roller burnishing, surface heat treatment by laser and laser surface texturing. The determination of the tool load is precondition for the selection of the appropriate surface treatment method. Thus, to find out which of the three methods can be used for tool surfaces in selected case studies, process simulation by finite-element-analysis (FEA) becomes mandatory. Accordingly, FEA is used to select the optimum surface treatment, which is then applied and tested in industrial applications.

Overview: Bit Technology (December 2006)

Drilling activity has increased in the last couple of years, with wells being drilled deeper and into harder and more-abrasive formations. These drilling environments present serious challenges for drill bits in terms of rate of penetration (ROP) and bit durability. The high drilling-activity level and increased demand led to increased rig rates. To reduce drilling costs, drilling engineers have had to re-evaluate bottomhole-assembly designs, drilling processes, drilling fluids, and applications. Drill bits, although insignificant in terms of price, have huge effects on operational costs. To improve drilling performance, considering the challenges, drill bits must drill faster and last longer. These targets are what drilling engineers have come to expect and what bit companies are delivering to the industry. Several types of drill bits are available for different applications and drilling challenges—polycrystalline-diamond-compact (PDC), impregnated, and roller-cone bits. To reduce drilling costs substantially in the current environment, technology development must expand and permeate into all the different bit types. For PDC bits, new modeling tools and bit designs are being developed on a continuous basis. Bit-behavior analysis, especially the characterization of the different vibration modes, has become a standard in the bit-design process. New PDC cutters with very high abrasion-resistance properties continue to be developed. These cutters stay sharper for longer periods of time, thus improving ROP and durability. Substantial ROP and durability improvements are also being seen with impregnated bits. These improvements resulted from detailed evaluations that focused on the effects of drive tools (rotation speed and power regime), down-hole-pressure environment, and depth of cut on impregnated-bit development and performance. For roller-cone bits, new technologies are improving seal reliability and cutting-structure durability. In addition, new developments in metal-seal-bearing technology have drastically increased the on-bottom drilling time of roller-cone bits, especially in directional wells. Drill-bit companies have accepted the challenges, and they do not plan on slowing down. Bit Technology additional reading available at the SPE eLibrary: www.spe.org SPE 102182 "Coupling of Downhole-Dynamics Recorder Enhances System-Matched Approach to Drill-Bit Design and Application With a Specific Rotary-Steerable System" by S. Barton, SPE, ReedHycalog, et al. SPE 102134 "Vibration Analysis, Model Prediction, and Avoidance: A Case History" by G. Robello Samuel, Halliburton Drilling, Evaluation, and Digital Solutions, et al. SPE 99193 "Real-Time Downhole Torsional Vibration Monitor for Improving Tool Performance and Bit Design" by D.C.-K. Chen, Halliburton Sperry Drilling Services, et al.

Improvement of tool life in cold forging by locally optimized surfaces

Cold forging tools are exposed to extremely high loads. Depending on the most critical combination of the dominant factors characterizing the load which can be different even within the same tool, different damaging mechanisms will be initiated at least one of which is finally limiting tool life by either wear or fatigue. Since these failure mechanisms are mostly initiated on the tool surface the adjustment of surface properties to the local effective load combination might improve tool performance and increase tool life. In this paper, three different methods are being investigated: hard roller burnishing, laser beam treating and surface texturing. The determination of the tool load is a precondition for the selection of the appropriate surface treatment method. Thus, to find out which of the three methods can be used for tool surfaces in selected case studies, process simulation by finite-element-analysis becomes mandatory. Accordingly, FEA is used to select the optimum surface treatment which is then applied and tested in industrial applications.

Study of diffusion across PVD-coated cermet tool/workpiece interface

Further possibilities to improve tool performance might be found in reducing thermochemical wear, taking into account the limitations that exist when it comes to improving the mechanical properties of cutting tools, which is a result of a diffusion process. This reduction is possible if we choose a favourable combination of substrate and PVD (Physical Vapour Deposition) coating where the process of diffusion wear is slowed down as much as possible or is not detrimental to the mechanical properties of the basic tool material. The diffusion-couple method was used to study the thermochemical wear of Ti(C, N)-based cermets coated with TiN (PVD) and TiZrN (PVD) coatings as a diffusion barrier. The result of the diffusion process of the element from the tool and the workpiece through the interface is a change in the composition of the boundary layers of the tool, which increases the possibility of mechanical damage of the cutting edge.

Diffusion across PVD coated cermet tool/workpiece interface

According to the limitations in improving the mechanical properties of cermet cutting tools, further possibilities seem to exist to improve tool performance on the basis of reducing thermo-chemical wear, which is a result of diffusion process. This is possible by choosing a favourable combination between the substratum and PVD coating in which the process of diffusion wear is slowed down as much as possible or is not detrimental for the mechanical properties of the substratum — the basic material of the tool. In this work the diffusion across the coated cermet tools/workpiece interface has been studied. Recently, the diffusion couple method was used to study the thermochemical wear of Ti(C, N)-based cermets coated with TiN (PVD) and TiZrN (PVD) coatings as a diffusion barrier. The result of the diffusion process of the element from the tool and the workpiece through the interface is a change in the composition of the boundary layers of the tool, which increases the possibility of mechanical damage of the cutting edge. In the case of cutting with coated tools, these phenomena occur after a longer time of service in comparison to uncoated ones.

