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Category: Profilometry | Texture and Grain

 

Mechanical Properties of Hydrogel

MECHANICAL PROPERTIES OF HYDROGEL

USING NANOINDENTATION

Prepared by

DUANJIE LI, PhD & JORGE RAMIREZ

INTRODUCTION

Hydrogel is known for its super absorbency of water allowing for a close resemblance in flexibility as natural tissues. This resemblance has made hydrogel a common choice not only in biomaterials, but also in electronics, environment and consumer good applications such as contact lens. Each unique application requires specific hydrogel mechanical properties.

IMPORTANCE OF NANOINDENTATION FOR HYDROGEL

Hydrogels create unique challenges for Nanoindentation such as test parameters selection and sample preparation. Many nanoindentation systems have major limitations since they were not originally designed for such soft materials. Some of the nanoindentation systems use a coil/magnet assembly to apply force on the sample. There is no actual force measurement, leading to inaccurate and non-linear loading when testing soft materials. Determining the point of contact is extremely difficult as the depth is the only parameter actually being measured. It is almost impossible to observe the change of slope in the Depth vs Time plot during the period when the indenter tip is approaching the hydrogel material.

In order to overcome the limitations of these systems, the nano module of the NANOVEA Mechanical Tester measures the force feedback with an individual load cell to ensure high accuracy on all types of materials, soft or hard. The piezo-controlled displacement is extremely precise and fast. This allows unmatched measurement of viscoelastic properties by eliminating many theoretical assumptions that systems with a coil/magnet assembly and no force feedback must account for.

MEASUREMENT OBJECTIVE

In this application, the NANOVEA Mechanical Tester, in Nanoindentation mode, is used to study the hardness, elastic modulus and creep of a hydrogel sample.

NANOVEA

PB1000

TEST CONDITIONS

A hydrogel sample placed on a glass slide was tested by nanoindentation technique using a NANOVEA Mechanical Tester. For this soft material a 3 mm diameter spherical tip was used. The load linearly increased from 0.06 to 10 mN during the loading period. The creep was then measured by the change of indentation depth at the maximum load of 10 mN for 70 seconds.

APPROACH SPEED: 100 μm/min

CONTACT LOAD
0.06 mN
MAX LOAD
10 mN
LOADING RATE

20 mN/min

CREEP
70 s
RESULTS & DISCUSSION

The evolution of the load and depth as a function of time is shown in FUGURE 1. It can be observed that on
the plot of the
Depth vs Time, it is very difficult to determine the point of the change of slope at the
beginning of the loading period, which usually works as an indication where the indenter starts to contact the
soft material. However, the plot of the
Load vs Time shows the peculiar behavior of the hydrogel under an
applied load. As the hydrogel begins to get in touch with the ball indenter, the hydrogel pulls the ball indenter
due to its surface tension, which tends to decrease the surface area. This behavior leads to the negative
measured load at the beginning of the loading stage. The load progressively increases as the indenter sinks
into the hydrogel, and it is then controlled to be constant at the maximum load of 10 mN for 70 seconds to
study the creep behavior of the hydrogel.

FIGURE 1: Evolution of the load and depth as a function of Time.

The plot of the Creep Depth vs Time is shown in
FIGURE 2, and the Load vs. Displacement plot of the nanoindenation test is shown in FIGURE 3. The hydrogel in this study possesses a hardness of 16.9 KPa and a Young’s modulus of 160.2 KPa, as calculated based on the load displacement curve using the Oliver-Pharr method.

Creep is an important factor for the study of a hydrogel’s mechanical properties. The close-loop feedback control between piezo and ultrasensitive load cell ensures a true constant loading during the creep time at the maximum load. As shown in FIGURE 2, the hydrogel subsides ~42 μm as a result of creep in 70 seconds under the 10 mN maximum load applied by the 3 mm ball tip.

FIGURE 2: Creeping at a max load of 10 mN for 70 seconds.

FIGURE 3: The Load vs. Displacement plot of the hydrogel.

