Animated Visualization Of The Maximum Material Requirement.pdf

Measurement 45 (2012) 2283–2287

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Animated visualization of the maximum material requirement Zbigniew Humienny a,⇑, Piotr Turek b a b

Warsaw University of Technology, Institute of Machine Design Fundamentals, Narbutta 84, 02-524 Warsaw, Poland Tachion Engineering S.A. Gen. L. Okulickiego 7/9, 05-500 Piaseczno, Poland

a r t i c l e

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Article history: Available online 29 September 2011 Keywords: Tolerancing GPS Geometrical product specifications MMR

a b s t r a c t The usage of animation technique applied as a powerful tool to explain the complex concept of the maximum material requirement (MMR) is shown. The concepts of datum system and the maximum material virtual condition envelope, that is located by theoretically exact dimensions are highlighted. The maximum material virtual condition state, that limits the collective effect of the feature maximum material size and the maximum acceptable geometrical deviation for that size is examined. The tolerances of perpendicularity and position with the maximum material modifiers applied in the tolerance frames for the toleranced features or respectively for the datum features are explored. The simplicity of the verification of the conformance with the specification employing the MMR by the gauge that represents the matting counter part is emphasized. Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction The staff in a manufacturing enterprise needs competences in appropriate specification of tolerances [1]. Correct, unambiguous geometrical product specification and therefore clear interpretation of the specified requirements is also essential for reliable uncertainty estimation of coordinate measurements [2]. The usage of the maximum material requirement (MMR) for tolerancing of matting features of size enables unique specification of functional requirements with highest allowable tolerances that output significant technical and economic benefits [3,4]. So it shall be widely applicable in the industry, especially in automotive industry with the high production volume. The effective implementation of the MMR may be performed only by the people, who well understand the requirement. The fundamentals of the geometrical tolerancing according to the ISO 1101 and other GPS standards [5,6] are presented at the Warsaw University of Technology and the other Universities [3] starting from macro up to micro-geometry issues [7]. For some students, that have ⇑ Corresponding author. E-mail addresses: [email protected] (Z. Humienny), [email protected] (P. Turek). 0263-2241/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.measurement.2011.09.018

problems with understanding the basic concepts of the geometrical tolerancing the MMR looks very mystique and they give up. The similar situation is in several companies, even world wide spread, some ‘‘strange’’ drawings with encircled M are sent by customers. A picture explaining the geometrical dimensioning and tolerancing rules is worth a thousand words, but the animated simulation and the workpiece with relevant gauge, that may be handled are priceless. That is clear conclusion from the university lectures and number of trainings conducted for industry people. So the authors decided to demystify effectively the MMR by the application of animation technique as well as fabrication of ‘‘real’’ material workpieces and especially designed gauge, that can be manipulated by the students. 2. Maximum material requirement The maximum material requirement is defined in the recently revised International Standard ISO 2692 [8]. When the MMR is specified the two requirements – size and geometrical tolerance – are combined into one collective requirement (Figs. 1 and 2). The actual surface of the toleranced feature shall not violate the maximum material virtual condition (MMVC) state i.e. envelope defined

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Fig. 1. Maximum material requirement for an external cylindrical feature based on size and position requirements – specification.

Fig. 2. Maximum material requirement for an internal cylindrical feature based on size and position requirements – specification.

respectively to the MMR specification (Figs. 3 and 4). For external features of size the envelope size (maximum material virtual size – MMVS) is equal to the sum of maximum material size (MMS) and the geometrical tolerance, whereas for internal features of size, it is equal to the difference between MMS and the geometrical tolerance. The intended function of the part toleranced in Fig. 1 could be an assembly with a part as shown in Fig. 2. The functional requirement is, that the two planar faces marked on both drawings as datum A shall be in contact, while the two planar faces marked as secondary datum B shall both simultaneously be in contact with the bearing plane. More over the toleranced pin shall be in the middle of the base sides, that are nominally spread 40 mm apart (Fig. 1) and similarly the toleranced hole shall be in the middle of the block sides that are nominally spread 40 mm apart (Fig. 2). According to the set of rules given in the International Standard ISO 2692:2006 the MMR specification marked in Fig. 1 outputs the following requirements:  the extracted feature shall not violate the maximum material virtual condition, MMVC, which has the diameter MMVS = MMS + Tposition = 20,3 mm;

Fig. 3. Maximum material requirement for an external cylindrical feature based on size and position requirements – interpretation.

