Influence of chemical postprocessing on mechanical properties of laser-sintered polyamide 12 parts

2019 ◽  
Vol 39 (9) ◽  
pp. 830-837
Author(s):  
Andreas Wörz ◽  
Livia C. Wiedau ◽  
Katrin Wudy ◽  
Andreas Wegner ◽  
Gerd Witt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Morphology ◽  
Surface Quality ◽  
High Surface ◽  
Dimensional Accuracy ◽  
Limiting Factor ◽  
Polyamide 12 ◽  
High Surface Roughness ◽  
Powder Particles

Abstract A limiting factor for industrial usage of laser-sintered parts is the high surface roughness due to the semi-molten or attaching powder particles resulting from tool and pressureless manufacturing. An approach to improve the surface quality is the postprocessing with acids to smoothen the surface as it enables improvement without geometrical restrictions of the parts. The present work deals with the usage of nitric, hydrochloric, and trifluoroacetic acids, and exhibits the influence on the resulting surface morphology, dimensional accuracy, and the mechanical properties. The results exhibit different interaction mechanics and show great differences in the resulting part properties.

scholarly journals Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy

Machines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 75
Author(s):  
Nikolaos E. Karkalos ◽  
Panagiotis Karmiris-Obratański ◽  
Szymon Kurpiel ◽  
Krzysztof Zagórski ◽  
Angelos P. Markopoulos
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Process Parameters ◽  
Manufacturing Industry ◽  
High Surface ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
High Surface Quality ◽  
Trochoidal Milling

Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness.

scholarly journals Influence of cutting parameters on surface quality when machining a CoCrWNi alloy

2018 ◽  
Vol 178 ◽  
pp. 01009
Author(s):  
Manuela-Roxana Dijmărescu ◽  
Ioan-Cristian Tarbă ◽  
Maria-Cristina Dijmărescu ◽  
Vlad Gheorghiţă
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Quality ◽  
Cutting Parameters ◽  
Medical Applications ◽  
Medical Implants

Due to their excellent biocompatibility and mechanical properties, the use of Co-Cr based alloys in medical applications has increased substantially. An important characteristic of the medical implants is their surface quality, this being a significant constraint when machining this kind of products. The aim of this paper is to present a research conducted in order to determine and expose the influence of turning cutting parameters on the surface roughness of a CoCrWNi alloy.

scholarly journals Effects of Sintering Behaviors on Dimensional Accuracy, Surface Quality, and Mechanical Properties of Stereolithography-printed 3Y-ZrO2 Ceramics

2021 ◽  
Author(s):  
Cheng Zhang ◽  
Zhaoliang Jiang ◽  
Li Zhao ◽  
Weiwei Guo ◽  
Chengpeng Zhang
Keyword(s):  
Mechanical Properties ◽  
Dental Implants ◽  
Surface Quality ◽  
Dimensional Accuracy ◽  
Scanning Speed ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Air Atmosphere ◽  
Length Width ◽  
Technical Guide

Abstract Sintering process is essential to acquire the final components by stereolithography (SLA), which is a promising additive manufacturing technology for the fabrication of complex, custom-designed dental implants. 3Y-ZrO2 ceramics at different sintering behaviors in air atmosphere were successfully obtained in this study. Firstly, the curing properties of homemade pastes were studied, and the penetration depth and critical exposure of the pastes were calculated as 17.2 μm and 4.80 mJ/cm2, respectively. The green ceramic parts were performed at 154 mW laser power and 6000 mm/s scanning speed. Then, the dimensional accuracy, surface quality, and mechanical properties of 3Y-ZrO2 ceramics were investigated. The shrinkages of length, width, and height were 26%~27 %, 30%~31 %, and 27%~33 % in sintered ceramics, respectively. The Ra values of XOY, YOZ, and XOZ surfaces showed an anisotropic feature, and they were smallest as 0.52 μm, 2.40 μm, and 2.46 μm, respectively. Meanwhile, the mechanical properties presented a similar trend that they grew first and then dropped at various sintering behaviors. The optimal parameters were 1500 ℃, 60 min, and 4 ℃/min, and the maximum relative density of 96.18 %, Vickers hardness of 12.45 GPa, and fracture toughness of 6.35 MPa·m1/2 were achieved. Finally, the X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) analysis demonstrated that no change was observed in crystal transformation and phase composition, and the organic was completely removed in sintered ceramics. This research is expected to provide a technical guide for the fabrication of ceramics for dental implants using SLA technique.

