Bolt Hole Pattern Checklist for Wear Plates
A replacement wear plate can have the correct grade and thickness and still be unusable when its bolt pattern does not match the current structure. Hole diameter alone is not enough. A manufacturing drawing must establish datums, X/Y coordinates, orientation, hole type, positional tolerance, countersink or slot geometry, and the relationship between adjacent panels.
This checklist is intended for buyers, maintenance planners and fabricators preparing drawing-based wear-plate RFQs. It does not prescribe one universal clearance or edge distance. The responsible engineer must approve the joint, fastener and remaining plate section for the actual loading.
Quick drawing checklist
| Drawing control | Required information | Risk if omitted |
|---|---|---|
| Primary datums | Stable face and two perpendicular edges or another defined datum system | Different inspectors measure the pattern from different references. |
| Hole coordinates | X/Y basic or toleranced dimensions from the datums | Chain-dimension error accumulates across the panel. |
| Hole type | Round, slotted, countersunk, counterbored, keyhole or plug-weld opening | The fabricator assumes the wrong process or orientation. |
| Fastener | Standard, nominal size, grade, head and washer arrangement | Clearance or recess does not fit the production bolt. |
| Orientation | Flow direction, material face, rear face and part hand | The pattern is mirrored or installed backwards. |
| Acceptance | Size tolerance, positional tolerance and inspection method | A hole can pass individual dimensions but fail assembly. |
Start from functional datums
A datum should represent how the liner locates in the equipment or how the pattern will be verified. Avoid measuring every hole from a flame-cut edge that is not itself controlled. For a rectangular panel, the drawing may use the mounting face as the primary datum and two finished or controlled edges as secondary and tertiary datums. Curved, bent or irregular liners may require a fixture, centre plane or mating feature.
ISO 5459:2024 specifies current terminology and rules for datums and datum systems. ISO 1101:2017 defines the symbol language for geometrical tolerancing. Use the drawing standard required by the purchaser rather than mixing ISO and ASME conventions without agreement.
Avoid uncontrolled chain dimensions
When each hole is dimensioned from the previous hole, small variations can accumulate at the final position. Coordinate dimensions from common datums make the intended pattern clearer and support inspection by template, coordinate measurement or a controlled manual layout. If a legacy drawing uses chains, state which dimensions govern and how accumulated tolerance is handled.
Select clearance from the joint requirement
ISO 273:1979, confirmed current in 2024, gives fine, medium and coarse clearance-hole series for general-purpose bolts and screws, while noting that special applications require design-based selection. A chute liner can be a special application because shell distortion, field replacement and wear may require a deliberate fit strategy.
Do not enlarge holes simply to make installation easier. More clearance can reduce bearing engagement and allow movement. Too little clearance can make a replacement panel impossible to install against an as-built structure. Record the chosen series or exact diameter and the engineering reason.
Round holes, slots and special features
| Feature | Useful when | Control on drawing |
|---|---|---|
| Round clearance hole | Pattern and structure are stable and accurately measured | Diameter, position and tolerance. |
| Slotted hole | Approved adjustment is needed in one direction | Width, total length, end radius, orientation and positional tolerance. |
| Countersunk hole | A flush material-side head is required | Included angle, major diameter, depth and permitted head position. |
| Keyhole slot | A controlled installation/removal sequence uses a headed fixing | Large and narrow widths, centre distance, direction and clearance. |
| Plug-weld opening | The approved design uses welded attachment | Hole geometry, weld procedure reference and inspection requirement. |
Control countersink geometry separately
A note such as “CSK for M20” is incomplete. Head angle and profile depend on the selected fastener. State the fastener standard and control the recess without leaving an inadequate residual section. See the countersunk bolt hole design guide for the required drawing inputs.
Edge distance and remaining ligament
Hole centres near a free edge or panel joint can create a narrow ligament. The safe distance depends on fastener force, plate thickness, material toughness, support and impact. Identify free edges, unsupported spans and major wear zones so the responsible engineer can review the arrangement. Do not copy a minimum distance from an unrelated structural standard and assume it applies to a replaceable wear liner.
Measure the current structure, not only the worn liner
A removed liner may be bent, elongated at the holes or damaged during extraction. Record the support-shell pattern and compare it with the original drawing. Useful evidence includes a coordinate sheet, verified template, scaled photograph with datums, or a scan. Mark which values are measured, nominal or proposed.
Mirrored and handed panels
Symmetrical-looking panels are a common source of errors. Put the material-flow direction, “wear face,” part number and left/right hand directly on the drawing and part marking. If the CAD view is from the rear, say so. A single orientation arrow can prevent an entire pattern from being mirrored.
Machining and hole finish
Wear-resistant plate requires suitable tooling, stable clamping and grade-specific cutting data. SSAB’s official Machining of Hardox wear plate guide includes drilling recommendations and troubleshooting for oversized, undersized and asymmetric holes. Apply the instructions of the actual material producer; one supplier’s data is not universal.
The purchase drawing should state whether thermally cut holes are acceptable, whether machining is required after rough cutting, and how burrs, taper and heat-affected surfaces will be handled.
Inspection plan before shipment
| Characteristic | Suggested evidence | Acceptance question |
|---|---|---|
| Overall panel geometry | Length, width, thickness, diagonal or profile record | Is the reference geometry within drawing tolerance? |
| Hole size/type | Gauge or measured diameter/slot/recess values | Does each feature match the approved type? |
| Pattern position | Coordinate report or verified template | Is position measured from the stated datums? |
| Orientation | Marked-face photograph and part number | Can site personnel identify hand and flow direction? |
| Trial fit | Mating fixture/template result when required | Will the panel assemble without field rework? |
RFQ package
- controlled PDF and CAD drawing with revision;
- as-built support pattern or verified template data;
- liner material, thickness and finished profile;
- fastener standard, size, head and installation direction;
- hole type, tolerances and required processing method;
- part marking, quantity and inspection-report requirements;
- site photos showing access and material-flow direction.
Related pages: bolt-on chute liner plates, countersunk bolt wear plates, and slotted versus round holes. Send the drawing and as-built measurements for quotation.
Engineering boundary and technical review
This guide supports drawing review; it is not a fastener-load or joint-capacity calculation. The purchaser’s engineer must approve the joint, access, structural capacity and installation method. Updated by the EB China engineering-content team against the cited ISO and manufacturer sources; the controlled drawing and contract govern production.