The Tier Below 32 mm — Small-Diameter SDS-Max for Mining
Application Overview
Mining buyers quoting the 32 mm broca minera almost always need a second tier in the same container: Ø16 / 19 / 22 / 25 mm SDS-Max bits for smaller cartridge holes, mesh and pin anchoring, and auxiliary drilling underground. Zhonghuan manufactures this small-diameter tier on the same platform as the 32 mm mining line — SDS-Max shank, heat-treated alloy body, controlled-atmosphere brazed virgin carbide — so one machine fleet and one supplier cover every hole the operation drills. OEM / private label, factory-direct.
Why SDS-Max at These Diameters — and Not SDS-Plus
Ø16–25 mm exists in SDS-Plus catalogs, so the question is fair. Underground, three things decide it:
- One machine fleet. Small mines run 10 kg-class SDS-Max combination hammers (Makita HR5212C, DeWalt D25773, Bosch GBH 8-45). A small-diameter SDS-Max bit means the same machine drills the ø22 mm cartridge hole and the 32 mm production hole — no second hammer riding down the shaft.
- Shank robustness at 12–20 J. The SDS-Max interface was engineered for this impact class. Driving a slender bit with a 20 J machine concentrates everything at the shank and the flute runout — the SDS-Max shank carries it; a light-duty interface battered all shift does not.
- Slenderness is the real enemy. A Ø19 mm bit at mining lengths is the most flexible drill column on site. Off-axis hand drilling bends it every stroke, which is why this tier runs the same heat-treated alloy body engineering as the 32 mm line rather than construction-grade steel.
What Each Diameter Does Underground
| Diameter | Typical duty | Note |
|---|---|---|
| Ø25 mm | Blast holes for the smaller cartridge format | A 25 mm hole gives a ø22 mm (7/8") cartridge — the smaller format common in Peruvian small-scale mining — working clearance, the same logic as 32 mm → ø25 mm cartridges |
| Ø22 mm | Narrow-vein and trim/perimeter holes | Where the vein is thin, smaller rounds waste less rock; tighter perimeter holes protect the walls |
| Ø19 mm | Pin and accessory anchoring | Mesh pins, eye bolts, pipe and cable brackets, ladder and platform fixing underground |
| Ø16 mm | Light anchoring and pilot work | Smallest practical SDS-Max mining size — light fixings, pilot and relief holes |
Rock-bolt systems (split sets, resin bolts, expansion shells) sit above this tier at Ø28–38 mm — covered on the rock bolt & ground support page. The 32 mm production-hole program is on the SDS-Max mining drill bits manufacturer page.
Program Specs
| Spec | Range | Notes |
|---|---|---|
| Diameter | Ø16 / 19 / 22 / 25 mm | All SDS-Max shank — same fleet as the 32 mm line |
| Total length | By drawing or sample | Quoted per SKU within the same 320–920 mm envelope as the main mining platform |
| Head | 4-cutter cross (ZHMAX-5X class) or multi-segmented cutter (ZHMAX-7 class, from Ø16 up) | Cross head is the workhorse at these diameters; progressive S for hard abrasive rock — locked by drawing at RFQ |
| Body | Heat-treated alloy steel | Slender columns bend hardest — body steel and heat treatment matter most at this tier |
| Carbide | Controlled-atmosphere brazed virgin carbide | Same brazing line and carbide policy as the 32 mm mining bits |
Trade note: Latin American buyers quote mining bits by working length in centimetres — "(40)", "(60)", "(80)" ≈ 400 / 580–600 / 800 mm usable. Our quotations state both total and working length per SKU.
Head Choice on Small Diameters
At Ø16–25 mm the full-width 4-cutter cross (ZHMAX-5X class) is the standard mining head: tough, self-supporting on uneven faces, and economical at the consumption rates cartridge drilling produces. From Ø16 mm upward the multi-segmented cutter (ZHMAX-7 class) is available for hard, abrasive rock. The 3-plate / 6-edge architecture starts higher in the range — it belongs to the Ø28–38 mm tier on the 6-edge program page.
OEM & Ordering
The small-diameter tier ships under the same terms as the main mining program: MOQ 200 pcs per size, laser-etched private label, custom packaging, samples freight-paid for witness testing, ISO 9001 with material certificates per lot. Most distributors order it as add-on lines in a mixed container with the 32 mm volume sizes — send your diameter mix (e.g. 16 / 25 / 32) and target rock, and we quote the matrix in one sheet. Machine-pairing guidance for the 20 J class is on the 20 J rotary hammer page.