The camshaft's material determines how much load the lobe surface can take, how long it lasts and what type of lifter it can run with. The choice between cast iron and steel, and which surface treatment goes on top, is not about prestige. It is about mechanics.
Cast iron: the most common cam core
Most camshafts, both original equipment and aftermarket, are made from alloyed cast iron. Newman Cams, one of Britain's most established camshaft manufacturers, specifies that the standard material for cast camshafts is a chromium-alloyed cast iron, often referred to as "chilled cast iron" or Grade 17, typically with 1% chromium.
"Chilled" refers to the manufacturing process: the lobes are cast against chilled molds that make the surface solidify quickly and form a hard, white iron structure in the lobe face, while the core stays tougher grey cast iron. The result is an extremely hard contact surface that stands up to the sliding load from a flat tappet lifter.
COMP Cams produces both cast and billet cores and notes that their cast camshafts work very well with flat tappet lifters, provided break-in and lubrication are handled correctly.
Billet steel: machined precision
A billet camshaft is machined from a solid steel bar, unlike cast iron, which is poured into a mold. Newman Cams describes billet as the preferred material for performance camshafts and states that their billet blanks are normally nitrided after grinding.
Common steel grades for billet camshafts include 5150 (chrome vanadium), 8620 (nickel chrome molybdenum) and 9310, all alloy steels with high fatigue strength. CylinderHead MFG notes that billet delivers superior strength, allows tighter tolerances, and resists bending and twisting better under high loads.
The downside is cost. Turning, grinding and nitriding a camshaft from solid bar costs considerably more than casting one.
EN40B: the nitriding steel
Newman Cams highlights EN40B as a steel designed specifically for nitriding. It contains aluminium, chromium and molybdenum, all of which form hard nitrides during heat treatment. The result is an extremely hard surface (typically 65 to 70 HRC) that withstands high contact loads, ideal for camshafts run with roller lifters and high spring pressures.
Surface treatments
Phosphate coating (Parkerizing)
OnAllCylinders describes Parco Lubrite (manganese phosphate) as the standard treatment for cast iron camshafts, and it has been for decades. The phosphate coating creates a porous, oil-retaining surface that holds a lubricating film through the critical break-in phase. The dark, matte finish you see on a new camshaft is the phosphate coating. It is not cosmetic. It is functional.
Nitriding
In nitriding, the camshaft is heat treated in a nitrogen atmosphere. Nitrogen atoms diffuse into the surface of the steel and form extremely hard nitrides. OnAllCylinders describes it as a process that case hardens the cam core, giving a wear surface considerably harder than untreated steel.
Nitriding is standard on billet camshafts and is also used on reground camshafts where the original surface hardening has been ground away and needs replacing.
DLC (Diamond-Like Carbon)
DLC is a thin, extremely hard carbon-based coating applied to the lifter's contact face (and sometimes to the cam lobe). OnAllCylinders notes that DLC surfaces are very slippery and highly wear resistant. NASCAR teams ran DLC-coated lifters with steel core camshafts during the era when the rulebook required flat tappets.
CatCams in Belgium has developed its own "slipper followers", flat lifters with a DLC coating and an extended contact face, specifically to enable more aggressive cam profiles than conventional roller finger followers can handle.
Micro finishing
Beyond phosphate coating, some manufacturers micro finish the cam journals and lobe contact surfaces. The process leaves an extremely smooth surface that reduces initial friction and improves the stability of the oil film. It is more common on performance camshafts than on standard replacement parts.
Blanks and cam grinding
Meksta grinds camshafts from blanks, meaning camshaft cores that have the correct basic shape, journal diameters and mounting dimensions but do not yet carry their final lobe profiles. By grinding the desired profile onto a blank, any cam specification can be created without casting a new mold.
This is the standard process for aftermarket camshafts worldwide. Manufacturers like COMP Cams, Newman Cams and ENEM all use grinding as their primary manufacturing method. The quality lies in the precision of the grinding machine, the accuracy of the program and the base properties of the material.
Material and lifter type go hand in hand
The choice of material and surface treatment does not stand alone. It has to match the lifter type:
- Flat tappet, cast iron cam: requires phosphate coating, correct hardening of the lobe surface and ZDDP-rich oil. The sliding contact relies on the sacrificial film between lobe and lifter.
- Flat tappet, billet steel: requires nitriding to reach sufficient surface hardness. Without nitriding, untreated steel is too soft for the sliding load.
- Roller lifters: the rolling contact allows harder materials and higher spring pressures. Nitrided billet steel is the standard choice for aggressive roller cams.
What it comes down to
The material is not a detail you see, but it is the detail that decides how long the camshaft lives. Cast iron with correct hardening works very well with flat tappets and the right oil. Nitrided billet steel gives maximum wear resistance under high loads. And the surface treatment, whether phosphate, nitriding or DLC, is what actually protects the lobe through the thousands of contacts per minute the camshaft has to survive.
Contact Meksta. We know which materials and processes give the right result for your build.