scholarly journals Observation of the a-C:H run-in behaviour for dry forming applications of aluminium

2018 ◽  
Vol 190 ◽  
pp. 14001
Author(s):  
Tim Abraham ◽  
Günter Bräuer ◽  
Felix Kretz ◽  
Peter Groche
Keyword(s):  
Tribological Properties ◽  
Forming Process ◽  
Premature Failure ◽  
Dry Forming ◽  
Coating Roughness ◽  
Tool Performance ◽  
Coated Tool ◽  
Tool Coatings ◽  
Strip Drawing ◽  
Amorphous Hydrogenated Carbon

Amorphous hydrogenated carbon coatings (a-C:H) are well known for their exceptional tribological properties and are established as tool coatings for numerous forming applications. However, utilized in dry forming processes of aluminium a premature failure of an a-C:H coated tool often occurs due to strong adhesive wear. In this paper the run-in behaviour of a-C:H is investigated and as a possible reason for the premature tool failure evaluated. Therefore, oscillating ball-on-disc tribometer tests and strip drawing tests, for a more realistic emulation of real forming processes, will be conducted. According to these tests, the run-in period of a-C:H coatings is characterized by a high friction value and adhesion tendency and thus is decisive for the tool performance. Based on a subsequent analysis of the coating wear, the predominating wear mechanisms during the run-in period are discussed. The intrinsic nanomater-scale a-C:H roughness is identified as a crucial factor determining the tribological properties of the run-in behaviour. By reducing the coating roughness prior to the forming process, the adhesion tendency and friction value can be reduced significantly. The results demonstrate the tribological performance of pre-treated a-C:H coatings for dry sheet metal forming of aluminium EN AW-5083.

Physicochemical Analysis of Machine Hammer Peened Surface Structures for Deep Drawing: Determination of the Work of Adhesion and Spreading Pressure of Lubrication to Surface Structure

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
D. Trauth ◽  
F. Klocke ◽  
M. Terhorst ◽  
P. Mattfeld
Keyword(s):  
Deep Drawing ◽  
Research Work ◽  
Physicochemical Analysis ◽  
Point Of View ◽  
Friction Reduction ◽  
Surface Structures ◽  
Work Of Adhesion ◽  
Forming Process ◽  
Spreading Pressure ◽  
Strip Drawing

Increasing demands concerning the performance of tribological systems for metal forming due to ecological restrictions or increased process loads demand the development of innovative tribological solutions. In preliminary works, it could be shown that surface structures on deep drawing tools manufactured by the incremental forming process machine hammer peening (MHP) have the potential to reduce friction. The friction reduction can be observed in strip drawing when comparing different surface structures against a state-of-the-art reference. A subsequently conducted wear analysis showed an adhesive wear on the structures. This leads to the conclusion that the lubricant film breaks due to increased contact pressures. In order to optimize the wetting of the lubricant and to avoid film break-ups, the molecular interactions in terms of the work of adhesion and spreading pressure between lubricant and MHP tool surfaces are investigated from a physicochemical point of view in this research work. The investigation approach is based on the use of the drop shape analysis.

Investigation Performance of AlCrN_Based Coated Broaching Tool in Broaching of Gas Turbine Material X12CrMoWVNbN1011

2014 ◽  
Vol 1017 ◽  
pp. 361-366
Author(s):  
Zhi Qiang Liu ◽  
Ming Chen ◽  
Cheng Dong Wang ◽  
Qing Long An ◽  
Chun Xin Ge ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Cutting Temperature ◽  
High Hardness ◽  
Heavy Duty ◽  
Machining Processes ◽  
Tool Performance ◽  
Tool Coating ◽  
Tool Edge ◽  
Coated Tool ◽  
Heavy Duty Gas Turbine

