Scalable production of large components by industrial robots and machine tools through segmentation.

The production of large components currently requires cost-intensive special machine tools with large workspaces. The corresponding process chains are usually sequential and hard to scale. Furthermore, large components are usually manufactured in small batches; consequently, the planning effort has a significant share in the manufacturing costs. This paper presents a novel approach for manufacturing large components by industrial robots and machine tools through segmented manufacturing. This leads to a decoupling of component size and necessary workspace and enables a new type of flexible and scalable manufacturing system. The presented solution is based on the automatic segmentation of the CAD model of the component into segments, which are provided with predefined connection elements. The proposed segmentation strategy divides the part into segments whose structural design is adapted to the capabilities (workspace, axis configuration, etc.) of the field components available on the shopfloor. The capabilities are provided by specific information models containing a self-description. The process planning step of each segment is automated by utilizing the similarity of the segments and the self-description of the corresponding field component. The result is a transformation of a batch size one production into an automated quasi-serial production of the segments. To generate the final component geometry, the individual segments are mounted and joined by robot-guided Direct Energy Deposition. The final surface finish is achieved by post-processing using a mobile machine tool coupled to the component. The entire approach is demonstrated along the process chain for manufacturing a forming tool.

Factors associated with trigger digit following carpal tunnel release.

BACKGROUND: Trigger digit is a common disorder of the hand associated with carpal tunnel syndrome. Carpal tunnel release (CTR) surgery may be a risk factor for trigger digit development; however, the association between surgical approach to CTR and postoperative trigger digit is equivocal. AIM: To investigate patient risk factors for trigger digit development following either open carpal tunnel release (OCTR) or endoscopic carpal tunnel release (ECTR). METHODS: This retrospective chart analysis evaluated 967 CTR procedures from 694 patients for the development of postoperative trigger digit. Patients were stratified according to the technique utilized for their CTR, either open or endoscopic. The development of postoperative trigger digit was evaluated at three time points: within 6 mo following CTR, between 6 mo and 12 mo following CTR, and after 12 mo following CTR. Firth's penalized likelihood logistic regression was conducted to evaluate sociodemographic and patient comorbidities as potential independent risk factors for trigger digit. Secondary regression models were conducted within each surgical group to reveal any potential interaction effects between surgical approach and patient risk factors for the development of postoperative trigger digit. RESULTS: A total of 47 hands developed postoperative trigger digit following 967 CTR procedures (4.9%). In total, 64 digits experienced postoperative triggering. The long finger was most commonly affected. There was no significant difference between the open and endoscopic groups for trigger digit development at all three time points following CTR. Furthermore, there were no significant independent risk factors for postoperative trigger digit; however, within group analysis revealed a significant interaction effect between gender and surgical approach (P = 0.008). Females were more likely to develop postoperative trigger digit than males after OCTR(OR = 3.992), but were less likely to develop postoperative trigger digit than males after ECTR (OR = 0.489). CONCLUSION: Patient comorbidities do not influence the development of trigger digit following CTR. Markedly, gender differences for postoperative trigger digit may depend on surgical approach to CTR.