Die Wear Research Articles

The Influence of Temperature in the Wire Drawing Process on the Wear of Drawing Dies.

This paper presents a wear analysis of tungsten carbide drawing dies in the process of steel wire drawing. The finite element method (FEM) analysis showed a significant correlation between drawing die geometry, single reduction size and drawing speed on the rate of drawing die wear. It has been shown that in steel wire drawing at higher drawing speeds, intense heating of the drawing die occurs due to friction at the wire/drawing die interface, leading to premature wear. Tribological tests on the material for the drawing die cores (94%WC+6%Co) confirmed the gradual abrasion of the steel and carbide sample surfaces with the "products" of abrasion sticking to their surfaces. The increase in temperature increases the coefficient of friction, translating into accelerated wear of the drawing dies.

A Practical Analysis of Wire Drawing Operation Effects on the Die and Product Behaviors

This study analyse the effects of different wire drawing experimental tests on the die and product properties. Drawing load, temperature, and wear rate are main die factors, that concerned with the interaction effects of drawing speed variation, wire angle alignment and lubrication. For the product, two factors; tensile strength and hardness are taken. A copper wire is drawing from (4.3 mm) into (3.5 mm) diameter with an area reduction of 1.65, 34% ratio.Six dies were employed in various alignments at three different angles (0°, 1°, and 2°), each has two different drawing speeds of (20 mm/min and 40 mm/min). Results show, the highest drawing load and temperature values in die no.5. The effect of using grease on the die wear rate found that the die wear decreases compared to without. But, when using mixed gradients under the same working conditions, the wear rate changed into coating layer on the die surface. The interaction effect of wire alignment on the product strength showing very small when dealing with low or higher speed, but elongation and ductility are significantly reduced with increasing the angle. The wire produced from die no.1, gives the highest micro hardness.

Study on Flat Die Wear Characteristics in Flat Die Pelletizing with Different Material Ratios Based on DEM-FEM

Wear can occur in flat die pelletizers, often reducing service life. This study explores the issue of die hole wear in the pelletizing process of a standard Total Mixed Ration (TMR) feed. The selected TMR formulation comprises varying proportions of corn, alfalfa hay, and quinoa. A coupled DEM-FEM analysis was used to examine stress–strain conditions in various die hole regions at different material ratios, predict the fatigue life of flat die materials in the pelletizing process, and validate the accuracy of investigating flat die wear through friction wear tests. It was found that the entrance of the die hole experiences the most severe conditions in terms of equivalent stress and elastic strain. The fatigue life is shortest at the entrance, with a maximum equivalent stress of 42.8 MPa, a maximum equivalent elastic strain of 2.5 × 10−3, and a minimum fatigue life stress cycle of 5.0 × 105. In contrast, the equivalent stress and equivalent elastic strain at the middle and upper parts of the die hole are minimal, with an equivalent stress of 4.8 MPa and a minimum equivalent elastic strain of 2.8 × 10−4. Material wear tests revealed that the most severe wear on the flat die specimen occurred when the ratio of corn, alfalfa hay, and quinoa straw was 7:2:1, consistent with the findings from the DEM-FEM coupling method. The pelleting process, arising from the contact between the material and metal, encompasses adhesive wear, abrasive wear, and fatigue wear.

Die wear analysis and pre-forging process optimization of hot forging for automobile flange fork

Die wear analysis and pre-forging process optimization of hot forging for automobile flange fork

The effect of Bias configuration on the properties of AlCrN based thick coatings deposited by Cathodic Arc Evaporation

Die wear in forming high strength steels (HSS) operations causes increased die maintenance cost and scrap rate, being a major obstacle for automation industries to meet upcoming market requirements. Advanced PVD (Cathodic Arc) coatings of high thicknesses (> 15 μm) can be optimum solution from both an economic and technical point of view, compared to the current CVD or duplex surface treatments. Bias voltage becomes a key parameter to minimize residual stresses in the coating during its growth while ensuring optimal mechanical properties of the coating. Different configurations and their relation to coating properties have been studied. Thick coatings (up to 18 μm thickness) with optimal adhesion have been deposited at 7 μm/h under bipolar bias voltage conditions. The as deposited coatings are showing promising performance in real deep drawing production process.

