RELATÓRIO DE ESTÁGIO 2/3 (segundo de três) Período: de 13/10/2008 a 15/12/2008

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1 Universidade Federal de Santa Catarina Centro Tecnológico Departamento de Engenharia Mecânica Coordenadoria de Estágio do Curso de Engenharia Mecânica CEP Florianópolis - SC - BRASIL estagio@emc.ufsc.br RELATÓRIO DE ESTÁGIO 2/3 (segundo de três) Período: de 13/10/2008 a 15/12/2008 HEIDENHAIN GmbH Nome do aluno: James S. Eger Nome do supervisor: Dr. Andreas M. Straube Nome do orientador: Dr. Carlos A. Schneider Traunreut, 15 de dezembro de 2008

2 1. Mobile Measurement Test Station Introduction Developed Activities Data Acquisition Program (Test-scheme) Check of the length gauges mounting Measurement System Analysis (MSA) Development of a brief instruction manual Documentation of the Online Data Acquisition and Visualization Software Introduction Developed Activities Quick Guide to the Process Analysis Sheet Introduction Developed Activities Other Activities Pressing-out experiment Pressing-on (interference fit) experiment Conclusion

3 1. Mobile Measurement Test Station 1.1. Introduction Our mobile measuring station is equipped for the measurement of ball bearings and shafts (see Picture 1). This station must be made available for use in the manufacturing sector by the workers. The preparation includes: Development / adaption of data acquisition program test schemes Check of the length gauges mounting Perform of a measurement system analysis Development of a brief instruction manual. The objective is to make the test station ready to be used by the manufacturing line workers. Picture 1: Mobile Test Station 1.2. Developed Activities Data Acquisition Program (Test-scheme) The programs used for viewing and acquiring data called test-schemes - are built by means of the Online Data Acquisition and Visualization Software available in the company. This software provides pre-defined functions which can be arranged and edited so that the resulting test-scheme fulfils our requirements. The application of our mobile test station is of high relevance to experiments, such as the pressing of ball bearings onto the shafts. For example: we develop and use testschemes that save the data from the parts dimensions, read the values of force and calculate parameters, like the overlap between shaft and bearing. 3

4 The test-scheme guides the user through the measuring procedure. For example, the user is prompted to place the part on the measuring device and told which button to press in order to execute a certain function (see Picture 2). Picture 2: Examples of screens viewed by the user * The test-scheme must be user-friendly and self-explaining, so that there is no need of previous experience to run it. The adaption of such programs includes the implementation of a hardware a box with function buttons (see Picture 1), which will be used for running the program Check of the length gauges mounting For the measurement of the ball-bearings internal diameter, we assemble a HEDENHAIN length gauge together with a plug gauge (see Picture 3). The working principle of the plug gauge is shown in Picture 4. * Transcription to Picture 2: Left: Place in the part; drive plate (where the part lies) up; to measurement with <Button 1>; to calibration with <Button 2>; to data distribution with <Button 3> Right: data is being saved and converted. 4

5 Picture 3: Assembly - Length gauge and plug gauge Picture 4: Plug gauge The guide cylinder (4) centers the gauging contacts (6) in the bore. The lapped cone of the needle (3) translates the distance traveld by the gauge contacts (6) 1:1 to the plunger of the length gauge (1). When using HEIDENHAIN length gauges it is fundamental that its reference mark is crossed - i.e. detected by the scanning unit - during the measurement (see Picture 5 und Picture 6). The photoelectric scanning of grid structures results in an incremental measurement. The reference mark is an absolute mark placed on the measuring standard of the length gauge, and enables the exact reestablishment of a defined datum. For this function to work properly, the reference mark must be crossed during the measurement. The Online Data Acquisition Software provides a function that enables the identification of the reference mark position. This way we carry out the mounting of the devices in the station, making sure that the reference mark will be crossed during every measurement. 5

6 Picture 5: Reference mark Picture 6: Internal view of a HEIDENHAIN length gauge Measurement System Analysis (MSA) After software and hardware are prepared, a measuring system analysis should be carried out. For the case of our Mobile Test Station, the measuring system analysis will be performed according to Type 1 and Type MSA Type 1 This analysis evaluates the variation and the systematic error. During the analysis, all external influence should be eliminated or kept constant. A measurement standard should be used as reference piece, and its measure should be close to the medium of the tolerance. Still, its uncertainty should be smaller than 10% of the tolerance range. The reference piece has to be measured repeatedly at least 25 times (better 50), always in the same position. Each time, the piece needs to be taken out and replaced again. The capability indices are calculated as follows: 6

7 Where If the threshold values are not reached, the system must be verified and improved MSA Type 2 This procedure complements the previous one. MSA Type 2 includes the influences of the work pieces to be measured and of the operator. This model is to be used when the influence of the user on the system can not be eliminated. In the procedure, 10 parts and 3 inspectors are needed. The MSA is carried out for certain characteristics. In this case, the characteristic is a diameter. The diameter values of the parts should cover the complete deviation of the process to be analyzed in the future by the system. The following relations must be satisfied Common numbers are: n = 10 parts, k = 3 appraisers and r = 2 repetitions. The sequences of parts and users have no influence. The deviation range R i,k is calculated for each part and each appraiser. Abbildung 7: Example for the analysis with MSA Type 2 7

