The Boxes That Jammed at the Corner
We ran a roller conveyor. The boxes came off the conveyor at a 90° turn (a corner). At the corner, the boxes jammed — they tilted and stuck. The side guides (which kept the boxes on the conveyor) were fixed. At the corner, the guide rail was too tight. The box caught the rail edge. We adjusted the side guide: at the corner, the guide opened up (funneled the box) and used a low-friction UHMW strip (article 116). The boxes rounded the corner without jamming. The mistake was using a fixed, rigid guide through the corner — the box needs room to turn.
Conveyor side guide design keeps the product on the conveyor. At corners and diverts, the guide must funnel (not pinch). This article covers the design.
What the Side Guide Does
The side guide (a rail on each side of the conveyor) keeps the product centered. It prevents the product from wandering off (or falling off). For a straight conveyor, the guide is parallel. At corners or diverts, the guide must funnel (guide the product through the turn).
Step 1: Adjustable Width
The guide should be adjustable (for different product sizes). A fixed guide only works for one product. For multiple product widths, use:
- Manual adjustment: A handwheel (or a screw) that moves the guide in/out. The operator sets it for the product.
- Quick-change: The guide has a quick-release (a lever) that opens for size change. No tools.
- Automatic width adjustment: A servo or pneumatic actuator adjusts the guide width (recipes in the HMI). For high-mix, fast changeover.
The guide width is product width + 10–20 mm (the product has room to move, but not enough to wander). Too tight, and the product jams. Too loose, and it wanders.
The side guide rule: Set the guide width to product width + 10–20 mm. At corners, funnel the guide (open it up). The boxes that jammed had a tight guide at the corner. Funnel it, and the product rounds the turn.
Step 2: Corner (Turn) Design
At a 90° corner (a curve or a transfer), the side guide must:
- Funnel: Open up as the product enters the turn. The box has room to swing around.
- Use low-friction material: UHMW strips (article 116) on the guide. The box slides, not scrapes.
- Radius: The outside rail follows the turn radius. The box follows the curve.
For a right-angle transfer (the box leaves one conveyor and goes onto another at 90°), use a powered transfer (article 93), not a guide rail (the box doesn’t “turn” — it’s transferred).
Step 3: Guide Height
The side guide height is about half the product height. Taller guides can catch the product (if it tips). Shorter guides don’t contain it. For a box (100 mm tall), a 50 mm guide is standard. For a tall, unstable product, use a taller guide (or a top hold-down belt).
Step 4: Pressure (Hold-Down)
For a steep incline (or a product that tips), add a hold-down (a belt or chain over the top). The hold-down presses the product onto the conveyor. The side guide alone doesn’t stop tipping on an incline.
| Guide Feature | Design |
|---|---|
| Width | Product width + 10–20 mm |
| Adjustment | Manual, quick-change, or automatic |
| Corner | Funnel (open up), UHMW strip |
| Height | Half the product height |
| Incline/tips | Add a hold-down belt/chain |
A Side Guide Checklist
- What is the product width? (Range?)
- Is the guide width adjustable? (For multiple sizes?)
- Is the width product + 10–20 mm?
- At corners: is the guide funneled? (UHMW strip?)
- Is the guide height right? (Half product height?)
- Does the product tip? (Hold-down needed?)
- Is the guide material low-friction? (UHMW?)
- Is the adjustment accessible? (For changeover?)
- Does the product jam at the corner? (Test?)
- Is the guide bolted securely? (No vibration?)
The Bottom Line
Conveyor side guide design contains without pinching. The boxes that jammed had a tight guide at the corner. Set the width to product + 10–20 mm, funnel the guide at corners (with UHMW strips), and add a hold-down for inclines. Make the width adjustable for product changes. The product that flows through wasn’t held tightest — it had room to move.
