Coordinate Measuring Machine Research Articles

COBALT CHROMIUM DEBRIS RELEASE IN CONTEMPORARY TOTAL KNEE ARTHROPLASTY MAY BE AN UNDER-RECOGNIZED CLINICAL ISSUE

AbstractIntroductionSeveral studies have reported significant cobalt(Co) and chromium(Cr) elevations in the blood of patients with total-knee-replacements (TKRs), and histological signs of metal sensitivity have been reported in up to 44% of patients undergoing revision of their TKRs. We carried out this investigation to determine the source and quantity of metal release in TKRs.MethodologyWe identified all TKRs with polished CoCr trays (N=59) [Vanguard=29, Attune=4 and PFC=26]. These were analysed using peer-reviewed [coordinate-measuring-machine (CMM)] methodology to measure the volumetric wear of the polyethylene (PE) bearing surfaces and trays. The trays were analysed using 2D-profilometry (surface roughness-Ra) and 4D-microscopy. Histological and blood metal ion concentration analyses were performed.ResultsThe median(IQR) PE wear rate was 10(6to20) mm3/year. Microscopic analysis identified pitting on superior surface of 36(49%) trays. Ra [median (IQR)] of superior surface of pitted trays [0.076 (0.060–0.084) µm] showed a statistically significant increase (p<0.001) compared with unpitted trays [0.057(0.049–0.066) µm]. 4D-microscopy and CMM analysis estimated wear volumes of up to 2mm3 secondary to pitting. The median (range) Co and Cr concentrations were 2.5µg/l (0.2–69.4) and 1.7µg/l (0.5–12.5) respectively in 40 patients. Of the tissue samples examined in 30 patients,6 had at-least “mild”-ALVAL infiltrate. All corresponding “ALVAL” explants were found to be pitted and/or show evidence of loosening of the tray.ConclusionThis study provides further evidence that CoCr release in TKR appears to be an under-recognised cause of adverse clinical outcomes. Gross metal ion elevations occurred in association with micromotion/loosening of the tray.

Tooth Surface Registration of Spiral Bevel Gear Based on Improved Genetic Algorithm

To reduce the tooth surface measurement error of spiral bevel gear, a tooth surface registration method using an improved genetic algorithm (GA) was proposed according to the measuring principle of a coordinate measuring machine (CMM). To improve the performance of GA, the unit quaternion method was used to limit the initial population generation space, and then the simulated annealing algorithm was used to improve the search process. Finally, the measured and theoretical tooth surface was matched. Experimental results show that the improved genetic algorithm can compensate for more than 55% of the measurement error of the tooth surface.

A novel flank correction method for face gear ground by CNC worm wheel grinder

Face gear will be widely used in the fields of intersecting shaft transmission due to its insensitivity to pinion axis misalignment. Considering the requirements of machining efficiency, face gear is mainly ground by worm wheel. However, due to the complexity of face gear tooth flank, worm wheel profile and grinder machining settings, the ground tooth flank accuracy is very difficult to meet the actual requirements. This paper proposes a novel flank correction method to improve face gear tooth flank accuracy based on computer numerical control (CNC) grinder. Firstly, the tooth flank is enveloped by worm wheel in a continuous indexing process. Secondly, the machining settings of grinder and a 5 × 9 measurement grid for coordinate measuring machine (CMM) are determined. Lastly, a high-order flank correction model is established and solved iteratively considering the measured tooth flank deviations, and the sum of squared errors of deviation is reduced by 91.6%. A machining simulation is carried out to verify the flank correction method. This method can significantly improve face gear tooth flank accuracy and provide a basis for its widespread promotion.

