The addition of 1–3% tellurium to copper improves its machinability to a level similar to brass, eliminating the “gummy” properties normally exhibited by copper when it is machined. Unfortunately, the EDM performance of copper is somewhat compromised by the addition of the tellurium. Compared to electrolytic copper, tellurium copper (also known as TELCO) exhibits 15–25% higher wear and 10% decreased metal removal rate. However, due to the ease of machining this material, most customers are willing to accept this trade-off. TELCO comes in the “as rolled” condition. Being a cold rolled material, the bars exhibit a significant amount of stress movement when being machined.