Harrow Disc Blade Sizes: Chart, Notched vs Plain and How to Order

Choosing the right harrow disc blade sizes is the fastest way to keep a disc harrow cutting deep and saving fuel. Worn or wrong-sized blades ride on top of hard ground, need extra passes and leave clods behind. This guide gives you the full size chart, explains plain vs notched blades and 65Mn vs boron steel, and shows how to order replacements that fit first time.

Why Harrow Disc Blade Sizes Matter

The disc is the wearing heart of every disc harrow, disc plough and ridger. Its diameter decides how deep the gang can work, its thickness decides how much impact it can take, and its centre hole decides whether it fits your gang shaft at all.

Shenghang makes plain and notched discs from 12 to 36 inches in diameter and 3 to 12 mm thick, from 65Mn spring steel or 30MnB5 boron steel, heat-treated to HRC 38–44. You can see the full range on our harrow discs page.

Harrow Disc Blade Sizes Chart: Diameter, Thickness and Weight

The most common sizes we produce, with blade weights to help you estimate freight:

Diameter	Thickness (mm)	Plain blade (kg)	Notched blade (kg)
Ø355 mm (14″)	3 / 4	2.53 / 3.37	2.33 / 3.12
Ø410 mm (16″)	3 / 4	3.10 / 4.12	2.85 / 3.82
Ø460 mm (18″)	3 / 4 / 5	4.15 / 5.54 / 6.92	3.85 / 5.19 / 6.52
Ø510 mm (20″)	3 / 4 / 5 / 6	5.15 / 6.87 / 8.67 / 10.3	4.80 / 6.47 / 8.22 / 9.80
Ø560 mm (22″)	4 / 5 / 6	8.12 / 10.15 / 12.2	7.67 / 9.65 / 11.6
Ø610 mm (24″)	4 / 5 / 6 / 7	9.78 / 12.2 / 14.67 / 17.12	9.28 / 11.6 / 14.02 / 16.42
Ø660 mm (26″)	5 / 6 / 7 / 8	14.66 / 17.6 / 20.53 / 23.4	14.01 / 16.9 / 19.78 / 22.6
Ø710 mm (28″)	6 / 7 / 8	20.8 / 24.26 / 27.73	20.05 / 23.46 / 26.83

Larger harrow disc blade sizes up to 36 inches and 12 mm thick are made for folding and extra-large harrows. Specifications are for reference; we can produce to drawing.

How to Match Blade Size to Your Harrow and Tractor

The right blade depends on the machine and the tractor pulling it. As a general guide:

• Light mounted harrows (12–55 HP): 16″ to 20″ blades, 3–4 mm thick.
• Medium mounted harrows (25–80 HP): 20″ to 24″ blades, 4–5 mm thick.
• Heavy offset harrows (80–140 HP): 26″ (660 mm) blades, 6–8 mm thick, often notched on the front gang.
• Folding and extra-large harrows: 26″ to 36″ blades, 6–12 mm thick.

For example, our light series uses 460 mm discs, the medium series 560 mm discs, and the hydraulic heavy and folding disc harrows run 660 mm discs. Not sure of your machine class? Try the selection assistant.

Plain vs Notched Disc Blade

A notched disc blade has cut-outs around the edge. The notches grip the soil, pull the blade into hard ground and chop long stalks and roots. That makes the notched disc blade the first choice for the front gang of a harrow and for heavy residue such as corn stalks and sugarcane trash.

A plain blade has a smooth, continuous edge. It slices cleanly, leaves a smoother finish and is usually fitted on the rear gang of a harrow and on disc ploughs, ridgers and seeders. Every plough disc blade we supply for disc ploughs is plain unless you ask otherwise.

65Mn or Boron Steel Disc Blade?

65Mn is a high-carbon manganese spring steel: tough, economical and well suited to light and medium harrows.

A boron steel disc blade is made from 30MnB5. A small amount of boron lets the steel harden more deeply and evenly during heat treatment, so the blade keeps its strength right through the thickness. In abrasive sandy soil and stony fields, boron steel resists wear and impact better and usually lasts longer between changes, which lowers the cost per hectare on heavy harrows.

How to Order the Right Replacement Discs

Measure a new or lightly worn blade and send us:

1. Diameter in inches or millimetres.
2. Thickness measured at the centre of the blade, not at the worn edge.
3. Centre hole – square or round, and its size across the flats or diameter.
4. Edge – plain or notched – and the steel grade you want.
5. Concavity (dish depth) if the blade is for a plough or a special machine.
6. Drawing or photo if the blade has bolt holes or a special shape.

We also supply matching bearing assemblies, grease-lubricated or oil-bath, in any size.

Common Buying Mistakes

• Measuring a worn blade. Worn blades give the wrong diameter; measure a spare or check the manual.
• Ignoring the centre hole. The right diameter with the wrong hole will not fit the gang bolt.
• Buying thin blades for heavy work. Thin blades on an 80–140 HP offset harrow bend in hard ground.
• Mixing concavity on one gang. Blades with different dish depth cut at different depths and wear the bearings unevenly.

Why Buy Direct from the Factory

As a harrow disc manufacturer China buyers can deal with directly, Shenghang produces blades for the disc harrows, disc ploughs, ridgers and seed drills we build, and for most similar machines from other makers. You order from the factory with SH marking or OEM options, and blades are packed on pallets or in wooden cases for export by sea, rail or air. See our export and shipping page for details. Sharp, correctly sized blades support sustainable agricultural mechanization: fewer passes, less fuel.

For the machines that carry these blades, read our heavy duty disc harrow guide.

Related guide: our disc harrow size chart helps you match a complete light or medium harrow to your tractor.

FAQ

What are the most common harrow disc blade sizes?

The most common sizes are 20″, 22″, 24″, 26″ and 28″ (510–710 mm). Light harrows mostly use 16–20″ blades, medium harrows 20–24″ and heavy offset harrows 26″ blades 6–8 mm thick.

When should I use a notched disc blade instead of a plain one?

Use notched blades on the front gang, in hard ground and in heavy residue such as corn stalks or sugarcane trash. Use plain blades on the rear gang and on ploughs and ridgers for a smoother finish.

Is a boron steel disc blade worth it?

In sandy, abrasive or stony soil, yes – 30MnB5 hardens evenly through the full thickness and usually lasts longer between replacements. For light work in soft soil, 65Mn is an economical choice.

Can one plough disc blade (plow disc) fit both harrows and ploughs?

Not always. Plough (plow) discs often have a different concavity and hole pattern from harrow discs. Send the diameter, thickness, centre hole and dish depth and we will match the right blade.

Get a Quote

To get a fast quote, send us: blade diameter and thickness, plain or notched, steel grade (65Mn or 30MnB5), centre hole type and size, quantity, the harrow model and tractor HP, and your destination port. Message us on WhatsApp +86 133 8469 2372 or browse all sizes on the harrow discs page.