Heading for improvement

END USER: Precision 1 Machine Inc., (702) 301-6419.
CHALLENGE: Drill holes in 304 stainless steel used for header plates.
SOLUTION: An HSS drill.
SOLUTION PROVIDER: OSG Tap & Die Inc., (800) 837-2223, www.osgtool.com

Bolt-on exhaust headers improve engine performance by making it easier for the engine to push exhaust gases out of the cylinders. Most headers for naturally aspirated engines are made of mild steel. Turbocharged engines create more heat and therefore the headers are often made of stainless steel. Stainless is the next step up from mild steel in both heat resistance and durability.

Recently, header plate manufacturer Precision 1 Machine, Las Vegas, had to drill 10mm-dia. through-holes in ½ "-thick 304 stainless steel. The part was approximately 16 " long × 2¾ " wide and required 12 holes. Nick Robertson, president and owner of the one-man job shop, had been applying standard cobalt drills but was experiencing poor tool life and encountered an abnormal sound during the operation.

“I’d get maybe one or two holes and then the drill would break,” Robertson said. “I tried about 20 different ways to drill the hole and probably went through at least 10 to 15 various drills, but they kept breaking.”

As for the abnormal sound, “if the feeds and speeds weren’t exactly correct, the cutting edges would be destroyed within the first hole. As soon as that happened, the drill would start screeching,” Robertson added.

As a temporary solution to get some parts out, Robertson contracted a local waterjet shop to produce the holes at $40 per part. Robertson was not only losing money by using an outside vendor, he also had to extend his lead time.

Courtesy of OSG

OSG’s EX-SUS-GDR drills from the EX-GOLD series allow Precision 1 Machine to produce 109 10mm holes with one drill in ½ "-thick 304 stainless steel.

So Robertson called OSG Tap & Die Inc., Glendale Heights, Ill., to find a solution. After a careful examination of the application, District Manager Darrel McCoy recommended the EX-SUS-GDR drill from the EX-GOLD series. The HSS drill has a regular flute length and is effective for machining stainless steels, mild steels and aluminum alloys, according to the company. A TiN or TiAlN coating improves wear resistance and prolongs tool life.

During the first test, the EX-SUS-GDR drill also screeched and broke after the second hole. But McCoy and Robertson both felt that once chip formation was under control, the sound would be eliminated and tool life would increase.

“We were getting long, thick, stringy chips, basically because of the material I was using,” Robertson said. “But the more we worked with the feeds and speeds, chip formation started being more akin to what we wanted to see and it sounded a lot better.”

Running the 10mm EX-SUS-GDR drill at 480 rpm and 0.009 ipr, Robertson was able to produce 109 holes with one drill and finish the job. Drilling consumed about 1 to 2 minutes per part.

“The design of the cutting edge, coupled with using the correct feeds and speeds for both the drill and my material, allowed me to do the job with excellent results,” Robertson said. “It never failed. I could have probably produced a few more holes with the drill but I went from one or two holes to 109 with a single drill so there was no need to push it.”

Significant cost savings can only be achieved with the right cutting tool and strategy. Robertson was not only able to produce holes efficiently and effectively, but also reduce lead time and cost per part by eliminating the need to use an outside vendor.