Numerical Simulation of Fine Blanking Die Wear and Die Performance Analysis

In order to study the die wear law of rotary fine blanking helical cylindrical gear, a three-dimensional rigid plastic finite element model of rotary fine blanking helical cylindrical gear is established on the Deform-3D software platform. Based on the Archard wear model, this paper analyzes the die wear in the fine blanking process, obtains the wear distribution of each point on the working surface of the die, determines the maximum wear area, and makes a comparative analysis with the fine blanking die wear of spur gear. Through the single factor variable method, this paper studies the effects of reverse jacking force, blank holder force, blanking speed, punch and die clearance, die fillet radius, and die initial hardness on die wear. The test results show that when the punch reduction is the same, the wear of the female die of fine blanking helical cylindrical gear is greater than that of fine blanking spur cylindrical gear. When the counter jacking force increases from 100 kN to 200 kN, the maximum wear of the die gradually increases from 6.91 × 10–6 mm to 9.38 × 10–6 mm; when the blank holder force increases to 3/4 of the blanking force, the die wear decreases with the increase of blank holder force; it is ideal when the blanking clearance is 0.5% t (0.02 mm). Conclusion. The wear model can accurately predict the relationship between main process parameters and wear in the process of rotary fine blanking, and the measures to reduce die wear are put forward from the aspect of process design.

Die and Punch Wear Reduction in Stamping Process by Lean Six Sigma Approach

This research aimed to reduce die and punch wear and improved the quality of the production process with the application of the Lean Six Sigma methodology. Die and punch had limited capability in cutting material edges in the case study company. The root-cause analysis showed a correlation between the hard coating and the lubricant effect on wear reduction using the design of experiments and DMAIC based on the Six Sigma approach. The results indicated that a combination of AICrN-PVD coating and aloe vera oil provided the most outstanding results in terms of wear reduction. Moreover, it had the potential to minimize the cost of product defects or repairs significantly. These findings showed the effect of the Lean Six-Sigma approach at the die production process, which increased operational efficiency and consistency to enhance business performance and meet customer requirements.

Die wear reduction by multifactorial Design of Experiments applied to forging simulations

Both wear and fracture mechanisms of 32CrMoV12 dies after hot forging were investigated through SEM and metallographic tests. In order to contain wear mechanisms and to prevent fracture occurrence, a multifactorial Design of Experiments (DoE) has been executed on the Finite Element simulated process. Considered design factors have been limited to process parameters directly modifiable in the actual industrial process. Two step forging cycle has been accounted in the evaluation of stress distribution on the dies and in the estimate of die wear. Despite high process variability, the possibility to effectively hinder fracture and to control most of the wear sources was demonstrated.

Reduction of Die Wear and Structural Defects of Railway Screw Spike Heads Estimated by FEM

Railway spike screws are manufactured by hot forging on a massive scale, due to each kilometer of railway track needing 8600 spike screws. These components have a low market value, so the head must be formed in a single die stroke. The service life of the dies is directly related to the amount of energy required to form a single screw. The existing standard for spike screws specifies only the required tolerances for the head dimensions, particularly the angle of the hub faces and the radius of agreement of the hub with the cap. Both geometrical variables of the head and process conditions (as-received material diameter and flash thickness) are critical parameters in spike production. This work focuses on minimizing the energy required for forming the head of a railway spike screw by computational simulation. The variables with the highest degree of incidence on the energy, forging load, and filling of the die are ordered statistically. The results show that flash thickness is the variable with the most significant influence on forming energy and forming load, as well as on die filling. Specifically, the minimum forming energy was obtained for combining of a hub wall angle of 1.3° an as-received material diameter of 23.54 mm and a flash thickness of 2.25 mm. Flash thickness generates a lack of filling at the top vertices of the hub, although this defect does not affect the functionality of the part or its serviceability. Finally, the wear is mainly concentrated on the die splice radii, where the highest contact pressure is concentrated according to the computational simulation results.

