Soldering instead of crimping

In a manufacturing process, crimping is just as effective as soldering and much faster. In a proper crimp, the heat produced by the compression force is enough to cause the metals in the lug and wire to soften and flow together. The lug and wire become welded. If you have ordinary hand tools, instead of specialized crimp tools, this compression weld does not happen and all you have is a relatively good mechanical connection. Moisture can get into the connection and cause corrosion and eventually its failure. Soldering the lug and wire welds them together and lessens the chance of corrosion failure.