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AR Category: Profilometry Testing
Pharmaceutical Tablets Surface Roughness Inspection
Pharmaceutical Tablets
Inspecting Roughness using 3d profilometers
Author:
Jocelyn Esparza
Introduction
Pharmaceutical tablets are the most popular medicinal dosage used today. Each tablet is made up by a combination of active substances (the chemicals that produce pharmacological effect) and inactive substances (disintegrant, binder, lubricant, diluent – usually in the form of powder). The active and inactive substances are then compressed or molded into a solid. Then, depending on the manufacturer specifications, the tablets are either coated or uncoated.
To be effective, tablet coatings need to follow the fine contours of embossed logos or characters on tablets, they need to be stable and sturdy enough to survive handling of the tablet, and they must not cause the tablets to stick to each other during the coating process. Current tablets typically have a polysaccharide and polymer-based coating which include substances like pigments and plasticizers. The two most common types of table coatings are film coatings and sugar coating. Compared to sugar coatings, film coatings are less bulky, more durable, and are less time-consuming to prepare and apply. However, film coatings have more difficulty hiding tablet appearance.
Tablet coatings are essential for moisture protection, masking the taste of the ingredients, and making the tablets easier to swallow. More importantly, the tablet coating controls the location and the rate in which the drug is released.
MEASUREMENT OBJECTIVE
In this application, we use the NANOVEA Optical Profiler and advanced Mountains software to measure and quantify the topography of various name brand pressed pills (1 coated and 2 uncoated) to compare their surface roughness.
It is assumed that Advil (coated) will have the lowest surface roughness due to the protective coating it has.
NANOVEA
HS2000
Test Conditions
Three batches of name brand pharmaceutical pressed tablets were scanned with the Nanovea HS2000
using High-Speed Line Sensor to measure various surface roughness parameters according to ISO 25178.
Scan Area
2 x 2 mm
Lateral Scan Resolution
5 x 5 μm
Scan Time
4 sec
Samples
Results & Discussion
After scanning the tablets, a surface roughness study was conducted with the advanced Mountains analysis software to calculate the surface average, root-mean-square, and maximum height of each tablet.
The calculated values support the assumption that Advil has a lower surface roughness due to the protective coating encasing its ingredients. Tylenol shows to have the highest surface roughness out of all three measured tablets.
A 2D and 3D height map of each tablet’s surface topography was produced which show the height distributions measured. One out of the five tablets were selected to represent the height maps for each brand. These height maps make a great tool for visual detection of outlying surface features such as pits or peaks.
Conclusion
In this study, we analyzed and compared the surface roughness of three name brand pressed pharmaceutical pills: Advil, Tylenol, and Excedrin. Advil proved to have the lowest average surface roughness. This can be attributed to the presence of the orange coating incasing the drug. In contrast, both Excedrin and Tylenol lack coatings, however, their surface roughness still differ from each other. Tylenol proved to have the highest average surface roughness out of all the tablets studied.
Using the NANOVEA HS2000 with High-Speed Line Sensor, we were able to measure 5 tablets in less than 1 minute. This can prove to be useful for quality control testing of hundreds of pills in a production today.
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Dental Tools: Dimensional and Surface Roughness Analysis
INTRODUCTION
Having precise dimensions and optimal surface roughness are vital to the functionality of dental screws. Many dental screw dimensions require high precision such as radii, angles, distances, and step heights. Understanding local surface roughness is also highly important for any medical tool or part being inserted inside the human body to minimize sliding friction.
NON-CONTACT PROFILOMETRY FOR DIMENSIONAL STUDY
Nanovea 3D Non-Contact Profilers use a chromatic light-based technology to measure any material surface: transparent, opaque, specular, diffusive, polished or rough. Unlike a touch probe technique, the non-contact technique can measure inside tight areas and will not add any intrinsic errors due to deformation caused by the tip pressing on a softer plastic material. Chromatic light-based technology also offers superior lateral and height accuracies compared to focus variation technology. Nanovea Profilers can scan large surfaces directly without stitching and profile the length of a part in a few seconds. Nano through macro range surface features and high surface angles can be measured due to the profiler’s ability to measure surfaces without any complex algorithms manipulating the results.
MEASUREMENT OBJECTIVE
In this application, the Nanovea ST400 Optical Profiler was used to measure a dental screw along flat and thread features in a single measurement. The surface roughness was calculated from the flat area, and various dimensions of the threaded features were determined.
Sample of dental screw analyzed by NANOVEA Optical Profiler.
Dental screw sample analyzed.
RESULTS
3D Surface
The 3D View and False Color View of the dental screw shows a flat area with threading starting on either side. It provides users a straightforward tool to directly observe the morphology of the screw from different angles. The flat area was extracted from the full scan to measure its surface roughness.
2D Surface Analysis
Line profiles can also be extracted from the surface to show a cross-sectional view of the screw. The Contour Analysis and step height studies were used to measure precise dimensions at a certain location on the screw.
