Fine Blanking Research Articles

Microstructure – Fracture toughness relationship in a sub-zero treated 0.9C-7.8Cr sub-ledeburitic tool steel

The Sleipner steel (0.9C-7.8Cr sub-ledeburitic tool steel) is a widely utilized tool steel currently being adopted to produce tools used in fine blanking, shearing, forming, coining, deep drawing, and others. In these branches, tailoring the final mechanical properties, such as hardness and toughness, to specific application is highly appreciated. The Sleipner steel was subjected to sub-zero treatments (at –140 °C for 17 h and 36 h) in the current work. The resulting microstructures, hardness variations, and changes in fracture toughness were analyzed and discussed. It was observed that sub-zero treatments reduced the retained austenite amounts by 14–15 % and slightly refined the martensite. However, the impact of this treatment on carbide count was marginal. The hardness of the sub-zero treated steel increased when tempered at temperatures up to 400 °C, but it decreased after tempering at 520 °C compared to cryogenically treated specimens.Sub-zero treatment reduced the fracture toughness in the steel tempered up to a temperature of 400 °C, but an increment in this property was found after 520 °C tempering. Nevertheless, the obtained results indicate that it is impossible to simultaneously enhance both the hardness and fracture toughness of this particular steel grade. Therefore, it is necessary to carefully choose the principal goal of the treatment (either hardness or toughness) even before subjecting the tools to the heat/sub-zero treatment.

Energy efficiency improvement of heavy-load hydraulic fine blanking press for sustainable manufacturing assisted by multi-stages pressure source system

The fine blanking process has the highest forming accuracy in the field of metal forming and its production volume has increased sharply. However, hydraulic fine blanking presses (HFBP) – the core equipment of the fine blanking process, have suffered from significant energy loss due to the inefficient hydraulic system. To enhance the energy efficiency of the hydraulic system, this study introduced a novel approach – a multi-stage pressure source system comprised of distinct pump-accumulator groups, each operating at varied supplied pressures to narrow the mismatch of the installed and demanded power. This adaptive system is capable of automatic adjustments to align with the required pressure, thereby mitigating energy losses while concurrently preserving superior dynamic working performance. First, this study commenced with a theoretical analysis of the system configuration and energy characteristics of HFBP. Subsequently, a comprehensive exploration into the inherent inefficiencies of the hydraulic system is undertaken by formulating a precise energy consumption model. Finally, a novel energy-saving optimization design was carried out on the fast-approaching subsystem. The results demonstrated that the implementation of the proposed system led to a notable reduction of 76.87% in energy loss within the flow-regulating module, and an overall diminution of 13.53% in energy dissipation compared to the conventional system. This study will significantly advance sustainable manufacturing practices within the metal-forming domain by reducing electricity consumption and production cost.

Research on the Method of Identifying the Collapsed Angle Surface of Fine Punching Small Gear

Aiming at the requirement of automatic assembly of automobile rear wiper for automatic identification of the collapsed corner surface of finely-punched pinion, this paper proposes a method based on the mean value of the area of multi-toothed region of finely-punched pinion as the characteristic parameter, which can better identify the collapsed corner surface. Firstly, the industrial camera is used to obtain the pinion image, and the Halcon operator is used to fit the circle in the pre-segmented region to obtain the pinion circle position parameter, and the parameter is used as the reference to accurately segment the toothed annulus ROI, and then carry out the dynamic thresholding of the region, merging the regions, shape convex package transformation, and the conditional filtering to obtain the multiple toothed regions, and then rank the toothed regions, and the maximum top three toothed regions area mean value is the feature parameter to achieve the fine blanking pinion surface automatic identification of the collapsed corner surface. The mean value of the area of the first three tooth-shaped areas is used as the characteristic parameter to achieve the identification of the collapsed angle surface of the fine blanking pinion gear. The application on the assembly line shows that the recognition accuracy of this method reaches 99.9%, with good robustness and stable operation, which meets the production requirements, and also provides a method for the recognition of collapsed corner surfaces of other fine blanking parts.

