How To Identify The Root Cause of Abnormal Early Failure of Jaw Plates And Systematic Preventive Measures

Severe wear or damage to the jaw plate before it reaches its expected lifespan is a prominent pain point in the operation of mines and sand and gravel production lines. Abnormal early failure not only directly increases production costs, but may also lead to secondary equipment damage and unplanned downtime. Effectively identifying its root causes and implementing prevention is an engineering and technical task that requires systematic thinking. This article will provide a diagnostic method from phenomenon to root cause, as well as corresponding prevention strategies.

1、 Typical modes of abnormal early failure and rapid identification

Firstly, make a preliminary judgment based on the failure mode:

Typical on-site manifestations of failure modes may point to the root direction

1. The jaw plate is fractured or partially fractured, with obvious cracks visible on the cross-section. Excessive impact load, insufficient material toughness, casting defects, and poor installation support.

2. The abnormally rapid wear of the tooth peak severely flattens in a short period of time, but the wear surface is relatively uniform. The material hardness/wear resistance does not match the ore, the work hardening is not stimulated, and the abrasion is extremely strong.

3. Local severe grooves/indentations appear on the surface of the jaw plate, with deep grooves or pits that are inconsistent with overall wear. Uneven feeding, presence of unbreakable materials (iron), and local mutations in material composition.

4. Loosening or detachment of the toothed plate, cutting or loosening of the fixing bolts, and displacement or detachment of the jaw plate. Improper installation and fastening, insufficient or ineffective pre tightening force of bolts, and loose equipment body.

5. Peeling and chunking occur on the working surface in the form of flakes or blocks, rather than normal wear and tear. Internal defects in the material (such as pores and slag inclusions), improper heat treatment leading to poor organization, and high cycle fatigue.

2、 Root cause diagnosis process: Five step analysis method

Step 1: On site data collection and preliminary survey

Record failure time: Accurately record the working hours and processing tonnage from the new jaw plate being put into operation until failure.

Check the failure morphology: Take high-definition photos, focusing on recording the color of the fracture surface, crack direction, and wear surface morphology.

Review of operating condition records: Check whether there are oversized materials or unbreakable objects (such as drill bits and shovel teeth) entering during the failure period, and whether there are any sudden changes in the particle size distribution of the feed.

Step 2: Material and Manufacturing Quality Inspection

Verify quality assurance documents: Request material reports, heat treatment records, and mechanical performance testing reports (impact energy ak value, hardness HB/HRC) for this batch of jaw plates from the supplier.

Fracture analysis:

Fresh fracture surface (silver white): mostly indicates overload fracture or insufficient impact toughness. Check if the AK value meets the standard.

Old fracture surface (with rust or oxidation color): indicates that the crack has been generated for a long time and is slowly expanding, possibly due to casting microcracks, fatigue, or installation stress.

Third party testing: If conditions permit, take samples of the failed parts for metallographic analysis to observe whether there are defects such as coarse grains, carbide network precipitation, shrinkage porosity, slag inclusion, etc.

Step 3: Installation and Device Status Traceability

Installation record check: Review whether bolts of the specified specifications and grades were used during installation, whether the torque met the requirements, and whether anti loosening measures were used.

Support surface inspection: Check the contact surface between the jaw plate and the jaw bed body (or between jaw plates). If there are obvious gaps or only partial contact on the contact surface, it will lead to insufficient support and bending fracture under impact.

Equipment body status: Check whether the jaw bed, bearing seat, and foundation are loose or cracked, and whether the vibration values during equipment operation are abnormal.

Step 4: Process and Operation Review

Feeding situation: Is the uniform and full cavity feeding maintained? Is there a long-term single-sided feeding or feeding segregation?

Discharge port setting: Does it operate under a too small discharge port for a long time? This will lead to excessive layering, crushing, and grinding in the lower part of the crushing chamber, rapidly accelerating wear.

Iron protection: Check whether the hydraulic iron protection or mechanical protection device is sensitive and effective, and whether it has been triggered recently.

Step 5: Cross comparison verification

Horizontal comparison: Are jaw plates from different batches or suppliers performing normally on the same device?

Vertical comparison: Is the service life of the jaw plate normal when crushing other types of ores with this equipment?

3、 Targeted preventive measures system

Establish a hierarchical prevention system based on the diagnosed root cause:

Regarding material and manufacturing issues

Optimize selection and supplier management:

Based on the abrasion resistance (Ai value) and impact load of the ore, scientifically select materials (such as choosing high toughness Mn22Cr2 for high impact and considering composite plates for strong abrasion).

Choose suppliers with comprehensive quality systems (ISO 9001) and testing capabilities, and prioritize partners who can provide full process quality assurance documents (from melting to heat treatment).

Arrival acceptance: Conduct a preliminary inspection of the size, weight, and appearance (for any obvious casting defects) of the new jaw plate, and if conditions permit, perform hardness sampling.

2. Regarding installation and maintenance issues

Standardized Installation Operating Procedure (SOP):

Ensure that all mating surfaces are clean, free of burrs, and free of old liner residue.

Use a torque wrench to tighten the bolts step by step according to the manufacturer's specified sequence and torque.

After installation, run it without load for a period of time, tighten the bolts again, and regularly check during the initial operation.

Ensure effective support: If necessary, use specialized compression pads or high fluidity epoxy resin grout to fill between the jaw plate and the body, ensuring 100% contact.

3. Regarding process and operational issues

Optimize feeding system: Install iron remover and metal detector. Adjust the feeder to ensure that the material falls continuously, evenly, and centrally into the crushing chamber.

Set reasonable discharge ports: Avoid operating below the minimum allowable discharge port of the equipment for a long time in pursuit of fine products.

Establish a point inspection system: Regularly (such as every shift) check the tightening of the jaw plate fixing bolts, observe whether the wear is uniform, and listen for any abnormal impact sounds from the equipment.

4. Establish technical archives and feedback loop

Establish a file for each set of jaw plates, recording their supplier, material, installation date, expiration date, processing tonnage, failure photos, and cause analysis.

Feedback the failure analysis conclusion to the supplier and equipment management department as a decision-making basis for future selection, procurement, and maintenance, forming a continuous improvement loop.

Conclusion

Abnormal early failure of jaw plates is rarely caused by a single factor. It is usually the ultimate manifestation of the failure of one or more links in the chain of materials, design, installation, operation, and maintenance. The solution lies in shifting from "passive replacement" to "active management", accurately locating the root cause through systematic diagnostic methods, and building a prevention system covering the entire process of procurement, installation, operation, and maintenance. This will not only significantly reduce the consumption cost of wear-resistant parts, but also lay a solid foundation for the stable and efficient operation of the entire production line, which is an important symbol of the refined operation capability of modern mining and sand and gravel enterprises.