Transformerwood bond-line inspection should locate separation within the volume relevant to the support. Distinguish the intended veneer construction from defects and map examination coverage onto the loaded interfaces. [1]
Calculation basis. Project-specific values and gates in the illustrative screens below are assumptions; cited catalogue values retain their source test conditions.
Keep the stock identity and layup with the inspection plan. Parallel, crossed and other veneer arrangements create different section appearances. Resin distribution, wood structure and preparation marks can be misclassified when inspectors use one generic photograph.
Interpret the section direction
| Observation | What it can show | Limit to retain |
|---|---|---|
| Section crossing the layers | Several bond lines at the cut plane | Continuity elsewhere along those interfaces is unexamined |
| Section approximately along a layer | Local veneer and interface area | Other depths and bond planes may not be reached |
| Open gap at an interface | A visible separation at that location | Extent and origin still require examination |
| Dark resin seam | Contrast associated with the bond region | Colour alone does not establish either sound bonding or failure |
| Torn wood beside the seam | Damage involving the veneer region | Preparation damage must be excluded before interpreting service relevance |
Document cutting and preparation methods. A rough section may pull fibers out or open a weak-looking seam during examination. Compare prepared surfaces with original observations and, where needed, use a second method that can resolve the uncertainty.
Connect sampling to the stock and finished part
Select locations through the relevant stock thickness and area, including the material that will remain near loaded holes, notches and contacts. An offcut remote from those regions establishes evidence about that offcut, not every future machined support.
Record local findings by plane, depth and position. Averaging them into a single stock score can hide one interface that intersects a critical load path. Use sections and representative mechanical observations together where the bond condition governs the part’s duty.
An internal nondestructive method needs validation for the actual veneer arrangement, resin and thickness. Reference defects and confirmed sections should establish which locations and defect types the method can detect. A successful ultrasonic technique for bonded steel laminations supplies neither acoustic properties nor detection coverage for transformerwood.
If the method cannot resolve a region, show that region as a coverage gap. Calling it sound because no indication was obtained confuses absence of an observation with demonstrated inspection capability.
Keep qualification evidence at the intended conditioning and oil state where those conditions affect the decision. Manufacturer datasheet averages do not certify internal bond continuity in a delivered stock piece.
Locate separation and the critical material volume it affects. Check that the machined support’s load-bearing interfaces fall within the examined stock coverage.
Keep sampling depth visible in bond-line inspection
Match the material identity and relevant test direction before comparing densified-wood evidence [2].
Assume a 40 mm thick laminate contains 20 bond-line planes and five selected bond-depth planes are exposed by layer-parallel polishing in representative critical regions. Plane-count coverage is 25%, without establishing full areal coverage on those planes; the remaining 15 planes are not established by those sections alone. Define complementary inspection and sampling from the actual defect mechanism rather than interpreting one clean exterior face as complete bond integrity.
References
- Röchling Industrial, Lignostone L I/2-E3-HQ (P2R), Technical Data Sheet, version 2.0, released 20 September 2023.
- IEC, IEC 61061-2:1992, Specification for non-impregnated, densified laminated wood for electrical purposes — Part 2: Methods of test.