Energy consumption analysis for the fine blanking process

Energy consumption analysis for the fine blanking process

Thermomechanical modeling of the shearing process during fine blanking of quenched and tempered steel

In order to develop an alloy design for fine blanking of deformation mechanism-based sheet metal materials such as high manganese steel, knowledge of the temperature during the shearing process is required. Thermomechanical modeling of shear zone temperature requires consideration of contact heat transfer, which depends on stress state as well as temperature. This paper deals with a methodology for calibrating the contact heat transfer coefficient during fine blanking using indirect temperature measurements. For this purpose, a thermomechanically coupled finite element (FE) model was designed considering thermoviscoplasticity, temperature-dependent physical and thermophysical parameters as well as a steady-state calibrated contact heat transfer coefficient. Experimental fine blanking tests were carried out to validate the model using force, die roll and thermography measurements based on varied blanking velocities. The thermomechanically coupled FE modeling showed a sufficiently accurate correspondence regarding the experimentally determined blanking force, die roll as well as sheared surface temperature. Thermographically determined sheared surface temperatures allowed calibration of locally different contact heat transfer coefficients as a simplified approach under steady-state conditions.

Study on material-data-driven process parameterization in fine blanking

In industrial sheet-metal processing, processes are parameterized based on the material specifications. However, the manufacturing process of sheet-metal coils determines the material properties and as every manufacturing process is subject to variations, variations in material properties occur in the semi-finished product influencing the subsequent sheet-metal processing. The production of high-quality parts requires considering these varying material properties to adapt the processes accordingly. This paper shows that material data from non-destructive eddy current measurements and process data of the coil production enable decision support for the parameterization of fine blanking processes. A material-data-driven approach using material data recorded in an industrial setting is employed to investigate the influence of parameter settings in the fine blanking process on specific quality characteristics of fine blanked workpieces.

Study on the explainability of deep learning models for time series analysis in sheet metal forming

In recent research, force signals have been utilized to estimate the wear of tool components in sheet metal processing using, e.g., artificial neural networks (ANNs). ANNs learn predictive models from raw time series signals without requiring prior knowledge and manual feature engineering. However, ANNs are black-box models. Existing research on explainable AI provides methods to increase the transparency of ANNs, but mainly focusses on computer vision problems. This publication proposes an approach to learn explainable ANNs for time series data. The presented approach is applied to a tool wear prediction task using force signals from a fine blanking machine.

Prediction of Tool Wear in Fine Blanking Punch with PVD Coating with TiCN for JIS.SKH51 High Speed Tool Steel Using Archard Wear Model

The aim of this study is predict tool wear in the fine-blanking process using a tribometer tester with ASTM G99-17 standard. Then, the result of wear volume and tool life were confirmed with finite element simulation and experiment. The punch material used in fine blanking process was selected to be hight speed steel JIS.SKH51 with surface coating thickness 4 µm of TiCN, the work piece material was used as hot-rolled steel JIS.SPHD P/O, with a thickness of 8 mm. The experimented and simulated results were found that the pressure, and sliding velocity were increase in term of linear curve with slope K = 2.09x10-6 and K = 2.07x10-6 ,respectively, and the hardness of material was increase in term of power at 1.983 and slope of K = 2.14 x10-6. These three factors were effect to the wear volume and tool life, simultaneously, the summation of three factors will average as K = 2.10 x10-6. From comparison of the applied wear equation model with tribology tester the simulated and experimented results were similarly equal with 0.05 by significance at 95% reliability confident. The resulted were precisely confirmed according to the previous research.

