Tolerance zone

An amber zone / area exists if the AGW is exceeded (the tolerable zone / area), Here a health risk must be assumed for the exposed workforce. To continue work under these conditions requires additional measures (like personal protective equipment) and an authorisation from the surveillance authority is necessary. 

FIGURE 77.5 Transient response analysis. Tolerance zones RZ is the reaction zone, and TZ is the target zone. Performance parameters RT is the reaction time, PMT istheprimary movement time, SCT is the secondary correction time, TET is the target entry time, PV is the peak velocity, PME is the primary movement error, and MAE is the mean absolute error over a fixed interval following stimulus. 

Error, Fig. 3 Production error, tolerance zone, and measurement uncertainty. Measurement 1 product is within specification measurement 2 fulfilling of specification not proven measurement 3 product out of specification... 

Also here any measurement error is of importance. The measurement error, expressed by the measurement uncertainty, has to be applied for checking any specification Any measurement uncertainty reduces the specification zone (or tolerance zone) according to ISO 14253-1 1998. If the measurement results in a measured quantity not within the specification zone... 

In measurement, 2 measured quantity value plus/minus measurement uncertainty is partly out of the tolerance zone. Therefore, it is not sure if there is a production error. It is tmcer-tain that the product fulfills the specification. Measurements shall be carried out with smaller measurement uncertainty. 

In measurement 3, measured quantity value plus/minus tolerance is fully outside the tolerance zone. Therefore, we obey a production error. 

Fig. 3 (a) Setting tools for the machining of a design dimension (D) with its given tolerance IT(D). The manufactured dimension (C) with its tolerance IT(C), here equal to rr(D), can only be obtained when the machine dimension (L) stays in a tolerance interval of IT(C-e), where e is the positioning tolerance of the part in its jig (Halevi and Weill 1995) (b) Engine example nominal and tolerance zone (Latombe et al. 1997)... 

Due to the variations associated with manufacturing process, it is not possible to attain the theoretical dimensions in a repetitive manner it is accepted that there will be a certain amount of variation in terms of manufacturing geometry and dimensions. It causes a degradatimi of characteristics of the product. In order to ensure the interchangeability (interchangeability of manufactured parts is a critical element of present-day production — mass productirai, mass customization, modular product, maintenance, etc.), the desired behavior, and the functional requirements of the product in spite of variatirais, the part features are assigned a tolerance zone within which the value of the feature, i.e., situation and intrinsic, lies (Weill et al. 1988 Bjorke 1989). 

Kinematic tolerancing is one of many techniques proposed to model tolerances (Hong and Chang 2002). In kinematic tolerancing the tolerance chain is treated as a kinematic loop with virtual links, with the understanding that the movements of these links are actually small displacements of the part s geometric features (here called functional element, or FE) within their prescribed tolerance zones. 

The mapping of the permitted movements of an FE inside its tolerance zone is done using a small displacement torsor (SDT) consisting of at most three translations and three rotations. Table 1 shows this mapping for seven common tolerance zone shapes, where t represents the tolerance value and u, v, co, a, jS, y represent, respectively, the permitted small translation of a FE in directions X, y, z as well as its permitted small rotations about X, y, z. By permitted we mean the small displacement values that are such that the FE will... 

If a dimensional tolerance zone is refined by some geometric tolerance zone on the same FE, then the kinematic tolerancing approach can also be used to account for the more restricted displacements in the smaller geometric tolerance zone that results. Figure 1 shows an example for the planar surface tolerance zone in Table 1. The FE is a theoretical plane (in continuous bold) positioned by nominal dimension d. The small translations of this plane are limited by dimensional tolerance t (continuous planes in Fig. 1) and the small rotations are limited by parallelism tolerance p (dotted planes in Fig. 1). In this case it is assumed that the small translation co of the theoretical plane in the z direction is not permitted to cross the boundary defined by the limiting planes of t. This is ensured by restricting this translation to the interval ... 

Tolerancing (Kinematic Approach to). Table 1 Common tolerance zone shapes and associated torsor parameters Tolerance zone and typical... 

For this tolerance zone the translations in x and y as well as the rotation about z are irrelevant and are thus assigned to interval [0, 0] in the corresponding SDTI. Assuming that angles a and (3 are small, then using dimensions Li and L2, give the final SDTI presented in Fig. 1. 

FIGURE 10 Temperature tolerance zones for young sockeye salmon as a function of acclimation temperature. [Reprinted with permission from Brett, J. R. (1960). Thermal requirements of fish—Three decades of study. In Biological Problems of Water Pollution. (C. M. Tarzwell, ed.), pp. 110-117. U.S. Dept, of Health, Education, and Welfare.]... 