Influence of Manufacturing Process on the Fatigue Strength of Gears

2014 ◽  
Vol 1018 ◽  
pp. 269-276
Author(s):  
Andrea Reiß ◽  
Ulf Engel
Keyword(s):  
Fatigue Strength ◽  
Surface Quality ◽  
Fatigue Behavior ◽  
High Surface ◽  
Research Work ◽  
Dimensional Accuracy ◽  
Cold Forging ◽  
Hardness Distribution ◽  
Forming Process ◽  
High Surface Quality

With cold forging processes it is possible to produce parts characterized by high strength, high dimensional accuracy and high surface quality. In order to optimize the forming process and to be able to use the advantages of cold forging specifically and combined, it is necessary to find correlations between manufacturing parameters on the one side, strength and other properties like hardness distribution and surface quality of the component on the other side. The research work covered in this paper focuses on the correlation of the components properties influenced by its manufacturing history and their fatigue strength. The used component is a gear produced by a lateral cold forging process. For the investigations an experimental setup has been designed. The aim for the design of the setup is to reproduce the real contact condition for the contact of two gears. To obtain different component properties the production process of the gear was varied by producing the parts by a milling operation. First of all, the components’ properties, for example hardness distribution, remaining residual stresses, orientation of fibers and surface quality, were determined. The components’ fatigue behavior was determined using a high frequency pulsator and evaluated in terms of finite life fatigue strength and fatigue endurance limit. These examinations were used to produce Woehler curves for the differently manufactured components with a certain statistical data analysis method.

Influence of energy density on polyamide 12 processed by SLS: from physical and mechanical properties to microstructural and crystallization evolution

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tiago Czelusniak ◽  
Fred Lacerda Amorim
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Energy Density ◽  
Laser Energy ◽  
Polymer Degradation ◽  
High Energy ◽  
Content Type ◽  
Polyamide 12 ◽  
Line Spacing ◽  
Scan Line

Purpose This paper aims to provide a detailed study on influence of the laser energy density on mechanical, surface and dimensional properties of polyamide 12 (PA12) parts produced by selective laser sintering (SLS), providing the microstructural and crystallization evolution of the samples produced at different energy densities. Design/methodology/approach Making use of a space filling design of experiments, a wide range of laser sintering parameters is covered. Surface morphology is assessed by means of profile measurements and scanning electron microscopy (SEM) images. Mechanical testing, SEM, X-ray diffraction (XRD), differential scanning calorimeter (DSC) and infrared spectroscopy (FTIR) were used to assess the influence of energy density on structural and mechanical properties. Findings Results show a high dependency of the properties on the laser energy density and also a compromise existing between laser exposure parameters and desired properties of laser sintered parts. Surface roughness could be associated to overlap degree when using higher scan line spacing values and lower laser speeds improved surface roughness when high scan line spacing is used. Higher mechanical properties were found at higher energy density levels, but excessively high energy density decreased mechanical properties. A transition from brittle to ductile fracture with increasing energy density could be clearly observed by mechanical analysis and SEM. XRD and DSC measurements show a decrease on the crystal fraction with increasing energy densities, which corroborated the plastic behavior observed, and FTIR measurements revealed polymer degradation through chain scission might occur at too high energy densities. Originality/value Valuable guidelines are given regarding energy density optimization for SLS of PA12 considering not only quality criteria but also microstructure characteristics. Surface properties are studied based on the concept of degree of overlap between laser scanning lines. For the first time, crystallization behavior of SLS PA12 parts produced at different energy levels was studied by means of XRD measurements. Polymer degradation of SLS PA12 parts was evaluated with FTIR, which is a non-destructive and easy test to be conducted.

scholarly journals Micromachining of Biolox Forte Ceramic Utilizing Combined Laser/Ultrasonic Processes

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3505
Author(s):  
Basem M. A. Abdo ◽  
Syed Hammad Mian ◽  
Abdualziz El-Tamimi ◽  
Hisham Alkhalefah ◽  
Khaja Moiduddin
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Thermal Damage ◽  
High Surface ◽  
Dimensional Accuracy ◽  
Ultrasonic Machining ◽  
Rotary Ultrasonic Machining ◽  
Machining Time ◽  
Laser Beam Machining ◽  
Wide Range

Micromachining has gained considerable interest across a wide range of applications. It ensures the production of microfeatures such as microchannels, micropockets, etc. Typically, the manufacturing of microchannels in bioceramics is a demanding task. The ubiquitous technologies, laser beam machining (LBM) and rotary ultrasonic machining (RUM), have tremendous potential. However, again, these machining methods do have inherent problems. LBM has issues concerning thermal damage, high surface roughness, and vulnerable dimensional accuracy. Likewise, RUM is associated with high machining costs and low material-removal rates. To overcome their limits, a synthesis of LBM and RUM processes known as laser rotary ultrasonic machining (LRUM) has been conceived. The bioceramic known as biolox forte was utilized in this investigation. The approach encompasses the exploratory study of the effects of fundamental input process parameters of LBM and RUM on the surface quality, machining time, and dimensional accuracy of the manufactured microchannels. The performance of LRUM was analyzed and the mechanism of LRUM tool wear was also investigated. The results revealed that the surface roughness, depth error, and width error is decreased by 88%, 70%, and 80% respectively in the LRUM process. Moreover, the machining time of LRUM is reduced by 85%.

