10 Questions to Ask Before Choosing a Dry Film Lubricant
Does the part move slowly or intermittently?
Dry film lubricants excel where movement is occasional rather than continuous. Because the lubricant is bonded to the surface, it won't migrate away while the part sits idle.
Will oil or grease attract dirt and contaminants?
Dust, grit, and debris can turn conventional lubricants into an abrasive paste. A dry film coating leaves a clean surface that is far less likely to collect contaminants.
Does the application experience high contact pressure?
Sliding surfaces, splines, cams, threaded fasteners, and similar components often benefit from dry film lubricants because they resist galling under heavy loads.
Will the part be exposed to extreme temperatures?
Conventional lubricants eventually thin out, evaporate, or harden outside their operating range. Dry film lubricants can continue performing across much wider temperature extremes.
Does the component need to stay clean?
Medical devices, optical equipment, cleanroom hardware, and precision instruments often cannot tolerate oily residue. Dry film lubricants provide lubrication without leaving a wet surface.
Will the part spend months or years in storage?
Many aerospace and defense components are stored for long periods before entering service. A bonded dry film lubricant remains in place and is ready when the component is finally used.
Is the component operating in a vacuum or other unusual environment?
Applications in aerospace or vacuum environments often require dry film lubricants because conventional oils can outgas or evaporate under those conditions.
Does the drawing specify a heat-cured or air-cured coating?
Specifications such as MIL-PRF-46010 and MIL-PRF-46147 aren't interchangeable. Understanding which one the application requires is essential before processing begins.
Would a phosphate base coat improve performance?
Many demanding applications pair a dry film lubricant with manganese phosphate to improve adhesion, wear resistance, break-in performance, and corrosion protection.
Would oil or grease actually be the better solution?
Not every application should use a dry film lubricant. High-speed bearings, continuously rotating equipment, and systems that rely on circulating oil generally perform better with conventional lubrication. Understanding where dry films do not belong is just as important as knowing where they do.
01.
Selecting the Right Coating System for Long-Term Performance
Every part that moves against another part needs some way to manage friction. For most of manufacturing history, that meant oil or grease. But there is a whole category of parts where wet lubricants cause more problems than they solve, and that is where a dry film lubricant earns its place. JH Metal Finishing has helped manufacturers across Connecticut (and nationally) make this call since 1953, working through corrosion, wear, and lubrication challenges for defense, aerospace, automotive, and industrial customers from its shop in New Britain. One question the team hears often is a simple one: when do you actually need a dry film lubricant instead of just oiling or greasing the part?
The short answer is that it depends on how the part is used, not just what it is. This article walks through how to tell the difference.
02.
What a dry film lubricant actually is
A dry film lubricant, also called a solid film lubricant or just a dry lube, is a thin coating of a solid lubricant bonded to the metal surface. The lubricating solids are usually molybdenum disulfide (MoS2), graphite, or PTFE, the polymer many people know by the brand name Teflon. Those solids are mixed with a resin binder, sprayed or dipped onto the part, much like paint, and then cured so the film adheres to the surface.
The finished film is thin, typically in the range of two to five ten-thousandths of an inch. That matters more than it sounds. A coating that thin adds almost no dimension to the part, so it can go on finished, close-tolerance components without throwing off a fit.
Once cured, the film lubricates itself. There is no oil to apply, no grease to pack, and nothing that has to be topped off. The lubrication is built into the surface.
03.
The three lubricating solids, and why the choice matters
Not all dry film lubricants behave the same way, because the solid doing the work is not the same in every formulation.
Molybdenum Disulfide (MoS₂)
Molybdenum disulfide is the heavy-duty option. It carries very high contact pressures, holds up across a wide temperature range, and actually performs better in a vacuum, where there is no air or moisture to interfere. It is the go-to for loaded, sliding, high-pressure parts.
PTFE
PTFE offers the lowest friction of the three and is chemically inert, which makes it a good fit where a slick, non-stick, chemically resistant surface matters more than raw load capacity. It gives up some high-temperature and high-load performance in exchange.