CONCLUSION
In this application, we have showcase the Nanovea 3D Non-Contact Profiler’s ability to precisely calculate local surface roughness and measure large dimensional features in a single scan.
The data shows a local surface roughness of 0.9637 μm. The radius of the screw between threads was found to be 1.729 mm, and the threads had an average height of 0.413 mm. The average angle between the threads was determined to be 61.3°.
The data shown here represents only a portion of the calculations available in the analysis software.
Prepared by
Duanjie Li, PhD., Jonathan Thomas, and Pierre Leroux
In-line Roughness Inspection
Instant Error Detection With In-Line Profilers
Learn more
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IMPORTANCE OF NON-CONTACT PROFILER FOR IN-LINE ROUGHNESS INSPECTION
Surface defects derive from materials processing and product manufacturing. In-line surface quality inspection ensures the tightest quality control of the end products. The Nanovea 3D Non-Contact Profilometers utilize chromatic confocal technology with a unique capability to determine the roughness of a sample with-out contact. Multiple profiler sensors can be installed to monitor the roughness and texture of different areas of the product at the same time. The roughness threshold calculated in real-time by the analysis software serves as a fast and reliable pass/fail tool.
MEASUREMENT OBJECTIVE
In this study, the Nanovea roughness inspection conveyor system equipped with a point sensor is used to inspect the surface roughness of the acrylic and sandpaper samples. We showcase the capacity of Nanovea non-contact profilometer in providing fast and reliable in-line roughness inspection in a production line in real-time.
RESULTS AND DISCUSSION
The conveyor profilometer system can operate in two modes, namely Trigger Mode and Continuous Mode. As illustrated in Figure 2, the surface roughness of the samples are measured when they are passing under the optical profiler heads under the Trigger Mode. In comparison, Continuous Mode provides non-stop measurement of the surface roughness on the continuous sample, such as metal sheet and fabric. Multiple optical profiler sensors can be installed to monitor and record the roughness of different sample areas.
During the real-time roughness inspection measurement, the pass and fail alerts are displayed on the software windows as shown in Figure 4 and Figure 5. When the roughness value is within the given thresholds, the measured roughness is highlighted in green color. However, the highlight turns red when the measured surface roughness is out of the range of the set threshold values. This provides a tool for the user to determine the quality of a product’s surface finish.
In the following sections, two types of samples, e.g. Acrylic and Sandpaper are used to demonstrate the Trigger and Continuous Modes of the Inspection system.
Trigger Mode: Surface inspection of the Acrylic Sample
A series of Acrylic samples are aligned on the conveyor belt and move under the optical profiler head as shown in Figure 1. The false color view in Figure 6 shows the change of the surface height. Some of the mirror-like finished Acrylic samples had been sanded to create a rough surface texture as shown in Figure 6b.
As the Acrylic samples move at a constant speed under the optical profiler head, the surface profile is measured as shown in Figure 7 and Figure 8. The roughness value of the measured profile is calculated at the same time and compared to the threshold values. The red fail alert is launched when the roughness value is over the set threshold, allowing users to immediately detect and locate the defective product on the production line.
Continuous Mode: Surface Inspection of the sandpaper sample
Surface Height Map, Roughness Distribution Map, and Pass / Fail Roughness Threshold Map of the sandpaper sample surface as shown in Figure 9. The sandpaper sample has a couple of higher peaks in the used part as shown in the surface height map. The different colors in the pallet of Figure 9C represent the roughness value of the local surface. The Roughness Map exhibits a homogeneous roughness in the intact area of the sandpaper sample, while the used area is highlighted in dark blue color, indicating the reduced roughness value in this region. A Pass/Fail roughness threshold can be set up to locate such regions as shown in Figure 9D.
As the sandpaper continuously passes under the in-line profiler sensor, the real-time local roughness value is calculated and recorded as plotted in Figure 10. The pass/fail alerts are displayed on the software screen based on the set roughness threshold values, serving as a fast and reliable tool for quality control. The product surface quality in the production line is inspected in situ to discover defective areas in time.
CONCLUSION
In this application, we have shown the Nanovea Conveyor Profilometer equipped with an optical non-contact profiler sensor works as a reliable in-line quality control tool effectively and efficiently.
The inspection system can be installed in the production line to monitor the surface quality of the products in situ. The roughness threshold works as a dependable criteria to determine the surface quality of the products, allowing users to notice the defective products in time. Two inspection modes, namely Trigger Mode and Continuous Mode, are provided to meet the requirement for inspection on different types of products.
The data shown here represent only a portion of the calculations available in the analysis software. Nanovea Profilometers measure virtually any surface in fields including Semiconductor, Microelectronics, Solar, Fiber, Optics, Automotive, Aerospace, Metallurgy, Machining, Coatings, Pharmaceutical, Biomedical, Environmental and many others.
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Block-On-Ring Wear Test
IMPORTANCE OF BLOCK-ON-RING WEAR EVALUATION
Sliding wear is the progressive loss of material that results from two materials sliding against each other at the contact area under load. It occurs inevitably in a wide variety of industries where machines and engines are in operation, including automotive, aerospace, oil & gas and many others. Such sliding motion causes serious mechanical wear and material transfer at the surface, which may lead to reduced production efficiency, machine performance or even damage to the machine.