Characterization of Cutting-Induced Heat Generation in Ultra-Precision Milling of Aluminium Alloy 6061

2013 ◽  
Vol 552 ◽  
pp. 201-206
Author(s):  
Su Juan Wang ◽  
Suet To ◽  
Xin Du Chen
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Heat Generation ◽  
Feed Rate ◽  
Dimensional Accuracy ◽  
Precision Machining ◽  
Machined Surface ◽  
Single Crystal Diamond ◽  
Ultra Precision ◽  
Alloy 6061

The technology of ultra-precision machining with single crystal diamond tool produces advanced components with higher dimensional accuracy and better surface quality. The cutting-induced heat results in high temperature and stress at the chip-tool and tool-workpiece interfaces therefore affects the materials and the cutting tool as well as the surface quality. In the ultra-precision machining of al6061, the cutting-induced heat generates precipitates on the machined surface and those precipitates induce imperfections on the machined surface. This paper uses the time-temperature-precipitation characteristics of aluminum alloy 6061 (al6061) to investigate the effect of feed rate on the cutting-induced heat generation in ultra-precision multi-axis milling process. The effect of feed rate and feed direction on the generation of precipitates and surface roughness in ultra-precision raster milling (UPRM) is studied. Experimental results show that heat generation in horizontal cutting is less than that in vertical cutting and a larger feed rate generates more heat on the machined workpiece. A smaller feed rate produces a better surface finish and under a larger feed rate, scratch marks are produced by the generated precipitates and increase surface roughness.

scholarly journals Experimental Study on the Effects of Coolants on Surface Quality and Mechanical Properties of Micromilled Thin-Walled Elgiloy

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1497 ◽  
Author(s):  
Da Qu ◽  
Peng Zhang ◽  
Jiadai Xue ◽  
Yun Fan ◽  
Zuhui Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Quality ◽  
Lower Surface ◽  
Work Piece ◽  
Dry Machining ◽  
Core Component ◽  
The Core ◽  
Thin Walled ◽  
The One

In this study, minimum quantity coolant/lubrication (MQCL) is found to have significant impact on the surface quality and mechanical properties of the micromilled thin-walled work piece that is the core component of an aeroaccelerometer. Three kinds of coolants were used in the micromilling process to analyze their effects on surface quality and mechanical properties of the component. The experiment results show that an appropriate dynamic viscosity of coolant helps to improve surface roughness. The high evaporation rate of the coolants can enhance the cooling performance. Comparing with the dry machining case, MQCL has better performance on improving tool wear, surface quality, and mechanical properties of the micromilled work piece. It yielded up to 1.4–10.4% lower surface roughness compared with the dry machining case in this experiment. The machined work piece with the best mechanical properties and the one with the worst mechanical properties appeared in the ethyl alcohol and the dry machining case, respectively. The reasons for deteriorating surface quality and mechanical properties in dry machining cases are also analyzed. For improving the micromilling process, the penetration and cooling effect of the coolants are more important. This paper gives references to obtain better service performance of the component by improving the micromilling process.

scholarly journals Impact of vapor polishing on surface quality and mechanical properties of extruded ABS

2018 ◽  
Vol 24 (2) ◽  
pp. 501-508 ◽  
Author(s):  
Clayton Neff ◽  
Matthew Trapuzzano ◽  
Nathan B. Crane
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Surface Quality ◽  
Complex Geometry ◽  
Substantial Impact ◽  
Solvent Vapor ◽  
Content Type ◽  
Minimal Impact ◽  
End Use ◽  
Traditional Manufacturing

Purpose Additive manufacturing (AM) is readily capable of producing models and prototypes of complex geometry and is advancing in creating functional parts. However, AM processes typically underperform traditional manufacturing methods in mechanical properties, surface roughness and hermeticity. Solvent vapor treatments (vapor polishing) are commonly used to improve surface quality in thermoplastic parts, but the results are poorly characterized. Design/methodology/approach This work quantifies the surface roughness change and also evaluates the effect on hermeticity and mechanical property impacts for “as-printed” and acetone vapor-polished ABS tensile specimens of 1-, 2- and 4-mm thicknesses produced by material extrusion (FDM). Findings Vapor polishing proves to decrease the power spectral density for surface roughness features larger than 20 µm by a factor of 10× and shows significant improvement in hermeticity based on both perfluorocarbon gross leak and pressure leak tests. However, there is minimal impact on mechanical properties with the thin specimens showing a slight increase in elongation at break but decreased elastic modulus. A bi-exponential diffusion decay model for solvent evaporation suggest a thickness-independent and thickness-dependent time constant with the latter supporting a plasticizing effect on mechanical properties. Originality/value The contributions of this work show vapor polishing can have a substantial impact on the performance for end-use application of ABS FDM components.

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