Traceability for ballistics signature measurements in forensic science

The National Institute of Standards and Technology (NIST) in collaboration with the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) has developed the Standard Reference Material (SRM) 2460 Bullets and 2461 Casings. NIST has also developed a 2D and 3D Topography Measurement and Correlation System for ballistics signature measurements. This system includes stylus instruments and a confocal microscope for 2D and 3D topography measurements, and a 2D and 3D topography correlation program developed by NIST. NIST and ATF are proposing to establish a National Ballistics Measurement Traceability and Quality System using these materials. In this paper, basic concepts and specific requirements for establishing ballistics measurement traceability are introduced; three key issues are discussed that include: (1) establishing a reference standard; (2) establishing an unbroken chain of calibrations; and (3) evaluating measurement uncertainty for both the geometrical topography measurements and the optical image correlations of the ballistics signatures.     

Surface roughness and texture analysis in microscale

The capacity of various instruments in roughness measurements and analysis is compared. Review of various models of roughness is made and the models of contact mechanics are presented, when taking account the nanometer scale roughness and relating phenomena of adhesion and surface forces. The concept of multi-level models of roughness and contact area is presented. Analysis of surface topography as a spatial pattern is given, when using the approaches of image recognition theory operating with the 3D digital images processing. Qualitatively the spatial structure is often characterized in terms of texture features such as random, linear, wavy etc., and some national standards introduce spatial structure of machined surfaces. However, texture characteristics are not adequately investigated. AFM images of different surfaces were used as initial data and multi-dimensional scaling technique was used for the data analysis. The study has shown that there are at least four types surface textures on nanoscale level. The correlation was found between texture types and reasons of their formation.     

Surface topography analysis in high speed finish milling inclined hardened steel

The surface texture of a milled surface is an inherently important process response in finish milling. It is one of the most commonly used criteria to determine the machinability of a particular workpiece material. However, literature survey on the study of the surface topography analysis relating to the cutter path orientations when high speed finish inclined milling is scant. Previous works were either involved in conventional milling of easy-to-cut workpiece materials or machining at different workpiece inclination angles. Furthermore, none of the previous work has detailed the true surface topography of the machined surface with regards to the cutter condition. Instead, the works provided quantitative values in terms of the Ra value. This article is concerned with evaluating cutter path orientations on an inclined workpiece angle of 75° to simulate finish milling of free form moulds and dies. Surface topography effects are assessed with regards to different cutter path orientations on its surface. The aims of this study are to provide an in-depth understanding on the surface texture produced by various cutter path orientations when high speed finish inclined milling hardened steel at a workpiece inclination angle of 75° using surface topography analysis and determine the best cutter path orientation with respect to the best surface texture achieved. 3D topography maps together with 2D surface profiles are used to assess the experimental results. The conclusion is that milling in a single direction vertical upward orientation gave the best workpiece surface texture.     

The Effect of Belt Finishing Process Variables on the Topography of Finished Surfaces

The high performance of industrial applications requires increasingly technical functional surfaces, particularly from the point of view of topography and micro texture. Belt finishing is one of the finest machining processes widely used to improve surface texture and to increase wear resistance and fatigue life. It modifies the surface topography in a wide range of roughness and waviness scales, and consequently modifies the functionality of the surface in terms of the bearing area, local plasticity, and durability. In this paper, the topographic signature of the belt finishing process on a wide range of wavelengths of surface topography is analyzed to track the effect of each working parameter, and makes it possible then to understand the principal physical mechanisms activated during the super finishing operations (cutting, ploughing, and friction). To this aim, a multiscale decomposition of the surface topography before and after finishing by using a 2D continuous wavelet transform is introduced.     

Internet based software system for surface texture and form analysis

With the emergence of a global market and the recent trend of outsourcing, it has become increasingly necessary for companies to have remote access to data for process diagnostics and quality control. This paper presents an Internet based surface texture and form analysis system that will allow a user at one geographic location to upload surface profiles into a database that another user can later analyze. This system has all the features found on commercial instruments and also some special analysis tools such as wavelet analysis, valley removal algorithms etc. The capabilities include surface texture analysis with database support, straightness, flatness, roundness and cylindricity analysis.     

Simple method to determine linearity deviations of topography measuring instruments with a large range axial scanning system

The use of areal characterization of surface texture with high accuracy in a quality control process requires reliability. Therefore, regular inspection of the measurement systems is needed. Important metrological features of a measurement system in dimensional metrology are the amplification factor and linearity.This paper presents a simple method for characterizing the axial scanning system of areal topography measuring instruments with little expense and effort, well suited for industrial routine calibration in the field. The method is based on employing a single material measure with a range of step heights. It is shown that the amplification factor and linearity deviations can be determined and adjusted for large axial measurement ranges.     

