Pulp & Paper

Pulp & Paper

BTI builds balancing systems for pulp and paper — refiner plates, machine rolls, process fans and pump impellers. Refiner plate balancing is a BTI specialty, built as a fully automatic production cell rather than a bench operation.

What BTI Balances in Pulp & Paper

BTI balancing machines are built on four platforms — VNR (vertical non-rotator), H (horizontal cradle), VR (vertical rotator) and P (platform suspension) — plus tool holder balancers, spinners and test stands. The platform follows the part geometry and how it has to be held; the correction method follows the material and where there is room to add or remove mass.

How a Machine Gets Sized

A BTI machine designation names a platform and a class. A P-5 is the platform suspension base, class 5. The number is a class, not a part weight limit — it describes the size and load envelope of the base.

Sizing works from the tooling and the part together, not the part alone. Tooling is not specified until the part prints are reviewed and the fixture is concepted, and the heavier the tooling-plus-part assembly is relative to the class, the less repeatable the measurement becomes. A shop that needs one machine to cover a wide range of parts, and does not need tight repeatability, can run a much broader weight range on a given class than a production program can.

Tell BTI the part weight and BTI will name a class the same day. See BTI machine platforms for the full platform and class architecture.

Balance Grade and Tolerance

Balance tolerances are set by ISO 21940-11, which superseded ISO 1940-1. The standard assigns a balance quality grade G, and the permissible residual specific unbalance follows from that grade and the service speed:

e_per = (G × 60) ÷ (2π × n)

where e_per is permissible residual specific unbalance in g·mm/kg, G is the balance quality grade in mm/s, and n is the service speed in rev/min. Permissible residual unbalance is then U = e_per × m, divided across the correction planes.

Work out a specific tolerance with the ISO balance tolerance calculator.

Refiner Plates

A refiner plate is an awkward balancing subject: a large-diameter, relatively thin casting carrying a pattern of bars and grooves that is itself asymmetric, mounted in a machine that runs continuously and is expensive to stop. BTI has built fully automatic refiner plate cells with predictive balance optimisation, measuring and correcting the plate as a production operation rather than a bench task.

Correction Methods

Standards

BTI certifies machines to ISO 21940, SAE International balancing specifications, and DIN specifications. Where a program carries a measurement system capability requirement, BTI evaluates the part and the process first, then confirms what is achievable and commits to it in the machine specification.

Frequently Asked Questions

How are refiner plates balanced?

As individual plates, with correction applied so the mounted set meets tolerance. The specifics depend on the refiner and the plate pattern, which is why the part print drives the tooling design.

What balance grade applies to paper machine rolls?

ISO 21940-11 lists paper machinery rolls at G 6.3, alongside fans and pump impellers.

Does BTI rebuild or retrofit existing balancing machines?

Yes, including machines built by other manufacturers. See BTI rebuilds and retrofits, competitor rebuilds and retrofits, and PC upgrades.

How are BTI lead times quoted?

Lead times are quoted in weeks at the time of quotation. They move with current backlog, so BTI confirms the schedule for a specific machine as part of the quote rather than publishing a fixed figure.

What information does BTI need to quote?

The part print, the part weight, the service speed, the balance tolerance if one is specified, and the required production rate.

Related applications: refiner plates, pumps, fans, impellers and blowers. Related equipment: balancers.

Browse BTI balancing machines or request a quote.