I enjoy learning about advancements in science and technology. During the 50-plus years of my metalworking career I was not involved in high-volume part production. A few months ago, I wrote two columns about thread milling. During that time, I had correspondence with an EMUGE-FRANKEN USA engineer who lives in the high-volume part production world. He introduced me to tools that shine when making threaded holes in large quantities.

First a little background about myself. The highest part volumes I have been involved with were in the 1990s when I manufactured a line of chrome-plated accessories for custom V-twin motorcycles. Chromeplated billet aluminum was the rage so I made a lot of chips from 6061- T6 alloy. I recall a taillight housing that had four blind holes with 6-32 threads 3/8" deep. That alloy will make long stringy chips. The housings were machined from 2" x 2" bar stock on a vertical machining center except for the threading operation. That was done on a drill press with a Procunier tapping head.

Why?

Drilling a 0.65" deep hole with a #29 twist drill and a G81 drilling cycle will produce one chip going up each gullet of the drill that will wrap around the drill and cause trouble. The solution to that problem is to use a G87 peck drill cycle. That cycle drills at a prescribed feed rate for a short distance, then makes rapid moves up and down to break the chip, and repeats until the depth of the hole is reached.

When using a tap to thread a blind hole it is best to use a spiral flute tap. Those taps are shaped like a twist drill in that they have helical gullets to pull the chips out of the hole. The problem is you can't peck with a tap.

So, tapping this hole produced long stringy chips wrapped around the tap. I tapped the holes manually on a drill press and cleaned the chips off the tap after every hole. Kind of slow, but better than breaking a tap and scraping a part that had 15 minutes of machining time into it. There is a burr caused by the tap entering the workpiece. I cleaned that off with an abrasive disk in a right angle die grinder.

A hole can also be made with an endmill, and I don't mean plunging the tool into the work. Using an endmill that is smaller in diameter than the hole to be made — and using helical interpolation for the tool path — an accurately sized hole can be made and the chips will be small, regardless of the workpiece material.

Now back to the EMUGE tool for blind holes — the THRILLER-MAX. It has an endmill end and threadmill teeth on the side of the cutter (see THRILLER-MAX image). With this tool using helical interpolation the hole is drilled and threaded in one or two passes depending on the amount of material to be removed in the threading operation. One tool can do the operations of two tools. This results in the elimination of one tool change operation and milling cycle and the associated rapid moves between holes. You also don't have to worry about breaking a tap.

These coated or uncoated solid carbide tools can be used with high pressure through the spindle coolant for altogether rapid threaded hole making. And another thing, EMUGE offers resharpening and recoating services so they can partner with you to keep your production up and running.

EMUGE also has tools for through holes that include a feature for chamfering. This tool is called the THRILLER and is shown in the THRILLER image. The procedure is to peck drill through, engage the threading teeth, thread with one or two revolutions of helical interpolation (depending on thread pitch and material), center the tool in the hole, chamfer and then retract. Pretty darn quick.

If you have a high-volume threaded hole-making operation, you may know better than me that seconds matter. At 77 years of age, this old dog has learned some new tricks.