How to Write a Wear Parts Purchase Contract: Material, Tolerance, Warranty and Penalty Clauses

When buying wear parts, most plants put all their effort into haggling over price while the contract says almost nothing — "manganese steel liners, quantity XX, unit price XX". Across 40 years of experience since the 1980s, Grand Heavy has found that the vast majority of disputes are not caused by deliberate fraud, but by what the contract failed to state. This guide breaks down the eight clauses most likely to cause trouble, with a ready-to-use checklist.

图：大美智造耐磨件实物——合同中的材质、公差、性能指标应与实物可核查对应

I. The Eight Essential Clauses

Clause 1: Material and grade (most important)

• Must state: the specific grade plus the governing standard number, for example "ZGMn13-2 to GB/T 5680";
• Never state: only "manganese steel", "premium alloy steel" or "wear resistant steel" — such vague wording is the root of disputes, because a low grade can also be called manganese steel;
• Also: for composites or custom materials, describe the structure (e.g. insert or composite method) and the matrix and reinforcement materials.

Clause 2: Chemical composition and mechanical properties

• Composition: state the range of key elements (C, Mn, Cr, Si and so on), not just the grade — the same grade varies between heats;
• Properties: hardness (Brinell HBW, with test standard and location) and impact toughness (e.g. AKU, with specimen type and temperature);
• Key point: hardness and toughness are in tension. Specifying hardness without toughness lets a supplier trade toughness for hardness and cause chipping in service.

Clause 3: Heat treatment

• Must state: the heat treatment type (for manganese steel, water toughening) and its requirements;
• Documents: require the heat treatment process record (heat number, temperature curve, holding time) to ship with the goods — the strongest evidence of quality;
• Why it matters: toughness depends heavily on heat treatment quality, which can only be traced through process records.

Clause 4: Dimensional and weight tolerances

• Dimensions: state tolerances for critical dimensions (mounting holes, mating faces, thickness) and attach the drawing as a contract annex;
• Weight tolerance: casting weight directly affects price and dynamic balance (especially hammers and blow bars). Agree an allowable weight deviation;
• Common dispute: priced per piece with no weight control means a thinner casting is still "compliant" — and insufficient wall thickness sharply reduces life.

Clause 5: Inspection and acceptance

• State: inspection items (composition, hardness, metallography, NDT), governing standards, acceptance level, sampling method and decision rules;
• Report requirements: reports must include test standard, acceptance level, test locations, inspector and date;
• Cost allocation: agree that retest costs fall on the supplier when the item fails — otherwise plants become reluctant to send samples at all;
• Acceptance point: define whether acceptance is on delivery or on commissioning, and the process for non-conforming items.

Clause 6: Warranty period and life guarantee

• Warranty start (where buyers lose most): "12 months from delivery" looks reasonable, but a delayed commissioning eats the usable period. Write "from the date of successful installation acceptance and commissioning", or use a dual condition (whichever comes first, with a guaranteed minimum from commissioning);
• Life guarantee wording: a guaranteed life without duty conditions is unenforceable. State that under the agreed duty (material type, throughput, feed parameters, equipment model) the life will be at least Y hours or the cost per tonne no more than X;
• Definition of failure: define what counts as failure (wear to a given thickness, chipping, breakage) to avoid disagreement.

Clause 7: Delivery and liability for breach

• State: lead time, delivery method and delay penalties (daily rate and a cap);
• Key point: the purpose of a delay penalty is to keep lead times reliable — too high is unfair, missing entirely leaves lead time unconstrained;
• Suggestion: for critical spares, agree partial shipments so a single delay does not stop the whole line.

Clause 8: Non-conformance handling and claims

• Options: return, replacement, acceptance at reduced price or repair, with conditions and time limits stated;
• Damages: whether and how downtime losses from quality problems are compensated should be stated in the contract — the most contested area, and clearer is safer for both sides;
• Records: agree the shipping document list (material certificate, heat treatment record, test report, certificate of conformity); missing documents mean delivery is incomplete.

II. A Field Lesson: "Manganese Steel" in the Contract Meant No Claim Could Be Made

A cement plant bought jaw plates for its limestone crushing line. The material field in the contract contained four words: "manganese steel jaw plates" — no grade, no standard number, no hardness requirement.

Not long after installation the plates suffered early chipping — not normal wear but large pieces breaking off the tooth surface. The plant suspected the material and raised it with the supplier, who replied: "What we delivered is indeed manganese steel, in accordance with the contract."

The investigation found:

• No grade in the contract: there was no way to show which grade should have been delivered, and a lower grade of manganese steel did not breach the literal wording;
• No performance indicators: with no hardness or toughness requirements, non-conformance could not be established;
• No document requirement: neither a material certificate nor a heat treatment record existed — there was not even a starting point for tracing;
• Outcome: the claim lacked any basis and the plant absorbed the loss.