Pull broaching fir-tree slots of gas turbine is one of the most productive precision machining processes when machining simple surfaces or complex contours. Tool edge chipping and wear of uncoated broaching tool become a serious problem in the currently broaching of gas turbine discs. Therefore, tool coating can be used to improve the wear resistance of broaching tool. AlCrN-based coatings have been developed as a high hardness coating for cutters due to excellent resistance to oxidation which is higher than that of conventional coatings. However, few researches had paid attention to investigating AlCrN-based coating tool performance in the broaching process, especially in machining of heat-resisting material of heavy-duty gas turbine discs. In this paper, experiments of broaching heat-resisting material X12CrMoWVNbN1011 were investigated. In order to obtain suitable and ideal broaching tool, the AlCrN coated or uncoated T15 broaching tools were also compared. Cutting force, cutting temperature, and tool wear were measured in the broaching experiments. Results showed that: (1) with a little changed cutting load and tool edge radius, AlCrN-based coating was found to have more significantly influence in improving the tool life as comparing to uncoated tool. The similar wear forms was observed by comparing coated tool and uncoated tool. The conclusions of the study can help to improve heavy-duty gas turbine disc broaching process and broaching tool. (2) Owing to AlCrN coating’s unique combination of heat resistance and hardness, broaching tool could reach higher cutting performance levels. AlCrN coated tool compared with uncoated tool have much better performance in term of cutting strains or cutting temperature.

Tribological Behavior of Different Tool Steels and Surface Properties under Hot Stamping Conditions

2018 ◽  
Vol 767 ◽  
pp. 212-219 ◽  
Author(s):  
Patrik Schwingenschlögl ◽  
Jennifer Tenner ◽  
Marion Merklein
Keyword(s):  
Tribological Behavior ◽  
Hot Stamping ◽  
Manganese Steel ◽  
Pvd Coatings ◽  
Tool Steels ◽  
Forming Process ◽  
Workpiece Surface ◽  
Part Quality ◽  
Strip Drawing

Hot stamping is a well-established technology for producing safety relevant components. The use of hot stamped components in modern car bodies offers the possibility of improving the crash performance while reducing the fuel consumption by using thinner sheet thicknesses. Hot stamped components are mainly produced out of the boron-manganese-steel 22MnB5. To avoid oxide scale formation during the heat treatment and the subsequent forming process AlSi coatings are applied on the workpiece surface. Due to the high forming temperatures, the use of lubricants is not suitable for the hot stamping process. Consequently, high friction and severe wear occur during the forming process and affect the resulting quality of hot stamped parts as well as the tool wear. In order to improve the part quality and increase the efficiency of industrial hot stamping applications, measures for reducing the tribological load during the forming have to be found. Within this study, the tool-sided impact on the tribological conditions is analyzed. Three different hot working tool steels were characterized based on strip drawing experiments under hot stamping conditions. Based on these investigations the tool steel characteristics hardness, thermal conductivity as well as chemical composition have been identified as possible influencing factors on the tribological conditions. Furthermore, the influence of the surface finish on the tribological performance was investigated by analyzing tool surfaces with three different roughness values and two PVD coatings. The experiments indicate a significant reduction of friction and wear due to application of PVD coatings while the tool roughness did not affect the tribological behavior under hot stamping conditions.

Wear Analysis of Tool Surfaces Structured by Machine Hammer Peening for Foil-Free Forming of Stainless Steel

2014 ◽  
Vol 1018 ◽  
pp. 317-324 ◽  
Author(s):  
Fritz Klocke ◽  
Daniel Trauth ◽  
Michael Terhorst ◽  
Patrick Mattfeld
Keyword(s):  
Stainless Steel ◽  
Wear Resistance ◽  
Contact Area ◽  
Deep Drawing ◽  
Surface Structures ◽  
Main Concern ◽  
Forming Process ◽  
Machine Hammer Peening ◽  
Strip Drawing ◽  
Hammer Peening

