The explosion and fire in the German plant making resin for the auto industry has cut off about 50 percent of the supply. This is one more in a series of disasters that have hit the industry--floods in Thailand, tsunamis in Japan and now fire in Germany. To top it all off, the suppliers cannot keep up with the demand for parts. Supply chains can be delicate things; lean supply chains can be super delicate. Firms face the constant trade-off between potential shortages and the costs of holding safety stock inventory.