The effect of clamping sequence on dimensional variability of a manufactured automotive sheet metal sub-assembly

Figures & data

Table 1. A brief overview of the existing literature on clamping sequence studies with research gap identification.

		Simulation-based study	Experimental investigation	Use of real part with features
M&A fixture	Clamping sequence for a given fixture layout	Matuszyk, Cardew-Hall, and Rolfe 2007; Qin, Zhang, and Wan 2006; Raghu and Melkote 2004; Bazrov and Sorokin 1982; Cogun 1992	Raghu and Melkote 2004
Inspection fixture	Clamping sequence		Research gap and scope of the study

Figure 1. (a) A representative non-ideal complaint sheet-metal sub-assembled part used in the study along with four classified zones (b) the location of the clamps, the locator pins (XYZ1 and Z2) and RPS alignment.

(a) Photograph of the right side of the rear quarter of a car Body-In-White which is divided into four different zones: left-top, right-top, left-bottom, right bottom (b) a fixture that holds the car sub-assembly vertically with 13 clamps.

Figure 2. The measurement systems used in this study (a) A horizontal arm CMM, (b) a Laser Tracker.

(a) Photograph of a horizontal coordinate measuring machine arm while measuring the car assembly (b) Photograph of a laser tracker while measuring the car assembly.

Figure 3. Effect of the clamping sequence on measurement repeatability for 16 points measured using a Laser Tracker.

A four-section line graph based on zones defined on the car assembly plotting the measurement repeatability for 16 points measured using a laser tracker in comparison with four different clamping sequences. Significantly more deviations occur in Zone 4.

Figure 4. Effect of the clamping sequence on region-specific measurement repeatability, calculated by adding up SD of the points located within the same region. These are obtained from the Laser Tracker measurement results.

A four-section 2-D Column graph shows the effect of clamping sequence on region-specific measurement repeatability, calculated by adding up the SD of the points located within the same region based on zones defined on the car assembly plotted using a laser tracker in comparison with four different clamping sequences. Significantly more deviations occur in Zones 2, 3 and 4.

Figure 5. Effect of the clamping sequence on measurement repeatability for 18 features measured using a CMM touch probe.

A four-section line graph based on zones defined on the car assembly plotting the measurement repeatability for 18 points measured using CMM in comparison with four different clamping sequences. Significantly more deviations occur in Zone 4.

Figure 6. Effect of the clamping sequence on region-specific measurement repeatability, which was calculated by adding up the SD of the feature located within the same region. These are obtained from the CMM touch probe measurement results.

A four-section 2-D Column graph shows the effect of the clamping sequence on region-specific measurement repeatability, calculated by adding SD of the points located within the same region based on zones defined on the car assembly plotted using CMM in comparison with four different clamping sequences. Significantly more deviations occur in Zones 2, 3 and 4.

Figure 7. Effect of the clamping sequence on measurement bias for the 18 features measured using a CMM touch probe.

A four-section line graph based on zones defined on the car assembly plotting the measurement bias for 18 points measured using CMM in comparison with four different clamping sequences. Significantly more deviations occur in Zone 4.

Figure 8. Effect of clamping sequences on the minimum tolerances (Tmin) that the measurements system would be capable of measuring when the limit of Cgk value was considered as 1.33 i.e. to maintain 8 SD (±4 SD) measurement repeatability.

A four-section line graph based on zones defined on the car assembly plotting the effect of clamping sequences on the minimum tolerances of 3 mm that the measurement system would be capable of measuring when the limit of gage capability value was considered as 1.33 with four different clamping sequences. Most values failed.

Matuszyk, T. I., M. Cardew-Hall, and B. F. Rolfe. 2007. “The Effect of Clamping Sequence on Dimensional Variability in Sheet Metal Assembly.” Virtual and Physical Prototyping 2 (3): 161–171.

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Qin, G., W. Zhang, and M. Wan. 2006. “Analysis and Optimal Design of Fixture Clamping Sequence.”

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Raghu, A., and S. N. Melkote. 2004. “Analysis of the Effects of Fixture Clamping Sequence on Part Location Errors.” International Journal of Machine Tools and Manufacture 44 (4): 373–382.

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Bazrov, B. M., and A. I. Sorokin. 1982. “The Effect of Clamping Sequence on Workpiece Mounting Accuracy.” Soviet Engineering Research 2 (10): 92–95.

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Cogun, C. 1992. “The Importance of the Application Sequence of Clamping Forces on Workpiece Accuracy.”

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Data availability statement

Data is available on request from the authors.