Sliding wear often involves complex wear mechanisms taking place at the contact surface, such as adhesion wear, two-body abrasion, three-body abrasion and fatigue wear. The wear behavior of materials is significantly influenced by the work environment, such as normal loading, speed, corrosion and lubrication. A versatile tribometer that can simulate the different realistic work conditions will be ideal for wear evaluation.
Block-on-Ring (ASTM G77) test is a widely used technique that evaluates the sliding wear behaviors of materials in different simulated conditions, allows reliable ranking of material couples for specific tribological applications.
Block-on-Ring (ASTM G77) test is a widely used technique that evaluates the sliding wear behaviors of materials in different simulated conditions, allows reliable ranking of material couples for specific tribological applications.
MEASUREMENT OBJECTIVE
In this application, the Nanovea Mechanical Tester measures the YS and UTS of stainless steel SS304 and aluminum Al6061 metal alloy samples. The samples were chosen for their commonly recognized YS and UTS values showing the reliability of Nanovea’s indentation methods.
The sliding wear behavior of an H-30 block on an S-10 ring was evaluated by Nanovea’s tribometer using the Block-on-Ring module. The H-30 block is made of 01 tool steel of 30HRC hardness, while the S-10 ring is steel type 4620 of surface hardness 58 to 63 HRC and ring diameter of ~34.98 mm. Block-on-Ring tests were performed in dry and lubricated environments to investigate the effect on wear behavior. Lubrication tests were performed in USP heavy mineral oil. The wear track was examined using Nanovea’s 3D non-contact profilometer. Test parameters are summarized in Table 1. The wear rate (K), was evaluated using the formula K=V/(F×s), where V is the worn volume, F is the normal load, s is the sliding distance.
RESULTS AND DISCUSSION
Figure 2 compares the coefficient of friction (COF) of the Block-on-Ring tests in dry and lubricated environments. The block has significantly more friction in a dry environment than a lubricated environment. COF
fluctuates during the run-in period in the first 50-revolution and reaches a constant COF of ~0.8 for the rest of the 200-revolution wear test. In comparison, the Block-on-Ring test performed in the USP heavy mineral oil lubrication exhibits constant low COF of 0.09 throughout the 500,000-revolution wear test. The lubricant significantly reduces the COF between the surfaces by ~90 times.
Figures 3 and 4 show the optical images and cross-section 2D profiles of the wear scars on the blocks after dry and lubricated wear tests. The wear track volumes and wear rates are listed in Table 2. The steel block after the dry wear test at a lower rotational speed of 72 rpm for 200 revolutions exhibits a large wear scar volume of 9.45 mm˙. In comparison, the wear test carried out at a higher speed of 197 rpm for 500,000 revolutions in the mineral oil lubricant creates a substantially smaller wear track volume of 0.03 mm˙.
The images in ÿgure 3 show severe wear takes place during tests in the dry conditions compared to the mild wear from the lubricated wear test. High heat and intense vibrations generated during the dry wear test promotes oxidation of metallic debris resulting in severe three-body abrasion. In the lubricated test the mineral oil reduces friction and cools the contact face as well as transporting abrasive debris created during wear away. This leads to signiÿcant reduction of wear rate by a factor of ~8×10ˆ. Such a substantial di˛erence in wear resistance in di˛erent environments shows the importance of proper sliding wear simulation in realistic service conditions.
Wear behavior can change drastically when small changes in test conditions are introduced. The versatility of Nanovea’s tribometer allows wear measurement in high temperature, lubrication, and tribocorrosion conditions. The accurate speed and position control by the advanced motor enables wear tests to be performed at speeds ranging from 0.001 to 5000 rpm, making it an ideal tool for research/testing labs to investigate the wear in di˛erent tribological conditions.
The surface condition of the samples was examined by Nanovea’s non-contact optical proÿlometer. Figure 5 shows the surface morphology of the rings after the wear tests. The cylinder form is removed to better present the surface morphology and roughness created by the sliding wear process. Signiÿcant surface roughening took place due to the three-body abrasion process during the dry wear test of 200 revolutions. The block and ring after the dry wear test exhibit a roughness Ra of 14.1 and 18.1 µm, respectively, compared to 5.7 and 9.1 µm for the long-term 500,000 – revolution lubricated wear test at a higher speed. This test demonstrates the importance of proper lubrication of piston ring-cylinder contact. Severe wear quickly damages the contact surface without lubrication and leads to irreversible deterioration of the service quality and even breakage of the engine.
CONCLUSION
In this study we showcase how Nanovea’s Tribometer is used to evaluate the sliding wear behavior of a steel metal couple using the Block-on-Ring module following the ASTM G77 Standard. The lubricant plays a critical role in the wear properties of the material couple. The mineral oil reduces the wear rate of the H-30 block by a factor of ~8×10ˆ and the COF by ~90 times. The versatility of Nanovea’s Tribometer makes it an ideal tool for measuring wear behavior under various lubrication, high temperature, and tribocorrosion conditions.
