When it comes to crank journal boring operations, precision machining is crucial. The finished bores must be perfect, as anything less will directly impact on an engine's performance and lifetime.

For crankshaft journals, line boring is considered to be the most precise and effective manufacturing option to ensure size and concentricity in one machining operation.

Rigibore's engineering excellence takes the machining of crankshaft bearing journals to a new level by automating the compensation of the tool's cutting edges, accelerating productivity and improving quality.

Line Boring With ActiveEdge technology

Rigibore is the only company in the world with the capability to automatically adjust multiple cutting edges independently with micron accuracy on a single boring tool.

Delivering an unparalleled level of automation and sophistication, ActiveEdge line boring tools can be easily integrated with in-process measurement to adjust automatically to meet fine tolerance requirements.

Zenith control loop process

Closed-Loop Boring Cycle
The diagram highlights the closed-loop cycle of boring, measuring and adjusting so precision tolerances can be dynamically maintained during production.

Innovation in compensation

During a production run, cutting edge wear and changes in environmental parameters can lead to the gradual loss of size on one or more bores.

This can be a headache for manufacturers, as Rigibore's chairman Roger Bassett explains: "With other line boring solutions, in order to compensate for unavoidable wear, the machine must be stopped to make manual adjustments, which results in unacceptable production delays and risks operator error". With pressure to meet production deadlines, operators often leave inserts to wear as long as possible to reduce the number of adjustments made.

Manual Adjustment
Setting the tools close to top limit to reduce the number of production stoppages results in a wide variation of bore sizes from nominal (+/- 0.017mm in this case), and risks exceeding the specification limits. This has a negative impact on consistency and overall quality, as well as increasing the risk of scrap parts.

ActiveEdge technology allows manufacturers to set pre-determined upper and lower warning limits on bore sizes within the specification limit.

"If any bore measurements hit the warning limit, Rigibore macros automatically adjust one or more of the tool's cutting edges back to nominal, with micron accuracy, before the next part is machined" states Roger Bassett, "This virtually eliminates production stoppages whilst increasing the quality and consistency of the finished bores".

Automatic Adjustment
More frequent cutting edge adjustments are possible with ActiveEdge, without negatively impacting on production. This allows each bore to maintain a tighter tolerance and reduces the risk of scrapped parts.

Independent Adjustment

ActiveEdge line bar technology solves the historical problem of how to maintain machining tolerances on all crank journals throughout a production run. Inserts do not wear evenly, so managing journal size is typically a trade-off between quality and production delays to carry out manual cutting-edge adjustments. Some line boring systems allow all cutting edges to be adjusted by the same amount, but this does not solve the problem.

Only ActiveEdge technology stands alone in its ability to adjust each cutting edge totally independently, ensuring that each journal is machined within the required parameters.

Nominal bore size: ∅53mm.

In-process measurements are sent to the machine control, where compensation values for each journal are calculated.

Compensation values are sent to the ActiveEdge tool which drives each cutting edge by the commanded amount, with micron accuracy, ready for the next part.

You can learn more about the ActiveEdge line boring solution here, or learn about our industry success in our latest case brief.

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