A case erector that takes 45 minutes to change over is not a flexible machine, whatever the brochure says. On a two-shift plant running four SKUs a day, a 45-minute changeover burns over an hour of production per day – about 1,500 boxes of lost capacity on a 25 CPM frame. That is the real reason size changeover dominates operator time in mixed-line plants.

This guide is the exact changeover procedure we train ZRAY operators on. It covers the four adjustment zones on our frames, the reference values for each, and the pitfalls that make changeovers stretch from 5 minutes to 40. If your operators follow the order below, the whole change sits under 5 minutes per size, including the first box test.

The four adjustment zones on a ZRAY case erector

Every size change on our machines touches the same four zones. Learn them in this order and you never touch a screw twice:

1. Hopper guides and blank pusher – adjusts blank width and depth at the magazine.
2. Forming/folding section – folding rails, flap closers, and the forming mandrel position.
3. Sealing section – tape head height, brush/wipe-down position, glue nozzle height if hot melt is used.
4. Outfeed and case size sensors – position of the size verification photocells and reject gate.

On the high-speed double-head frame, zones 1-2 repeat per head, which is why large-format changes there are best done with two operators in parallel.

Step 1: Prepare before you stop the line

The changeover clock starts when the machine stops, so everything below must be done while the previous SKU is still running:

• Get the new blank from storage and confirm its dimensions against the job card.
• Set the new glue target temperature (if hot melt): standard 150-170°C, adjust for board weight – heavy BC-flute 500-700 gsm board runs hot, lightweight E-flute 200-280 gsm runs cooler.
• Pre-position the tools: hex key set, depth gauge, and the HMI changeover screen already open.
• Note the old SKU dimensions on the changeover log – you will need them when you change back.

Step 2: Set the hopper section

1. Release the hopper side guides. Loosen both side plates, set the width to blank width + 5-8 mm. Tighter than +5 mm and the pusher binds on humid board; wider than +8 mm and the blank skews during feed.
2. Set the back stop to blank length plus 2-3 mm.
3. Adjust the pusher stroke so it advances the blank fully into the pick position without over-running. The pusher tip should finish flush with the first vacuum cup face.
4. Recheck stack weight/height limit – the hopper holds roughly 50-80 single-wall blanks or 30-40 double-wall blanks depending on board thickness.

Step 3: Set the forming and folding section

1. Position the forming mandrel so its top face matches the new case height. On ZRAY frames the mandrel carrier has a locking lever plus a dial indicator – read the dimension, do not eyeball it.
2. Set folding rail width to case width + 1.5-2.5 mm. This is the clearance that decides whether the case folds clean or jams at the first flap.
3. Adjust flap closer height so the closer presses the flap for 300-400 ms before the sealing station fires.
4. Check the bottom flap breaker position for board thickness. For B-flute 2.5-3.0 mm and C-flute 3.5-4.0 mm single wall, the default position works; for double wall 6.0-7.0 mm, open the breaker gap by one step so the flap pre-break does not crush the flute.

Step 4: Set the sealing section

1. Move the tape head to the new case height. The tape center line should sit 8-12 mm above the case bottom on the bottom head and 8-12 mm below the top edge on the top head.
2. Set the brush/wipe-down assembly so it presses the tape with light-to-moderate force. Too hard and you see tape scuffs; too light and the tape lifts at the corners.
3. If hot melt is in use: adjust the glue nozzle height so the bead lands in the center of the flap overlap, and check the nozzle temperature on the machine – not the HMI – with a contact thermometer.
4. Verify the case size sensors are repositioned to the new L×W. Sensors are mechanical on standard frames; on the high-speed frame they are servo-positioned from the HMI changeover recipe.

Step 5: Run the first-box test

The first box is your proof. Watch it through one full cycle:

• Blank feeds straight from the hopper – no skew.
• Flaps pre-break along the score without crushing the flute.
• Case forms square; check the diagonal measurement – difference under 3 mm is acceptable.
• Tape lays full length over the seams with no gap over 0.5 mm.
• The box passes the size verification sensor and does not trigger the reject gate.

If any of the five fails, adjust the relevant zone and run a second test box. Two consecutive clean boxes and the changeover is done. Log the new SKU settings in the HMI recipe bank for the next time.

Reference table: changeover values on ZRAY frames

The three pitfalls that turn 5 minutes into 40

1. Skipping the mandrel position check. Operators adjust rails and hopper, then wonder why the case forms crooked. The mandrel is the reference point for everything downstream. Always set it first.
2. Guessing clearance by feel. The +1.5-2.5 mm rail gap is not something you feel through a glove. Use a feeler gauge or the depth gauge. Every minute you spend on setup saves three minutes of jamming later.
3. Forgetting the sensors. A perfect mechanical change still sends the first five boxes to the reject gate if the size photocells were left at the old position. Reposition them in the same pass as the rails.

PLC alarms related to changeover mistakes

Changeover maintenance schedule

A machine that changes size four times a day wears differently from one that runs a single SKU. Track this:

Keep a changeover log with actual times. When a change takes more than 7 minutes three times in a row, something mechanical has drifted – usually guide wear or a loose lock lever – and it is cheaper to find it on a Thursday afternoon than a Monday morning.

Why the HMI recipe bank pays for itself

On our frames, the changeover recipe saves the dimension values, clearance offsets, and sensor positions per SKU. A call-up at the panel does the whole numeric setup in under a minute; the operator still does the mechanical part but verifies against the recipe instead of a job card. Two practical notes from the field:

• Store recipes in the machine, not in a spreadsheet. When a recipe lives on a laptop, someone forgets to update it and the line runs the wrong dimensions for half a shift.
• Re-verify recipes quarterly against the actual blanks – board suppliers change thickness and the recipe tolerances drift.

When frequent changeover is your core operation

If you run more than four SKUs per shift, changeover time is effectively your production time. This is the case where our Double-Head High-Speed Case Former earns its keep – two heads, 99 stored recipes, and servo-positioned changeover zones bring the per-change time down and remove the second-guessing that eats mixed-line shifts.

If your mix is smaller but you still touch size three or four times a day, the Single-Piece Case Erector covers the same adjustment zones on a compact frame with 30 recipes – enough for most single-line plants.

The changeover summary card

Print this and mount it beside the machine panel:

1. Stop the line. Start the clock.
2. Set mandrel position first – it is the reference point.
3. Set hopper: width +5-8 mm, back stop +2-3 mm.
4. Set folding rails: width +1.5-2.5 mm. Use a gauge.
5. Set flap closer dwell 300-400 ms.
6. Set tape head to case height ± 8-12 mm.
7. Move the size sensors with the rails, same pass.
8. Glue at 150-170°C, verify with contact thermometer.
9. Run first-box test. Two clean boxes = done.
10. Save the recipe in HMI. Log the time.

Done in order, this is a sub-5-minute changeover on a compact frame and under 8 minutes on the double-head. Done out of order, it is a 40-minute scramble. The procedure does not need more tools – it needs the order.

Need changeover training for your operators or a recipe-migration review of your line? Email [email protected] or message WhatsApp +86 13681839278 – our engineers respond within 24 working hours, and we can join a live changeover via remote diagnostics to time and optimize each step. You can also book a session through our contact page. Tell us your machine model, current average changeover time, and SKU count per day, and we will send a tailored procedure sheet for your exact machine.