CONCLUSION

In this study, we showcased that the NANOVEA Mechanical Tester, in Nanoindentation mode, provides a precise and repeatable measurement of a hydrogel’s mechanical properties including hardness, Young’s modulus and creep. The large 3 mm ball tip ensures proper contact against the hydrogel surface. The high precision motorized sample stage allows for accurate positioning of the flat face of the hydrogel sample under the ball tip. The hydrogel in this study exhibits a hardness of 16.9 KPa and a Young’s modulus of 160.2 KPa. The creep depth is ~42 μm under a 10 mN load for 70 seconds.

NANOVEA Mechanical Testers provide unmatched multi-function Nano and Micro modules on a single platform. Both modules include a scratch tester, hardness tester and a wear tester mode, offering the widest and the most user friendly range of testing available on a single
system.

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Piston Wear Testing

Piston Wear Testing

Using a Tribometer

Prepared by

FRANK LIU

INTRODUCTION

Friction loss accounts for approximately 10% of total energy in fuel for a diesel engine[1]. 40-55% of the friction loss comes from the power cylinder system. The loss of energy from friction can be diminished with better understanding of the tribological interactions occurring in the power cylinder system.

A significant portion of the friction loss in the power cylinder system stems from the contact between the piston skirt and the cylinder liner. The interaction between the piston skirt, lubricant, and cylinder interfaces is quite complex due to the constant changes in force, temperature, and speed in a real life engine. Optimizing each factor is key to obtaining optimal engine performance. This study will focus on replicating the mechanisms causing friction forces and wear at the piston skirt-lubricant-cylinder liner (P-L-C) interfaces.

 Schematic of power cylinders system and piston skirt-lubricant-cylinder liner interfaces.

[1] Bai, Dongfang. Modeling piston skirt lubrication in internal combustion engines. Diss. MIT, 2012

IMPORTANCE OF TESTING PISTONS WITH TRIBOMETERS

Motor oil is a lubricant that is well-designed for its application. In addition to the base oil, additives such as detergents, dispersants, viscosity improver (VI), anti-wear/anti-friction agents, and corrosion inhibitors are added to improve its performance. These additives affect how the oil behaves under different operating conditions. The behavior of oil affects the P-L-C interfaces and determines if significant wear from metal-metal contact or if hydrodynamic lubrication (very little wear) is occurring.

It is difficult to understand the P-L-C interfaces without isolating the area from external variables. It is more practical to simulate the event with conditions that are representative of its real-life application. The NANOVEA Tribometer is ideal for this. Equipped with multiple force sensors, depth sensor, a drop-by-drop lubricant module, and linear reciprocating stage, the NANOVEA T2000 is able to closely mimic events occurring within an engine block and obtain valuable data to better understand the P-L-C interfaces.

Liquid Module on the NANOVEA T2000 Tribometer

The drop-by-drop module is crucial for this study. Since pistons can move at a very fast rate (above 3000 rpm), it is difficult to create a thin film of lubricant by submerging the sample. To remedy this issue, the drop-by-drop module is able to consistently apply a constant amount of lubricant onto the piston skirt surface.

Application of fresh lubricant also removes concern of dislodged wear contaminants influencing the lubricant’s properties.

NANOVEA T2000

High Load Tribometer

MEASUREMENT OBJECTIVE

The piston skirt-lubricant-cylinder liner interfaces will be studied in this report. The interfaces will be replicated by conducting a linear reciprocating wear test with drop-by-drop lubricant module.

The lubricant will be applied at room temperature and heated conditions to compare cold start and optimal operation conditions. The COF and wear rate will be observed to better understand how the interfaces behaves in real-life applications.

TEST PARAMETERS

for tribology testing on pistons

LOAD ………………………. 100 N

TEST DURATION ………………………. 30 min

SPEED ………………………. 2000 rpm

AMPLITUDE ………………………. 10 mm

TOTAL DISTANCE ………………………. 1200 m

SKIRT COATING ………………………. Moly-graphite

PIN MATERIAL ………………………. Aluminum Alloy 5052

PIN DIAMETER ………………………. 10 mm

LUBRICANT ………………………. Motor Oil (10W-30)

APPROX. FLOW RATE ………………………. 60 mL/min

TEMPERATURE ………………………. Room temp & 90°C

LINEAR RECIPROCATING TEST RESULTS

In this experiment, A5052 was used as the counter material. While engine blocks are usually made of cast aluminum such as A356, A5052 have mechanical properties similar to A356 for this simulative testing [2].

