CRIMP TOOLING WHERE FORM MEETS FUNCTION The cost of quality can be expensive Introduction Quality, cost, and throughput are associated with specific It is difficult to distinguish critical tooling attributes with visual measurements and linked to process variables. Crimp height, pull inspection only. Some attributes cannot be inspected even by test values, leads per hour, and crimp symmetry are some of the running crimp samples. This paper will present the reader with measures used to monitor production termination processes. information that identifies key crimp tooling attributes and the effect of those attributes on the crimping process. Many variables affect the process such as wire and terminal quality, machine repeatability, setup parameters, and operator skill. Geometry and Associated Tolerances Crimp tooling is a significant contributor to the overall crimp Terminals are designed to perform to specification only when the termination process. The condition of crimp tooling is constantly final crimp form is within a narrow range of dimensions. monitored in production by various means. These means are often Controlling critical crimp dimensions is influenced by many factors indirect measures. Crimp Quality Monitors and crimp cross including: sections are methodologies that infer the condition of the crimp Wire size and material variation tooling. Visual inspection of the crimp tooling can be used to check Terminal size and material variation for gross failures such as tool breakage or tooling deformation Equipment condition which occurred as a result of a machine crash. Continuous monitoring of production will help determine when the process The final quality and needs to be adjusted and the replacement of crimp tooling can be consistency of a one of the adjustments that is made. crimp can never be any better than the quality and consistency of the tooling that is used. If other variations could be eliminated, tooling can and should be Cross Section Defining Crimp Width, Crimp Height and Flash able to produce crimp forms that are well within specified tolerances. In addition, variation from one tooling set to another should be held to a minimum. Crimp tooling features that are well controlled and exhibit excellent consistency from tooling set to tooling set can result in shorter setup time as well as more consistent production results. Crimp tooling can a have positive effect on the quality, cost, and throughput of the termination process. High quality crimp tooling Some critical crimp characteristics are directly defined by the can produce high quality crimps with less in-process variation over tooling form and are obvious. These include crimp width & crimp a greater number of terminations. length. APPLICATION TOOLING /// WHERE FORM MEETS FUNCTION Page 1 WHERE FORM MEETS FUNCTION Other critical crimp characteristics can be related to several A typical design point for AI is 80%. In order to maintain the same tooling form features and/or other system factors. These may be AI, the crimp height, CH, needs to change inversely to the change less obvious and include: of crimp width, CW, in approximately the same proportion. Thus, if the CW increases +2%, the CH needs to change approximately - Flash 2% in order to achieve the same AI design point. At first glance Roll, twist, and side-to-side bend that may not seem significant, but in reality it can be very Up/down bend significant. Using another general industry design rule of the ratio Crimp symmetry of CH to CW of approximately 65%, a typical set of dimensions Bellmouth used as an example may be: CW = 0.110 in, CH = 0.068 in The following discussion focuses on two characteristics, crimp width and flash, as examples of how tooling affect crimp form. Therefore, varying the CW by 2% would result in a CH variation of Similar arguments can be applied to the others. 2%, or 0.0014 in. At a CH tolerance of 0.002 in, 35% of the total Crimp Width CH tolerance would be used by a 2% variation in CW. Thus, the importance of crimp width control is obvious when tooling is Crimp width is a good example of a feature that should be changed during a production run. consistent and in control between different crimpers of the same part number. The reason for this is quite straightforward. For a given terminal and wire combination, it is necessary to achieve an area index, AI, which is determined by the terminal designer for optimal mechanical and electrical performance. Crimp height, CH, and crimp width, CW, directly affect achieving proper AI. Area index, AI (as a percentage), is defined as: (a) where A is the total area of the wire and barrel after crimping. A t W and A are, respectively, the initial cross-sectional areas of the B wire and barrel before crimping. (b) APPLICATION TOOLING /// WHERE FORM MEETS FUNCTION Page 2