Dynamical modeling and characteristics analysis of tooth spalling in gear system with weight reduction structure

Focusing on gear transmission systems having thin web and hole structures for energy saving and weight reduction, this work aims to propose an effective method for dynamical modeling and characteristics identification of spalling in lightweight gear systems. A novel three-dimensional (3D) spalling morphology modeling method is developed by the optical scanner. Subsequently, an analytical-finite element (AFE) model is established to calculate the mesh stiffness with weight reduction structures and spalled teeth. Additionally, the discrete tooth surfaces from coordinate measuring machines (CMMs) are used to calculate the no-load static transmission error (NLSTE). A rigid-flexible coupling dynamic model is introduced into the gear-rotor-bearing system considering the lightweight rotor and friction characteristics. The effects of spalling fault levels, the number and distribution form of spalled teeth on dynamic characteristics of the lightweight gear system are investigated. The numerical and experimental results demonstrate the existence of coupling modulation between spalling and holes, but it can still be identified by time and frequency domain characteristics. The proposed model and analysis results provide important references for identifying spalling in lightweight gear systems.

A Comparison of CMM and CMA Capabilities in Product Feature Verification Metrology

To control variations and guarantee that a part will function as intended in an assembly, measurement verification must be conducted with specialized metrology equipment. The Coordinate Measuring Machine (CMM) and the Articulated Arm CMM (AA-CMM) are analyzed in this comparative study, to identify their respective advantages and disadvantages when measuring flatness. The goal of this pilot study is to detect the measuring limitations of each machine and propose a methodology to identify appropriate use of each device based on its capabilities. For measuring flatness, contact and contactless measurement experiments were designed. As expected, it is observed that the CMM performs better than the CMA in flatness measurement because it has a higher resolution [1]. By looking at the measured flatness obtained during the experiment, it was determined that the CMM had a smaller minimum measurable tolerance in all permutations of the test when compared to its counterpart. Resulting in the proposal of different functional working envelopes for these machines. Establishing working envelopes permits the use of both machines for overlapping working purposes as the versatility of CMAs in Geometry verification in settings where CMMs cannot be deployed, could have a great impact as long as they operate on the corresponding working envelopes defined in this research, which were defined as follows: CMM has a minimum measurable tolerance of 0.0006in, CMA contact, has a minimum measurable tolerance of 0.0024in and CMA contactless, has a minimum measurable tolerance of 0.0045in.

Study of the TIG Welding Process of Thin-Walled Components Made of 17-4 PH Steel in the Aspect of Weld Distortion Distribution.

This article presents the results of a study on the distribution of weld distortion in thin-walled components made of 17-4 PH steel, resulting from TIG (Tungsten Inert Gas) welding. Both manual and automatic welding processes were examined. Physical simulation of the automated welding process was conducted on a custom-built welding fixture. Analysis of weld distortion in thin-walled components made of 17-4 PH steel was based on the results of measurements of transverse shrinkage and displacement angle values. These measurements were taken on thin-walled parts before and after the welding process using a coordinate measuring machine (CMM). To determine the effect of manual and automated welding processes on the microstructure of the welded joint area, metallographic tests and hardness measurements were performed. The microstructure was analyzed using a scanning electron microscope (SEM). An analysis of the chemical composition of selected welded joint zones was also conducted. These tests were performed using an optical emission spectrometer (OES). According to the results, the use of automated welding and special fixtures for manufacturing thin-walled aircraft engine components made of 17-4 PH steel reduces the propensity of these components for distortion due to the effects of the thermal cycle of the welding process. This conclusion is supported by the results of the observation of the microstructure and analysis of the chemical composition of the various zones of the welded joint area.

Near-Field Microwave Microscopy for 3D Surface Assessment of Manufactured Structures

Using near-field scanning microwave microscopy as a contact and non-contacting investigative tool for 3D surface metrology with three differing measurement modes, it has been possible to analyse structures that may be difficult for existing metrology systems. The system utilizes the small change in capacitance between a coaxial resonant probe (at around 2 GHz) ending in an open circuit tip, and the sample surface. This is measured in the frequency domain by the shift in the resonance frequency of the voltage transmission coefficient |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> |. It is also possible to investigate various materials (metallics, plastics etc.) owing to their differing dielectric properties. The probe has been tested on a computer-controlled 3D stage but is suitable for incorporation into a commercial co-ordinate measurement machine (CMM) to enhance its capability to inspect the inside surfaces of structures, e.g., threads in small bores.