Under the testing conditions, significant wear was
observed on the piston skirt at room temperature
compared to at 90°C. The deep scratches seen on the samples suggest that contact between the static material and the piston skirt occurs frequently throughout the test. The high viscosity at room temperature may be restricting the oil from completely filling gaps at the interfaces and creating metal-metal contact. At higher temperature, the oil thins and is able to flow between the pin and the piston. As a result, significantly less wear is observed at higher temperature. FIGURE 5 shows one side of the wear scar wore significantly less than the other side. This is most likely due to the location of the oil output. The lubricant film thickness was thicker on one side than the other, causing uneven wearing.


[2] “5052 Aluminum vs 356.0 Aluminum.” MakeItFrom.com, makeitfrom.com/compare/5052-O-Aluminum/A356.0-SG70B-A13560-Cast-Aluminum

The COF of linear reciprocating tribology tests can be split into a high and low pass. High pass refers to the sample moving in the forward, or positive, direction and low pass refers to the sample moving in the reverse, or negative, direction. The average COF for the RT oil was observed to be under 0.1 for both directions. The average COF between passes were 0.072 and 0.080. The average COF of the 90°C oil was found to be different between passes. Average COF values of 0.167 and 0.09 were observed. The difference in COF gives additional proof that the oil was only able to properly wet one side of the pin. High COF was obtained when a thick film was formed between the pin and the piston skirt due to hydrodynamic lubrication occurring. Lower COF is observed in the other direction when mixed lubrication is occurring. For more information on hydrodynamic lubrication and mixed lubrication, please visit our application note on Stribeck Curves.

Table 1: Results from lubricated wear test on pistons.

FIGURE 1: COF graphs for room temperature oil wear test A raw profile B high pass C low pass.

FIGURE 2: COF graphs for 90°C wear oil test A raw profile B high pass C low pass.

FIGURE 3: Optical image of wear scar from RT motor oil wear test.

FIGURE 4: Volume of a hole analysis of wear scar from RT motor oil wear test.

FIGURE 5: Profilometry scan of wear scar from RT motor oil wear test.

FIGURE 6: Optical image of wear scar from 90°C motor oil wear test

FIGURE 7: Volume of a hole analysis of wear scar from 90°C motor oil wear test.

FIGURE 8: Profilometry scan of wear scar from 90°C motor oil wear test.

CONCLUSION

Lubricated linear reciprocating wear testing was conducted on a piston to simulate events occurring in a
real-life operational engine. The piston skirt-lubricant-cylinder liner interfaces is crucial to the operations of an engine. The lubricant thickness at the interface is responsible for energy loss due to friction or wear between the piston skirt and cylinder liner. To optimize the engine, the film thickness must be as thin as possible without allowing the piston skirt and cylinder liner to touch. The challenge, however, is how changes in temperature, speed, and force will affect the P-L-C interfaces.

With its wide range of loading (up to 2000 N) and speed (up to 15000 rpm), the NANOVEA T2000 tribometer is able to simulate different conditions possible in an engine. Possible future studies on this topic include how the P-L-C interfaces will behave under different constant load, oscillated load, lubricant temperature, speed, and lubricant application method. These parameters can be easily adjusted with the NANOVEA T2000 tribometer to give a complete understanding on the mechanisms of the piston skirt-lubricant-cylinder liner interfaces.

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Organic Surface Topography using Portable 3D Profilometer

 

ORGANIC SURFACE TOPOGRAPHY

USING PORTABLE 3D PROFILOMETER

Prepared by

CRAIG LEISING

INTRODUCTION

Nature has become a vital pool of inspiration for the development of improved surface structure. Understanding the surface structures found in nature has led to adhesion studies based on gecko’s feet, resistance studies based on a sea cucumbers textural change and repellency studies based from leaves, among many others. These surfaces have a number of potential applications from biomedical to clothing and automotive. For any of these surface breakthroughs to be successful, fabrication techniques must be developed so surface characteristics can be mimicked and reproduced. It is this process that will require identification and control.