Graphite
Graphite lubricates well and handles heat, but it has a quirk worth knowing: it needs a little adsorbed moisture to work, so it performs poorly in dry or vacuum conditions. It can also promote galvanic corrosion on some metals. That is why graphite formulations are chosen deliberately rather than by default.
Understanding which solid is in a coating is part of matching the finish to the job, and it is one of the details JH Metal Finishing works through before a part is processed.
04.
Why oil and grease fall short in certain situations
Oil and grease are excellent lubricants, and for most rotating, high-speed, continuously loaded parts they remain the right choice. The trouble starts when the operating conditions work against them.
Lubricant Migration
Wet lubricants move. Gravity, centrifugal force, and heat all pull oil away from where it is needed. On a slow-moving linkage or a part that sits idle for long stretches, the oil can migrate off the contact surface entirely, leaving bare metal to gall the next time the part moves.
Dirt and Contamination
Wet lubricants also attract dirt. Grease is sticky by design, and in a dusty or gritty environment that stickiness becomes a liability. The lubricant turns into a grinding paste. Manufacturers JH Metal works with in sandy, dusty, or high-particulate settings run into this constantly, and a clean dry film often solves it outright.
Temperature Limits
Then there is temperature. Most oils and greases have a usable range, and outside it they either cook off at the high end or stiffen at the low end. A dry-film lubricant based on MoS2 keeps working from cryogenic temperatures up to several hundred degrees, well past where a conventional grease would fail.
Cleanliness Requirements
Finally, some parts simply cannot tolerate an oily residue. Optical assemblies, food-contact hardware, cleanroom equipment, and mechanisms that must remain visually clean all suffer when grease creeps where it should not.
05.
When a dry film lubricant is the better choice
Put those failure modes together, and a pattern emerges. Dry film lubricants tend to win in a handful of recognizable situations.
Threaded Fasteners and Anti-Seize Applications
Threaded fasteners and anti-seize applications are a classic case. A coated bolt goes together with a consistent, predictable torque and comes apart later without galling or seizing, even after years in the field. That predictability matters for anyone who has to trust a torque spec on hardware that will be disassembled down the line.
Press Fits, Splines, Cams, and Sliding Linkages
Press fits, splines, cams, and sliding linkages are another. These parts move slowly, intermittently, or under high contact pressure, exactly the conditions where oil migrates away and metal-to-metal galling begins. A bonded film stays put because it is part of the surface.
Aerospace and Defense Components
Aerospace and defense linkages, flap tracks, and actuator components frequently call out dry film lubricants for the same reason, with the added benefit that the film provides its own corrosion protection during long storage. A part can sit in a depot for years and still move correctly when it is finally needed.
Vacuum and Space Environments
Parts that operate in a vacuum or in space are almost a requirement rather than a choice. Oil outgasses and boils away in a vacuum, while MoS2 lubricates better in the absence of air and moisture.
Clean and Contamination-Sensitive Parts
And any part that has to stay dry and clean, from medical devices to precision instruments, benefits from lubrication that leaves no film to collect contaminants.
06.
Heat-cured or air-cured: a practical fork in the road
Once a dry film lubricant is the right approach, the next question is how it is cured, and this is where two common specifications come into play.
MIL-PRF-46010
MIL-PRF-46010 covers heat-cured dry film lubricants. The part is coated and then baked, and that bake is what gives the film its durability, wear life, and load-carrying ability. Heat-cured films are the workhorse choice for parts that see real service loads. The tradeoff is that the part has to survive the oven. Some heat-treated or temperature-sensitive components cannot.
MIL-PRF-46147
MIL-PRF-46147 covers air-cured dry film lubricants. These cure at room temperature, so nothing goes in an oven. That makes them the answer for parts too large to bake, assemblies that would be damaged by heat, or field touch-up of a coating that was originally heat-cured. Air-cured films generally do not wear as long as heat-cured films, so the choice is a genuine engineering trade, not a matter of one being simply better.
Knowing which spec a drawing calls out, and understanding why, is part of what keeps a finishing job from going wrong. In JH Metal Finishing's experience, a fair number of quoting problems trace back to a part specified for a heat-cured film that could not actually withstand the heat. Catching that before processing saves scrapped parts and lost time.
