How Printhead Count Works on a Corrugated Press: 3 to 72 Heads Explained

Open a corrugated digital press spec sheet and the printhead count is often the first number buyers compare: 3, 8, 16, 36, 72. The spread is wide enough to look like a capability ranking, and it is not one. Head count is an output of four decisions — print width, imaging method, colour channels and resolution target — not a starting point you can rank machines by. The same number of heads does completely different work on a single-pass press and on a scanning press. Below is how that arithmetic plays out across the configurations published for Ruisheng presses.

1. A counter-intuitive pair

Put two machines side by side and the numbers look backwards. The RS2500-E8 uses 8 heads and prints 2,500 mm (98.4 in) wide. The RS2500-E32S uses 32 heads and prints 530 mm (20.9 in) wide — four times the heads, less than a quarter of the width.

Neither machine is mis-specified; they image differently. Read the specs in this order instead: imaging method first, then width, then head count.

2. Single-pass: heads span the full width, count buys speed

On a single-pass press the heads are arranged in an array across the print width and the board passes underneath once. The array has to cover the whole web, so wider formats need more heads.

• RS2500-E36S — 36 piezo heads, 1,200 mm (47.2 in) wide, rated up to 106 m/min (348 ft/min), >600 × 300 dpi.
• RS2500-E72G — 72 piezo heads, the same 1,200 mm width, rated up to 150 m/min (492 ft/min), >600 × 300 dpi.

Width and resolution are identical; only head count and speed move. Going from 36 to 72 heads takes the rated speed from 106 to 150 m/min. The relationship is not linear — doubling the heads buys roughly 40% more speed, because feeder cadence, board thickness and coverage all cap real output. The published note makes the same point: 150 m/min is a rated figure that excludes feed time, and actual throughput varies with board thickness, coverage, resolution mode and continuity of supply.

The third machine shows the same trade-off from the other side. The RS2500-E32S carries 32 heads but only 530 mm of width, and it is rated at 200 m/min (656 ft/min): a head count close to the E36S, 44% of the width, higher speed. That is the rule on a single-pass press — the same row of heads covering a narrower web passes more metres per minute, so speed is bought with width. The cost sits in resolution. The E32S is rated >1200 × 150 dpi, with a comparatively low figure in the feed direction, and its spec note restricts it to text, barcodes and solid areas. Photographic artwork needs a sample before you commit.

3. Scanning: heads cover a strip, width comes from travel

A scanning press mounts the heads on a beam that traverses the width, laying the image down strip by strip. The array does not have to span the format, which is why 8 or 16 heads can cover 2,500 mm.

• RS2500-E8 — 8 piezo heads, 2,500 mm (98.4 in) wide, auto feed up to 2,500 × 1,350 mm, rated 600 m²/h (6,458 sq ft/h), >360 × 600 dpi.
• RS2500-E16 — 16 piezo heads, same width and feeding, also rated 600 m²/h, >360 × 1,200 dpi.

This pair is the cleanest illustration of what extra heads buy on a scanning machine: same format, same rated throughput, and feed-direction resolution doubles from 600 to 1,200 dpi. On a scanning press, heads buy resolution first, not width. Both models carry the same 600 m²/h rating excluding feed time, so the real throughput gap has to be measured with your own artwork.

The UV scanning models follow the same logic. The RS2500-E20UV runs 20 heads at 2,500 × 1,350 mm auto feed and is rated 90 m²/min (about 969 sq ft/min); the RS2500-R16UV runs 16 heads at the same format and is rated 400 m²/h (4,306 sq ft/h). One caution: the range mixes three units — m/min, m²/h and m²/min. Converted, 90 m²/min is roughly 5,400 m²/h, but the two machines also differ in imaging, curing and downstream flow, so a converted figure is not a like-for-like comparison. Normalise the units, then confirm with a print trial.

4. Head type sets the speed band too

• Thermal inkjet — the RS1800-HPA3 uses 3 thermal heads across 900 mm (35.4 in), rated 10–30 m/min (33–98 ft/min) at ≥1200 × 300 dpi, aimed at short and mid runs with frequent changeovers.
• Piezo — the RS2500 range and the RS1900-E16 use piezo heads, and in 36- and 72-head layouts they support line speeds above 100 m/min.

Two ejection principles, two speed bands. “More heads” and “faster heads” are separate questions: three thermal heads deliver ≥1200 × 300 dpi at 10–30 m/min, while 72 piezo heads reach 150 m/min at >600 × 300 dpi. The same head count on a different platform tells you nothing on its own.

5. Beyond the heads: feeding and registration

Head height is 2–4 mm (0.08–0.16 in) across the range — a few millimetres between nozzle plate and board. At that distance an unstable feed or a drifting board will spoil the print no matter how many heads are firing. That is why the E8 and E16 list an in-house feed belt with high-precision automatic correction, an in-house controller board and software, automatic image feathering, skip-white printing and multi-job queueing alongside the head count. The RS1800-HPA3 lists a fully automatic ink path with visible secondary tanks and negative-pressure control; the RS2500-R16UV lists high-torque servo motors with precision planetary gearboxes and a head temperature control system. None of that shows up in a head count, and all of it decides whether registration holds through a shift.

6. Colour channels divide the head count

Heads are grouped by colour, and one head fires one ink. CMYK means the array is split into four groups. The RS1900-E16 carries red, yellow, blue and black plus light cyan, light magenta, light black and light-light black — eight channels sharing 16 heads. The UV models come in CMYK or CMYK + White, and a white channel takes heads of its own.

So confirm the colour configuration before comparing two head counts. The published notes say the same: head count, format and channel configuration are options, and the signed technical annex governs.

7. A better reading order

• Width first, from your dominant blank size: 900 mm (RS1800-HPA3), 1,200 mm (E36S, E72G), 530 mm (E32S), 2,500 mm (E8, E16, E20UV, R16UV). The RS1900-E16 is a 1.9 m (74.8 in) paper-fed print-laminate-cut line.
• Then imaging method: fixed sizes and long runs point to single-pass; many sizes and detailed graphics point to scanning.
• Then head and resolution configuration: 8 vs 16 heads maps to >360 × 600 vs >360 × 1,200 dpi on scanning presses; 36 vs 72 heads maps to 106 vs 150 m/min on single-pass presses.
• Then a sample run on your own board, at both ends of your grammage range, checking barcode scan rate, small text and registration drift.
• Finally, hand your order mix — number of box sizes, average run length, daily square metres — to an advisor for configuration sizing. For budget and pricing, ask an advisor for a quotation.

Takeaway

Head count is a result, not a starting point. Width, imaging method, colour channels and resolution produce it: single-pass presses spread heads across the full width and turn count into speed; scanning presses travel across the width and turn count into resolution. When you see a head count, ask four questions instead — how wide, single-pass or scanning, what feed-direction resolution, and how the feed and registration are built. Answer those and the head count explains itself.