IMPORTANCE OF PORTABLE 3D NON-CONTACT OPTICAL PROFILER FOR ORGANIC SURFACES

Utilizing Chromatic Light technology, the NANOVEA Jr25 Portable Optical Profiler has superior capability to measure nearly any material. That includes the unique and steep angles, reflective and absorbing surfaces found within natures broad range of surface characteristics. 3D non-contact measurements provide a full 3D image to give a more complete understanding of surface features. Without 3D capabilities, identification of nature’s surfaces would be solely relying on 2D information or microscope imaging, which does not provide sufficient information to properly mimic the surface studied. Understanding the full range of the surface characteristics including texture, form, dimension, among many others, will be critical to successful fabrication.

The ability to easily obtain lab-quality results in the field opens the door for new research opportunities.

MEASUREMENT OBJECTIVE

In this application, the NANOVEA Jr25 is used to measure the surface of a leaf. There is an endless list of surface parameters that can be automatically calculated after the 3D surface scan.

Here we will review the 3D surface and select
areas of interest to further analyze, including
quantifying and investigating the surface roughness, channels and topography

NANOVEA

JR25

TEST CONDITIONS

FURROW DEPTH

Mean density of furrows: 16.471 cm/cm2
Mean depth of furrows: 97.428 μm
Maximum depth: 359.769 μm

CONCLUSION

In this application, we have shown how the NANOVEA Jr25 portable 3D Non-Contact Optical Profiler can precisely characterize both the topography and the nanometer scale details of a leaf surface in the field. From these 3D surface measurements, areas of interest can quickly be identified and then analyzed with a list of endless studies (Dimension, Roughness Finish Texture, Shape Form Topography, Flatness Warpage Planarity, Volume Area, Step-Height and others). A 2D cross section can be easily chosen to analyze further details. With this information organic surfaces can be broadly investigated with a complete set of surface measurement resources. Special areas of interest could have been further analyzed with integrated AFM module on table top models.

NANOVEA also offers portable high-speed profilometers for field research and a wide range of lab-based systems, as well as provides laboratory services.

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Sandpaper Roughness Profilometer

Sandpaper: Roughness & Particle Diameter Analysis

Sandpaper: Roughness & Particle Diameter Analysis

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SANDPAPER

Roughness & Particle Diameter Analysis

Prepared by

FRANK LIU

INTRODUCTION

Sandpaper is a common commercially available product used as an abrasive. The most common use for sandpaper is to remove coatings or to polish a surface with its abrasive properties. These abrasive properties are classified into grits, each related to how smooth or
rough of a surface finish it will give. To achieve desired abrasive properties, manufactures of sandpaper must ensure that the abrasive particles are of a specific size and have little deviation. To quantify the quality of sandpaper, NANOVEA’s 3D Non-Contact Profilometer can be used to obtain the arithmetic mean (Sa) height parameter and average particle diameter of a sample area.

IMPORTANCE OF 3D NON-CONTACT OPTICAL PROFILER FOR SANDPAPER

When using sandpaper, interaction between abrasive particles and the surface being sanded must be uniform to obtain consistent surface finishes. To quantify this, the surface of the sandpaper can be observed with NANOVEA’s 3D Non-Contact Optical Profiler to see deviations in the particle sizes, heights, and spacing.

MEASUREMENT OBJECTIVE

In this study, five different sandpaper grits (120, 180, 320, 800, and 2000) are scanned with the NANOVEA ST400 3D Non-Contact Optical Profiler. The Sa is extracted from the scan and the particle size is calculated by conducting a Motifs analysis to find their equivalent diameter

NANOVEA

ST400

RESULTS & DISCUSSION

The sandpaper decreases in surface roughness (Sa) and particle size as the grit increases, as expected. The Sa ranged from 42.37 μm to 3.639 μm. The particle size ranges from 127 ± 48.7 to 21.27 ± 8.35. Larger particles and high height variations create stronger abrasive action on surfaces as opposed to smaller particles with low height variation.
Please note all definitions of the given height parameters are listed on page.A.1.

