Quick Answer: Eight Numbers Decide a Core Bit
A diamond core bit datasheet comes down to eight specs: diameter, usable length, segment height, segment count, bond grade, diamond concentration, thread/connection, and the wet/dry rating tied to welding method. Read those eight and you can compare any two bits — and write a precise RFQ — without a brand name. This guide decodes each line, then shows a sample datasheet translated into what it means for you.
Reusable RFQ Tables
If a supplier quotes only "102 mm diamond core bit", the quote is not comparable. Use the blocks below as the minimum data structure for a distributor RFQ, catalogue line or private-label SKU sheet.
| RFQ field | Example | Why it prevents mistakes |
|---|---|---|
| Diameter x usable length | Ø102 x 400 mm | Separates hole size from true drilling depth. |
| Segment height / shape | 10 mm roof segment | Controls life, price comparison and cutting feel. |
| Bond / substrate | Soft bond for cured reinforced concrete | Prevents hard-bond-on-hard-concrete glazing. |
| Thread / machine | 1¼-7 UNC rig | Avoids adapter runout and wrong spindle fit. |
| Wet/dry + welding | Wet/dry, laser-welded | Makes dry use and rebar contact a safety claim. |
| Diameter band | Typical connection | Buyer note |
|---|---|---|
| Ø25–52 mm | 5/8-11, 1/2 BSP, small rig or handheld | MEP holes, conduit, handheld ranges; check dry rating carefully. |
| Ø52–102 mm | 5/8-11 or 1¼-7 UNC | Plumbing and wall penetrations; thread depends on machine class. |
| Ø102–152 mm | 1¼-7 UNC rig | Structural wet coring; water flow, barrel runout and segment weld matter. |
| Ø152–350 mm | 1¼-7 UNC rig / custom | Heavy openings; quote barrel steel, wall thickness and extension plan. |
Diameter & Usable Length
Diameter (OD) is the hole size you get. Usable (drilling) length is how deep you can core before you need an extension — and it is shorter than the overall barrel length, because the connection and barrel head consume some of it. Read both: a "14-inch" bit may give only ~12 inches of usable depth. If you core deep, check the usable length and whether the barrel takes an extension.
Segment Height & Count
Segment height is the wear reserve — the usable diamond depth before the bit is spent — and the best single proxy for life. A 10 mm segment carries roughly twice the life of a 5 mm one. Segment count rises with diameter: more segments distribute load and clear slurry on larger bits. Judge a bit on cost-per-meter using segment height, not on sticker price.
Bond Grade
The bond (matrix) is the metal that holds the diamond; its hardness sets the wear rate. Datasheets show it as a grade or code — soft / medium / hard, or a bond letter. The rule is inverse: soft bond for hard material (cured concrete, granite), hard bond for soft/abrasive material (green concrete, asphalt). The bond grade is the most important line for matching the bit to your substrate.
Diamond Concentration & Grit
Concentration is how much diamond is loaded into the bond — higher for hard/abrasive, long-life jobs; lower for faster cuts in softer material. Grit/mesh sets finish and speed (coarser = faster/rougher). Together they place the bit on the life-versus-speed trade. Don't chase the highest concentration; match it to the material.
Thread & Connection
The connection must fit your machine: 1¼-7 UNC (rig and large-bit standard), 5/8-11 UNC (handheld and US bits), ½" BSP / G½" (CNC and stone fabrication), and metric M-threads on some tile bits. Adapters cross between them but add length and runout, so specify the native connection where possible.
Wet/Dry Rating & Welding
This line is a safety classification, not a feature. Laser-welded cores are rated for dry and high-speed cutting; sintered (silver-brazed) and brazed cores are wet-only, because dry heat can release the segment. If the datasheet does not state the welding method or a max dry RPM, treat dry use as unsupported and run wet.
A Spec Sheet, Decoded
| Spec field | Example | What it means for you |
|---|---|---|
| Diameter (OD) | Ø102 mm | Hole size — match the penetration/anchor. |
| Usable length | 400 mm | Max depth before an extension (barrel is longer). |
| Segment height | 10 mm | Wear reserve — ~2× the life of 5 mm. |
| Bond grade | Soft | For hard/cured concrete or stone. |
| Concentration | High | Long life on abrasive/hard material. |
| Thread | 1¼-7 UNC | Fits standard core-drill rigs. |
| Welding | Laser-welded | Rated for wet and dry, incl. rebar. |
| Barrel | Seamless 30CrMnSi | Runs true; rebar-safe rigidity. |
Zhonghuan View: A Datasheet You Can Hold Us To
Zhonghuan publishes the full spec on every OEM core bit — diameter, usable length, segment height and count, bond grade, concentration, thread, welding, and barrel steel — because a bit you can specify is a bit you can verify. Segments are laser-welded as standard and barrels are seamless alloy tube (30CrMnSi / 42CrMo class), so the wet/dry and rebar ratings are real, not aspirational.
Send us the five-line minimum — substrate and strength class, diameter, usable length, wet/dry, and machine/thread — to WhatsApp +1 437 876 7774, and we will return a full datasheet and a witness-cut offer before you commit volume.
