Heading for improvement

Author Alan Richter
Published
January 01, 2013 - 10:30am

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.

OSG%20SUS%20Drills_CTE.tif

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.

Related Glossary Terms

  • alloys

    alloys

    Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

  • aluminum alloys

    aluminum alloys

    Aluminum containing specified quantities of alloying elements added to obtain the necessary mechanical and physical properties. Aluminum alloys are divided into two categories: wrought compositions and casting compositions. Some compositions may contain up to 10 alloying elements, but only one or two are the main alloying elements, such as copper, manganese, silicon, magnesium, zinc or tin.

  • high-speed steels ( HSS)

    high-speed steels ( HSS)

    Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.

  • stainless steels

    stainless steels

    Stainless steels possess high strength, heat resistance, excellent workability and erosion resistance. Four general classes have been developed to cover a range of mechanical and physical properties for particular applications. The four classes are: the austenitic types of the chromium-nickel-manganese 200 series and the chromium-nickel 300 series; the martensitic types of the chromium, hardenable 400 series; the chromium, nonhardenable 400-series ferritic types; and the precipitation-hardening type of chromium-nickel alloys with additional elements that are hardenable by solution treating and aging.

  • tap

    tap

    Cylindrical tool that cuts internal threads and has flutes to remove chips and carry tapping fluid to the point of cut. Normally used on a drill press or tapping machine but also may be operated manually. See tapping.

  • titanium aluminum nitride ( TiAlN)

    titanium aluminum nitride ( TiAlN)

    Often used as a tool coating. AlTiN indicates the aluminum content is greater than the titanium. See coated tools.

  • titanium nitride ( TiN)

    titanium nitride ( TiN)

    Added to titanium-carbide tooling to permit machining of hard metals at high speeds. Also used as a tool coating. See coated tools.

  • wear resistance

    wear resistance

    Ability of the tool to withstand stresses that cause it to wear during cutting; an attribute linked to alloy composition, base material, thermal conditions, type of tooling and operation and other variables.

Author

Editor-at-large

Alan holds a bachelor’s degree in journalism from Southern Illinois University Carbondale. Including his 20 years at CTE, Alan has more than 30 years of trade journalism experience.

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