Nanovea’s Tribometer o˛ers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modes, with optional high-temperature wear, lubrication, and tribo-corrosion modules available in one pre-integrated system. Nanovea’s unmatched range is an ideal solution for determining the full range of tribological properties of thin or thick, soft, or hard coatings, ÿlms, and substrates.
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Composite Material Analysis using 3D Profilometry
Importance of Non-Contact Profilometry for Composite Materials
It is crucial defects are minimized so composite materials are as strong as possible in reinforcement applications. As an anisotropic material, it is critical weave direction is consistent to maintain high performance predictability. Composite materials have one of the highest strength to weight ratios making it stronger than steel in some cases. It is important to limit exposed surface area in composites to minimize chemical vulnerability and thermal expansion effects. Profilometry surface inspection is critical to quality control production of composites to ensure strong performance over a long service time.
Nanovea’s 3D Non-Contact Profilometer is unlike other surface measurement techniques such as touch probes or interferometry. Our profilometers use axial chromatism to measure nearly any surface and open staging allows for samples of any size with no preparation needed. Nano through macro measurements are obtained during surface profile measurement with zero influence from sample reflectivity or absorption. Our profilometers easily measure any material: transparent, opaque, specular, diffusive, polished, and rough with the advanced ability to measure high surface angles with no software manipulation. The Non-Contact Profilometer technique provides the ideal and user-friendly capability to maximize composite material surface studies; along with the benefits of combined 2D & 3D capability.
Measurement Objective
The Nanovea HS2000L Profilometer used in this application measured the surface of two weaves of carbon fiber composites. Surface roughness, weave length, isotropy, fractal analysis, and other surface parameters are used to characterize the composites. The area measured was randomly selected and assumed large enough that property values can be compared using Nanovea’s powerful surface analysis software.
Results and Discussion
Surface Analysis
Height parameters determine how rough composite parts will be with a low fiber to matrix ratio. Our results compare different weave types and fabric to determine surface finish post-processing. Surface finish becomes critical in applications where aerodynamics may become involved.
Isotropy
Isotropy shows directionality of the weave to determine expected property values. Our study shows how the bidirectional composite is ~60% isotropic as expected. Meanwhile, the unidirectional composite is ~13% isotropic due to the strong single fiber path direction fiber.
Weave Analysis
Weave size determines the consistency of packing and width of fibers used in the composite. Our study shows how easily we can measure weave size down to micron accuracy to ensure quality parts.
Texture Analysis
Texture analysis of the dominant wavelength suggests strand size for both composites are 4.27 microns thick. Fractal dimension analysis of the fiber surface determines smoothness to find how easily fibers will set in a matrix. The fractal dimension of the unidirectional fiber is higher than the bidirectional fiber which may affect the processing of composites.
Conclusion
In this application, we have shown the Nanovea HS2000L Non-Contact Profilometer precisely characterizes the fibrous surface of composite materials. We distinguished differences between weave types of carbon fiber with height parameters, isotropy, texture analysis, and distance measurements along with much more.
Our profilometer surface measurements precisely and quickly mitigate composite damage which decreases defects in parts, maximizing composite material capability. Nanovea’s 3D profilometer speed ranges from <1mm/s to 500mm/s for suitability in research applications to the needs of high-speed inspection. The Nanovea profilometer is the solution
to any composite measurement need.
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Wear and Scratch Evaluation of Surface Treated Copper Wire
Importance of Wear and Scratch Evaluation of Copper Wire
Copper has a long history of use in electric wiring since the invention of the electromagnet and telegraph. Copper wires are applied in a wide range of electronic equipment such as panels, meters, computers, business machines, and appliances thanks to its corrosion resistance, solderability, and performance at elevated temperatures up to 150°C. Approximately half of all mined copper is used for manufacturing electrical wire and cable conductors.
Copper wire surface quality is critical to application service performance and lifetime. Micro defects in wires may lead to excessive wear, crack initiation and propagation, decreased conductivity, and inadequate solderability. Proper surface treatment of copper wires removes surface defects generated during wire drawing improving corrosion, scratch, and wear resistance. Many aerospace applications with copper wires require controlled behavior to prevent unexpected equipment failure. Quantifiable and reliable measurements are needed to properly evaluate the wear and scratch resistance of the copper wire surface.
Measurement Objective
In this application we simulate a controlled wear process of different copper wire surface treatments. Scratch testing measures the load required to cause failure on the treated surface layer. This study showcases the Nanovea Tribometer and Mechanical Tester as ideal tools for evaluation and quality control of electric wires.
Test Procedure and Procedures
Coefficient of friction (COF) and wear resistance of two different surface treatments on copper wires (Wire A and Wire B) were evaluated by the Nanovea tribometer using a linear reciprocating wear module. An Al₂O₃ ball (6 mm diameter) is the counter material used in this application. The wear track was examined using Nanovea’s 3D non-contact profilometer. Test parameters are summarized in Table 1.
