Gun Drill Oil for Deep-Hole Drilling

Gun drill oil for gun drilling and deep-hole drilling, on dedicated gun drill machines and on CNC lathes and mills with high-pressure through-tool supply. NMO121 (ISO 12) is the thin oil gun drilling usually calls for; NMO241 (ISO 24) is a step thicker, for deep holes where the load is higher. Both are chlorine-free neat oils with EP additives, used undiluted.

In stock in Canada in 5-gallon pails and 55-gallon drums, NMO121 also in 270-gallon totes. Order online 24/7, no quote needed.

Total found: 3

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Only in stock

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EASYCUT NMO121 Cutting Oil ISO 12 for Light to Medium Machining, 5 Gallon Pail

NMO121-57 unit in stock

CA$111.00

excl. taxesCA$165.62

Total discount 33%

EASYCUT NMO361 Cutting Oil ISO 36 for Heavy-Duty Machining, 5 Gallon Pail

NMO361-57 unit in stock

CA$126.00

excl. taxesCA$187.71

Total discount 33%

EASYCUT NMO241 Cutting Oil ISO 24 for Medium-Duty Machining, 55 Gallon Drum

NMO241-554 unit in stock

CA$1,099.00

excl. taxesCA$1,653.73

Total discount 34%

What the oil does in a gun drill

A gun drill cuts with a single edge and rides on its guide pads, deep inside a hole it cannot see out of. The oil is pumped through the drill at high pressure, reaches the tip and carries the chips back out along the V-flute. That flow is the only way chips leave the hole, so in gun drilling the oil is part of the process, not an extra: it lubricates the pads against the bore, cools the cutting edge and keeps the chip channel open.

Why gun drilling runs on oil

Gun drilling can run on emulsion, and some machines do. Neat oil is still the standard: the pads rub against the bore along the whole depth of the hole, and a film of oil with EP additives protects both the pads and the surface of the hole far better than water-based coolant. The result is longer tool life, a better finish in the bore and fewer surprises deep in the hole. The price is a machine built for oil — enclosure, mist extraction, fire safety — which dedicated gun drill machines already have.

ISO 12 or ISO 24

The oil has to get through the drill's coolant channel and back out through the flute, and both get narrow on small drills. That is why gun drilling usually starts with a thin oil: at the same pump pressure, NMO121 (12 mm²/s at 40 °C) delivers more flow through a small drill than a thicker oil would, and flow is what clears the chips.

Step up to NMO241 (24 mm²/s) when the drill is large enough that flow is no longer the limit and the load on the pads and the edge is — tougher steels, larger diameters, deep-hole drilling with heavy feeds. It also has a higher flash point, above 190 °C against above 160 °C for NMO121.

Gun drilling problems the oil can cause

Chips pack in the flute and the drill breaks. Not enough flow: pressure too low for the depth, a blocked filter, or an oil too thick for a small drill.
Pads wear fast and the bore is scored. The film between pad and bore is breaking down — wrong oil, oil diluted by coolant, or fine particles circulating because filtration is too coarse.
The hole runs off straight. Mostly alignment, the guide bushing and the start of the hole. Oil plays a part only when unstable pressure lets the drill wander.
Tool life drops on long shifts. The tank is heating up and the oil thins out. A larger tank or an oil cooler keeps viscosity stable.
Smoke and mist around the machine. High pressure atomises oil. Run a mist collector and keep the enclosure closed.

Keeping the oil clean

Gun drilling is harder on oil than most machining: fine chips and pad wear particles go straight back through the pump and the drill if the filter lets them. Fine filtration, regular filter changes and skimming any coolant or hydraulic oil that leaks into the tank do more for tool life than any change of oil. Top up with the same oil; unopened, NMO oils keep for 12 months.

FAQ

Looking for coolants or other oils? See all metalworking fluids.

What the oil does in a gun drill

Why gun drilling runs on oil

ISO 12 or ISO 24

Gun drilling problems the oil can cause

Chips pack in the flute and the drill breaks. Not enough flow: pressure too low for the depth, a blocked filter, or an oil too thick for a small drill.

Pads wear fast and the bore is scored. The film between pad and bore is breaking down — wrong oil, oil diluted by coolant, or fine particles circulating because filtration is too coarse.

The hole runs off straight. Mostly alignment, the guide bushing and the start of the hole. Oil plays a part only when unstable pressure lets the drill wander.

Tool life drops on long shifts. The tank is heating up and the oil thins out. A larger tank or an oil cooler keeps viscosity stable.

Smoke and mist around the machine. High pressure atomises oil. Run a mist collector and keep the enclosure closed.

Keeping the oil clean

Gun Drill Oils

What the oil does in a gun drill

Why gun drilling runs on oil

ISO 12 or ISO 24

Gun drilling problems the oil can cause

Keeping the oil clean

FAQ

What the oil does in a gun drill

Why gun drilling runs on oil

ISO 12 or ISO 24

Gun drilling problems the oil can cause

Keeping the oil clean

FAQ