Some effects of cutting edge preparation and geometric modifications when turning INCONEL 718™ at high cutting speeds

The geometry of the cutting edge and its preparation can play a significant role on the insert performance, directly affecting tool life, surface finish and surface integrity. This paper evaluates the performance of some inserts subjected to modifications on the edge geometric form and preparation, when turning, at high cutting speed, a nickel-based alloy, INCONEL 718™, hardened by solution and precipitation (44 HRc). The modifications were applied to different tool materials (Al 2O 3-based, Al 2O 3-based+SiC w and PCBN), in an attempt to improve tool performance when turning this difficult-to-machine alloy at high speed. The evaluation addressed tool wear, surface roughness and temperature at 1.5 mm away from the cutting edge, turning with finishing cutting conditions (500 m/min, cutting speed, 0.1 mm/rev feed rate and 0.35 mm depth of cut). The results show that some modifications caused significant improvements on the insert performance for all the tool materials tested. When using the best modification, tool wear, temperature and surface roughness are lower, residual stress were highly compressive while subsurface hardness did not show any significant modification. Microstructure alterations were also not observed in any surface produced at the cutting condition investigated.

Improved tool performance by heat spreading diamond layer in a multi-layer coating : N.Dedelik, B.Lux. (University of Technology, Vienna, Austria.) Int. J. Refractory Metals Hard Mater., vol 17, no 4, 1999, 275–282

Improved tool performance by heat spreading diamond layer in a multi-layer coating : N.Dedelik, B.Lux. (University of Technology, Vienna, Austria.) Int. J. Refractory Metals Hard Mater., vol 17, no 4, 1999, 275–282

Improved tool performance by application of heat-spreading diamond layers within a multilayer coating?

A thermal model created with the general purpose FEM/ANSYS program allowed the simulation of various multilayer coatings on tools and the corresponding temperature distributions that occurred during metal cutting operations. Heavy duty metal cutting tools could considerably benefit from surface temperature reductions based on a thick heat-spreading diamond underlayer integrated in a multilayer coating on the tool. Thus, a significant increase of cutting speeds, without using cooling fluids, could be achieved. Such developments require a sophisticated tool design with appropriate materials and shapes. Experimental work must confirm the industrial feasibility of such coatings.

The Effect of Hard Coating Properties on Substrate Stresses Under Tribological Loads

A study has been carried out using finite element methods to investigate the influence of hard coatings on substrate stresses under tribological and thermal loads. The study was performed under a uniform distribution of traction (normal and tangential pressure) and temperature. The stresses have been calculated in terms of the ratio of the modulus of elasticity between coating and substrate and the ratio of the coating thickness to the loading strip length at different coefficients of friction and temperatures. The heat transfer problem was solved with regard to a variety of coating properties and the output temperature applied as a thermal load in the structure problem. It is shown that altering the coating modulus of elasticity and coefficient of friction in the presence of a temperature change affects the maximum equivalent stress in the substrate and changes its location. The simulations carried out are discussed in terms of the potential benefits of plasma-based surface coatings and treatments in improving tool performance and the requirements for coating design specifications which will allow design engineers to build surface treatments into new tool designs.

Process Control Challenges and Solutions: TEOS, W, and CU CMP

Various options that afford control of the TEOS, W, and Cu/barrier polishes were explored in the building of multilevel dual inlaid structures. Improved tool performance that enables more sophisticated down pressure control with higher resolution backpressure adjustments was employed for the oxide module to control the interlevel capacitances. Planarity at both the global and local levels at the oxide polish affords a good starting point for successive builds without metal pooling. In W CMP, small and controllable oxide erosion and plug recess was obtained with harder polishing pads. In Cu/barrier CMP, the tight overpolish/underpolish margin was maintained by head control and appropriate endpoint algorithms. A six-level build with tight and low sheet resistances and leakages was demonstrated.

Improved tool performance through metastability in hard coatings

As a basis for modeling fractural mechanics, a new concept of PVD coatings has been developed using an advanced cathodic arc technology. In comparison with the well-known TiN and TiCN, tests in several applications show that this concept can be a new approach to optimize tool lifetime and wear resistance. The specific features of the applied PVD cathodic arc technology allows the deposition of partially metastable coatings. The use of the concept leads to an increased fracture toughness of the coating without the need of reaching hardness values towards that of diamond. The metastability of a part of the grains in the coating allows absorption of the propagation energy of the microcracks and therefore reduces the mechanical wear. With such coatings, solutions for dry machining, for machining stainless steels and other difficult materials can be offered to manufacturers of tools and to end-users. The validity of this ‘metastability’ model will be discussed and must be studied through additional tests measuring the improved fracture toughness of the coatings. This type of PVD metastable coatings in combination with soft top layers like MoS 2 appears to have a promising future.