These guide the mold halves back together. They should be on the centerlines of the mold. Some locks do not have an angle and are straight. The designer should always take care to make sure that if the locks are on and angle they should be at least one degree less than any shut off between the core and cavity. Round taper locks are not as effective, but can be used if the plate temperatures between the two plates that are being aligned are the same. The only effective way of aligning plates that have different temperatures is with the straight locks.