Introduction
What does line speed mean? Line speed is one of the most cited specs in secondary packaging and also one of the most frequently misunderstood. When an OEM says their machine runs at “30 cases per minute,” that statement means almost nothing without context. Here’s why and what you should actually be asking.
The Problem with Nameplate Speed
Machine manufacturers spec the line speed at nameplate, which is the maximum theoretical rate the machine is designed to achieve under ideal conditions. That typically means:
- Single SKU, no changeovers
- Consistent, in-spec packaging materials
- Perfect product infeed at rated speed
- No upstream or downstream constraints
Real production environments rarely look like this. The moment you introduce changeovers, product variability, operator interventions, or line imbalances, actual throughput drops. Sometimes that drop can be significant.
CPM vs. PPM — Make Sure You’re Comparing the Same Metric
Line speed is often quoted in cases per minute (CPM), cartons per minute, or products per minute (PPM), and these are not interchangeable. A machine running 30 CPM on a 24-count case is producing 720 products per minute. The same machine running 30 CPM on a 6-count case is producing 180 products per minute.
Pro Tip
Always clarify: speed in what units, at what pack count, and under what conditions?
Sustained Speed vs. Peak Speed
Another source of confusion is peak speed vs. sustained production speed. Many machines can hit their rated speed in short bursts but can’t sustain it continuously over a full production shift. Factors like motor thermals, mechanical wear, and material feeding all effect sustainable throughput.
When evaluating a machine, ask for demonstrated throughput data from a comparable application that includes same product type, similar pack configuration, and similar run length. That’s the number that matters for your ROI calculation.
What to Ask Instead
Rather than asking “How fast does it run?”, ask:
- What is the demonstrated OEE at rated speed in a comparable application?
- What is the average sustained speed across a full production shift?
- What does speed look like across my specific product range, including my most difficult SKU?
These questions give you a realistic picture of what the machine will actually do, which is ultimately the only number that matters when you’re planning your line.
Want to Understand Line Speed?
Reach out with questions. With 60+ years of industry experience, Douglas specialists are ready to share the knowledge you need so you can make more informed packaging decisions.
