Preventing Mechanical Ink Set off Contamination in Converted Flexible Packaging Web Stock
Prevent mechanical ink set-off in flexible web stock by matching tension taper curves to core pressure limits and verifying cure thresholds.
Contact Pressure
Meaning
Mechanical force per unit of area exerted between two mating surfaces defines the seal integrity and part quality in molding operations. Proper contact pressure prevents the pressurized melt from escaping between mold plates or around moving cores. It acts as the primary barrier against the formation of excess material at the parting line.
Sealing Efficiency
Maintaining a tight shut-off requires the clamping force to exceed the internal cavity pressure by a safe margin. When the contact pressure drops below the local melt pressure, the mold halves separate slightly and create a gap. This condition results in flashes that require manual trimming and increase the scrap rate of the production lot.
Overly high forces can also compress the steel to a point where the vents are pinched shut, causing gas burns on the final parts.
Interface Force
Sensors placed behind ejector pins or inside the mold base provide real-time data on the distribution of load across the tool face. Uneven loading causes premature wear on the mold guides and can lead to permanent deformation of the cavity edges.
Mechanical Stress
High-tonnage machines generate immense loads that must be distributed evenly to avoid crushing the delicate venting structures of the tool. Precision machining of the parting surfaces ensures that the contact pressure remains uniform across the entire footprint of the mold.