Quick answer: do not approve a bulk DTH drill bit shipment from appearance, nominal diameter, or a supplier’s “passed QC” statement alone. A useful inspection starts from the approved configuration—hammer shank, bit diameter, face design, button arrangement, flushing layout, foot-valve or valveless requirement, and any controlled drawing or data-sheet revision—then checks the critical interfaces and records against that agreed specification.
For B2B buyers, the goal is not to create a universal DTH-bit tolerance table. Different shanks, bit sizes, designs, manufacturers and revisions can legitimately use different dimensions. The lower-risk approach is to define what must match, how it will be checked, what evidence will be retained, and what constitutes a nonconformity before the purchase order is released.
1. Start with the Approved DTH Bit Configuration
A DTH bit is not defined by diameter alone. OEM catalogues encode or list multiple product-defining variables. Epiroc’s current DTH catalogue, for example, separates shank design, bit diameter, front design, button configuration and carbide grade in its product coding. Caterpillar’s DTH bit catalogue likewise distinguishes shank type, bit diameter, face shape, wear protection and gauge-button quantity/size. Mincon lists shank support and whether a hammer/bit system uses a foot valve or valveless design.
That means the first inspection document should be a configuration control sheet, not a generic visual checklist. Before production or shipment, the buyer and supplier should be able to point to the same ordered definition.
| Configuration Item | What the Buyer Should Confirm | Why It Matters |
|---|---|---|
| Hammer / shank family | Exact hammer model, shank designation and controlled drawing or cross-reference | A bit can have the correct nominal diameter and still be mechanically incompatible with the hammer. |
| Bit diameter | Ordered diameter and its agreed dimensional tolerance | Controls the intended hole size and must match the hammer/bit system and drilling plan. |
| Face design | Flat, concave, convex, drop-center or other agreed design | Face geometry changes the ordered product and cannot be substituted from a photo alone. |
| Button configuration | Gauge/front button quantity, size, shape and layout where specified | Button arrangement is a controlled bit characteristic in OEM catalogues. |
| Flushing layout | Number/position of flushing passages or other agreed geometry | Flushing is part of the bit design and must match the approved configuration. |
| Foot-valve condition | Foot-valve or valveless/tubeless requirement | Some hammer families support different airflow architectures; the wrong version can be unusable. |
| Marking / identification | Part number, batch/lot or other agreed identification | Links the physical goods to the purchase order, drawing and inspection record. |
PerfoMax’s current DTH bit selection page follows the same procurement logic: final selection is based on the exact shank interface plus diameter, face, button pattern and flushing layout, and the written quotation with its attached drawing/data sheet controls the supplied configuration. Review the current PerfoMax DTH drill bit selection page before preparing an RFQ.
2. What Should Be Checked on the Physical Bit?
Once the ordered configuration is locked, inspection can move from “what did we order?” to “does this lot conform?” The following checks are practical categories for buyer-side or supplier-side final inspection. The actual tools, measurement points and tolerances should come from the approved drawing, data sheet, inspection instruction or purchase specification.
Shank and drive interface
- Confirm the shank family and major identifying geometry against the approved drawing or reference sample.
- Check splines, drive features, retaining features, shoulders and foot-valve interface where applicable.
- Look for visible cracks, deformation, heavy burrs, impact damage or machining defects that could affect fit.
- If gauges or master components are part of the agreed inspection method, record the pass/fail result rather than relying on visual similarity.
Buyer risk: “same inch class” is not a compatibility certificate. Mincon’s current DTH ranges show multiple shank supports and foot-valve configurations within hammer classes, so acceptance should be tied to the exact ordered interface.
Head diameter and critical dimensions
- Measure the dimensions identified as critical on the controlled drawing or data sheet.
- Record the measuring instrument and result when the purchase specification requires traceable dimensional evidence.
- Do not invent a generic ± tolerance if the drawing does not state one; resolve the missing tolerance before shipment.
For repeat orders, a dimensional trend can be more useful than a single “pass” stamp. If a characteristic is consistently drifting toward one edge of the agreed tolerance, the buyer can raise it before it becomes a field-fit or hole-size problem.
Face, buttons and flushing features
- Verify the ordered face profile and visible button layout.
- Confirm gauge and front button counts/sizes where they are part of the order definition.
- Check for missing, visibly damaged, incorrectly seated or obviously inconsistent carbide buttons.