07.
Why the base coat underneath matters
A dry film lubricant is only as good as its bond to the metal. That bond is where a base coat earns its keep.
Manganese phosphate is a common and effective base for a dry film lubricant. The phosphate crystals give the surface a slightly rough, absorbent texture that the lubricant film can grip, much like primer under paint. The phosphate layer also adds its own measure of corrosion resistance and helps parts through their initial break-in period, when surfaces are still seating against each other.
This is why the question "Can a dry film lubricant go over phosphate?" comes up so often. The answer is yes, and in many demanding applications, it is the preferred approach. The right base depends on the part material and the performance the drawing requires, and that's a conversation worth having before parts are processed, not after.
08.
When oil or grease is still the right answer
Being honest about where dry film lubricants do not belong is part of specifying them well.
Rolling-Element Bearings
Rolling-element bearings, the ball and roller bearings inside high-speed rotating equipment, are usually better served by oil or grease. Those bearings depend on a continuously replenished lubricant film to carry load and carry away heat, and a bonded dry film cannot renew itself the way circulating oil can.
Continuous High-Speed Sliding
Continuously loaded, high-speed sliding contacts fall into the same category. A dry film holds a finite amount of lubricant. Once it wears through, it is gone, and there is no reservoir to draw from. Where a part runs constantly and generates real heat, wet lubrication that can be filtered, cooled, and topped off is the better system.
Hydrodynamic Lubrication
Applications that need a true hydrodynamic film, where the moving parts ride on a pressurized wedge of oil and never actually touch, also belong to wet lubrication. A dry film cannot create that separating layer.
The practical rule of thumb: dry film lubricants excel at slow, intermittent, high-pressure, contamination-sensitive, or wide-temperature work, and at parts that must be lubricated once and left alone. Fast, continuous, heavily loaded, heat-generating machinery usually still wants oil or grease. In many assemblies, the two work together, with a dry film serving as backup lubrication beneath the grease so the part does not fail outright if the primary lubricant is ever depleted.
09.
What the specifications are really telling you
Specifications can read like alphabet soup, but each one is shorthand for a real performance promise.
MIL-PRF-46010
MIL-PRF-46010, the heat-cured standard, is written around wear life, load-carrying capacity, and corrosion protection. Films meeting it can carry very high contact pressures and, when applied over phosphated steel, offer meaningful corrosion protection through years of indoor storage. For an engineer, calling out 46010 is a way of saying the part needs durable, load-bearing dry lubrication that will also protect the surface while it waits to be used.
MIL-PRF-46147
MIL-PRF-46147, the air-cured standard, trades some of that wear life for the ability to coat parts that cannot be baked. Specifying it is a way of saying the geometry or the material rules out an oven.
SAE AS5272
For aerospace work, the SAE standard AS5272 now carries the types that older military documents used to cover, so a modern aerospace drawing may reference it directly. The intent is the same: a defined, tested, repeatable dry film lubricant.
None of these specs mean much without process control behind them. That is what accreditation like NADCAP and ISO 9001 is really about. NADCAP, in particular, is an aerospace-industry program that audits a finishing process in detail, confirming that a shop does what its paperwork says, every time, with documentation to prove it. For a purchasing manager, a NADCAP-accredited supplier is a way to reduce the risk that a coating passes on paper but fails in service.
10.
Making the call
The decision between a dry film lubricant and conventional oil or grease comes down to a few honest questions about the part. How fast and how continuously does it move? How heavily is it loaded? What temperatures does it see? Does it sit idle for long periods? Does it need to stay clean, or survive years in storage before it is used?
Work through those questions and the right lubrication strategy usually becomes clear. When it does not, that is exactly the kind of thing worth talking through with someone who has seen a lot of parts come through the shop.
If you are weighing dry film lubrication against oil, grease, or another finish, or you are simply not sure which specification your part should call out, the team at JH Metal Finishing is glad to talk it through. Bring a drawing, a specification, or just a description of how the part is used, and they can help you compare the options and confirm the finish that fits the application.
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