Fig. 4. Maximum material requirement for an internal cylindrical feature based on size and position requirements – interpretation.

 the extracted feature shall have everywhere a local diameter equal or larger than least material size, LMS = 19,9 mm and equal or smaller than maximum material size, MMS = 20,0 mm;  the orientation of the MMVC is perpendicular to the primary datum A, whereas the location of the MMVC is in the theoretically exact position 15 mm from the secondary datum B and theoretically exact position 0 mm from the tertiary datum C. The datum A is established by the plane associated to datum feature A – i.e. the extracted integral surface. The default associated criteria for the primary datum is to minimize the maximum distance

Fig. 5. The maximum material requirement for an internal cylindrical feature based on size and perpendicularity requirements, the maximum material requirement for an internal prism feature based on size and position requirements, the maximum material requirement for the pattern of three internal cylindrical features based on size and position requirements.

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Fig. 6. Snapshots from the flash clips show – verification of the MMR for an internal cylindrical feature based on size and perpendicularity requirements.

between the associated plane and the datum feature. The primary datum imposes orientation constraint on the secondary datum defined by theoretically exact perpendicularity between the secondary and the primary datums. Taking perpendicularity constraint the datum B is established by the associated plane that minimizes the maximum distance to the datum feature B. For the tertiary datum the datum indicator with letter C identifying the datum is placed on the extension of the dimension line and therefore indicates as the datum derived plane obtained from two actual surfaces, that are nominally parallel planes. The datum C is the situation feature of the collection of two parallel planes associated together to the surfaces used for establishing the tertiary datum (the symmetry plane). The pair of two parallel planes (C1 and C2 in Fig. 3) that is associated to the actual base sides respects the orientation constraints (perpendicular-

ity), firstly from the primary datum (datum A) and secondarily from the second datum (datum B) and minimizes the maximum distance to the two base extracted surfaces. The analogous set of requirements is implied by specifications marked in Fig. 2, particularly:  the extracted feature shall not violate the maximum material virtual condition, MMVC, which has the diameter MMVS = MMS Tposition = 20,3 mm;  the extracted feature shall have everywhere a local diameter equal or larger than MMS = 20,7 mm and equal or smaller than LMS = 20,9 mm;  the orientation of the MMVC is perpendicular to the primary datum A, whereas the location of the MMVC is in the theoretically exact position 15 mm from the secondary datum B and theoretically exact position 0 mm from the tertiary datum C.

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Fig. 7. Snapshot from the flash clip – the MMR for the pattern of three internal cylindrical features based on size and location requirements.

3. Animation The animation is developed to help discussion over the functional advantages and verification procedure of the requirements specified in Fig. 5. The disk with one central hole, the slot and the circular pattern of three holes is analyzed. The tolerances of perpendicularity and position with maximum material modifiers applied for the toleranced features or respectively for the datum features are explored. The purpose of the developed animation is also to show, how the functional gauges shall be used to verify maximum material requirements. The animation is divided into seven clips. The PLAY button is used to initialize animation sequentially (Fig. 6). So during the stops the lecturer has the time to discuss with the students the design intend as well as the concepts of datum system and the theoretically exact dimensions, that orient or locate the tolerance zones. Before the execution of the next clip the students shall prove their competence to find the size of the gauge, that was shown to check the requirement. The first animation clip is preceded by the workpiece drawing displayed on the screen left side. The students have to comment the specifications and enumerate the sequence of the inspection operations. This drawing is displayed permanently to facilitate understanding the way in which the maximum material requirements are verified. The snapshot taken from the first clip is shown in Fig. 6a. The lower surface of the toleranced disk (datum feature A) is placed against the datum plane which is materialized by the datum feature simulator (the top plane of the gauge plate). After the part is set over, the pin is placed in the central hole. The last frame from the second clip is displayed in Fig. 6b. The pin inserted perpendicularly to the datum A represents the MMVC. The students are asked to give the pin size. The right answer is maximum material virtual size, MMVS = MMS Tperpendicularity = 19,9 mm. The