Comparison of fatigue life behavior between deep groove radial ball bearings possessing conventional and micro-grooved outer races operating under dry condition

A comparative study on fatigue life of deep groove radial ball bearings possessing conventional and micro-grooved outer races by experimental investigation is discussed in this paper. This research has been carried out to explore and understand the fatigue life of a micro-grooved ball bearing (MGB) with a circumferential micro-groove on outer race by conducting long duration tests under dry condition (i.e. wiping out the applied grease from the races by using tissue paper and lint free cloth) and compare the results with same size SKF BB1B 420206 conventional bearing (CB) at the identical operating parameters. Frictional torque (FT), bulk temperature, and overall vibration level of the test bearings (CB and MGB) at the maximum load zone have been measured at 800 N ( pH = 1.7 GPa) radial load and 1800 rpm (4.2 m/s) for the entire duration (7.8 million revolutions) of the experiments. Comparison of the surface conditions of the bearing components by means of the captured scanning electron microscope (SEM) images, roundness and deviation in profile of the races measured by co-ordinate measuring machine (CMM), and photographs captured before and after the experiment indicates lesser damage of the MGB components as compared to the conventional cases. Moreover, the initiation of fatigue failure in CBs is faster as compared to the MGBs for the same test condition, indicating longer bearing life in MGBs as compared to the CBs.

WILL MODEL-BASED DEFINITION ACCELERATE THE INSPECTION PHASE IN THE MANUFACTURING PROCESS?

AbstractModel-Based Definition provides several benefits for communicating between engineering and other downstream stakeholders. Particularly, semantic PMI information included in 3D models benefits both CAM programming and inspection phases. However, the efficiency of generating CAM- and CAI codes automatically according to the semantic PMI information varies due to the compatibility of different systems. This paper focuses on the experiment that we made on inspecting three different parts with the Coordinate Measuring Machine (CMM). We compared four different programming methods and found that the efficiency of inspecting depends on the serial size of the parts. The completely automatic CAI-programming method does not necessarily produce the most effective CAI code compared to the competent human programmer. This is notable, especially in large series due to achieved cumulative time savings in the inspection of each part. With small series, fully automatic PMI method and human-assisted automatic PMIfp method provide significant benefits in the inspection process due to time savings in CAI-programming work.

Effect of Lankford Coefficients on Springback Behavior during Deep Drawing of Stainless Steel Cylinders.

Accurate prediction of springback is increasingly required during deep-drawing formation of anisotropic stainless steel sheets. The anisotropy of sheet thickness direction is very important for predicting the springback and final shape of a workpiece. The effect of Lankford coefficients (r00, r45, r90) with different angles on springback was investigated using numerical simulation and experiments. The results show that the Lankford coefficients with different angles each have a different influence on springback. The diameter of the straight wall of the cylinder along the 45-degree direction decreased after springback, and showed a concave valley shape. The Lankford coefficient r90 had the greatest effect on the bottom ground springback, followed by r45 and then r00. A correlation was established between the springback of workpiece and Lankford coefficients. The experimental springback values were obtained by using a coordinate-measuring machine and showed good agreement with the numerical simulation results.

Geometric Error Parameterization of a CMM via Calibrated Hole Plate Archived Utilizing DCC Formatting

This study implemented the measurement results and administrative information obtained from the hole plate into the Digital Calibration Certificate (DCC). The DCC comprises three parts: Norms and Standards, Hierarchical Structure, and XML as Exchange Format. DCCs play a significant role in the field of metrology and statistics by ensuring data interoperability, correctness, and traceability during the conversion and transmission process. The hole plate is a length standard used for two-dimensional geometric error measurements. We evaluated the accuracy of the high-precision coordinate measuring machine (CMM) in measuring a hole plate and compared the measurement error results obtained from the hole plate with those of the laser interferometer, autocollimator, and angle square. The results show that the maximum difference in linear error is −0.30 μm, the maximum difference in angle error is −0.78″, and the maximum difference in squareness error is 4.54″. The XML is designed for machine-readability and is modeled and edited using the XMLSpy 2022 software, which is based on information published by PTB. The administrative management and measurement results tasks are presented in PDF format, which is designed for human-readability and ease of use. Overall, we implemented the measurement results and information obtained from the hole plate into the DCC.