8 The equipment variation is The appraiser variation is The R&R is The part variation is For the assessment of the measurement system capability, the following values are used:, In case of the results for the chosen parts are too similar. The procedure must be repeated with another set of parts Development of a brief instruction manual An instruction manual is needed, in order to facilitate the introduction of new users to the mobile test station. A brief manual written in local language, German, has been developed. It consists basically of objective advices accompanied by example pictures and screen-shots, and was built by means of the Microsoft Office tools. The manual gives instruction on how to start the equipment, log-in the computer and the software, choose the appropriate test-scheme (program that proceeds the data acquisition) and create / start a test-document. 8

9 2. Documentation of the Online Data Acquisition and Visualization Software 2.1. Introduction A manual for the data acquisition software has been reviewed and post-edited. The manual s first version was internally developed by another intern. In the form of a tutorial, its objective is to introduce programmers to the software. The external documentation on this software is not much detailed, what makes this internal documentation even more important. It will be helpful for the training of new users of the software Developed Activities First, the text was reviewed. Then, I suggested some changes, intending to make the text clearer and facilitate the search for specific information within it. New information has also been included. The use of the software in the company is relatively recent, therefore a few people have experience with it. Besides, since the external documentation on it is not vast, new relevant details we come to learn are to be documented. By doing this, we convey our experience to less experienced users, and that will allow these new programmers (i.e. interns or engineers) to have a faster familiarization with the software. The text consists of objective instruction accompanied by illustrating pictures, and was developed by means of the Microsoft Office tools. The text s language is German. The documentation is a continuous process, to which there is no defined end point or dead line. 3. Quick Guide to the Process Analysis Sheet 3.1. Introduction The Process Analysis Sheet is the results sheet automatically generated by the Offline Data Analysis Software. It contains information about the process under analysis, such as: machine data, test-station, design, measured and statistical data, and more. This sheet contains a big amount of information in only one page. The objective of this work is to develop a quick guide with brief instruction on how to understand and extract information from the results sheet. The guide will be schematically organized so that one can have quick access to the desired information. It also contains short explanation on some concepts behind the results shown in the Process Analysis Sheet. 9

10 3.2. Developed Activities The guide should be organized in a format as compact as possible, allowing the reader to quickly find the information he / she is looking for. The fields in the Process Analysis Sheet were logically grouped and then, numbered. For example: group 6.1 design data; group 6.2 measured data; group 3 statistical data. In the guide, the information is found in fields with corresponding numeration (see Picture 8) For the elucidation of the meaning of some concepts present in the sheet, first I gathered the background theory and then elaborated short explanation on each subject. Tools used were Microsoft Office image and text editors. The document is to be added to the company s internal information database, from where it can be accessed by the employees. Picture 8: Excerpt from the HEIDENHAIN - Quick Guide to the Process Analysis Sheet 4. Other Activities 4.1. Pressing-out experiment By means of a pressing machine, the ball bearings are pressed out of the stator coupling. The experiment is done for the evaluation of the force needed for the pressing-out. This force is a criterion for the assessment of the product s quality, i.e. a quality characteristic. The developed activity here was the participation in the experiment procedure. 10

11 4.2. Pressing-on (interference fit) experiment In another pressing machine, the ball bearings are pressed onto the shafts. The data from pressing force and press way are process characteristics, and are analyzed for the evaluation of the process. Developed activities were sorting of parts to be used in the experiment and participation in the experiment procedure. This experiment took place after the equipment was prepared and checked, as described in item

12 5. Conclusion This second period of internship comprised tasks with diversified characteristics, such as: documentation, experimental procedures and data acquisition and visualization. In the engineering area, as well as in any other field of study, documentation is a very important matter. The registration of procedures, new found information, and the ability of making this data accessible for other people is fundamental. The clear documentation and explanation of activities make the continuity of a process easier and faster. The activities focused on documentation and elaboration of instruction guides allowed me to improve my ability of creating and organizing explanatory texts. It was also accompanied by a further development of my German language knowledge and Office tools experience. Through the data acquisition and visualization activities, I improved my knowledge on the software used for these purposes, and applied it for creating and editing testschemes, and for the documentation on the subject. Here can also be quoted the learning and exercising of concepts about: statistics, metrology, hardware set-up and visual interfaces. The activities involving experiments provided the possibility of enhancing my knowledge and of learning important aspects of experimental procedures. In order to execute an experiment, one must have such aspects clear in mind: the working principle of the equipment, the control / elimination of unwanted influences (for example, the presence of dust might influence accurate measurements), and, specially, what is the goal of the experiment. If we miss one of these aspects, we will probably conduce a meaningless experiment. In the case of a measuring experiment, not only does the measurement system analysis allow us to evaluate the capability of the system, but also gives us evidence for investigating the causes of a possible problem. 12

13 [DIAT08] DIATEST: URL: [viewed 04/12/2008]. [DIET05] Dietrich, E. Schulze, A. (2005) Statistische Verfahren zur Maschinen und Prozessqualifikation. HANSER. [HEID08] HEIDENHAIN: URL: [viewed 01/10/2008]. [KERN08] KERN, B. (2008) JH-Richtlinie zur Messsystemfähigkeit. [STRA08] Straube, A. M. (2008) JH-Richtlinie zur Prozessfähigkeit. [UFSC08] UFSC EMC: URL: [viewed 01/10/2008]. 13