How do you calculate line speed matching for a loss-in-weight feeder?

Divide finished linear feet by the runtime in minutes. With 1,200 ft over 8 hours (480 minutes) the average line speed is 2.5 ft/min; at 90% sync efficiency the line was moving about 2.78 ft/min during locked production.

What is the average speed versus the in-sync speed here?

The average (2.5 ft/min in the example) spreads finished length across every runtime minute, refill dips included. The in-sync speed (about 2.78 ft/min) is the pace held during the 90% of the run the feeder was in gravimetric lock.

What is a good synchronization efficiency for gravimetric feeding?

Well-tuned loss-in-weight feeders on a steady line often hold 92-97% effective sync. Below 85% usually points to aggressive refill cycles, an undersized hopper, or a control loop that lags the line encoder.

Why does my feeder over-dose when line speed drops?

If the feeder is running mass-per-time instead of mass-per-length, a line slowdown deposits the same mass over less distance. Matching the feeder to the line encoder rather than a fixed rate prevents this.

Line speed matching vs. simple throughput rate?

Throughput rate just measures how much you made. Line speed matching ties that rate to the feeder's ability to keep pace, exposing the gap between nameplate speed and what the dosing loop can actually sustain.

How do refill cycles affect effective line speed?

During refill, a loss-in-weight feeder switches to volumetric estimation and briefly loses gravimetric accuracy. Frequent refills on a small hopper are a leading cause of the efficiency discount you see in the effective number.

Weighing, Dosing & Loss-in-Weight Feeding calculator

Line Speed Matching Calculator

Line Speed Matching converts your finished output and runtime into an effective line speed in feet per minute, then discounts it by the efficiency at which the loss-in-weight feeder stays synchronized with the downstream conveyor or extruder. On a continuous dosing line, feed rate and line speed must track each other or you get either starvation (light coating, under-dose) or flooding (surging, over-dose). Process engineers and line supervisors on extrusion, coating, and continuous-mix lines use this to see the real deliverable speed, not the nameplate number. It matters because a feeder tuned to nameplate line speed will drift out of spec the moment refill cycles, gain-in-weight corrections, or splice slowdowns eat into runtime.

What this calculator does

Line Speed Matching converts your finished output and runtime into an effective line speed in feet per minute, then discounts it by the efficiency at which the loss-in-weight feeder stays synchronized with the downstream conveyor or extruder.
Use it when line speed matching in weighing, dosing and loss-in-weight feeding is being committed and you need a throughput number you can defend.
It computes the average line speed in ft/min by dividing finished length by the runtime in minutes, and divides by sync efficiency to show the pace held while the feeder was in gravimetric lock.

Formula used

Average line speed = finished length ÷ (runtime × 60)
Speed while in sync = average speed ÷ (sync efficiency ÷ 100)

Inputs explained

Finished linear feet produced this run:
Conveying line runtime:
Feeder-to-line synchronization efficiency:

How to use the result

Use it when commissioning a loss-in-weight feeder against a moving line, or when auditing why measured throughput trails the target speed on a continuous dosing process.
It assumes output and runtime share the same units of length and time; it does not model transient refill dips or the lag between a line-speed change and the feeder's gravimetric correction.

Common questions

How do you calculate line speed matching for a loss-in-weight feeder? Divide finished linear feet by the runtime in minutes. With 1,200 ft over 8 hours (480 minutes) the average line speed is 2.5 ft/min; at 90% sync efficiency the line was moving about 2.78 ft/min during locked production.
What is the average speed versus the in-sync speed here? The average (2.5 ft/min in the example) spreads finished length across every runtime minute, refill dips included. The in-sync speed (about 2.78 ft/min) is the pace held during the 90% of the run the feeder was in gravimetric lock.
What is a good synchronization efficiency for gravimetric feeding? Well-tuned loss-in-weight feeders on a steady line often hold 92-97% effective sync. Below 85% usually points to aggressive refill cycles, an undersized hopper, or a control loop that lags the line encoder.
Why does my feeder over-dose when line speed drops? If the feeder is running mass-per-time instead of mass-per-length, a line slowdown deposits the same mass over less distance. Matching the feeder to the line encoder rather than a fixed rate prevents this.
Line speed matching vs. simple throughput rate? Throughput rate just measures how much you made. Line speed matching ties that rate to the feeder's ability to keep pace, exposing the gap between nameplate speed and what the dosing loop can actually sustain.

Last reviewed 2026-08-11.