How to Run Incoming Inspection on Wear Parts: Process, Tool List and Handling Non-Conformance

Incoming inspection is the last and most easily skipped gate in wear parts quality management. After 40 years since the 1980s, Grand Heavy observes that many plants "inspect" by counting pieces, glancing at appearance and signing the sheet — while the three steps that actually catch problems (document check, hardness testing, weight check) are routinely skipped. This guide sets out a workable seven-step process, a tool list and non-conformance rules.

图：大美智造耐磨件实物——随批提供材质成分单与热处理过程记录，炉号可追溯

I. The Seven-Step Incoming Inspection Process

Step 1: preparation

• Bring out the technical agreement, drawing and tolerance table to define the items, standards and levels for this acceptance;
• Decide the sampling plan: ratio, method and decision rules (first-article full check plus batch sampling for critical parts);
• Prepare the tools (see the list below) and the inspection record form.

Step 2: delivery check (quantity, specification, marking)

• Check quantity against the delivery note and contract;
• Check specification and model against the drawing and contract — the most common wrong-item error;
• Check part marking: heat number, batch number and grade marks must be clear and traceable.

Step 3: document check (most skipped, most important)

• The four documents: material certificate, heat treatment process record, test report and conformity certificate;
• Elements to check: whether reports carry test standard, acceptance level, test locations, inspector and date, and whether heat and batch numbers match the parts;
• Key discipline: make complete documents a precondition for warehousing. Missing documents break the traceability chain: if early failure occurs, the material cannot be evidenced and a claim has no foundation.

Step 4: visual inspection

• Visual check: cracks, blowholes, sand holes, shrinkage, slag inclusions, obvious distortion, burrs;
• Focus areas: load-bearing zones, mounting hole edges, wall thickness transitions and sharp corners — stress concentration areas crack first;
• Aids: confirm suspected cracks with penetrant testing — note that manganese steel is non-magnetic, so magnetic particle testing is ineffective;
• Records: photograph defects and mark their locations as the basis for a decision or claim.

Step 5: dimensional check

• Critical dimensions: mounting hole positions and diameters, mating faces, main wall thickness, overall length and width;
• Tools: tape or steel rule (large sizes), caliper or depth gauge (holes and thickness), template or feeler gauge (mating faces);
• Reference: tolerances in the contract annex drawing; mark out-of-tolerance parts separately.

Step 6: hardness testing (the most technical step)

• Point 1: grind flat. The as-cast skin carries scale and a decarburised layer, and testing directly on it gives a distorted reading, usually high;
• Point 2: remove the as-cast skin to a defined depth. Measure after removal (depth per the standard or agreement) so the reading reflects the parent material;
• Point 3: average several points. Take at least three points at the specified locations on the same part; a single reading is not representative;
• Instrument choice: a Leeb tester is fine for on-site screening, but arbitration must use a Brinell tester (GB/T 231.1), since Leeb readings are affected by surface roughness, thickness and curvature;
• Records: note test locations, grinding, instrument model, readings and the average.

Step 7: weight check, decision and handling

• Weight check: weigh against the theoretical drawing weight. Weight affects both price and dynamic balance (especially hammers and blow bars); noticeably light parts usually mean insufficient wall thickness;
• Decision: compare each item against the technical agreement to reach accept, reject or retest;
• Handling: apply the rules in section III and record everything.

II. A Field Lesson: Counting and Looking Cost a Whole Batch of Liners

A quarry ran incoming inspection like this: the storekeeper counted the pieces, glanced for obvious cracks and signed them in. The contract contained material and performance requirements, but nobody checked the documents and nobody tested hardness.

One batch of liners failed early in service, far short of previous batches. When the plant tried to claim against the supplier, the investigation revealed:

• No material certificate: the actual composition could not be evidenced;
• No heat treatment record: there was no way to judge whether water toughening was done properly;
• No test report: hardness and toughness compliance could not be shown;
• Outcome: the traceability chain was completely broken, the claim lacked evidence and the plant absorbed the loss.

We helped rebuild the inspection process around three changes:

• 1. No documents, no warehousing: the four-document set became a precondition, and missing any one blocks receipt;
• 2. Hardness testing after grinding: sample each batch, grind off the skin, take at least three points and average, and keep the records;
• 3. Weight check: weigh critical parts against theoretical weight and mark deviations beyond range.

The very first inspection under the new process paid off: one batch of liners showed hardness below the agreed lower limit after grinding, so it was rejected and replaced, avoiding a whole-batch early failure and the downtime that would have followed.

There was also a disagreement between Leeb and Brinell readings: on-site Leeb screening gave low readings and the batch was nearly rejected, but the supplier asked for Brinell arbitration and the Brinell result was compliant — the cause was the rougher surface of that part affecting the Leeb reading. That established the discipline: Leeb for screening, Brinell for arbitration.