A smooth Al₂O₃ ball as a counter material was used as an example in this study. Any solid material with different shape and surface finish can be applied using a custom fixture to simulate the actual application situation.
Nanovea’s mechanical tester equipped with a Rockwell C diamond stylus (100 μm radius) performed progressive load scratch tests on the coated wires using micro scratch mode. Scratch test parameters and tip geometry are shown in Table 2.
Results and Discussion
Wear of copper wire:
Figure 2 shows COF evolution of the copper wires during wear tests. Wire A shows a stable COF of ~0.4 throughout the wear test while wire B exhibits a COF of ~0.35 in the first 100 revolutions and progressively increases to ~0.4.
Figure 3 compares wear tracks of the copper wires after tests. Nanovea’s 3D non-contact profilometer offered superior analysis of the detailed morphology of wear tracks. It allows direct and accurate determination of the wear track volume by providing a fundamental understanding of the wear mechanism. Wire B’s surface has signi¬ficant wear track damage after a 600-revolution wear test. The profilometer 3D view shows the surface treated layer of Wire B removed completely which substantially accelerated the wear process. This left a flattened wear track on Wire B where copper substrate is exposed. This may result in significantly shortened lifespan of electrical equipment where Wire B is used. In comparison, Wire A exhibits relatively mild wear shown by a shallow wear track on the surface. The surface treated layer on Wire A did not remove like the layer on Wire B under the same conditions.
Scratch resistance of the copper wire surface:
Figure 4 shows the scratch tracks on the wires after testing. The protective layer of Wire A exhibits very good scratch resistance. It delaminates at a load of ~12.6 N. In comparison, the protective layer of Wire B failed at a load of ~1.0 N. Such a significant difference in scratch resistance for these wires contributes to their wear performance, where Wire A possesses substantially enhanced wear resistance. The evolution of normal force, COF, and depth during the scratch tests shown in Fig. 5 provides more insight on coating failure during tests.
Conclusion
In this controlled study we showcased the Nanovea’s tribometer conducting quantitative evaluation of wear resistance for surface treated copper wires and Nanovea’s mechanical tester providing reliable assessment of copper wire scratch resistance. Wire surface treatment plays a critical role in the tribo-mechanical properties during their lifetime. Proper surface treatment on Wire A significantly enhanced wear and scratch resistance, critical in the performance and lifespan of electrical wires in rough environments.
Nanovea’s tribometer offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modes, with optional high temperature wear, lubrication, and tribo-corrosion modules available in one pre-integrated system. Nanovea’s unmatched range is an ideal solution for determining the full range of tribological properties of thin or thick, soft or hard coatings, films, and substrates.
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Dynamic Load Tribology
Dynamic Load Tribology
Introduction
Wear takes place in virtually every industrial sector and imposes costs of ~0.75% of the GDP1. Tribology research is vital in improving production efficiency, application performance, as well as conservation of material, energy, and the environment. Vibration and oscillation inevitably occur in a wide range of tribological applications. Excessive external vibration accelerates the wear process and reduces service performance which leads to catastrophic failures to the mechanical parts.
Conventional dead load tribometers apply normal loads by mass weights. Such a loading technique not only limits the loading options to a constant load, but it also creates intense uncontrolled vibrations at high loads and speeds leading to limited and inconsistent wear behavior assessments. A reliable evaluation of the effect of controlled oscillation on the wear behavior of materials is desirable for R&D and QC in different industrial applications.
Nanovea’s groundbreaking high load tribometer has a maximum load capacity of 2000 N with a dynamic load control system. The advanced pneumatic compressed air loading system enables users to evaluate the tribological behavior of a material under high normal loads with the advantage of damping undesired vibration created during the wear process. Therefore, the load is measured directly with no need for buffer springs used in older designs. A parallel electromagnet oscillating loading module applies well-controlled oscillation of desired amplitude up to 20 N and frequency up to 150 Hz.
Friction is measured with high accuracy directly from the side force applied to the upper holder. The displacement is monitored in situ, providing insight into the evolution of the wear behavior of the test samples. The wear test under controlled oscillation loading can also be performed in corrosion, high temperature, humidity, and lubrication environments to simulate the real work conditions for the tribological applications. An integrated high-speed non-contact profilometer automatically measures the wear track morphology and wear volume in a few seconds.
Measurement Objective
In this study, we showcase the capacity of the Nanovea T2000 Dynamic Load Tribometer in studying the tribological behavior of different coating and metal samples under controlled oscillation loading conditions.
Test Procedure
The tribological behavior, e.g. coefficient of friction, COF, and wear resistance of a 300 µm thick wear-resistant coating was assessed and compared by the Nanovea T2000 Tribometer with a conventional dead load tribometer using a pin on disk setup following ASTM G992.
Separate Cu and TiN coated samples against a 6 mm Al₂0₃ ball under controlled oscillation were evaluated by Dynamic Load Tribology Mode of the Nanovea T2000 Tribometer.