- Confirm flushing holes/passages are present in the agreed pattern and are not visibly obstructed.
Do not judge carbide grade from color or a photograph. If carbide grade, steel grade, heat treatment or hardness is a contractual requirement, the evidence and test method need to be specified in the order or inspection plan. Appearance alone cannot verify metallurgical compliance.
3. Separate Visual Inspection from Dimensional and Documentary Inspection
A common procurement mistake is to treat “QC” as one activity. In practice, different defects need different evidence. PerfoMax’s current Quality Control page separates incoming-material, in-process, final-dimensional, visual and packing checks, and states that the applicable plan depends on product type, critical dimensions, operating requirements and agreed order documentation.
| Inspection Layer | Typical Evidence | What It Can Establish | What It Cannot Establish by Itself |
|---|---|---|---|
| Visual | Photos, visual checklist, marking review | Obvious damage, finish issues, missing features, wrong marking | Hidden material properties or dimensional conformity |
| Dimensional | Caliper/micrometer/gauge results against drawing | Whether measured critical dimensions meet agreed limits | Carbide grade or heat-treatment quality unless separately tested |
| Configuration | Part number, drawing revision, shank/face/button record | Whether the physical type matches the ordered design | Actual service life in the buyer’s rock and operating parameters |
| Process / material | Agreed certificates or test records where contractually required | Evidence for specified process/material requirements | Anything not covered by the stated test scope |
| Packing | Quantity list, label photos, packing photos | Count, identification and agreed packing condition | Internal dimensional or metallurgical quality |
4. Define the Acceptance Rule Before the Lot Is Ready
The worst time to argue about inspection is after a container is packed. The purchase order or quality agreement should state which characteristics are critical, which are checked on every unit, which are sample-inspected, and what happens when a nonconformity is found.
If the buyer and supplier choose a formal acceptance sampling by attributes approach, ISO 2859-1:2026 is a current international framework for AQL-indexed lot-by-lot sampling schemes. However, ISO 2859-1 does not define the correct DTH-bit dimensions, shank tolerances, button pattern or metallurgy. Those product requirements still have to come from the approved technical specification.
A practical way to structure the inspection plan
- Classify characteristics. Identify compatibility-critical, dimensional, visual, marking and packing characteristics.
- Define the requirement. Reference the exact drawing, data-sheet field, approved sample or written purchase specification.
- Define the method. State gauge, measuring tool, visual standard, document review or other agreed method.
- Define inspection coverage. Specify 100% inspection or an agreed sampling plan for each characteristic.
- Define disposition. State what triggers segregation, rework, re-inspection, replacement or lot rejection.
- Define records. Decide which inspection reports, photos, certificates or packing evidence must be retained or sent to the buyer.
Important: an AQL number without a defined defect classification and product requirement is not a complete quality plan. “AQL passed” cannot tell you whether the wrong shank family was produced if shank identity was not part of the inspection characteristic.
5. What Evidence Should a Bulk Buyer Ask for Before Shipment?
The right evidence depends on order value, risk, product customization and the buyer’s internal quality system. PerfoMax states that available inspection records are confirmed before order placement and that third-party inspection scope, timing and cost should be agreed in advance. For a DTH bit bulk order, the following evidence package is a practical starting point:
- approved quotation and controlled drawing/data sheet for the exact configuration;
- lot or batch identification linked to the order;
- dimensional inspection results for the agreed critical characteristics;
- clear photos showing shank, face, buttons, flushing features and marking;
- material/process certificates only where they are specifically included in the order requirement;
- quantity, label and packing check before dispatch;
- nonconformity/rework record if an agreed characteristic failed during inspection;
- third-party inspection report when separately contracted.
For a first order, new shank family, custom face/button layout or high-cost shipment, the buyer may reasonably require a more detailed approval package than for a stable repeat order. The principle is proportional control: spend inspection effort on the characteristics that can create the largest compatibility, downtime or replacement cost if wrong.