Effect of grain size on fine micro-blanking for Inconel 718 foil

The influence of grain size on low-strength metal and alloy foils has been extensively discussed as an important factor in the “size effect” of micro-forming. It is relatively difficult to observe these effects in high-strength metal and alloy foils for micro-blanking. Blanking tests and simulations were conducted on Inconel 718 foils with a thickness of 100 μm to investigate the effects of different grain sizes on the fine micro-blanking process and results. A micro-blanking surface with full burnish depth and no fracture zone can be obtained using our fine blanking technique. Grain growth reduces burr height but increases rollover depth. The fine blanking empirical formula cannot be applied to calculate the maximum micro-blanking force for fine micro-blanking technology when grain sizes differ. A revised empirical formula was established for fine micro-blanking force. A size effect model for fine micro-blanking was established based on the grain deformation mechanism, which reflects the enhancement in shear sensitivity with grain growth. We established an advanced, effective method for Inconel 718 foil micro-blanking. This work may contribute to the optimal selection of forming force for fine micro-blanking applications.

Fine Blanking of Austenitic Stainless Steel Gears Using Carbon-Supersaturated High-Speed Steel Tools

Austenitic stainless steel gears were fabricated via the fine blanking process that can be used for mass production. A carbon-supersaturated (CS)-matrix high-speed steel punch was prepared to minimize the adhesive and abrasive wear damage. Its edge profile was tailored and finished to control the local metal flow around the punch edges and edge corners. This CS punch was utilized in fine blanking the AISI304 austenitic stainless steel gears. Ball-on-disc (BOD) testing was first employed to describe the frictional behavior of the CS tool steel disc against the AISI304 stainless steel balls. SEM-EDX analysis on the wear track revealed that a free-carbon tribofilm was formed in situ in the wear track to prevent adhesive wear via galling on the tool steel disc. No significant adhesive or abrasive wear was detected on the punch edges and punch edge corners after continuously fine blanking with 50 strokes. AISI304 gears were produced to have fully burnished surfaces. Their pitches, widths and circles were measured to evaluate their gear-grade balancing during the fine blanking process. The stabilized gear-grade balancing in JIS-9 to JIS-10 grades was attained for these as-blanked AISI304 gears without finishing processes.

Determination of the Influence of the Tool Side Stress Superposition and Tool Geometry on the Cut Surface Quality during Precision Shear Cutting

Shearing high-strength steels often leads to a subpar cut quality and excessive stress on the tool components. To enhance the quality of the cut surface, intricate techniques like fine blanking are commonly employed. However, for applications with lower quality requirements, precision shear cutting offers an alternative solution. This research paper introduces a novel approach to directly superimpose radial stress on a workpiece during the precision shear cutting process and showcases for the first time how the application of direct stress superimposition can impact the cut surface by concurrently modifying the shear cutting edge and punch surface. A statistical experimental design is employed to investigate the interrelationships between the parameters and their effects. The results indicate that the overall cut quality, including cylindricity, clean-cut angle, rollover height, and tool stress, defined by punch force and retraction force, is influenced by the superimposed stress. Regarding the clean-cut zone, the statistical significance of direct radially superimposed stress was not observed, except when interacting with sheet thickness and clearance. Additionally, the sheet thickness and cutting gap emerged as significant parameters affecting the overall quality of the cut surface.

Analisis Penggantian dan Biaya Perawatan Komponen Profibus dan Kontaktor pada Mesin Fine Blanking 1100 Ton di PT.XYZ

It is necessary to do research to replace the profit bus and contactor components on a 110 ton Fine Blanking machine at PT. XYZ to analyze the cost and time needed to replace the profibus and contactor components. The aim of the research is to obtain the replacement time for profibus components and contactors, to obtain the cost and replacement time needed to replace profibus components and contactors. Through the distribution suitability test with the Kolmogorov Smirnov method, it was found that the time between failures of the profibus components corresponds to the Weibull distribution with an average replacement time of 29.54 days with a reliability of 47%. The contactor components are in accordance with the Weibull distribution with an average replacement time of 30.42 days with a reliability of 46%. The average repair time required for each profibus component replacement on a 1100 ton Fine Blanking machine is 3.85 minutes. Contactor on a 1100 ton Fine Blanking machine for 24.75 minutes. The cost required for each replacement of the Profibus component is IDR 1,250,000. For the contactor component on the 1100 ton Fine Blanking machine, IDR 650,000.

