Mining, Crusher and Wear Structures
Mining structures are bought for wear life and impact resistance, and they are welded under constraints that do not apply anywhere else in fabrication.
The controlling fact is simple: abrasion resistant plate gets its hardness from a heat treatment, and welding it badly removes that hardness exactly at the joint where the structure is already most stressed.
What this application demands
- Heat input disciplinePlate makers publish preheat and heat input limits for their abrasion resistant grades. Exceeding them softens the heat affected zone and you lose the wear life you paid for. This is a procedure question, not a welder skill question.
- Wear plate as a liner, not a structureThe usual pattern is a mild or structural steel frame with abrasion resistant plate attached as replaceable liners. Building the whole structure from wear plate is expensive, hard to weld and hard to repair.
- Impact loadingCrusher and chute structures see shock, not steady load. That pushes toughness requirements, which is why grades with a specified low temperature impact test appear on these drawings.
- Machined interfacesBearing housings, shaft bores and bolted joints on a crusher frame are the machined features, and they have to hold position on a structure that is otherwise built from heavy rough plate.
- Field repairabilityThese parts are repaired in place, often by people who are not the original fabricator. A design that can only be repaired with equipment the mine does not own is a design problem.
What goes wrong
In roughly the order we see it on drawings.
Welding wear plate to a general procedure
The joint looks fine and the hardness is gone. Follow the plate maker limits or the wear face fails first at the weld.
Liners welded where they should be bolted
Welded liners are replaced with a gouging torch. Bolted liners are replaced with a spanner, during a shutdown window that is always too short.
Toughness not specified
A structure that survives at 20 degrees C can behave very differently at minus 20. If the site is cold, the impact requirement belongs on the drawing.
Machined features referenced to rough plate
Bearing bores positioned from an as-rolled, as-welded surface will not be where the drawing says.
What to put on the drawing
Every line here removes an assumption a shop would otherwise price as risk. Risk is always priced against you.
The full package is on the RFQ checklist, which is printable and remembers your ticks in your own browser.
- Abrasion resistant grade named, with the plate maker welding limits referenced or attached.
- Which surfaces are wear liners, and whether they are welded or bolted and replaceable.
- Toughness requirement where the site is cold, as a specified impact test.
- Machined features referenced to machined datums, with stress relief called out before machining.
- Weld quality level and inspection on the joints that carry impact load.
- Repair expectations, including whether the mine will weld on the part in the field.
Questions on this part type
Can abrasion resistant plate be welded normally?
It can be welded, and not to a general procedure. Plate makers publish preheat and heat input limits, and exceeding them removes the hardness in the heat affected zone. That is the whole reason the plate costs what it does.
Should wear liners be welded or bolted?
Bolted wherever the geometry allows it, because liners are consumable and get replaced during short shutdowns. Welded liners mean gouging them off, which is slower and puts heat back into the structure every time.
Do crusher frames need stress relief?
If they carry machined bearing bores that must hold position, usually yes. Heavy welding into a stiff structure stores a lot of residual stress, and machining releases it.
Go deeper
- A36, S355 or A514: What the Grade Does to Your Weldment PriceHow structural steel grade changes welding, preheat, distortion and machining on a weldment, and when the higher strength plate is worth paying for.
- When a Welded Frame Needs Stress Relief, and When It Does NotThermal and vibratory stress relief for weldments: when residual stress will move your machined faces, what a PWHT cycle involves and where it belongs in the sequence.
- Which Weld Inspection Method to Specify, and on Which WeldsVisual, dye penetrant, magnetic particle, ultrasonic and radiographic testing on weldments: what each method finds, what it misses and what it adds to the quote.
- Why Your Frame Came Out Bowed, and What a Shop Does About ItThe six causes of weld distortion in large weldments and the controls fabricators use: joint design, weld sequence, heat input, fixturing, prebending and balanced welding.
Have a drawing for one of these?
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