TABLE 1: Comparison between sandpaper grits and height parameters.

TABLE 2: Comparison between sandpaper grits and particle diameter.

2D & 3D VIEW OF SANDPAPER 

Below are the false-color and 3D view for the sandpaper samples.
A gaussian filter of 0.8 mm was used to remove the form or waviness.

MOTIF ANALYSIS

To accurately find the particles at the surface, the height scale threshold was redefined to only show the upper layer of the sandpaper. A motifs analysis was then conducted to detect the peaks.

CONCLUSION

NANOVEA’s 3D Non-Contact Optical Profiler was used to inspect the surface properties of various sandpaper grits due to its ability to scan surfaces with micro and nano features with precision.

Surface height parameters and the equivalent particle diameters were obtained from each of the sandpaper samples using advanced software to analyze the 3D scans. It was observed that as the grit size increased, the surface roughness (Sa) and particle size decreased as expected.

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Styrofoam Surface Boundary Measurement Profilometry

Surface Boundary Measurement

Surface Boundary Measurement Using 3D Profilometry

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SURFACE BOUNDARY MEASUREMENT

USING 3D PROFILOMETRY

Prepared by

Craig Leising

INTRODUCTION

In studies where the interface of surface features, patterns, shapes etc., are being evaluated for orientation, it will be useful to quickly identify areas of interest over the entire profile of measurement. By segmenting a surface into significant areas the user can quickly evaluate boundaries, peaks, pits, areas, volumes and many others to understand their functional role in the entire surface profile under study. For example, like that of a grain boundary imaging of metals, the importance of analysis is the interface of many structures and their overall orientation. By understanding each area of interest defects and or abnormalities within the overall area can be identified. Although grain boundary imaging is typically studied at a range surpassing Profilometer capability, and is only 2D image analysis, it is a helpful reference to illustrate the concept of what will be shown here on a larger scale along with 3D surface measurement advantages.

IMPORTANCE OF 3D NON CONTACT PROFILOMETER FOR SURFACE SEPARATION STUDY

Unlike other techniques such as touch probes or interferometry, the 3D Non Contact Profilometer, using axial chromatism, can measure nearly any surface, sample sizes can vary widely due to open staging and there is no sample preparation needed. Nano through macro range is obtained during surface profile measurement with zero influence from sample reflectivity or absorption, has advanced ability to measure high surface angles and there is no software manipulation of results. Easily measure any material: transparent, opaque, specular, diffusive, polished, rough etc. The technique of the Non Contact Profilometer provides an ideal, broad and user friendly capability to maximize surface studies when surface boundary analysis will be needed; along with the benefits of combined 2D & 3D capability.

MEASUREMENT OBJECTIVE

In this application the Nanovea ST400 Profilometer is used to measure the surface area of Styrofoam. Boundaries were established by combining a reflected intensity file along with the topography, which are simultaneously acquired using the NANOVEA ST400. This data was then used to calculate different shape and size information of each Styrofoam “grain”.

NANOVEA

ST400

RESULTS & DISCUSSION: 2D Surface Boundary Measurement

Topography image(below left) masked by reflected intensity image(below right) to clearly define grain boundaries. All grains below 565µm diameter have been ignored by applying filter.

Total number of grains: 167
Total projected area occupied by the grains: 166.917 mm² (64.5962 %)
Total projected area occupied by boundaries: (35.4038 %)
Density of grains: 0.646285 grains / mm2

Area = 0.999500 mm² +/- 0.491846 mm²
Perimeter = 9114.15 µm +/- 4570.38 µm
Equivalent diameter = 1098.61 µm +/- 256.235 µm
Mean diameter = 945.373 µm +/- 248.344 µm
Min diameter = 675.898 µm +/- 246.850 µm
Max diameter = 1312.43 µm +/- 295.258 µm

