SDS-Max Mining Drill Bits — Built for Hand-Held Blast-Hole Drilling
Application Overview
Small-scale and artisanal mining operations drill production blast holes with hand-held SDS-Max rotary hammers: a 32 mm hole, 450–800 mm deep, inclined about 15°, loaded with ø25 mm explosive cartridges. The drill bit is the consumable that decides advance rate and cost per metre. Zhonghuan manufactures SDS-Max mining bits factory-direct for this exact duty — 6-cutting-edge and ZHMAX-7 multi-segmented cutter heads on 42CrMo bodies, in the same 450 / 620 / 920 mm lengths the Latin American market knows from the DeWalt broca francesa and broca alemana lines — with OEM private-label supply for mining distributors.
Size Program
| Spec | Range | Notes |
|---|---|---|
| Diameter | Ø28–38 mm (Ø32 mm is the volume size); Ø16–25 mm small-diameter tier on its own program page | 32 mm hole fits ø25 mm (1") cartridges with working clearance |
| Total length | 450 / 570 / 620 / 920 mm | Matches the 450 / 620 / 920 mm market-standard mining lengths; other lengths by drawing or sample |
| Shank | SDS-Max | Fits all SDS-Max rotary hammers |
| Body | 42CrMo alloy steel, heat-treated | High fatigue resistance for repeated 12–20 J impact |
| Carbide | Controlled-atmosphere brazed virgin carbide to approved YG11C-class specification | Lot material certificate tied to the approved grade |
Trade note: Latin American buyers quote mining bits by working length in centimetres — “(40)”, “(60)”, “(80)” ≈ 400 / 580–600 / 800 mm usable, the convention the DeWalt fichas print as LONG. USO. Our quotations state both total and working length per SKU. The 1300 / 1500 mm XL / XXL tier has its own program page.
Two Head Architectures
| Head | Geometry | Best for |
|---|---|---|
| 6-Cutting-Edge Mining Head | Six brazed cutting edges distribute impact around the head; keeps holes round and resists chipping when the bit walks on uneven rock faces | Medium-hardness rock, mixed ground, general production drilling — the volume workhorse |
| ZHMAX-7 Multi-Insert 4-Cutter | Full-width multi-segmented primary insert with two inclined side inserts and vibration-optimized flutes | Hard, abrasive rock (quartzite, andesite, granite veins); deep holes where debris evacuation limits speed |
The engineering background on this geometry class is covered in our guide to SDS-Max carbide head geometry (ZHMAX-5X / 7 / 8). The 6-edge head also has a dedicated program page — 3-cutter / 6-edge SDS-Max drill bits manufacturer — and the benchmark line behind it is broken down in Diager Ultimax 168 explained. The ZHMAX-7 progressive head likewise has its own program page: multi-segmented cutter SDS-Max drill bits manufacturer.
Rotary Hammer Compatibility
| Machine (10 kg class) | Impact energy | Note |
|---|---|---|
| DeWalt D25773 / DCH733 (60V) | 19.4 J / 13.3 J | The combination DeWalt markets with its mining bit lines |
| Makita HR5212C | ≈20 J | The most common machine in Andean small-scale mining |
| Bosch GBH 8-45 D/DV | ≈12.5 J | Pairs with Bosch SDS max-7 / QX mining bits |
All bits use the universal SDS-Max interface — no machine-specific fitment. In deep blast holes, withdraw the bit every 200–300 mm of advance to clear cuttings; packed dust is the main driver of overheating and premature carbide wear. For machine-by-machine pairing guidance, see SDS-Max mining bits for the 20 J rotary hammer class.
Application Scenarios
1. Production Blast-Hole Drilling
Material: Medium to hard rock at the working face
Recommended: Ø32 mm, total length 620 or 920 mm; 6-edge head for medium rock, ZHMAX-7 for hard abrasive rock
Notes: Typical rounds drill 450–800 mm deep holes inclined ~15° to the face, loaded with ø25 mm cartridges. Hole straightness and gauge retention decide whether cartridges seat fully — retire bits once gauge wear approaches the cartridge clearance. Never re-drill a bootleg (remnant) hole.
2. Secondary Breaking
Material: Oversize boulders from the muck pile
Recommended: Ø32 mm × 450 mm; 6-edge head
Notes: Short holes for plug-and-feather splitting, expansive demolition mortar, or light secondary charges where regulations permit. The short bit gives the stiffest column and the roundest hole for wedge sets.
3. Rock Bolt and Support Holes
Material: Back and walls during ground support cycles
Recommended: Ø28–35 mm to match the bolt system, length per bolt embedment + 50 mm
Notes: The same hammers drill support holes between production rounds. See our mining & tunneling drilling solutions and rock bolt support page for bolt-matched selection.
Mining drill bit packing: photos from our factory
Our long SDS-Max mining drill bits in individual protective tubes inside a carton, followed by strapped cartons on a wooden pallet. Tell us your sizes, quantities and packaging requirements for an OEM quotation.
OEM & First-Order Terms
- MOQ: 200 pcs per size
- Samples: Paid samples; sample and shipping cost carried by the buyer; ~30 days sample lead after confirmation
- Production timing: Confirmed after specification and capacity review at order placement
- Branding: Laser-etched logo + custom packaging (bulk / blister / branded box)
- Quality: ISO 9001; material certificates linked to each shipment and the approved carbide grade
For the field engineering behind these specs — hole-to-cartridge sizing, electric vs pneumatic economics, bit wear modes — see the technical guide: rotary-hammer blast-hole drilling in small-scale mining.
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