Coal Shearer Pick Grade Comparison: YG8 vs YG13 | Ruixin

Why Grade Selection Decides Your Cost Per Meter — Not the Pick Price

A longwall operation in the Shanxi coalfield was replacing shearer picks every four shifts. The picks were YG8, sourced from their existing supplier, priced competitively. The engineering manager switched to YG13 based on a recommendation. Pick life jumped to eleven shifts in the same seam.

The grade cost 12% more per pick. The total cost per meter of coal cut dropped by 38%.

This is the central problem with coal shearer pick grade comparison: most procurement decisions are made on unit price, not on the failure mode that is actually destroying picks on the drum. YG8 and YG13 are not interchangeable upgrades — they are solutions to different problems. Using the wrong one in the wrong seam does not save money. It multiplies replacement frequency, increases drum downtime, and raises cost per ton.

The comparison below covers the three variables that determine which grade belongs in your operation: hardness, cobalt content, and grain size — and how each maps to the specific failure modes of longwall coal cutting.

The Three Variables That Separate YG8 from YG13

Tungsten carbide for shearer picks is a composite: tungsten carbide (WC) grains held in a cobalt (Co) metal binder. The ratio of cobalt to carbide, and the size of the WC grains, controls everything else.

Cobalt Content (%) is the single most important variable for longwall picks. Cobalt is the tough component — it bends rather than fractures under impact. Increasing cobalt from 8% to 13% reduces hardness by approximately 2–3 HRA points but raises flexural strength (resistance to cracking) by 400–600 MPa. In a seam with hard rock bands, that toughness is the difference between a pick that survives a shift and one that shatters on the second roof contact.

Hardness (HRA) determines abrasion resistance. The WC grains are the hard component. Higher hardness means the carbide surface resists being ground away by abrasive coal and quartz particles. But hardness and toughness trade off directly — you cannot have both at maximum.

Grain Size (µm) affects crack propagation. Finer grains (1–2 µm) create a denser, harder microstructure. Coarser grains (2–4 µm) allow micro-cracks to deflect around grain boundaries rather than propagating straight through the tip. For impact-loaded picks, coarser grain combined with higher cobalt is the correct combination.

Grade	Cobalt %	Hardness (HRA)	Flexural Strength (MPa)	Grain Size (µm)	Primary Failure Mode Addressed
YG8	~8%	89.0–90.0	~1,800–2,000	1.5–2.5	Abrasive wear
YG11	~11%	87.5–88.5	~2,200–2,400	2.0–3.0	Mixed wear + impact
YG13	~13%	86.5–87.5	~2,600–2,800	2.5–4.0	Impact fracture
Ruixin SR8C	~8–9%	89.0 ± 0.5	≥2,200	2.0–3.0	Wear, with improved toughness
Ruixin SR10C	10%+	88.0 ± 0.5	≥2,200	2.0–3.0	Mixed face, impact resistance

SR8C sits in the YG8 range but with tighter grain control and higher verified flexural strength than standard YG8. SR10C fills the YG11 slot — usable where YG8 fractures but YG13 would be overkill.

What Longwall Cutting Actually Does to a Carbide Tip

A coal shearer drum rotates at 25–45 RPM. Each pick on the drum strikes the coal face between 60 and 150 times per minute. In a clean soft-coal seam, each strike is predominantly compressive — the pick wedges into coal and the material fractures. This is primarily an abrasive loading condition: the coal and fine particles grind the carbide tip down over thousands of cycles.

In a seam with a stony band — a layer of sandstone or mudstone within the coal — the loading changes completely. Each time a pick hits the stone band, it receives a high-energy impact load perpendicular to the cutting direction. This is a fracture loading condition. A grade optimized for abrasion resistance (high hardness, low cobalt) will chip or shatter under this loading. The carbide has high compressive strength but low crack resistance.

Two distinct failure modes, two distinct grade requirements:

Failure Mode 1 — Abrasive Wear (smooth conical flat on tip)
– Cause: Soft coal, quartz particles, high RPM, continuous cutting
– What happens: The cobalt binder wears away first, WC grains fall out, tip flattens and shortens
– Correct grade: Higher hardness (lower cobalt) — YG8 / SR8C
– Wrong grade: YG13 — too soft, wears faster than necessary

Failure Mode 2 — Brittle Fracture (sharp, irregular chip or total tip loss)
– Cause: Rock inclusions, roof/floor contact, hard coal, end-line drum positions
– What happens: Impact stress exceeds the carbide’s fracture toughness, tip cracks catastrophically
– Correct grade: Higher toughness (higher cobalt) — YG13 / SR10C
– Wrong grade: YG8 — too brittle, shatters before completing a shift

The first diagnostic step in any coal shearer pick grade comparison is to pull failed picks from the drum and look at the failure surface. Worn tips = abrasion problem, use harder grade. Chipped tips = fracture problem, use tougher grade.