A Novel Iterative Field Search Approach to Minimum Zone Circle for Roundness Error Estimation

Abstract Roundness is one of the common attributes in the manufacturing industry. Roundness is the most prominent of the extant fundamental forms, as the majority of the fabricated components are round or cylindrical. The examination of roundness error associated with such features is critical since inadequate evaluation might result in the rejection of excellent parts. The performance of any equipment depends on the mating parts. Out-of-roundness components cause the inefficiency of such equipment’s system performance. As a result, roundness error assessment is critical for macro-sized specimens as well as for micro- and nano-sized components. The present article proposes a novel approach to Minimum Zone Circle (MZC) to evaluate the roundness error. An iterative field search methodology is used in the suggested approach. The proposed methodology evaluates the roundness error based on the generated discretized points within the search space and continues the same by decreasing the search space with an increase in the number of iterations to attain the Minimum Zone Error (MZE). The proposed algorithm has been tested with ten CMM (coordinate measuring machine) datasets and ten form datasets available in the literature studies and found to be excellent in comparison to the existing techniques. Further, the proposed methodology was also implemented to estimate the MZE of centerless ground specimens at multiple cross sections, and the roundness error obtained was lesser as compared to the LSC, MCC, and MIC. The number of generated discretized points is flexible and can be varied to reduce the number of iterations and computations. The recommended method is quite effective in assessing the roundness error when compared to the existing techniques. It also works well on data that was both evenly and unevenly spaced. The results suggest that altering the search field area for higher computing efficiency is straightforward, resilient, and versatile.

Development of fused metrology methods for the analysis of hip implant tribology

In order to advance the study of wear phenomena involved in total hip implants a fused metrology system has been designed and constructed. The novel fixture system has been designed and built to facilitate large area surface measurement for hip implant bearing wear. The system allows coordinate measurement machine (CMM) wear map data to be used for precise positional targeting of areal surface metrology using high spatial resolution optical interferometry. The complete measurement process allows Coordinate Measuring Machine measurement and surface metrology datasets to be ‘fused’ thus facilitating carefully positioned wear scar analysis. The fixture utilises two digital rotary stages, in a gimble configuration, to precisely position the bearing component during CMM measurement and surface metrology. To test the effectiveness of the fixture system a cohort of explanted large metal-on-metal (MoM) femoral heads were assessed. Application of the fixture system allowed a set of grouped surface measurements were taken within the wear area, the wear area boundary region, and at unworn locations across the femoral heads. Additionally, a series of stitched surface measurements are taken through the entire wear area and combined into a single surface measurement. The ‘fusion’ method, allowed areas of roughening (or smoothing) to be estimated and overlayed on the corresponding CMM wear map. The developed fixture system allows for better understanding of hip implant performance. Combined with areal surface metrology parameters such as areal average surface roughness Sa, developed surface area ration Sdr and areal surface skewness, Ssk the system could be utilised understand the wear mechanisms for both explanted, in-vitro and in-vivo wear testing and also detailed quality inspection of newly manufactured components. The significance of the system deployment is that wear location and detailed mechanism can be studied simultaneously, thus delivering understanding of typical wear mechanisms and hence the fixture becomes a tool for developing increased implant life through understanding surface interactions.

A COMPARATIVE STUDY ON PRECISION METROLOGY SYSTEMS FOR ADDITIVE MANUFACTURING

This paper presents a comparative study on precision metrology systems such as Coordinate Measuring Machine (CMM), 3-Dimensional Scanning (3DS) and Computed Tomography (CT) for polymer additive manufacturing. A special test sample was designed and manufactured by Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) AM systems. The manufactured parts were then measured by three different precision metrology systems and the results were compared in terms of different measurement and AM methods. Uncertainty analyses were conducted based on the results of CMM measurements. The benchmark highlighted the difference between part characteristics manufactured by FDM and SLS, where FDM part represented higher surface roughness and more deviation to the nominal design. Furthermore, expanded uncertainties computed for the FDM manufactured part were almost three times of the uncertainties computed for the SLS manufactured part. It was also demonstrated that one of the major contributors to the expanded uncertainty occurred because of rougher surface of FDM manufactured part. Similar tendency of part to nominal deviations were observable in all metrology systems including CMM, CT and 3DS. Findings of the study revealed the need of standardized measurement for inspection and control of AM parts.