Sliding and impact induced damage on industrial-scale D2 die inserts during trimming of advanced high strength steel using optical interferometry

Die wear during trimming of advanced high strength steel (AHSS) sheets adversely effects the edge quality of trimmed sheets. Due to the large size of the industrial scale dies, it is difficult to measure the wear at the trim edge of the die inserts as a function of the number of trimming cycles. In this work, an optical surface profilometry method was used to determine sliding wear and impact damage on AISI D2 die inserts used to trim 1.4mm thick DP980 sheets through a semi-industrial scale trimming press. Reduced peak height (Spk) and reduced valley depth (Svk) were determined by establishing the bearing ratio curves in the damaged areas of the trim dies as a function of the number of trimming cycles up to 80,000 cycles. The sliding-induced percentage of total volumetric loss (SPOTV) decreased with the number of trimming cycles on the upper sliding plane revealing that the main damage mechanism changed from sliding-induced wear to impact fracture. The dominant damage mechanism on lower sliding plane was fracture induced as SPOTV on this plane maintained a low and constant value and evidence for chipping was observed on the trim die edge. The performance of trim dies could be improved by increasing the fracture toughness of the lower die and increasing the wear resistance of the upper die by applying proper coatings.

Rapid Tooling for Impulse Forming

Compared to cutting processes such as milling, forming processes like electrohydraulic forming offer advantages regarding resource as well as energy efficiency. Due to high tooling costs, forming technologies are nonetheless considered as economically inefficient for low production quantities. Using a combination of high-speed forming with 3D printing technologies for tool manufacturing, three variants to reduce tooling time and costs for processing sheet metals for small quantities were proposed. Since the dies have to withstand high dynamic loads, 3D-printed low-cost dies made of polylactide (PLA) are limited regarding their form stability, mainly depending on the forming energy and sheet thickness. To enlarge the scope of application for 3D-printed dies a method to reinforce these dies is presented and investigated. Armoring of the dies was achieved by electrohydraulic cladding of the dies with 0.5 mm thick aluminum sheet metals. To characterize and compare the properties of the unarmored and the armored polylactide dies, specific characteristics of the formed sheet metals concerning the die wear and the molding quality were investigated. Polylactide dies enabled embossing of fine structures in addition to the forming of the die shape. Armoring of the dies led to a reduction of the embossed layer structure. Therefore, the armoring can be used as a way to control the characteristics of the formed sheet metals. In a further step, the cladding sheets were produced with copper sheet metals and used as sinking electrode for electric discharge machining of steel dies.

Determinación de los principales factores geométricos que influyen en el desgaste de las matrices de extrusión directa empleadas en la obtención en frío de perfiles de aleaciones de aluminio

Within most employed processes of forming for series productions are extrusion processes. Die wear is one of the major disadvantages of this technological process, so that efforts are made to predict and mitigate its effect on the tool. In this research it simulates by the Finite Element Method, using the DEFORMTM-2D, the process of cold direct extrusion of aluminum alloys 6061-O in a die material AISI D2. It was analyzed geometric parameters of the die such as: the insidence angle, the extrusion ratio, the input radii, the bearing entrance length on the tool, and the friction coefficient; to determine the influence on the tool wear. The Archard's wear model is used to determine the wear intensity in the critical area of tool. The Plackett-Burman fractional factorial design is used to determine the main factors influencing the die wear standing out: the extrusion ratio, friction coefficient and the incidence angle as the main factors that affect the die wear and to a less extent the bearing entrance length at the entrance of the tool of the material and inputs radii. The principal factors have been related from a linear response surface.