RESULTS & DISCUSSION: 3D Surface Boundary Measurement

By using the 3D topography data obtained, the volume, height, peak, aspect ratio and general shape information can be analyzed on each grain. Total 3D area occupied: 2.525mm3

CONCLUSION

In this application, we have shown how the NANOVEA 3D Non Contact Profilometer can precisely characterize the surface of Styrofoam. Statistical information can be gained over the entire surface of interest or on individual grains, whether they are peaks or pits. In this example all grains larger than a user defined size were used to show the area, perimeter, diameter and height. The features shown here can be critical to research and quality control of natural and pre fabricated surfaces ranging from bio medical to micromachining applications along with many others. 

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Contour Measurement using Profilometer by NANOVEA

Rubber Tread Contour Measurement

Rubber Tread Contour Measurement

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RUBBER TREAD CONTOUR MEASUREMENT

USING 3D OPTICAL PROFILER

Rubber Tread Contour Measurement - NANOVEA Profiler

Prepared by

ANDREA HERRMANN

INTRODUCTION

Like all materials, rubber’s coefficient of friction is related in part to its surface roughness. In vehicle tire applications, traction with the road is very important. Surface roughness and the tire’s treads both play a role in this. In this study, the rubber surface and tread’s roughness and dimensions are analyzed.

* THE SAMPLE

IMPORTANCE

OF 3D NON-CONTACT PROFILOMETRY

FOR RUBBER STUDIES

Unlike other techniques such as touch probes or interferometry, NANOVEA’s 3D Non-Contact Optical Profilers use axial chromatism to measure nearly any surface. 

The Profiler system’s open staging allows for a wide variety of sample sizes and requires zero sample preparation. Nano through macro range features can be detected during a single scan with zero influence from sample reflectivity or absorption. Plus, these profilers have the advanced ability to measure high surface angles without requiring software manipulation of results.

Easily measure any material: transparent, opaque, specular, diffusive, polished, rough etc. The measurement technique of the NANOVEA 3D Non-Contact Profilers provides an ideal, broad and user friendly capability to maximize surface studies along with the benefits of combined 2D & 3D capability.

MEASUREMENT OBJECTIVE

In this application, we showcase the NANOVEA ST400, a 3D Non-Contact Optical Profiler measuring the surface and treads of a rubber tire.

A sample surface area large enough to represent the entire tire surface was selected at random for this study. 

To quantify the rubber’s characteristics, we used the NANOVEA Ultra 3D analysis software to measure the contour dimensions, depth, roughness and developed area of the surface.

NANOVEA

ST400

ANALYSIS: TIRE TREAD

The 3D View and False Color View of the treads show the value of mapping 3D surface designs. It provides users a straightforward tool to directly observe the size and shape of the treads from different angles. The Advanced Contour Analysis and Step Height Analysis are both extremely powerful tools for measuring precise dimensions of sample shapes and design

ADVANCED CONTOUR ANALYSIS

STEP HEIGHT ANALYSIS

ANALYSIS: RUBBER SURFACE

The rubber surface can be quantified in numerous ways using built-in software tools as shown in the following figures as examples. It can be observed that the surface roughness is 2.688 μm, and the developed area vs. projected area is 9.410 mm² vs. 8.997 mm². This information allows us to examine the relationship between surface finish and the traction of different rubber formulations or even rubber with varying degrees of surface wear.

CONCLUSION

In this application, we have shown how the NANOVEA 3D Non-Contact Optical Profiler can precisely characterize the surface roughness and tread dimensions of rubber.

The data shows a surface roughness of 2.69 ­µm and a developed area of 9.41 mm² with a projected area of 9 mm². Various dimensions and radii of the rubber treads were measured as well.

The information presented in this study can be used to compare the performance of rubber tires with di­fferent tread designs, formulations, or varying degrees of wear. The data shown here represents only a portion of the calculations available in the Ultra 3D analysis software.