The test parameters are summarized in Table 1.
The integrated 3D profilometer equipped with a line sensor automatically scans the wear track after the tests, providing the most accurate wear volume measurement in seconds.
Results and Discussion
Pneumatic loading system vs. Dead load system
The tribological behavior of a wear-resistant coating using Nanovea T2000 Tribometer is compared to a conventional dead load (DL) tribometer. The evolution of the COF of the coating are shown in Fig. 2. We observe the coating exhibits a comparable COF value of ~0.6 during the wear test. However, the 20 cross-section profiles at different locations of the wear track in Fig. 3 indicate that the coating experienced much more severe wear under the dead load system.
Intense vibrations were generated by the wear process of the dead load system at high load and speed. The massive concentrated pressure at the contact face combined with a high sliding speed creates substantial weight and structure vibration leading to accelerated wear. The conventional dead load tribometer applies load using mass weights. This method is reliable at lower contact loads under mild wear conditions; however, under aggressive wear conditions at higher loads and speeds, the significant vibration causes the weights to bounce repeatedly, resulting in an uneven wear track causing unreliable tribological evaluation. The calculated wear rate is 8.0±2.4 x 10-4 mm3/N m, showing a high wear rate and large standard deviation.
The Nanovea T2000 tribometer is designed with a dynamic control loading system to dampen the oscillations. It applies the normal load with compressed air which minimizes undesired vibration created during the wear process. In addition, active closed loop loading control ensures a constant load is applied throughout the wear test and the stylus follows the depth change of the wear track. A significantly more consistent wear track profile is measured as shown in Fig. 3a, resulting in a low wear rate of 3.4±0.5 x 10-4 mm3/N m.
The wear track analysis shown in Fig. 4 confirms the wear test performed by the pneumatic compressed air loading system of the Nanovea T2000 Tribometer creates a smoother and more consistent wear track compared to the conventional dead load tribometer. In addition, the Nanovea T2000 tribometer measures stylus displacement during the wear process providing further insight into the progress of the wear behavior in situ.
Controlled Oscillation on Wear of the Cu sample
The parallel oscillating loading electromagnet module of the Nanovea T2000 Tribometer enables users to investigate the effect of controlled amplitude and frequency oscillations on the wear behavior of materials. The COF of the Cu samples is recorded in situ as shown in Fig. 6. The Cu sample exhibits a constant COF of ~0.3 during the first 330-revolution measurement, signifying the formation of a stable contact at the interface and relatively smooth wear track. As the wear test continues, the variation of the COF indicates a change in the wear mechanism. In comparison, the wear tests under a 5 N amplitude-controlled oscillation at 50 N exhibits a different wear behavior: the COF increases promptly at the beginning of the wear process, and shows significant variation throughout the wear test. Such behavior of COF indicates that the imposed oscillation in the normal load plays a role in the unstable sliding state at the contact.
Fig. 7 compares the wear track morphology measured by the integrated non-contact optical profilometer. It can be observed that the Cu sample under a controlled oscillation amplitude of 5 N exhibits a much larger wear track with a volume of 1.35 x 109 µm3, compared to 5.03 x 108 µm3 under no imposed oscillation. The controlled oscillation significantly accelerates the wear rate by a factor of ~2.7, showing the critical effect of oscillation on wear behavior.
Controlled Oscillation on Wear of the TiN Coating
The COF and wear tracks of the TiN coating sample are shown in Fig. 8. The TiN coating exhibits significantly different wear behaviors under oscillation as indicated by the evolution of COF during the tests. The TiN coating shows a constant COF of ~0.3 following the run-in period at the beginning of the wear test, due to the stable sliding contact at the interface between the TiN coating and the Al₂O₃ ball. However, when the TiN coating starts to fail, the Al₂O₃ ball penetrates through the coating and slides against the fresh steel substrate underneath. A significant amount of hard TiN coating debris is generated in the wear track at the same time, turning a stable two-body sliding wear into three-body abrasion wear. Such a change of the material couple characteristics leads to the increased variations in the evolution of COF. The imposed 5 N and 10 N oscillation accelerates the TiN coating failure from ~400 revolutions to below 100 revolutions. The larger wear tracks on the TiN coating samples after the wear tests under the controlled oscillation is in agreement with such a change in COF.
Conclusion
The advanced pneumatic loading system of the Nanovea T2000 Tribometer possesses an intrinsic advantage as a naturally quick vibration damper compared to traditional dead load systems. This technological advantage of pneumatic systems is true compared to load-controlled systems that use a combination of servo motors and springs to apply the load. The technology ensures reliable and better-controlled wear evaluation at high loads as demonstrated in this study. In addition, the active closed loop loading system can change the normal load to a desired value during wear tests to simulate real-life applications seen in brake systems.
Instead of having influence from uncontrolled vibration conditions during tests, we have shown the Nanovea T2000 Dynamic-Load Tribometer enables users to quantitatively assess the tribological behaviors of materials under different controlled oscillation conditions. Vibrations play a significant role in the wear behavior of metal and ceramic coating samples.
