How to size a chip bunker for container changes

How much buffer volume is needed for a container change?

First, the time during which no discharge is possible is recorded: from the interruption of loading through removal and staging to the release of the new container. Foreseeable delays are added to this. The key factor is the amount of chips generated during this time window; an average per shift can mask short-term peaks in load.

With a constant inflow and completely interrupted discharge, the simplified volume balance is as follows:

Required free buffer volume = chip volume per minute × buffer time

Calculation example: Assuming 0.12 m³ of chips per minute and a 15-minute interruption, 1.8 m³ of available usable volume is required. If there are already 1.0 m³ in the hopper, this results in a calculated requirement of 2.8 m³ of usable capacity before additional reserves are factored in. This example is not a design recommendation; peak loads, filling behavior, and operational reserves must be considered separately.

If quantities are given only in kg/h, the bulk density of the actual chips produced is needed for conversion. It describes the mass per unit volume, including the voids. The density of the solid material is not suitable for this purpose.

Why the nominal volume is insufficient

The geometric volume of a container cannot be fully utilized automatically during operation. Filling, the permissible fill level, and discharge determine the usable capacity. Therefore, in bulk material planning, discharge size, wall slope, and material properties are just as important as bulk density and flow rate.

The capacity of the hauling truck or the container used is also a factor in bunker design. Both the available loading volume and the permissible payload are key considerations. Depending on the bulk density of the chips, the weight limit may be reached before the loading volume is fully utilized. Bunker capacity, the intended discharge volume, and the pickup frequency should therefore be planned together.

For metal chips, the test should be conducted using representative material. A large storage bin is of little use if material accumulates at the outlet. Another consideration is how the hopper is emptied after a changeover: If the feed continues, the previously occupied buffer reserve can only be recovered if, for a time, more material is discharged than is fed in.

When loading multiple containers is an option

An additional container location can serve as an alternative or supplement to buffering. This requires that a container ready to receive material be available and that the system be able to reroute the material flow accordingly. Level signals, positioning, and release signals must align with the planned changeover sequence.

For container loading, KÖBO ECO>PROCESS uses, among other things, rotating and swiveling chutes as well as mobile conveyors. This allows for targeting different discharge points and filling containers more precisely. Whether a second container, a chip bunker, or a combination of the two is the best option depends on available space, chip volume, and pickup frequency.

What information is needed for planning

Suitable solutions from KÖBO ECO>PROCESS

KÖBO ECO>PROCESS integrates chip bunkers, container loading, and the associated conveyor technology into a solution tailored to your operation. Volume specifications, changeover times, and a layout sketch are helpful for the initial consultation.

Frequently asked questions

Conveyor systems for chip removal