Pengendalian Kualitas Untuk Meminimumkan kecacatan Produk Sprocket

PT. XYZ is a company engaged in the manufacturing sector (manufacturing automotive spare parts) with a production process using fine blanking machines and international standard press machines. Based on the data obtained, related to product quality, there are problems that occur during the production process and product results. These problems are related to the level of defects in the production process. From historical production data from July to November 2022, sprocket products contribute the most defective products, both congenital physical defects of the material itself and during the production process such as dakon, scratch, crack/hadan, and burry, which can affect the quality specifications that have been set with a tolerance limit of 0.4%. In general, defective sprocket products can still be reworked, but it takes a long time, so the company will be greatly disadvantaged because production costs will soar. Therefore, based on these problems, the researcher uses the American Military Standard (Mill STD 105D) and American Military Standard (Mill STD 414) methods, which aim to look at aspects of the causes of defects, the level of defects on sprockets, and provide advice to companies on how to minimize sprocket product failure. Based on the results of research conducted on quality control planning using this method, it is known that the results of inspection can be accepted as passing when the number of variable defects is less than 6 pcs in 13 pcs for major defects, while minor defects can be accepted as passing when the number of attribute defects is less than 15 pcs in 200 pcs.

Data-driven indirect punch wear monitoring in sheet-metal stamping processes

The wear state of the punch in sheet-metal stamping processes cannot be directly observed, necessitating the use of indirect methods to infer its condition. Past research approaches utilized a plethora of machine learning models to infer the punch wear state from suitable process signals, but have been limited by the lack of industrial-grade process setups and sample sizes as well as their insufficient interpretability. This work seeks to address these limitations by proposing the sheared surface of the scrap web as a proxy for the punch wear and modeling its quality from acoustic emission signals. The experimental work was carried out in an industrial-grade fine blanking process setting. Evaluation of the model performances suggests that the utilized regression models are capable of modeling the relationship between acoustic emission signal features and sheared surface quality of the scrap webs. Subsequent model inference suggests adhesive wear on the punch as a root cause for the sheared surface impairment of the scrap webs. This work represents the most extensive modeling effort on indirect punch wear monitoring in sheet-metal stamping both from a model prediction and model inference perspective known to the authors.

Failure Analysis of Boron Steel Components for Automotive Applications

The automotive industry is continuously looking for an innovative mix of new steels and manufacturing techniques in order to improve process chain efficiency and cost reduction. To this aim, boron steels are becoming increasingly popular thanks to their high hardenability and machinability. Due to their reduced finishing steps, boron steels are commonly processed using fine blanking technologies. The success of fine blanking on boron steel components is due to heat treatments which must be carefully designed to avoid precipitation of boron-rich compounds that would lower steel hardenability. At high temperature, boron is very reactive with oxygen and nitrogen. The main focus of this paper is to show some drawbacks that can occur during heat treatments of automotive components. An experimental campaign was performed on two different boron steels, namely EN 34MnB5 and EN 22MnB5. The steel samples were previously spheroidized annealed in a neutral environment (hydrogen/nitrogen atmosphere), and then fine blanked to obtain specific automotive components which were subsequently quenched and tempered. Experimental tests revealed precipitation of nanometric compounds, causing strong grain refinement and localized decrease of steel hardenability. Hardenability problems were brought back to nitrogen pick-up during initial spheroidize annealing treatments.

Galling-Free Fine Blanking of Titanium Plates Using Carbon-Supersaturated High-Speed Steel Punch

A carbon-supersaturated (CS-) high-speed steel punch was prepared using low-temperature plasma carburizing for fine blanking of pure titanium plates. The bare high-speed steel punch was also prepared as a reference to describe the adhesion and abrasive galling in the fine blanking of the titanium plates, even in a single shot. The CS-punch was free from severe chemical galling, even after repeatedly fine-blanking the pure titanium plates. A microstructure analysis, element mapping and a chemical composition analysis demonstrated that titanium debris fragments slightly deposited at the CS-punch edges in the presence of agglomerated free-carbon film due to the CS-punch. This galling-free fine-blanking behavior came from the in situ formation of free carbon tribofilms. This in situ lubrication resulted in the completely burnished surfaces of pure titanium blanks.

