![]() ![]() ![]() He also breaks the rules somewhat by using a water soluble, semisynthetic cutting fluid with a chlorinated lube additive. ![]() At 250 rpm, the OSG averages up to 9,000 holes through 1.575" thick material compared with 1,750 holes per tap with “the other brand.” That spindle speed is faster than Fares likes, and he thinks tool life would be even better by slowing things down, but he needs to run at that rpm to keep the spindle from stalling. He has nothing but good to say about the OSG oil tap, citing another example of a long-running job where he taps M30 holes in A514 grade 50 plate (a high-strength structural steel). He said he tried “every M30 forming tap I could find,” but this was the only one his Hurco VMX-84 50-taper belt-driven vertical machining center could actually turn without stalling the spindle. So when Tom Fares, president of TNT Custom Equipment in Stow, Ohio, called me out on that section of the article, saying that he routinely taps holes in 45 HRC steel alloy and thread mills into “the low 60s,” I listened to what he had to say.įares uses an OSG EXOPRO S-XPF oil tap to form M30 × 3.5 threads in a proprietary alloy similar to 1050 steel but heat-treated to 45 HRC. And if you’re going to try to tap them, be prepared to duck the flying shrapnel when the tap explodes!” In it, I stated, “There’s little chance of successfully thread milling metals much above 45 HRC. I received an email from a reader letting me know that he disagreed with my recent article on tapping versus thread milling. 72Ĭarbide Taps for all of your tapping needs.Published 10:15am Cutting Tool Engineering Magazine Excessive depth does not equal extra strength. A 65% thread is only 3% stronger than a 55%ĩ. Unless specifically required, 65% or less thread height is sufficient in Slow will cause chip packing and premature breakage.Ĩ. Spiral flute taps are designed to eject the chip. ![]() Chipping of spiral point taps is generally caused by RPM that isħ. Tapping, too slow can cause as many problems as running too fast.Ħ. Be aware of the correct RPM range for the material you are Surface treatments reduce friction and help prevent galling andĥ. Make sure you are using the correct GH Limit.Ĥ. Make sure the hole is clean,ĭo not over peck especially in stainless and nickel based materials.įor best results use OSG cobalt and carbide drills for the best holeģ. Use the correct style of tap for the job.Ģ. * To calculate metric threads divide the pitch by 25.4 and multiply by RPM to give you IPM.Įxample: M8 x 1.25 500 RPM 1.25/25.4=0.049x500=24.60ġ. Stainless Steels 300, 400 Series S/O, TiN, TICN Tool Steels A2, D2, S7, H13 etc up to 35 HrC S/O, TICN Low 1010 - High Carbon 1080, A36 Hot Roll. Use the right OSG tap and coating for the material and application. There are usually two processes, pvd a lower cost coating and cvd which provides better grain structure, harder surfaces and up to four times longer tool life. The hardest of all coatings, (8,000 vickers) used in non ferrous applications, aluminum, copper, graphite, etc. Dry machining in the high speed applications is possible.ĥ. It also has the highest oxidation temperature (800 c) primarily used on carbide drills and end mills. One of the hardest (2,800 vickers) with good lubricity (0.3 coef. Can also be used for aluminum and cast iron with good results.Ĥ. Harder than TiN (2,700 vickers) better for hard steels. A hard (2000 vickers) durable surface coating (5 microns) that offers high lubricity (coef, of friction 0.4) increases tool life and also utilizes higher speeds and feeds than uncoated tools.ģ. A porous surface that retains cutting fluids to help add lubricity, reducing heat and friction.Ģ. 220, right in the middle of the tolerance. 0005Įxample: for 1/4-20 tap using a GH5 limit the actual tap P.D. Slow spiral for hard materials Draws chips out Spiral flute for aluminum Flute design draws chips outĦ. Spiral flute (new style) necked or din style Draws chips outĥ. Spiral flute (old style) Draws chips outĤ. Hand style straight flute Chips stay in fluteģ. Written by Mike Whitney and OSG Tap & Dieġ. ![]()
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