How to Fix Soft Egg Trays? Practical Pulp Formulation Adjustments
Soft, low-rigidity egg trays that bend easily are a common headache for operators using an egg tray machine. This issue usually comes from unsuitable pulp formulas, instead of machine faults. Below are practical, testable adjustments you can apply on your production line step by step.
Choose the right fiber blend
Pure recycled cardboard pulp alone often makes egg trays soft and fragile. A reliable and economical mixing ratio is 80% recycled OCC pulp + 20% long-fiber wood pulp.
- Long fibers create stronger inter-fiber bonding and improve compression stiffness
- Avoid excessive refining. Over-beating cuts fiber length and reduces the final strength
- Keep your raw material source stable. Mixed low-grade waste paper will cause inconsistent stiffness between batches
Stabilize pulp concentration for egg tray machine
Slurry solid content directly affects the density of egg trays formed by your industrial egg tray machine. The ideal range for most standard lines is 3%–5%.
- Too dilute: fewer fibers deposit on the mold, producing lightweight, soft trays
- Too thick: water drains slowly during forming, leading to uneven wall thickness and defects
- Run small batch tests and standardize water feeding to avoid frequent concentration swings
Add strength agents properly
Dry strength agents are a simple way to boost stiffness without overhauling your fiber formula.
- Pour the additive evenly into the pulping tank for homogeneous mixing
- Control dosage carefully. Too much additive increases production cost and slows drainage on the mold
- Complete full stirring before the slurry flows into the forming section
Match formula with drying curve
Even a well-tuned pulp formula will fail if paper tray drying machine parameters are wrong. High residual moisture keeps trays flexible and weak.
- Use staged heating: evaporate surface moisture at a lower temperature first, then raise heat gradually
- Hot pressing after drying is an optional upgrade, which can greatly improve surface rigidity for high-end orders
Practical testing suggestion
When adjusting settings on your egg tray machine, change only one factor each time. Record key data including tray weight, moisture content and stiffness after each trial. This method helps you lock in the most suitable pulp recipe matching your local waste paper materials and workshop environment.