What to Prefer in Patients with Multibracket Appliances? Digital vs. Conventional Full-Arch Impressions-A Reference Aid-Based In Vivo Study.

This study aimed to investigate the transfer accuracy and required time for digital full-arch impressions obtained from intraoral scanners (IOSs) versus conventional alginate impressions (CAIs) in patients with multibracket appliances (MBA). Thirty patients with buccal MBAs (metal brackets, archwire removed) were examined using an established reference aid method. Impression-taking using four IOSs (Primescan, Trios 4, Medit i700, Emerald S) and one CAI with subsequent plaster casting were conducted. One-hundred-twenty (n = 30 × 4) scans were analyzed with 3D software (GOM Inspect) and 30 (n = 30 × 1) casts were assessed using a coordinate measurement machine. Six distances and six angles were measured and compared to the reference aid values (ANOVA; p < 0.05). Except for the intermolar distance, transfer accuracy was significantly higher with IOSs than with CAIs (p < 0.05). No such difference was found regarding the six angles. In patients with MBAs, digital impression-taking using IOSs can be recommended. For all measured variables except one, the transfer accuracy of IOSs was better than or at least equivalent to the data from CAIs. In addition, significantly (p < 0.001) less time was necessary for all IOSs in comparison to CAIs plus plaster casting.

Effect of deep cryogenic processing cycles on surface roughness, dimensional stability and microstructure of high carbon high chromium tool steel for cutting tool and dies applications

Abstract The main objective of this investigation is to analyze the influence of DCT cycles on microstructural evolution, surface roughness, hardness and dimensional stability of AISI D2 tool steel for cutting tools and dies applications. The cryogenic quenching was done using gaseous nitrogen. The AISI D2 tool steel was subjected to two DCT cycle: DCT-I (Hardening + DCT + tempering) and DCT-II (Hardening + tempering + DCT). The dimensional stability of AISI D2 tool steel was evaluated using standard Navy C-ring test. The coordinate measuring machine (CMM) was employed for the precise measurement of Navy C-ring subjected to different DCT cycle. The surface roughness was evaluated with R a (arithmetic mean roughness) and R t (total height of roughness profile) values using surface roughness tester. The microstructural features were analyzed using optical (OM) and scanning electron microscopy (SEM). The electrical resistivity and hardness of treated samples were measured using micro-Ohm meter and Vickers microhardness tester. Results showed that AISI D2 tool steel treated with DCT-I cycle exhibited greater surface finish, hardness and dimensional stability compared to DCT-II cycle. It is mainly attributed to the greater precipitation of finer carbides and balancing of tensile-compressive residual stresses.

Predictability of intraoral scanner error for full-arch implant-supported rehabilitation

ObjectivesThe present study aimed to analyze the behaviors of three intraoral scanners (IOSs): evaluating the interdistance and axial inclination discrepancies in full-arch scans, predictable errors were searched.Materials and methodsSix edentulous sample models with variable numbers of dental implants were used; reference data were obtained with a coordinate-measuring machine (CMM). Each IOS (i.e., Primescan, CS3600, and Trios3) performed 10 scans per model (180 total scans). The origin of each scan body was used as a reference point to measure interdistance lengths and axial inclinations. Precision and trueness of interdistance measurements and axial inclinations were evaluated to address error predictability. Bland–Altman analysis, followed by linear regression analysis and Friedman’s test (plus Dunn’s post hoc correction), was performed to evaluate the precision and trueness.ResultsRegarding interdistance, Primescan showed the best precision (mean ± SD: 0.047 ± 0.020 mm), while Trios3 underestimated the reference value more than the others (p < 0.001) and had the worst performance (mean ± SD: −0.079 ± 0.048 mm).Concerning the inclination angle, Primescan and Trios3 tended to overestimate angle values, while CS3600 underestimated them. Primescan had fewer inclination angle outliers, but it tended to add 0.4–0.6° to the measurements.ConclusionsIOSs showed predictable errors: they tended to overestimate or underestimate linear measurements and axial inclinations of scan bodies, one added 0.4–0.6° to the angle inclination values. In particular, they showed heteroscedasticity, a behavior probably related to the software or the device itself.Clinical significanceIOSs showed predictable errors that could affect clinical success. When performing a scan or choosing a scanner, clinicians should clearly know their behaviors.