Increasing demands concerning the performance of tribological systems for metal forming due to ecological restrictions or technologically increased process loads require the development of innovative tribological systems, especially in forming of stainless steel. It could be shown in preliminary work that surface structures on deep drawing tools manufactured by the incremental forming process machine hammer peening have the potential to reduce friction in strip drawing test by about 58 % in comparison with a ground reference surface. This is explained by the effect of lubricant pockets and a reduced true contact area in the interacting zone. However, due to the effect of a reduced contact area, the wear resistance of these surface structures is of main concern for the effectiveness of their application in deep drawing. Therefore, in this work strip drawing tests are performed over a minimum of 500 repetitions for the evaluation of friction characteristics. Additionally, the coating of the surface structures is investigated to improve the wear resistance of the structures.

scholarly journals Deposition of Nanoscopically Smooth DLC Tool Coatings for Dry Forming of Aluminum Sheets

JOM ◽  
2020 ◽  
Vol 72 (7) ◽  
pp. 2504-2510
Author(s):  
Tim Abraham ◽  
Ingmar Bialuch ◽  
Günter Bräuer ◽  
Felix Flegler ◽  
Peter Groche
Keyword(s):  
Aluminum Sheets ◽  
Dry Forming ◽  
Tool Coatings

Numerical Investigation of Fiber Flocculation in the Air Flow of an Asymmetric Diffuser

2014 ◽  
Author(s):  
Jelena Andric ◽  
Stefan B. Lindström ◽  
Srdjan Sasic ◽  
Håkan Nilsson
Keyword(s):  
Fluid Flow ◽  
Short Range ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Navier Stokes ◽  
Forming Process ◽  
Navier Stokes Equations ◽  
Flow Fluctuations ◽  
Dry Forming ◽  
Particle Level

A particle-level rigid fiber model is used to study flocculation in an asymmetric planar diffuser with a turbulent Newtonian fluid flow, resembling one stage in dry-forming process of pulp mats. The fibers are modeled as chains of rigid cylindrical segments. The equations of motion incorporate hydrodynamic forces and torques from the interaction with the fluid, and the fiber inertia is taken into account. The flow is governed by the Reynolds-averaged Navier–Stokes equations with the standard k–ω turbulence model. A one-way coupling between the fibers and the flow is considered. A stochastic model is employed for the flow fluctuations to capture the fiber dispersion. The fibers are assumed to interact through short-range attractive forces, causing them to interlock as the fiber-fiber contacts occur during the flow. It is found that the formation of fiber flocs is driven by both the turbulence-induced dispersion and the gradient of the averaged flow field.

scholarly journals TRIBOLOGY PROPERTIES EVALUATION FOR FRICTION PAIR Zn COATED STEEL –TiCN MP COATED/UNCOATED TOOL STEEL

2019 ◽  
Vol 25 (4) ◽  
pp. 208
Author(s):  
Emil Evin ◽  
Miroslav Tomáš
Keyword(s):  
Friction Coefficient ◽  
Tool Steel ◽  
Friction Pair ◽  
High Strength ◽  
Analytical Models ◽  
Drawing Test ◽  
Coated Tool ◽  
Metal Stamping ◽  
Strip Drawing ◽  
Low Alloyed Steel

<p class="AMSmaintext1"><span lang="EN-GB">When the sheet metal stamping processes are simulated, different values of the friction coefficient need to be defined in different regions, considering the nature of the deformation process. Thus, the regression and analytical models to determine the friction coefficient under the blankholder and on the die drawing edge by the strip drawing test are presented in the article. These models were verified by experimental strip drawing test under the same contact conditions. Zn coated high strength low alloyed steel sheet H220PD+Z100 was used at experiments and friction tests were done against the tool steel and TiCN MP coated tool steel. The results indicate, that values of friction coefficients evaluated by linear regression are lower than evaluated from analytical models. The positive effect of coating TiCN MP when applied on the contact surfaces was found, thus, decreases the friction coefficient and the drawing force scattering during the strip drawing test.</span></p>

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