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1. #Crack open a cold one with the boys and go fishing full#
2. #Crack open a cold one with the boys and go fishing crack#

A radius change or blank holder pressure change might help to solve the problem, but not if the necking failure is located in the center of the part. One of the most common corrective actions of necking is to increase the size of the punch radius. However, this is an unfair representation of the metal’s true capability, as technically metal’s true capability, as technically metal fails as soon as necking becomes visible. Many material suppliers include this extra stretching that occurs after necking is their total elongation metal report.

#Crack open a cold one with the boys and go fishing full#

It’s important to note that the metal can stretch even more after necking has occurred and before a full rupture is visible. This failure commonly is viewed as unacceptable, but for parts in which excessive localized thin-out does not affect the structural integrity or function, minor necking sometimes is permitted. Look for necking around the tops of deep-drawn parts. Necking usually reveals itself as a horizontal curved line in the metal somewhere just bellow a punch radius (see Figure 1 ). Commonly referred to in press and die shops as smiles or elongations, necking occurs when the metal has been stretched to its maximum threshold without reaching a see-through rupture. Necking is a type of tensile failure, meaning that it occurs as a result of overstitching the metal. The failure mechanism is different, as is the corrective action. Although both failure types results in an unacceptable part and essentially mean that the part won’t “hold water”, the reasons they occur and their deformation modes are very different.

#Crack open a cold one with the boys and go fishing crack#

For instance, there is a big difference between a crack and a split. The same basic concept apple to forming failures.

What type of tool steel should I be using to prevent this problem?” My typical response is, “What type of galling is occurring? Is it adhesive galling? Abrasive galling? Corrosive galling?” My recommendations will change depending on the type of galling that is occurring. For example, I have has tooling guys ask, “My forming punches are galling. To make a good, data-based decision with respect to solving a metal forming failure, you need to be able to identify the type of failure that is occurring. While many of these terms mean essentially the same thing-splitting, tearing, and ripping all are overstitching failures-it is important to keep in mind that some failures types are significantly different. Terms such as splitting, cracking, ripping, tearing, necking, laminations, and elongations often are the main points of discussion. During these conferences, the topic of metal failure almost always comes up.

I conduct and attend many technical conferences about die design techniques and metal forming methods.