三维表面形貌的逾渗特性表征

为了建立表面形貌微观结构与其功能特性之间的关系,基于逾渗理论建立了表面形貌的逾渗模型,用逾渗概率、空体集团平均大小和空体集团分布系数对三维表面形貌的逾渗特性进行了量化表征。采用数字滤波技术生成具有给定自相关函数和纹理取向的数字化粗糙表面,分析了具有相同均方根粗糙度而结构不同的三维表面形貌的逾渗特性,给出了表面纹理方向参数和自相关长度对表面逾渗特性的影响,并借助部分三维形貌参数(ISO25178)建立了表面形貌与逾渗特性参数间的量化关系。结果表明:对于各向异性表面,沿横向搜索跨越空体集团,表面逾渗发生时的表面高度、逾渗阈值和逾渗体积均随着表面纹理方向参数的增大呈减小趋势,而空体集团分布系数呈增大趋势;沿纵向搜索时,其变化规律与横向相反。对于各向同性表面,逾渗发生时的表面高度和逾渗阈值随着表面自相关长度的增大呈先减小后小幅增大趋势,而逾渗体积和空体集团平均大小呈逐渐减小趋势。研究结果为面向功能的表面形貌设计提供了理论基础。     

三维表面粗糙度的表征和应用

表面粗糙度会直接影响零部件的耐磨性、密封性以及抗腐蚀性等,是评定机械加工和产品质量的重要指标。现代科技水平的不断提高对零件表面性能的要求也日益严苛。传统的二维表面粗糙度的测量和表征已经不再能够满足技术发展的要求,三维表面粗糙度由于能够更加全面、真实地反映工件表面的状态而受到人们的重视,成为研究热点。本文回顾了三维表面粗糙度的发展历史,系统地介绍了三维表面粗糙度参数及标准的发展现状,分析了表面形貌与功能特性的联系,概述了三维粗糙度参数在制造业、生物医疗、摩擦学与材料科学等领域的广泛应用,并进一步指出了三维表面粗糙度表征和应用的发展方向。未来随着相关研究(比如,三维测量的溯源性、重复性、参数表征体系等问题)的深入以及三维表面测量手段的发展,三维表面粗糙度参数也将不断完善和推广,并更多地与实际功能相结合来预测并指导生产,确保工件的表面质量。     

基于形态变换的三维表面形貌方向特性研究

针对面向功能的三维表面形貌表征存在的问题,基于灰值形态学的基本运算构造了边缘检测形态算法,有效地提取了三维形貌的形态学边缘,实现了三维形貌的纹理方向特征的提取,获得了表征纹理方向特性的表征参数.该方法不仅适用于直线纹理,而且也适用于曲线纹理,为分析表征三维形貌的各向异性特征提供了一个新的方法.把它引入到粗糙表面的润滑分析中,能够更确切地揭示出各向异性表面的纹理方向特性对润滑性能的影响规律.     

磨粒形貌三维图像分析技术的发展趋势

磨损规律和机械故障诊断等研究都离不开磨粒分析技术。影响三维磨粒分析技术的两个重要因素是精确的磨粒表面形貌数据的获取和三给表面 纹理的数字描述，本文就是从这两方面着重介绍了当前国际上流行的磨粒形貌三维分析技术。描述了磨损颗粒的各种三维数据获取技术以及它们存在的优缺点，并对三维表面数字特征的提取方法进行了较为详细的综述，最后得到有关三维磨粒分析技术的四个结论。     

Inference engine for process diagnostics and functional correlation in surface metrology

The practice of surface metrology in the industry today has not advanced beyond simple parameter computation and tolerance verification. While surface texture measurements are intended to aid in process diagnostics or functional prediction, it is currently mostly used only as a go-no go gage for specification compliance. A primary reason for this is the lack of availability of tools and techniques for correlating surface texture parameters with functional measures. Current analysis systems are not geared towards analysis of multiple profiles or for correlating parameters with function. Thus, there is a need for the development of an advanced surface texture analysis system that can analyze multiple profiles and develop cause-effect models for process diagnostics and functional prediction. This paper presents the features of this analysis system and illustrates their use with a variety of case studies.     

Investigations of new possibilities in the calibration of diamond hardness indenters geometry

The influence of Rockwell and Vickers diamond indenters geometry in hardness measurements justifies the strict specifications and tolerances in the relative standards. Many methods, and consequently dedicated instruments, have been developed to investigate the geometrical parameters in order to calibrate the diamond indenters. Most of them, using contact or contactless methods, can only investigate some profiles of the indenters; from these partial measurements the whole geometry is derived. Few other instruments can investigate the whole shape but, since they are custom-developed, costs and difficulties in the calibration of these instruments have limited their use.A new method is proposed in this paper using a commercial and not dedicated instrument: a 3D measuring confocal microscope. This type of instrument has also the advantage that the whole geometry is analysed with a consequently knowledge improvement in the indenter calibration.In the paper the measurement method, the used instrument and its calibration to assure traceability to the length and angle standards are investigated.     

