Considering that conventional milling and turning processes are several hundred years old, EDM is a relatively new, non-traditional machining process having been developed in the late 1950’s. As such it offers many advantages and capabilities that traditional machining processes cannot. (Click here to read my Dad’s “Rob Report.”)
Since EDM is a specialty, many of the skills required for EDM success do not transfer well from conventional machining. For example, in conventional machining workholding and tool rigidity are typically given first priority. In EDM, rigidity isn’t particularly important because there are no physical forces between the work piece and the cutting tool (i.e., an EDM electrode). However, the flushing away of cutting debris is extremely critical, something not considered in conventional machining.
Many of today’s EDM shops are specialists in that they only perform EDM secondary operations on customer-supplied material. These shops don’t have a wide range of machining capabilities, nor the associated equipment and expertise needed to make complete parts. That’s why it can be argued that there are significant advantages to dealing with a full-service shop that has EDM capabilities, rather than an EDM specialty shop. Consider, for instance:
Convenience. The full-service shop offers the ease of one-stop shopping for complete, finished parts received against a single purchase order. When working with an EDM specialty shop, the customer also has to work with at least one, and often several additional suppliers for raw material, partially machined parts, and finish machining operations. Additional services may also be required such as heat treatment, passivation, outside inspection, plating, and so on. This requires multiple purchase orders and lots of tracking time.
Cost. When dealing with multiple suppliers to produce a single part, there is the possibility of scrap and losses at every step. These losses, which can be quite costly with nearly finished parts, must be absorbed by the customer. With a full-service shop, the supplier absorbs the cost.
Accountability. When multiple outside suppliers produce a part, there’s a decent chance that quality problems will arise, resulting in the proverbial finger pointing. Responsibility for the problem can be difficult to determine, and it can be even harder to assign costs. With a full-service shop, there is no question as to who has responsibility and accountability for both quality and unanticipated cost overruns.
Value. There are often unique process planning considerations required for parts with EDM operations that are unfamiliar to shops that do not have inside EDM capability. This may make it difficult or impossible to optimize the part’s manufacturing process, resulting in lower quality, lower part performance, and higher costs.
Although a specialty shop may have more sheer EDM capacity, allowing them to handle more EDM projects concurrently, a full-service shop with EDM capabilities is often the right choice to provide the optimal solution for complex, precision, performance-critical parts with EDM process requirements. That’s because they will provide the best combination of part quality, performance and value.