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Fresnel Lens Topography

Fresnel Lens Dimensions Using 3D Profilometry

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FRESNEL LENS

DIMENSIONS USING 3D PROFILOMETRY

Prepared by

Duanjie Li & Benjamin Mell

INTRODUCTION

A lens is an optical device of axial symmetry that transmits and
refracts light. A simple lens consists of a single optical component
for converging or diverging the light. Even though spherical surfaces are not ideal shape for making a lens, they are often used as the simplest shape which glass can be ground and polished to.

A Fresnel lens consists of a series of concentric rings, which are
thin parts of a simple lens with a width as small as a few thousandths of an inch. Fresnel lenses contain a large aperture and short focal length, with a compact design reducing the weight and volume of material required, compared to conventional lenses with the same optical properties. A very small amount of light is lost by absorption due to the thin geometry of the Fresnel lens.

IMPORTANCE OF 3D NON-CONTACT PROFILOMETRY
FOR FRESNEL LENS INSPECTION

Fresnel lenses are extensively employed in the automotive industry, lighthouses, solar energy and optical landing systems for
aircraft carriers. Molding or stamping the lenses out of transparent plastics can make their production cost-effective. Service quality of Fresnel lenses mostly depends on the precision and surface
quality of their concentric ring. Unlike a touch probe technique,
NANOVEA Optical Profilers perform 3D surface measurements
without touching the surface, avoiding the risk of making new
scratches. The Chromatic Light technique is ideal for precise scanning of complex shapes, such as lenses of different geometries.

 

FRESNEL LENS SCHEMATIC

Transparent plastic Fresnel lenses can be manufactured by molding or stamping. Accurate and efficient quality control is critical to reveal defective production molds or stamps. By measuring the height and pitch of the concentric rings, production variations can be detected by comparing the measured values against the specification values given by the manufacturer of the lens.

Precise measurement of the lens profile ensures that the molds or stamps are properly machined to fit manufacturer specifications. Moreover, the stamp could progressively wear out over time, causing it to lose its initial shape. Consistent deviation from the lens manufacturer specification is a positive indication that the mold needs to be replaced.

MEASUREMENT OBJECTIVE

In this application, we showcase NANOVEA ST400, a 3D Non-Contact Profiler with a high-speed sensor, providing comprehensive 3D profile analysis of an optical component of a complex shape.

To demonstrate the remarkable capabilities of our Chromatic Light technology, the contour analysis is performed on a Fresnel lens.

NANOVEA

ST400

The 2.3” x 2.3” acrylic Fresnel lens used for this study consists of 

a series of concentric rings and a complex serrated cross-section profile. 

It has a 1.5” focal length, 2.0” effective size diameter, 

125 grooves per inch, and an index of refraction of 1.49.

The NANOVEA ST400 scan of the Fresnel lens shows a noticeable increase in height of the concentric rings, moving outward from the center.

2D FALSE COLOR

Height Representation

3D VIEW

EXTRACTED PROFILE

PEAK & VALLEY

Dimensional Analysis of the Profile

CONCLUSION

In this application, we have showcased that the NANOVEA ST400 non-contact Optical Profiler accurately measures the surface topography of Fresnel lenses. 

The dimension of the height and pitch can be accurately determined from the complex serrated profile using NANOVEA analysis software. Users can effectively inspect the quality of the production molds or stamps by comparing the ring height and pitch dimensions of manufactured lenses against the ideal ring specification.

The data shown here represents only a portion of the calculations available in the analysis software. 

NANOVEA Optical Profilers measure virtually any surface in fields including Semiconductors, Microelectronics, Solar, Fiber Optics, Automotive, Aerospace, Metallurgy, Machining, Coatings, Pharmaceutical, Biomedical, Environmental and many others.


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Pharmaceutical Tablets: Inspecting Roughness Using 3D Profilometers

Pharmaceutical Tablets: Inspecting Roughness using 3D Profilometers

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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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Optical profilers

Mechanical Testers

Tribometers

Lab Services

Instant Error Detection With In-Line Profilers

Instant Error Detection With In-Line Profilers

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IMPORTANCE OF NON-CONTACT PROFILER FOR IN-LINE 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 surface 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.

Avoid Critical Wear Damage By Using Block-On-Ring Tests

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 mate-rials 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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