Micro-hole drilling, or micro-hole popping, is a precise technique carried out by a manual or CNC drill. It’s a lesser-known but important aspect of our wire EDM services at Arbiser Machine.

How Does EDM Micro-Hole Drilling Work?

Our wire EDM hole poppers—both manual and CNC—work by sending a spark from a tubular electrode to a machined part. Once the spark passes through the electrode, it removes the material, and a water-based dielectric fluid flushes away any debris. 

Since this process involves electricity, the part material must be conductive, meaning most plastics are out. At Arbiser Machine, we typically drill materials like hardened tool steel, titanium, Inconel, stainless steel, bronze, Kovar, Hastelloy, aluminum, and copper. 

The electrode’s diameter determines the size of the micro-hole, which can range from .006” to .120.” Our standard electrodes measure .040” to .060” in diameter. The speed of drilling depends on the purity of the material and the size of the electrode. 

Advantages and Disadvantages of EDM Micro-Hole Drilling

Micro-hole drilling is useful for aerospace and medical applications, gear splines, and replacement parts for prototypes and production runs. But customers should weigh the pros and cons when deciding if it’s suitable for their applications.

Advantages of EDM Micro-Hole Drilling

• Minimal material hardness limitations. Unlike manual drilling, EDM drilling can easily penetrate even the hardest materials. Occasionally, we use this process to release broken drill bits or tabs that break off in hard materials during machining so customers don’t have to scrap expensive parts. 

• Increased capability over conventional drilling. EDM micro-hole drilling can produce holes with length-to-diameter ratios that are impossible to achieve with manual drilling, including lengths up to 13.1.” Recently, we used micro-hole drilling to make a .040” diameter hole in an 8.25” stainless steel rod. 

Disadvantages of EDM Micro-Hole Drilling

• Limited hole size. When using wire EDM for micro-hole drilling, the hole diameter is restricted to the diameter of the electrodes used. 

• Rough finish. The wire used for micro-hole drilling is larger and more rigid than the one used for traditional wire EDM. It’s designed to drill a micro-hole as quickly as possible, and as a result, the holes tend to have a rough finish. However, the purpose of the micro-hole is to act as a starting point, after which we can use wire EDM to cut more precisely and with a smoother finish. 

Micro-Hole Drilling Part Feature

Golf, anyone? 

This image shows a computer vision perspective of a portion of a golf ball mold that needed a .080" hole, +/-.0002” through the hardened wall of the die. 

You can see the golf ball dimples in the mold cavity. The hole had to penetrate thick, hardened tool steel with the requirement that it could be anywhere between the dimples, but it couldn’t touch them. We used EDM micro-hole drilling for the initial hole and then finished it with wire EDM for greater accuracy and a superior finish.

If you think your application could benefit from this capability, Arbiser Machine has two CNC hole poppers, two conventional EDM hole drillers, and seven wire EDM machines. Request a quote today to get started!