Motor Grader Moldboard Basics

Flat edges are the standard choice for heavy road jobs because of their strength and available wear material. They’re a dependable option when you need durability and predictable cutting performance in tough grading environments.

Best for:

• Road development
• Heavy road maintenance
• Applications where strength and impact resistance matter most

Limitations:

• Flat edges struggle to carry material forward or work in packed, frozen or rocky conditions that require more bite. In high-abrasion environments, they also wear faster than serrated edges.

Pro tip:

• If you need more penetration in tough material, a flat serrated edge (see below) is often a better choice.

Curved edges penetrate the surface while carrying existing material forward, leaving a smooth, even finish. Their arc creates the rolling action you need for fine grading, reducing chatter and helping material flow cleanly up the moldboard.

Best for:

• Reconditioning existing road surfaces
• Fine grading and finish work
• Jobs where surface smoothness is the priority
• Applications that benefit from strong rolling action

Limitations:

• Curved edges aren’t ideal for aggressive cutting or high-impact conditions. If you need more penetration, a curved serrated edge (see below) is the better fit. However, a curved serrated edge won't leave as clean a surface as a standard curved edge.

Pro tip:

• If your finish tolerances are tight — less than ¼ inch (6 mm) — a narrow, thin curved edge can give you the control you need to dial in the final surface.

Serrated edges — whether flat or curved — are built for material that fights back. The teeth exert more down pressure than a continuous edge, helping you cut into hard material. They break the surface quickly so you can start shaping it.

Best for:

• Hard-packed gravel
• Frozen ground and icy surfaces
• Reclaiming or reconditioning tough roadbeds
• Jobs where you need more bite before you can grade

Limitations:

• Serrated edges won’t leave as clean a finish as a continuous edge, so you’ll likely need a follow-up pass to smooth out tooth marks. They’re also not ideal for high-impact conditions unless installed over a 6-inch (152 mm) base edge to reduce tooth breakage.

Flat or curved?

• Flat serrated edges deliver the most down pressure, making them ideal for breaking packed gravel, frozen ground and ice.
• Curved serrated edges penetrate even better than flat when used with a forward moldboard. They bite harder while still helping material roll more smoothly.

Shape determines how you cut. Material determines how long the edge lasts, how well it handles abrasion and how often you’ll be replacing sections. The three most common material types are:

1. Through-Hardened Steel

Most Cat^® edges are made of through-hardened steel for good reason: it offers high impact resistance and dependable wear life across a variety of grading conditions.

2. High-Carbon Steel

High-carbon edges bring strong surface hardness and perform well in light-duty applications where impact is extremely low — think finish work. They provide good wear life in abrasive material but won’t withstand heavy impact like through-hardened steel.

3. Tungsten Carbide

These edges combine a through-hardened base with tungsten carbide inserts for exceptional abrasion resistance. In high-abrasion, low-impact environments, they can last up to 20 times longer than through-hardened edges. They're ideal for:

• Unimproved earthen material roads
• Public sand and gravel roads
• Mining and logging haul roads

If your grading conditions shift throughout the day — fine finish work one hour, abrasive road maintenance the next — the Cat GraderBit2 system gives you the versatility a continuous edge can’t.

Instead of one solid cutting edge, GraderBit2 uses tungsten carbide bits mounted along a base, each designed to rotate and wear evenly. In high-abrasion, low-impact environments, these bits can deliver up to 20 times the life of standard through-hardened edges.

Different bit designs let you configure the system as a continuous edge or create serration patterns that let aggregate pass through. That makes GraderBit2 especially effective for finish grading, maintaining roadways, reconditioning haul roads and reshaping public sand or gravel surfaces.

When it’s time for maintenance, each bit installs and removes without tools thanks to a simple pull-ring retention system. The result is a cutting solution that adapts to multiple applications, stands up to abrasive conditions and keeps edge changes fast and straightforward.

Your cutting edges shape everything your grader does — from how many passes it takes to how long your components last. If you’re weighing a new machine, this is the time to get your moldboard setup right.

For a deeper look at moldboard configurations and options, talk with your local Cat dealer about how different edge types line up with your material, your production goals and the way you run your grader.

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