Ask any machinery supplier how fast their filler runs and you will get a number in bottles per hour, often abbreviated as BPH. It is a useful number, but it is rarely the number you will see on your production report at the end of a shift. If you are planning a new line or trying to understand why an existing one underperforms, it pays to know how to calculate realistic output.
Rated Speed Versus Actual Output
Rated speed is the maximum a machine can achieve under ideal conditions: correct bottle size, a free-flowing product, no stoppages and a full supply of containers. Actual output is what comes off the end of the line after every pause, changeover and rejection has taken its share.
The gap between the two is normal. The goal is to understand it, measure it and close it where possible.
Start With the Slowest Machine
A filling line is a chain, and its speed is limited by the slowest link. A 6,000 BPH filler followed by a 4,500 BPH labeller will never deliver more than 4,500 bottles per hour, no matter how good the filler is. When designing a line, the usual practice is to make the filler the reference machine and size the upstream and downstream machines faster. A common rule of thumb is a V-curve: machines just before and after the filler run around 10 to 20 percent faster, and machines further away run faster still. This lets them catch up after small stops and keeps the filler fed.
A Simple Calculation for Fill Time
For a piston or volumetric filler, you can estimate cycle output with a basic formula:
- Number of filling heads × 3,600 ÷ total cycle time in seconds = bottles per hour
The total cycle time includes bottle indexing in, nozzle descent, filling, nozzle retraction and indexing out. For example, an 8-head linear filler with a 12-second total cycle gives 8 × 3,600 ÷ 12 = 2,400 BPH. Change the product to something thicker and the fill time increases, so the output drops.
Accounting for Losses
Real output also depends on availability, performance and quality. Think about:
- Planned stops: shift handovers, cleaning, lunch breaks and changeovers
- Unplanned stops: jams, sensor faults, material shortages
- Speed losses: running slower than rated because of product behaviour or operator caution
- Quality losses: underfilled, poorly capped or mislabelled bottles that are rejected
If a line is available 85 percent of the time, runs at 90 percent of rated speed and has 98 percent good bottles, its effective output is roughly 75 percent of the brochure figure.
A Worked Example
Imagine a rinsing-filling-capping monoblock rated at 4,000 BPH. In an eight-hour shift, you lose 40 minutes to start-up and cleaning and another 30 minutes to small stops. That leaves 410 running minutes. If the machine runs at 3,700 BPH during that time and you reject 1.5 percent of bottles, your good output is about 3,700 × 410 ÷ 60 × 0.985, which comes to roughly 24,900 bottles. The brochure would suggest 32,000. That difference matters when you are promising a distributor a delivery date.
Using the Numbers to Improve
Once you track these losses daily, patterns appear quickly. Maybe changeovers take too long, or one sensor causes half the stops. Small improvements to the biggest loss usually give more output than buying a faster machine.
Planning a New Line
When you specify a new line, give your supplier the daily or monthly output you need, along with shift pattern and number of SKUs. A reliable supplier will work backwards to recommend the right rated speed. Hilden’s engineers do exactly this during line planning, so the capacity you pay for is the capacity you actually get.