Seam Geology Maps Directly to Grade

The geology of your coal seam is the dominant input for grade selection. The following framework maps Uniaxial Compressive Strength (UCS — the force required to crush a rock sample) and seam characteristics to the appropriate grade.

Soft Coal (UCS < 30 MPa, clean seam, no stone bands)
– Dominant failure mode: Abrasive wear
– Recommended: YG8 / Ruixin SR8C
– Rationale: High hardness maximizes tip life against continuous grinding. The seam is clean enough that impact fracture is not a significant risk.
– Expected tip life improvement over YG13: 20–35% longer wear life per tip

Medium Coal (UCS 30–60 MPa, occasional thin stone bands)
– Dominant failure mode: Mixed wear and impact
– Recommended: YG11 / Ruixin SR10C
– Rationale: Neither pure hardness nor pure toughness wins here. A mid-cobalt grade survives both loading types without optimizing for only one.
– Typical application: Most Shanxi and Inner Mongolia thermal coal seams

Hard Coal or Stone Bands (UCS > 60 MPa, frequent inclusions, roof contact)
– Dominant failure mode: Brittle fracture
– Recommended: YG13
– Rationale: If picks are chipping, only higher cobalt stops the failure. Accept the lower hardness — you were not getting wear life anyway if tips were fracturing after a few hours.
– End-line position note: Even in medium-coal operations, end-line picks should use YG13 regardless of center-pick grade

The Drum Position Variable Most Operations Ignore

Grade selection is not uniform across the drum. Different positions on the shearer cutting drum experience fundamentally different loading:

Center picks cut predominantly through the coal seam. They face high-volume abrasive contact with softer material. Abrasion resistance is the priority.

End-line picks (outer drum edges) contact the roof, floor, and any rock bands at the seam boundaries. They experience the highest impact loads on the drum. Fracture resistance is the priority.

Radial versus attack angle positions also affect loading — picks at shallower attack angles receive higher lateral bending loads, increasing fracture risk.

The practical implication: running a uniform grade across all drum positions is a compromise that serves neither position optimally. Operations that map grades to drum position — YG8 or SR8C for center positions, YG13 for end-line — consistently report 15–25% lower total pick consumption per meter of advance compared to single-grade configurations.

Ruixin supplies mixed-grade drum loading kits for customers who have established their seam profile. Provide your drum drawing and seam geology summary, and we map the grade allocation across positions.

Cost Per Meter: The Only Number That Matters

Pick unit price is irrelevant without cost-per-meter calculation. The formula:

Cost per meter = (picks consumed per meter) × (pick unit price)

If YG13 picks cost 12% more per unit but last 2.3× longer in a hard seam, the cost-per-meter drops by approximately 48%. The higher-priced pick is the lower-cost operating decision by a significant margin.

Conversely, in a soft clean seam, YG13’s lower hardness means faster wear. You consume more picks per meter at higher unit cost — a double loss.

The calculation requires one input you must measure in your operation: picks consumed per meter of advance at current grade. Track this over 30 shifts. Then trial a different grade for 30 shifts under the same cutting conditions. The cost-per-meter comparison tells you which grade to standardize on.

Ruixin provides trial quantities for grade qualification. Standard trial protocol: 500 picks per grade, same drum positions, same seam section, picks-per-meter tracked per shift.

Get the Grade Right for Your Seam

The coal shearer pick grade comparison is not a theoretical exercise. The wrong grade in your seam costs money on every shift it runs.

Send us your seam geology data — coal UCS (MPa), presence and thickness of stone bands, current pick failure mode (wear vs. fracture), and drum configuration — and our engineering team will specify the correct grade allocation across drum positions within 24 hours.

Contact Ruixin Tungsten Carbide:
– Email: info@ruixintungstencarbide.com
– WhatsApp: +86-15253178777

View our full range of carbide picks for coal shearer drums or request a mixed-grade trial kit for your operation.