The parallel electromagnet oscillating loading module provides precisely controlled oscillations at set amplitudes and frequencies, allowing users to simulate the wear process under real-life conditions when environmental vibrations are often an important factor. In the presence of imposed oscillations during wear, both the Cu and the TiN coating samples exhibit substantially increased wear rate. The evolution of the coefficient of friction and stylus displacement measured in situ are important indicators for the performance of the material during the tribological applications. The integrated 3D non-contact profilometer offers a tool to precisely measure the wear volume and analyze the detailed morphology of the wear tracks in seconds, providing more insight into the fundamental understanding of wear mechanism.
The T2000 is equipped with a self-tuned, high-quality, and high torque motor with a 20-bit internal speed and a 16-bit external position encoder. It enables the tribometer to provide an unmatched range of rotational speeds from 0.01 to 5000 rpm that can change in stepwise jumps or at continuous rates. Contrary to systems that use a bottom located torque sensor, the Nanovea Tribometer uses a top located high-precision load cell to accurately and separately measure friction forces.
Nanovea Tribometers offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modes (including 4ball, thrust washer, and block on ring tests), with optional high-temperature wear, lubrication and tribo-corrosion modules available in one pre-integrated system. Nanovea T2000’s unmatched range is an ideal solution for determining the full range of tribological properties of thin or thick, soft or hard coatings, films, and substrates.
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Paint Orange Peel Texture Analysis using 3D Profilometry
Paint Orange Peel Texture Analysis using 3D Profilometry
Introduction
The size and frequency of surface structures on substrates affect the quality of gloss coatings. Paint orange peel texture, named after its appearance, can develop from substrate influence and paint application technique. Texture problems are commonly quantified by waviness, wavelength, and the visual effect they have on gloss coatings. The smallest textures result in gloss reduction while larger textures result in visible ripples on the coated surface. Understanding the development of these textures and its relation to substrates and techniques are critical to quality control.
Importance of Profilometry for Texture Measurement
Unlike traditional 2D instruments used to measure gloss texture, 3D non-contact measurement quickly provides a 3D image used to understand surface characteristics with the added ability to quickly investigate areas of interest. Without speed and 3D review, a quality control environment would solely rely on 2D information that gives little predictability of the entire surface. Understanding textures in 3D allows for the best selection of processing and control measures. Assuring quality control of such parameters heavily relies on quantifiable, reproducible, and reliable inspection. Nanovea 3D Non-Contact Profilometers utilize chromatic confocal technology to have the unique capability to measure the steep angles found during fast measurement. Nanovea Profilometers succeed where other techniques fail to provide reliable data due to probe contact, surface variation, angle, or reflectivity.
Measurement Objective
In this application, the Nanovea HS2000L measures the paint orange peel texture of a gloss paint. There are endless surface parameters automatically calculated from the 3D surface scan. Here we analyze a scanned 3D surface by quantifying the characteristics of the paint orange peel texture.
Results and Discussion
The Nanovea HS2000L quantified isotropy and height parameters of the orange peel paint. The orange peel texture quantified the random pattern direction with 94.4% isotropy. Height parameters quantify the texture with a 24.84µm height difference.
The bearing ratio curve in Figure 4 is a graphical representation of the depth distribution. This is an interactive feature within the software that allows the user to view distributions and percentages at varying depths. An extracted profile in Figure 5 gives useful roughness values for the orange peel texture. Peak extraction above a 144 micron threshold shows the orange peel texture. These parameters are easily adjusted to other areas or parameters of interest.
Conclusion
In this application, the Nanovea HS2000L 3D Non-Contact Profilometer precisely characterizes both topography and nanometer details of the paint orange peel texture on a gloss coating. Areas of interest from 3D surface measurements are quickly identified and analyzed with many useful measurements (Dimension, Roughness Finish Texture, Shape Form Topography, Flatness Warpage Planarity, Volume Area, Step-Height, etc.). Quickly chosen 2D cross-sections provide a complete set of surface measurement resources on gloss texture. Special areas of interest can be further analyzed with an integrated AFM module. Nanovea 3D Profilometer’s speed ranges from <1 mm/s to 500 mm/s for suitability in research applications to the needs of high-speed inspection. Nanovea 3D Profilometers have a wide range of configurations to suit your application.
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3D Surface Analysis of a Penny with Non-contact Profilometry
Importance of Non-contact Profilometry for Coins
Currency is highly valued in modern society because it is traded for goods and services. Coin and paper bill currency circulates around the hands of many people. Constant transfer of physical currency creates surface deformation. Nanovea’s 3D Profilometer scans the topography of coins minted in different years to investigate surface differences.
Coin features are easily recognizable to the general public since they are common objects. A penny is ideal for introducing the strength of Nanovea’s Advanced Surface Analysis Software: Mountains 3D. Surface data collected with our 3D Profilometer allows for high level analyses on complex geometry with surface subtraction and 2D contour extraction. Surface subtraction with a controlled mask, stamp, or mold compares the quality of manufacturing processes while contour extraction identifies tolerances with dimensional analysis. Nanovea’s 3D Profilometer and Mountains 3D software investigates the submicron topography of seemingly simple objects, like pennies.
