Feature (Product Specifications)

The 1308 convex PDC cutters are 13.08mm diameter diamond composite inserts with a convex (domed) diamond surface profile, distinct from the standard flat-top 1308 cutters. The convex geometry features a central dome height of 0.3mm above the cutter perimeter, creating a lens-shaped diamond layer that concentrates cutting force at the apex. 

Diamond layer thickness at center: 1.8-2.2 mm; Substrate: tungsten carbide with 6%-8% cobalt. Diamond volume concentration: 80%. 

Hardness: HRA >80. Thermal stability: up to 700degrees C. The convex profile changes the contact mechanics between cutter and rock: instead of full-face contact, the dome engages the rock progressively from apex to periphery, producing a different fracture pattern than flat cutters. These cutters are manufactured by SUNGOOD TECH for coal mining drag bit construction as button insert replacements.

Advantage (Performance Advantages)

The convex dome geometry provides two performance advantages over flat-top cutters in coal mining applications. First, the concentrated force at the dome apex fractures rock at lower threshold weight on bit than flat cutters, which require full-face engagement before the cutter reaches its efficient operating zone. In soft to medium coal (15-40 MPa), convex cutters initiate cutting at approximately 15-20% less WOB, reducing the hydraulic and mechanical load on the drilling rig. Second, the progressive engagement from apex to periphery creates a natural self-sharpening effect: as the dome apex wears, the contact area increases, distributing force over a wider zone and maintaining cutting efficiency longer than flat cutters that develop uniform wear flats. In coal mining drag bit comparisons, convex 1308 cutters maintained 78% of initial ROP after 200m of drilling versus 55% for flat-top 1308 cutters at the same footage.

Benefit (Customer Benefits)

For coal mine operators using drag bits in soft to medium formations, convex cutters reduce the weight on bit required for efficient drilling and extend the useful life of each cutter before replacement. The practical benefit is most apparent on light-duty drilling rigs with limited thrust capacity, where the reduced WOB requirement allows the rig to maintain penetration rate without approaching its mechanical limits. In underground coal mining where rig weight and space are constrained, convex cutters enable drilling in formations that flat cutters cannot efficiently penetrate at available WOB. The self-sharpening effect also reduces the frequency of bit changes: on a 75mm two-wing drag bit in 20-35 MPa coal, convex cutters average 180-250m per bit versus 120-180m for flat cutters, a 35-40% improvement. Fewer bit changes mean less downtime and lower per-meter drilling cost in continuous mining operations.

Evidence (Field Proven Results)

An underground coal mine in Guizhou Province using 75mm two-wing drag bits on lightweight mobile drill rigs (limited to 800 kg thrust) tested SUNGOOD TECH convex 1308 cutters against standard flat-top 1308 cutters in coal seams at 20-35 MPa. The convex cutters achieved 2.8 m/min average ROP versus 2.2 m/min for flat cutters, a 27% improvement at the same WOB setting. Bit change interval increased from 145m to 210m on average. Over a 3-month evaluation covering 12,000m of total drilling, the mine reduced bit consumption from 83 bits to 57 bits and saved approximately 26 hours of non-drilling time from fewer bit changes. Per-meter drilling cost decreased by 22% including bit procurement and downtime. For operations in harder or more abrasive formations where the convex dome may wear faster than flat cutters, the 1313 high wear resistance drill Tool inserts PDC Cutters for coal mining provides 1313 high wear resistance PDC cutters with enhanced diamond properties for abrasive coal mining seams.

Type: 1308 High-Grade Convex PDC Cutters Diamond layer thickness at center: 1.8-2.2 mm; Substrate: tungsten carbide with 6%-8% cobalt. Hardness: HRA >80. Thermal stability: up to 700degrees C.