There was a second problem: the warranty was written as "12 months from delivery". Because the line upgrade was delayed, the plates were installed only in the fourth month after delivery. When early failure occurred in the tenth month, only two months of warranty remained and it expired shortly after. A little later and there would have been no warranty claim at all.

We helped the plant redraft its purchase contract template around three fixes:

• 1. Full material wording: "ZGMn13-2 to GB/T 5680" with hardness and impact toughness requirements;
• 2. Heat treatment and documents: water toughening required, with material certificate and heat treatment record shipped with each batch;
• 3. Warranty start: changed to "12 months from successful installation acceptance and commissioning".

After the change, disputes of this kind effectively disappeared — quality became verifiable, deliverables checkable and responsibilities clear. The rule: whatever the contract does not state cannot be claimed afterwards; vague material wording leaves the risk with the buyer.

图：材质单与公差图纸对照——把材质、公差、验收规则写进合同附件，争议自然归零

III. Wear Parts Contract Clause Checklist (Save This)

A material clause template (for reference — adjust to your situation)

Related reading: six dimensions of supplier evaluation, the purchase and acceptance checklist and GB/T 5680 explained.

IV. Insider Gotchas

• Vague material wording: the most frequent source of disputes. "Manganese steel" is a material family, not a grade — a lower grade carries the same name;
• Hardness without toughness: the two trade off against each other; testing hardness alone invites a supplier to sacrifice toughness and cause chipping;
• Warranty from delivery: project delays and slow stock turnover eat the warranty. Start it from commissioning acceptance instead;
• Life guarantee without duty conditions: unverifiable and unenforceable;
• No weight tolerance: priced per piece with no weight control means a thin casting still "passes" while life drops sharply;
• No retest cost allocation: unclear who pays makes plants reluctant to test, and problems stay hidden.

V. When the Contract Can Be Simplified

• Low-value consumables (bolts, gaskets): low price and low failure impact allow a simple order with incoming inspection;
• Emergency repair purchases: buy on a simple order first and add the technical agreement afterwards;
• Long-term suppliers: use an annual framework agreement plus a technical agreement so routine orders reference the framework instead of renegotiating;
• Critical parts cannot be simplified: liners, jaw plates, blow bars, hammers and mill liners cause major losses when they fail, so all clauses above are required — this protects both sides, not just the buyer.

Three actions: 1. Check the material field in your current template and replace vague wording with grade plus standard; 2. Change the warranty start to commissioning acceptance and add a duty-linked life commitment; 3. Fix drawing tolerances and the shipping document list as annexes.

FAQ

• Q: How should the material field in a wear parts contract be written? A: State the specific grade plus governing standard number, for example "ZGMn13-2 to GB/T 5680", and add key element ranges, hardness (with test standard and location) and impact toughness. Vague terms such as "manganese steel" or "premium alloy steel" abandon any quality constraint.
• Q: When should the warranty period start? A: Write "from the date of successful installation acceptance and commissioning" rather than "12 months from delivery". With a delayed commissioning, counting from delivery eats the warranty — one customer found early failure in the tenth month after installation with the warranty nearly expired.
• Q: Is a "guaranteed life" clause useful? A: Without duty conditions it is effectively unenforceable. It must be tied to material type, throughput, feed parameters and equipment model, with a defined metric (hours of life or cost per tonne) and a definition of failure.
• Q: Why agree a weight tolerance? A: Because casting weight affects both price and dynamic balance (especially hammers and blow bars). Priced per piece with no weight control, a thinner casting is still "compliant" but its life is clearly shorter.
• Q: Who should pay for testing? A: Agree that "acceptance testing is paid by the buyer and retesting of failed items by the supplier". Without this, plants avoid sending samples and problems stay hidden for a long time.
• Q: How does Grand Heavy support contracts and shipping documents? A: Grand Heavy can sign a technical agreement covering grade, standard, performance, tolerances and acceptance rules, ships material certificates and heat treatment records with each batch, and provides test reports as agreed. See also the purchase and acceptance checklist.

VI. Final Verdict

A wear parts purchase contract comes down to one phrase: whatever the contract does not state cannot be claimed afterwards. Three disciplines: 1. write grade plus standard number, never vague wording; 2. start the warranty from commissioning acceptance and tie any life guarantee to duty; 3. never omit dimensional and weight tolerances, retest cost allocation, or the shipping document list. Put those three into your template and most quality disputes disappear at the source. 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 a technical agreement template and sample shipping documents.

Grand Heavy — Grade in the contract, warranty from commissioning, and nothing unstated can be claimed!