Measurement Objective
The full upper surface of five pennies were scanned using Nanovea’s High-Speed Line Sensor. The inner and outer radius of each penny was measured using Mountains Advanced Analysis Software. An extraction from each penny surface at an area of interest with direct surface subtraction quantified surface deformation.
Results and Discussion
3D Surface
The Nanovea HS2000 profilometer took only 24 seconds to scan 4 million points in a 20mm x 20mm area with a 10um x 10um step size to acquire the surface of a penny. Below is a height map and 3D visualization of the scan. The 3D view shows the High-Speed sensor’s ability to pick up small details unperceivable to the eye. Many small scratches are visible across the surface of the penny. Texture and roughness of the coin seen in the 3D view are investigated.
Dimensional Analysis
The contours of the penny were extracted and dimensional analysis obtained inner and outer diameters of the edge feature. The outer radius averaged 9.500 mm ± 0.024 while the inner radius averaged 8.960 mm ± 0.032. Additional dimensional analyses Mountains 3D can do on 2D and 3D data sources are distance measurements, step height, planarity, and angle calculations.
Surface Subtraction
Figure 5 shows the area of interest for the surface subtraction analysis. The 2007 penny was used as the reference surface for the four older pennies. Surface subtraction from the 2007 penny surface shows differences between pennies with holes/peaks. Total surface volume difference is obtained from adding volumes of the holes/peaks. The RMS error refers to how closely penny surfaces agree with each other.
Conclusion
Nanovea’s High-Speed HS2000L scanned five pennies minted in different years. Mountains 3D software compared surfaces of each coin using contour extraction, dimensional analysis, and surface subtraction. The analysis clearly defines the inner and outer radius between the pennies while directly comparing surface feature differences. With Nanovea’s 3D profilometer’s ability to measure any surfaces with nanometer-level resolution, combined with Mountains 3D analysis capabilities, the possible Research and Quality Control applications are endless.
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Dimensional and Surface Finish of Polymeric Tubes
Importance of Dimensional and Surface Analysis of Polymeric Tubes
Tubes made from polymeric material are commonly used in many industries ranging from automotive, medical, electrical, and many other categories. In this study, medical catheters made of different polymeric materials were studied using the Nanovea 3D Non-Contact Profilometer to measure surface roughness, morphology, and dimensions. Surface roughness is crucial for catheters as many problems with catheters, including infection, physical trauma, and inflammation can be linked with the catheter surface. Mechanical properties, such as coefficient of friction, can also be studied by observing surface properties. These quantifiable data can be obtained to ensure the catheter can be used for medical applications.
Compared to optical microscopy and electron microscopy, 3D Non-Contact Profilometry using axial chromatism is highly preferable for characterizing catheter surfaces due to its ability to measure angles/curvature, ability to measure material surfaces despite transparency or reflectivity, minimal sample preparation, and non-invasive nature. Unlike conventional optical microscopy, the height of the surface can be obtained and used for computational analysis; e.g. finding dimensions and removing form to find surface roughness. Having little sample preparation, in contrast to electron microscopy, and non-contact nature also allows for quick data collection without fearing contamination and error from sample preparation.
Measurement Objective
In this application, the Nanovea 3D Non-Contact Profilometer is used to scan the surface of two catheters: one made of TPE (Thermoplastic Elastomer) and the other made of PVC (Polyvinyl Chloride). The morphology, radial dimension, and height parameters of the two catheters will be obtained and compared.
Results and Discussion
3D Surface
Despite the curvature on polymeric tubes, the Nanovea 3D Non-contact profilometer can scan the surface of the catheters. From the scan done, a 3D image can be obtained for quick, direct visual inspection of the surface.
2D Dimensional Analysis
The outer radial dimension was obtained by extracting a profile from the original scan and fitting an arc to the profile. This shows the ability of the 3D Non-contact profilometer in conducting quick dimensional analysis for quality control applications. Multiple profiles can easily be obtained along the catheter’s length as well.
Surface Analysis Roughness
The outer radial dimension was obtained by extracting a profile from the original scan and fitting an arc to the profile. This shows the ability of the 3D Non-contact profilometer in conducting quick dimensional analysis for quality control applications. Multiple profiles can easily be obtained along the catheter’s length as well.
Conclusion
In this application, we have shown how the Nanovea 3D Non-contact profilometer can be used to characterize polymeric tubes. Specifically, surface metrology, radial dimensions, and surface roughness were obtained for medical catheters. The outer radius of the TPE catheter was found to be 2.40mm while the PVC catheter was 1.27mm. The surface of the TPE catheter was found to be rougher than the PVC catheter. The Sa of TPE was 0.9740µm compared to 0.1791µm of PVC. While medical catheters were used for this application, 3D Non-Contact Profilometry can be applied to a large variety of surfaces as well. Obtainable data and calculations are not limited to what is shown.