Optimization of Hydraulic Fine Blanking Press Control System Based on System Identification

Fine-blanking is a molding process based on the common blanking process, which obtains hydrostatic stress through blank holder reverse jacking, in order to increase material plasticity. It requires special equipment, namely a fine-blanking press, to complete the fine-blanking process. In this paper, the problem of the speed of the slide block fluctuation found in the actual use of a 12,000 kN hydraulic fine-blanking press after multi-stage pressure source optimization is studied. Firstly, the mathematical model of the motion of the slide block in the blanking stage of the hydraulic fine blanking press is established, and the accurate mathematical model in the blanking stage of the hydraulic fine-blanking press is obtained through the least square method system identification experiment. Aiming at the complex working situation of the fine-blanking press, a phased PID control strategy is creatively proposed. The optimal PID control parameters are obtained by a genetic algorithm, and established a fuzzy PID controller for the blanking stage to accurately control the movement speed of the slide block. The results show that the new control strategy is very effective in improving the movement accuracy of the slide block, effectively improving the machining accuracy and reducing the impact vibration of the hydraulic system.

Influence of mechanical properties and alloying elements of low carbon steels on fine blanking and heat treatment processes response

The effect of the negative clearances between punch and die of a flange with different fine blanking half-cutting depths was investigated for two low carbon steels with various elongation rates, C18E (0.18%C) and 20MnB5 steels (0.2%C, with upper mechanical properties than the carbon steel), industrially used for forming car seat parts. A specific tool adaptable on a tensile machine was built to determine the force needed to fine blank a simple geometry, in the objective to further transpose the obtained results to the complex geometry of industrial parts. Heat treatment was carried out to optimize the microstructure, hardness and dimensional modifications for the combination material/clearance/half-cutting height tested. Increasing the elongation rate of the raw material allows to reach a better formability and reduces the force needed to create a given geometry, but cracks were detected for the extreme deformation rate. Moreover, after fine blanking and heat treatment operations, different microstructures were observed according to the material grade, stable for low alloy 20MnB5 steels (martensitic microstructure) while non reproducible for the low carbon steel (mix of ferrite, bainite and martensite).

Die design for fine micro-blanking process

As the increase in demand for microparts of metal foil, the micro-blanking process with many advantages of plastic deformation has been widely applied on microparts manufacturing area. But the fracture zone of shearing surface is always present and affects the service life of the part. This paper proposes a new micro-blanking die based on fine blanking technology. In this die, the rubber as the power transmission device is selected to provide a blank holder force and counter force. In the FEM simulation, the influence of a few key die parameters is considered such as punching clearance and fillet radius of female die and punch. And the fine micro-blanking experiments for superalloy foils were conducted to evaluate the feasibility of the die designs. The results had shown the fine micro-blanking die proposed was able to be used for micro-blanking and obtain metal microparts.

Fine Blanking Limits of Manganese-Boron-Steel in Fine Blanking Compared to Tempered Steel with Variation of Sheet Metal Temperature

Fine blanking is a key technology for the near-net-shape production of sheet metal components. It is often used in combination with processes such as deep drawing. With increasing environmental requirements, the processing of materials with lightweight construction potential is becoming more and more important. A group of materials with high potential for lightweight construction, not only due to their suitability for hot stamping, is the group of manganese-boron steels. The fine blanking properties of these steels have not yet been exhaustively investigated. In this work, the fine blanking properties of the manganese-boron steel 40MnB4 were investigated in comparison to the quenched and tempered steel 42CrMo4. This was done using a star-piece fine blanking layout with investigation of die roll as well as tooth tip cracking. Furthermore, an investigation of the high-temperature fine blanking properties were investigated by means of inductive heating prior to fine blanking. The process forces were evaluated depending on the sheet metal temperature. A good fine blanking capability of 40MnB4 could be confirmed. Process forces and product quality were comparable to 42CrMo4 steel. Accordingly, an industrial application of fine blanking to manganese-boron steels seems highly promising.