Experimental Study and Predictive Modelling of Fused Deposition Modelling (FDM) Using TOPSIS and Fuzzy Logic Expert System

Fused deposition modeling (FDM) is a well-liked additive fabrication method used to manufacture prototypes and components in industries. The quality of the 3D printed component depends on the temperature profile between the layers of the printed components and the process parameters. The deviations in the quality of manufactured components can be established using tools of metrology, including Coordinate-Measuring Machine and Machine Vision. This research is to determine the effect of temperature on the aforementioned phenomenon by using collected data to build a predictive model. The leading factor effect intrigue is stressed for the correlative closeness coefficient (Cn*) and Technique for Order of Preference by Similarity to Ideal Solution(TOPSIS). The most favorable combinations of the experiment were obtained from the response diagram at a layer thickness of 0.3 mm, print speed of 80 mm/sec, and infill percentage of 20%. It is noted that the parameters have a contribution of 55.60%, 33.16%, and 0.15%, respectively. The majority of agreeable combinations of the investigations were acquired from the main factor effect response diagram, a layer thickness of 0.3 mm, printing FDM speed of 80 mm/sec, and an infill percentage of material is 20% for maximizing the temperature gradient and minimizing shrinkage and warpage. A fuzzy logic expert system was used to predict the shrinkage allowances precisely with less than 5% error.

Uncertainty-aware temperature interpolation for measurement rooms using ordinary Kriging

Accurate measurements in dimensional metrology necessitate strict controls on spatial and temporal variations in the measurement room temperature. Due to limitations in the number of sensors that can be placed in a given room, interpolation methods that leverage information from multiple sensors are necessary to assess conditions at unsampled locations. In this contribution, Kriging is used to spatially interpolate room temperatures from a limited number of sensors with different measurement uncertainties in a temperature controlled room housing two coordinate measurement machines. A novel method to propagate sensor uncertainties to the interpolated values using a Monte Carlo simulation is also demonstrated. The uncertainty propagation is considered for the explicitly heteroskedastic, i.e. a constituent network of sensors with different measurement uncertainties. The influence of a localized disturbance in the form of a movable heating element in the room is also investigated.

Thermomechanical Process Simulation and Experimental Verification for Laser Additive Manufacturing of Inconel®718

Laser cladding has emerged as a promising technique for custom-built fabrications, remanufacturing, and repair of metallic components. However, frequent melting and solidification in the process cause inevitable residual stresses that often lead to geometric discrepancies and deterioration of the end product. The accurate physical interpretation of the powder consolidation process remains challenging. Thermomechanical process simulation has the potential to comprehend the layer-by-layer additive process and subsequent part-scale implications. Nevertheless, computational accuracy and efficacy have been serious concerns so far; therefore, a hybrid FEM scheme is adopted for efficient prediction of the temperature field, residual stress, and distortion in multilayer powder-fed laser cladding of Inconel®718. A transient material deposition with powder material modeling is schematized to replicate the fabrication process. Moreover, simulation results for residual stress and distortion are verified with in-house experiments, where residual stress is measured with XRD (X-Ray Diffraction) and geometric distortion is evaluated with CMM (Coordinate Measuring Machine). A maximum tensile residual stress of 373 ± 5 MPa is found in the vicinity of the layer right in the middle of the substrate and predicted results are precisely validated with experiments. Similarly, a 0.68 ± 0.01 mm distortion is observed with numerical simulation and showed a precise agreement with experimental data for the same geometry and processing conditions. Conclusively, the implemented hybrid FEM approach demonstrated a robust and accurate prediction of transient temperature field, residual stresses, and geometric distortion in the multilayer laser cladding of Inconel®718.