Study on the forming accuracy of the three-cylinder crankshaft using a specific die with a preformed dressing

The complexity and specificity of the three-cylinder crankshaft lead to under-filling in the balance slider. Normally, way of the precision of the crankshaft is to increase the blank diameter or the bridge size of flash, which result in high forging load, low service life of die, and material utilization. Therefore, a preformed dressing is designed in the balance slider of the pre-forging die. During the pre-forging period, a dressing will be formed in the balance slider, which is used to ensure the precision of the three-cylinder crankshaft in the final forging period. First, CAD models of the die and billet are established, then which are simulated by the Deform-3D software. The forging load and die wear depth are analyzed, and the area of the balance slider is under-filling. Second, a new pre-forging die is designed with a preformed dressing by the CAD software. Third, response surface analysis (RSA) and finite element technology are combined to optimize the pre-forging die of the three-cylinder crankshaft. According to variance analysis, the preformed dressing is not a significant influence factor on the die wear depth and load. Optimized factors’ R, D, H of the pre-forging die are 19 mm, 84 mm, and 6 mm, respectively. Fourth, the flash height of the final forging die is optimized, and the balance slider is filled well, and the die wear depth is reduced. Finally, physical experiment and practice forging are carried out to verify the optimal scheme of the finite element method (FEM), and the results of the experimental and finite element have a good consistency.

Mechanisms of die wear and wear-induced damage at the trimmed edge of high strength steel sheets

Die wear during trimming of advanced high strength steel (AHSS) sheets deteriorates the edge quality of trimmed sheets. In this work, the mechanisms of AISI D2 steel trim die wear and their effects on plastic deformation and fracture behaviour of the sheared edge of DP980 steel sheet were examined. A mechanical press equipped with D2 inserts was used to trim DP980 sheets with a clearance of 0.14 mm (10%). Abrasion and microchipping were identified as the wear mechanisms operating at the upper die, with microchipping becoming more dominant after 60,000 trimming cycles. The burr height and the length of the burnish zone of sheared DP980 sheets increased linearly with the chipped die edge percentage. The shear strains in the shear effected zone (SAZ) were estimated using martensite displacements as metallographic markers in the ferrite matrix as a function of the depth beneath the sheared edge. The depth of SAZ, and the plastic strains at a given depth within the SAZ increased with the number of trimming cycles. Correlation of the local stress and strain values generated in the SAZ showed that a saturation flow stress was reached near the sheared edge. The damage in SAZ occurred in the form of crack formation at the martensite/ferrite interfaces and fracture of martensite. Die wear reduced the tensile ductility of the DP980 sheets, and the fracture mode in tension changed from ductile with localized neck to more brittle sheared edge fracture initiating from surface cracks after 60,000 cycles.

Wear of Dies of Bulk Straining According to Criteria of Low-Cycle Fatigue and Plastic Crushing

Cyclically changing thermomechanical loads causing the stress–strain state of dies are part of the crushing mechanism of surface and crack propagation in stress concentration zones. In order to evaluate the maximum stresses causing the critical strains of a die, a mathematical model is developed making it possible to predict the durability of a die’s working parts. The durability of punches and matrixes is estimated by the average number of loading cycles up to the breakdown of the tool according to the criteria of low-cycle strength and plastic crushing.

Improvement of Tribology in Sheet Metal Forming of High-Strength Steel Sheets by PVD-Coated Dies

During sheet metal formation, the high strength of sheet material leads to high contact stress between the die and blank material, which results in increased die wear. Moreover, the reduction in the use of lubricants because of environmental concerns has led to greater wear of sheet metal–forming dies. It is important to understand the tribological behavior of the blank die contact so that steps can be taken to reduce the die wear to an acceptable level. Die wear reduction is possible by using alternative die materials, modifying die geometry, or by creating a wear-resistant surface on sheet metal–forming dies using Physical Vapor Deposition (PVD) coatings. PVD coatings have a thickness in the micro range and greatly improve the tribological properties of the die material. In this work, three pins made of AISI D2 steel were coated with Titanium Nitride, Titanium Aluminum Nitride (TiAlN), and Aluminum Chromium Nitride using the PVD process. Friction and wear tests were conducted on the pin-on-disk testing machine as per ASTM G99, Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus. The pins had diameters measuring 10 mm and lengths measuring 35 mm. They were heat treated until they reached 55 HRC and ground to a Ra value of 0.1 µm. A 5-mm-radius tip was provided on one end of the pin. D3 steel was used as counter material (disk). The normal load was 30 N, and the sliding speed was 0.3 m/s. The experiments were conducted in dry contact conditions. Based on the results, it was concluded that TiAlN coatings are an excellent choice to modify friction behavior and improve wear resistance of die material.