The rule: inspection is not paperwork but the last chance to stop a problem; without documents you have given up your right to trace.

图：到货抽检工具与硬度打点——打磨平整、避开表皮、多点取平均，仲裁用布氏

III. Inspection Tool List and Non-Conformance Rules (Save This)

Non-conformance handling rules

Related reading: wear parts purchase contract clauses, six dimensions of supplier evaluation, choosing a hardness test method and choosing an NDT method.

IV. Insider Gotchas

• Counting, glancing and signing: the most common "fake inspection", skipping all three useful steps — documents, hardness and weight;
• Not checking documents: missing documents break traceability, so early failure cannot be evidenced and no claim can be made;
• Testing hardness on the as-cast skin: scale and decarburisation distort the reading, usually high, hiding insufficient parent hardness;
• Concluding from a single reading: castings vary in structure and hardness, so one point is not representative — average several;
• Using Leeb readings for arbitration: Leeb is affected by roughness, thickness and curvature. Screening is fine, but arbitration must be Brinell;
• Magnetic particle testing on manganese steel: after water toughening the structure is austenitic and non-magnetic, so magnetic particle testing is ineffective — use penetrant.

V. When Inspection Can Be Simplified

• Low-value consumables (bolts, gaskets, plain screen mesh): simplify to quantity, specification and appearance, without hardness testing every piece;
• Emergency repair parts: fit them first to keep production running, but the documents and test records must still be completed, not abandoned;
• Stable long-term suppliers: reduce the sampling ratio (or move to skip-lot), but keep periodic verification and tighten immediately if anomalies appear;
• Critical parts cannot be simplified: jaw plates, blow bars, hammers and mill liners cause major losses when they fail, so document check, hardness testing and dimension plus weight checks are all mandatory.

Three actions: 1. Make the four-document set a precondition of the warehousing process; 2. Establish a hardness testing standard based on grinding before indenting, with multi-point averaging and records; 3. Define and apply non-conformance rules with records, and do not grant concessions on critical parts.

FAQ

• Q: Which step of incoming inspection is most often skipped? A: The document check. Most plants count pieces and look at appearance, but if the material certificate, heat treatment record, test report and conformity certificate are missing, the traceability chain breaks — early failure cannot be evidenced and a claim has no foundation.
• Q: What should we watch in hardness testing? A: Three points: 1. grind flat (scale and decarburisation distort readings); 2. remove the as-cast skin to a defined depth (measure the parent material); 3. average several points (one reading is not representative).
• Q: Can a Leeb tester be used for acceptance? A: A Leeb tester is portable and suited to on-site screening, but readings are affected by surface roughness, thickness and curvature, so it should not be used for arbitration. In a dispute, retest with a Brinell tester (GB/T 231.1).
• Q: Can magnetic particle testing find cracks in manganese steel? A: No. After water toughening, manganese steel has a single-phase austenitic, non-magnetic structure, so magnetic particle testing is ineffective. Use penetrant testing for surface cracks.
• Q: What should we do when delivered parts fail? A: Depending on the case: incomplete documents mean no warehousing; serious defects or hardness below spec mean return or replacement; minor non-functional flaws may be accepted as a recorded concession. Concession is not advised for critical parts, and every decision must be recorded and traceable.
• Q: Why check weight? A: Because casting weight affects both price and dynamic balance (especially hammers and blow bars). Weighing against the theoretical drawing weight reveals insufficient wall thickness — priced per piece with no weight control, a thinner casting is still "compliant" but wears out faster.
• Q: What documents does Grand Heavy ship with its wear parts? A: Grand Heavy ships material certificates and heat treatment process records with each batch, provides test reports and conformity certificates as agreed in the technical agreement, and supports incoming retesting and failure analysis. See also the purchase and acceptance checklist.

VI. Final Verdict

Incoming inspection of wear parts comes down to one phrase: inspection is not paperwork; it is the last chance to stop a problem. Three disciplines: 1. the four-document set must be complete before warehousing, or you have given up your right to trace; 2. hardness testing must grind flat, avoid the skin and average several points, with Brinell for arbitration; 3. record every non-conformance decision and never grant concessions on critical parts. Put those three in place and most batch problems are stopped before they reach the store. Foshan Grand Heavy Trading Co., Ltd. has built mining equipment and wear casting expertise for 40+ years, holds 20+ patents, partners with Central South University and Guangdong University of Technology, and is certified as a National High-Tech Enterprise [To be added: certificate number]. We serve CNBM, Conch Cement and clients across 6 overseas markets with 24-hour response from Guangzhou, Foshan and Changsha. Contact us for an inspection record template and sample shipping documents.

Grand Heavy — No documents, no warehousing; grind before testing; Brinell for arbitration!