to 2.5 in., the force only increases by 43 lb, which is a factor of just 1.4 times. If you reduce that same pin’s unsupported length by just 1/2 in., from 3 in.
This quadruple relationship only occurs when you cut the unsupported length in half. While that may be four times the amount of force, you need to be careful here. can push a part with 394 lb of force before it buckles. A pin with that same diameter and an unsupported length of 1.5 in. can push a plastic part with 99 lb of force before it buckles. ejector pin, with an unsupported length of 3 in. The formula is very useful in understanding how the unsupported length of a pin is directly related to the amount of force it can apply to eject a part before buckling.įor example, Table 2 shows that a 5/64-in. per side of “float” in the event the through hole in the plate does not precisely align with the through hole in the core.Įuler developed another, much more involved formula, and I will spare you from going into too many details about it other than to say the formula allows you to calculate the amount of force a slender column, like an ejector pin, can withstand before it buckles. This allows a standardsize drill to be used and provides roughly no more than 0.008 in.
Most mold designers will make the through hole for the pin in the ejector retainer plate 1/64-in. below nominal to as little as -0.0000 in. The tolerance for the diameter of an ejector pin varies depending on the size, type and manufacturer. Ejector-pin counter-bore sets, available through most molding supply companies, automatically add a chamfer to account for the radius on the pins. radius where the shaft of the pin meets the head, so clearance must be provided. The counter-bore depth for the head of a pin in the retainer plate is typically +0.001 to +0.003 in. The typical head-thickness tolerance for a standard ejector pin is +0.000 to -0.002 in. The counter-bore diameter for the head of a pin in the retainer plate is typically 1/32-in. The typical head-diameter tolerance of a standard ejector pin is +0.000 to -0.010 in. Ejector pins are mounted in the ejector retainer plate by means of a through hole for their body and a counter-bore for their head. Let’s start with the basics and build on that.
0 kommentar(er)