Some of the structural features required for inhibition of ribonucleoside diphosphate reductase have been determined [30]. These studies suggested that position 6 of (4) and position 3 of compound (1) are equivalent with respect to orientation of the inhibitor at the enzymatic binding site and that little or no tolerance exists for modification at this position. In addition, substitution of the terminal amino group of the thiosemicarbazone side chain decreased enzyme inhibition, suggesting the presence of a low bulk tolerance zone in this position [23]. The results also indicated that the isoquinoline derivative (1), which can be visualized as a pyridine derivative with a benzene ring fused across the 3- and 4-positions, is about 6-fold more potent as an inhibitor of the enzyme than is (4). Likewise, introduction of a Me group on the pyridine ring of (4) at either the 3-, 4-, or 5-positions resulted in derivatives that were better inhibitors of ribo-... 

As discussed under Target 1, the APIOOO design supports the licensee in operating within the limit and is judged to be within the tolerable zone. The APIOOO dose prediction calculation is experience-based and task-based. The database used for the calculation is mature operated plants so the impact of build-up of contamination is properly considered. Breakdown of the anticipated dose by major task is provided. Similar ALARP arguments apply as to Target 1. 

In some cases, tighter tolerances are required by optical figuring shops. Zerodur thin menisci or piano-spherical blanks can also be supplied in near net shape. Net shaping means linear dimension tolerances of 0.2 mm or smaller. The spherical grinding of such net shaped blanks leads to profile tolerance zones ranging from 0.05 to 0.40 mm P-V. These tolerances are achieved not only for blanks of 1.0 m in diameter but also for thin menisci of 8.2 m in diameter. 

Concave surface Radius of curvature Profile tolerance zone 28975 mm 2 mm 28968 mm 0.12 mm... 

Fig. 2. Cylindrical tolerance zone and geometric true position tolerancing for a cylindrical feature according to ISO 1101 (Kaisarhs et al, 2008)...

The versatility and economic benefits of true position tolerances are particularly enhanced when they are assigned at the Maximum Material Condition (MMC). At MMC, an increase in position tolerance is allowed, equal to the departure of the feature from the maximum material condition size, (ISO, 1988 ASMS, 2009). As a consequence, a feature with size beyond maximum material but within the dimensional tolerance zone and its axis lying inside the enlarged MMC cylinder is acceptable. The accuracy required by a position tolerance is thus relaxed through the MMC assignment and the reject rate reduced. Moreover, according to the current ISO and ASMS standards, datum features of size that are included in the DRF of position tolerances can also apply on either MMC, Regardless of Feature Size (RFS) or Least Material Condition (LMC) basis. 

The size and the form (cylindrical, circular, square, other) of the geometrical tolerance zone. Candidate datums and datum reference frames. Depending on the case more possible DRFs... 

The size of the total position tolerance zone is determined by the minimum clearance, minCL, of the (hole, screw-shaft) assembly. It ensures that mating features will assemble even at worst case scenario, i.e. when both parts are at MMC and located at the extreme ends of the position tolerance zone (ASME, 2009). The equations (16 -i) and (16-ii) apply for the fixed and floating fastener case respectively. 

For the floating fasteners case the total position tolerance Tpos of equation (16-ii) actually concerns only RE-features of the Hole type. Therefore, the RcanJi set only contains the Tpos element. The above tolerances attain, apparently, their maximum values when the RE feature own dimensional tolerance zone is added. 

Obviously, the values of the estimated Spearman correlation coefficients equal nearly 0. That means that there are no detectable interdependences between the important dental drill characteristics. This leads also to non-depending tolerances zones. This is one precondition for the presented method of MPCI regarding the analysed multidimensional tolerance area. 

The graphical interpretation shows that the multinormal-distribution of the characteristics Cl and C2 is not completely inside the tolerance area Cl is located within the tolerance zone, contrary to C2. The application of this approach is also possible for more than two product characteristics Within the case study, the dental drill has four important product characteristics (Fig. 2). The combination of C1-C4 leads two a four-dimensional normally distributed approach (based on eq. (5)), which obviously cannot be visualised. 

Based on the fitted multidimensional density function, the calculation of the failure probability regarding the given tolerance areas is feasible (step 5, Fig. 1). The integration of the multidimensional density functions by using the tolerance areas as integral limits (equation 6) leads to the probability of manufactured products within the combined tolerance zone. The complement (equation 7) leads to the failure probability. 

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