click on PLAY button displays the pin with its size in the window bottom right corner. The snapshot taken from the third clip is shown in Fig. 6c. The rectangular prism of the gauge is moving towards slot in the disk. This prism shall be guided by the slot in the gauge plate. The slot is located by symmetry plane, that is perpendicular to datum A and pass through the datum B, that is defined by axis of central pin. Next to the prism reached the disk slot the students are asked to give the prism size and conditions for its placement. The snapshot taken from the last but one clip is shown in Fig. 7. The pattern of three pins shall pass through three holes in the disk. The appropriate pins location is forced by the three holes in gauge plate that are oriented by theoretically exact angle 90° to the datum A and located by theoretically exact coaxiality to the datum B (the axis of the central hole) and theoretically exact radius 20 mm from the datum B. The theoretically exact angle 90° locates the pattern against the datum C. The diameter of each pin in the pattern is equal 9,86 mm.

4. Conclusions The usage of the animated explanations provides the powerful tool for the lectures to teach effectively the complex concept of the maximum material requirement. The presentations with animation enhance the content, attract the students’ attention and are better than equivalent static presentations. The correct understanding of the MMR ensures that the intent of the designer is precisely communicated and has the uniform interpretation across the whole production process. The successful implementations of presented animation technique during the onsite vocational trainings for various groups in manufacturing enterprises have been achieved. The animation is aided by hard gauge and two workpieces, that were manufactured on CNC machining

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center. The first one is intentionally manufactured with the holes and the slot at maximum material sizes, the second with the features at least material sizes. The participants can manipulate with them, that enhance effectiveness and efficiency in explanation of the MMR concept. Combination of virtual gauging and hard gauging enables to achieve sustainable learning effect. The experience gathered during development and usage of the discussed animation is now utilized to build out the new computer based learning package for computer aided teaching of the geometrical dimensioning and tolerancing principles and rules. References [1] A. Weckenmann, T. Werner, Computer-assisted generation of individual training concepts for advanced education in manufacturing metrology, Measurement Science and Technology 21 (5) (2010).

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[2] W. Jakubiec, Estimation of uncertainty of coordinate measurements according to the type B method, Key Engineering Materials 437 (2010) 253–257. [3] P.H. Osanna, M. Tamre, A. Weckenmann, L. Blunt, W. Jakubiec, in: Z. Humienny (Ed.), Geometrical Product Specifications – Course for Technical Universities, Warsaw University of Technology Printing House, Warsaw 2001, ISBN 83-912,190-9-9. [4] G. Henzold, in: Geometrical Dimensioning, and Tolerancing for Design, Manufacturing and Inspection, Butterworth-Heinemann, 2006. [5] Z. Humienny, State of Art in Standardization in GPS Area, CIRP Journal of Manufacturing Science and Technology 2 (2009) 1–7. [6] J.-Y. Dantan, A. Ballu, L. Mathieu, Geometrical product specifications – model for product life cycle, Computer Aided Design 40 (4) (2008) 493–501. [7] K.K. Manesh, B. Ramamoorthy, M. Singaperumal, Numerical generation of anisotropic 3D non-Gaussian engineering surfaces with specified 3D surface roughness parameters, Wear 268 (2010) 1371–1379. [8] ISO 2692:2006 GPS – Geometrical Tolerancing – Maximum Material Requirement (MMR), Least Material Requirement (LMR) and Reciprocity Requirement (RPR).