触针式三维粗糙度测量仪的开发及应用

基于表面微观形貌三维分析的完整性,介绍了一种新开发的触针式三维粗糙度测量仪。该测量仪可对表面各种功能属性、纹理结构、表面重要缺陷等进行量化描述,并通过对气缸套内表面珩磨平台网纹角度、分布、有效沟槽等的检测,验证了三维图像对实现表面个性化功能属性描述的重要意义,给人们认识和研究微观形貌提供了帮助。     

In situ non-contact measurements of surface roughness

Surface roughness measurements are often required to validate a machining process. However, when using a 3D surface roughness measuring instruments it is usually necessary to remove the part from the machine tool between two operations, potentially introducing systematic errors. Furthermore, surface roughness measuring instruments are not suited for measuring heavy and large parts such as stamping dies. This paper presents a method to measure the surface topography of a part in situ, i.e. directly on the machine tool without removing the part. After introducing the sensor technology and the data acquisition chain, the effects of geometric imperfections of the machine tool and compensation for thermal effects on the measurement results are discussed. An application of the method is then presented to assess a finishing process on a five-axis machining centre including milling and polishing operations.     

The factors affecting surface roughness measurements of the machined flat and spherical surface structures – The geometry and the precision of the surface

The quantitative determination of surface roughness is of vital importance in the field of precision engineering. This paper presents an experimental study of the roughness analyses for the flat and spherical surfaces of machined metal in order to compare the roughness data taken from the cloud data produced by the stylus type profilometer and two optical-based measurement instruments, namely the infinite focus microscope and the confocal laser scanning microscope.In this experimental study, the roughness measurements for fifteen flat and six spherical surfaces were repeated six times using three different measurement instruments. Great care was paid to measure the same location for each measurement. For the comparison of the measurement techniques, the same measurement process was applied to the flat and spherical surfaces individually, and the configurations of the measurement instruments (filter type, cut-off, resolution etc.) were synchronized. R_a, two-dimensional (2D) roughness parameter and S_a, three-dimensional (3D) roughness parameter were also compared. The measurement results for the samples having spherical surfaces indicated a considerably high difference in values taken from the stylus profilometer and two optical-based measurement instruments in contrast to those for flat surfaces.     

Effects of information loss in texture details due to the PIFS encoding on load and friction in hydrodynamic bearings

Textured surfaces can significantly improve the performance of hydrodynamic bearings. However, there is no generally accepted method for their accurate and automated 3D characterization. A promising solution to this problem is partition iterated function system (PIFS) model, which encapsulates information about 3D topography of textured surfaces. However, some loss in surface details can occur. Therefore, before PIFS could be used, effects of this information loss on load and friction need to be investigated. In this study, this issue was addressed using a textured hydrodynamic pad bearing. The results obtained showed that PIFS models might become useful in characterization of textured surfaces.     

Third generation wavelet for the extraction of morphological features from micro and nano scalar surfaces

This paper investigates wavelet theory and techniques for the extraction of morphological structures from micro/nano scalar surfaces. It will significantly extend the authors’ previous accomplishments in the programme (EU: SMT CT98-2209). This previous work identified problems in the extraction of morphological structures that requires further study. Under a new EPSRC found project, the present work tries to overcome these problems and facilitates more practical and feasible methodologies for the identification and extraction of morphological structures on micro/nano scalar surface textures.In the current work, a complex wavelet model is introduced to solve the problems of nanometre roughness analysis of surface texture with linear features and curve-like features, in which small shifts of the input signal can cause large variations in the distribution of energy between wavelet coefficients at different scales. As a result, linear and curve-like features on a surface topography can be identified and extracted with refined accuracy. Case studies are conducted using automotive cylinders and femoral heads to demonstrate the application of using the new wavelet model in the assessment of surface topography.     

表面三维微观形貌检测技术及其发展

从表面特征衡量的角度阐述三维参数评定的客观性及合理性,强调三维微观形貌测量的重要民生。介绍当前表面三维微观形貌检测的多种测量方法及其特点,并阐述该测量技术的发展及趋势,提出表面形貌检测应从简单过程检测的角度扩展到完成工艺优化角色的思想。     

切向车铣铝合金回转体工件表面形貌的试验研究

为研究切向车铣加工铝合金回转体工件的表面形貌,通过试验对轴向进给量和周向进给量对表面粗糙度和表面纹理的影响规律进行了研究。结果表明,轴向和周向进给量的增大都可导致表面粗糙度值增大;周向进给量比轴向进给量对表面纹理的影响更加显著,不但可使纹理间距发生变化,还可改变纹理的方向,并产生网格状表面纹理。