Simulation and Analysis of hot forging dies for Pan Head bolt and insert component.

Hot forging is a metal-forming process in which hot metal, in the form of bar stock or cut pieces, is shaped by pressing between impression dies. In high-temperature metal forming processes, die life has an important role on the productivity and the quality of the finished products. In this study wear analysis was carried out in a pan head bolt die in local industry. The simulation of the forging process on the die and the work piece was carried out by using commercially available software (ANSYS). In this paper discussed about to determine the stress distribution during hot forging operation of an asymmetric cross-sectioned in forging dies. The finite element simulation is used to find out the amount of stress occurred in dies that influence of friction on the die wear and the material flow is discussed for this forging component. This paper focuses on the modeling, simulation and analyses of the hot forging die for Pan head bolt and insert component die. The final results are in the form of different stresses distribution occurs in die cavity.

Structural Strength and Service Life of the Extrusion Forming Die for Agricultural Engine Piston Heads

Three-tier high-strength prestressed combination concave dies are designed to manufacture highpower corn combine harvester engine piston heads. This design integrates the advantages of traditional casting or hot die forging and warm extrusion. The following key parameters, viz radial dimensions of each mating layer, axial bonding and radial contact interaction, are obtained by theoretical calculation. Nonlinear analysis of the contact interaction was carried out, and the die contact condition was studied at no-load and full-load. Based on the Archard wear theory, thermomechanical bonding was studied in operation of the die. Through numerical simulation of the die wear in each operation cycle, the univariate linear regression equation of the die service life was derived, and the reliability of this equation was verified. The results show that the die contact is both stable and reliable if the radial contact interaction of the inner and outer layers is δ2 = 1.9716 mm and δ3 = 1.3870 mm, respectively. With the nitriding layer thickness of 0.24 mm, the extrusion die service life in the production of piston heads corresponds to 6357 pieces.

Numerical analysis of die wear characteristics in hot forging of titanium alloy turbine blade

This paper provides a simple and effective numerical modeling procedure to determine the thermal effects of initial workpiece temperature (Tw) and preheated die temperature (Td) on the die wear behavior in turbine blade forging. In particular, a local 3D finite element (FE) approach embedded with the modified Archard wear model is developed for the numerical modeling and subsequently validated by comparing the simulated average contact pressure to the analytical one, as well as the experiment from literature. Then, the wear evolution and distribution of blade forging dies are characterized numerically. Further, the thermal effects of both initial workpiece and preheated die temperatures on the die wear characteristics are assessed, and the strategies for decreasing the die wear volume are consequently suggested. The results show that the die wear depth distribution is uneven and the wear volume is more influenced by the preheated die temperature in hot forging process of the blade.

Effect of Preform Height on Die Wear in Hot Forging Process of Idle Gear by Finite Element Modeling

In hot forging process, the common failure modes of forging die are wear, fatigue fracture and plastic deformation. Normally die wear is occurred the most frequently and it influents directly to shape, dimension and surface quality of product. For this research, the hot forging process of idle gear was studied to focus on die wear. This product is forged in three steps. There are preform step, rougher step and finisher step. Height of preform shape in preform step was a parameter to study effect on die wear. Archard’s wear model in finite element modeling was used to predict die wear. The finite element modeling was verified by real hot forging process for reliable model and then it was used to determine the optimum preform height to reduce die wear. Finally the result showed that the maximum wear depth on the forging die was reduced 41.2% from original industry process.