6. Common DTH Bit Buying Mistakes
| Mistake | Why It Creates Risk | Better Control |
|---|---|---|
| Buying by nominal diameter only | Diameter does not define the shank, face, buttons or foot-valve architecture. | Approve the complete configuration before production. |
| Approving from product photos | Photos do not verify critical dimensions or hidden material/process requirements. | Use controlled drawing/data sheet plus inspection evidence. |
| Using “fits 4-inch hammer” as the interface specification | Hammer classes can support different shank families and variants. | State exact hammer model and shank designation/drawing. |
| Requesting certificates without defining what they must prove | A generic certificate can be irrelevant to the ordered characteristic. | Name the material/process/test requirement and required document in the PO. |
| Setting AQL but no defect definitions | Sampling logic cannot compensate for an undefined acceptance requirement. | Define characteristic, defect class, method and disposition first. |
| Waiting until packing to discuss inspection | Rework, segregation and third-party access become slower and more expensive. | Agree the inspection plan before production or order release. |
| Ignoring packing and identification | Correct bits can still be mixed, mislabeled or damaged in logistics. | Include quantity, labels, lot identity and packing in pre-shipment acceptance. |
7. Buyer RFQ Checklist for Quality-Controlled DTH Bit Orders
Send enough information for the supplier to quote the product and the inspection scope together:
- hammer brand/model and exact shank family or drawing;
- target bit diameter and tolerance requirement, if already controlled by your project;
- face profile and button configuration, or rock conditions if selection is still open;
- foot-valve or valveless/tubeless requirement;
- flushing layout or controlled reference where applicable;
- quantity and whether the order is first-off, repeat or custom;
- critical dimensions or interfaces requiring recorded inspection;
- required certificates/tests, with the exact requirement they must support;
- sampling or 100% inspection requirements for specified characteristics;
- third-party inspection requirement, if any;
- marking, packing, Incoterm and destination;
- required pre-shipment records and approval timing.
If the configuration is not yet fixed, start from the current PerfoMax DTH Tools collection and send the rig, compressor, hole diameter/depth and rock condition so the hammer, bit and pipe system can be reviewed before quotation.
Frequently Asked Questions
What is the most important quality check on a DTH drill bit?
There is no single universal check. The first priority is confirming that the physical bit matches the approved configuration, especially the hammer/shank interface and the ordered diameter. After that, the critical dimensional, button, flushing, material/process and packing checks depend on the controlled specification and purchase risk.
Can I accept DTH bits based on nominal diameter and weight?
No. Diameter and weight can be useful identification clues, but they do not establish shank compatibility, face design, button configuration, flushing layout or metallurgical compliance. Use the approved drawing/data sheet and the inspection characteristics defined for the order.
Should every DTH bit be dimensionally inspected?
Not necessarily. Inspection coverage should be agreed by characteristic and risk. Some buyers require 100% checks for identification or compatibility-critical features and sample other characteristics; others use a formal acceptance-sampling plan. The key is to define the rule before shipment rather than assume a universal default.
Does an AQL inspection guarantee DTH bit quality?
No. ISO 2859-1:2026 provides sampling schemes for inspection by attributes. It does not supply DTH-specific product tolerances or guarantee field performance. The sampling plan only works on defects and acceptance criteria that the buyer and supplier have already defined.
What should I ask for before approving shipment?
At minimum, confirm the exact ordered configuration, lot identity, agreed dimensional/visual inspection evidence, quantity and packing. If material, heat-treatment, carbide, hardness or third-party inspection requirements are important to your purchase, include the specific evidence and acceptance requirement in the order before production.
PerfoMax DTH Bit RFQ and Inspection Scope
PerfoMax’s DTH bit page is structured around configuration approval rather than a single generic bit specification. Review DTH Drill Bit Selection — Match Shank, Diameter, Face and Rock, then use the Quality Control page to align the applicable inspection stages and documentation.
Preparing a bulk order? Send PerfoMax your hammer model, shank, bit configuration, quantity and inspection requirements for a technical quotation.
Technical References
- Epiroc — DTH Equipment Product Catalogue. Used to verify that shank design, bit diameter, front design, button configuration and carbide grade are controlled DTH bit product variables.
- Mincon — DTH Drill Bits. Used to verify that DTH bit selection spans multiple shank types and foot-valve/valveless configurations.
- Caterpillar — Cat DTH Hammer and Bits Parts Catalog. Used to verify catalogue fields including shank type, bit diameter, face shape, wear protection and gauge-button configuration.
- ISO 2859-1:2026 — Sampling procedures for inspection by attributes. Used only as a reference for formal acceptance-sampling schemes; it does not define DTH-bit engineering tolerances.