Static Elimination in Plastics Processing
Bag Wicket
High static charges can cause the bags to cling together or repel on the collated stack. As a result they stack poorly, decreasing production yields and increasing rejects. Installing static eliminators as the bag enters the wicket area, while on the wickets, and at the stack will ensure that the single bags and the collated stack are fully neutralized and stack properly.
Recommended Solutions:
Slitting
During the unwind operation, as the web is pulled from the roll and the material separates, a static charge is created. The static charge increases as the web moves across rollers and when the material is slit. As the material starts to rewind the static can cause the layers to repel each other and decrease roll quality.
Installing a static eliminator prior to the rewind will neutralize the charge and prevent contamination and poor quality rolls.
Recommended Solutions:
Sheeting
In high speed applications, such as sheeting, static is generated by the fast speed, the friction, and the separation. As the sheeting process takes place, the individual sheets are attracted to the machine and repel each other when stacking.
Installing a static eliminator above and right after the sheeting operation will neutralize the static and lead to good stacking, a reduction in jamming and down time and increase productivity.
Recommended Solutions:
Winding
During the winding operation, as the web is pulled from the roll and the material separates, a static charge is created. This static attracts airborne dust and contaminates causing rejects, waste and operator shocks.
On both unwind and rewind applications, installing a static eliminator on top of the roll will neutralize the charge and prevent contamination and shock.
Recommended Solutions:
Blow Molding
As the plastic parison exits the die into the open mold, high static charges cause the parison to attract to the grounded metal mold. With multiple die heads the parisons will repel each other. This results in poor product quality and increased rejects.
Installing a static eliminator as the plastic is extruded and entering the mold (A) will neutralize the charge preventing quality failures. An eliminator at (B) eliminates static electricity from the molded container, preventing personnel shock and attraction of contaminants.
Recommended Solutions:
Film Extrusion
Static charges build up as the blown film cools and travels across rollers to the wind up, attracting dust and contaminants and causing operator shocks.
Static eliminators are recommended at the point of extrusion (A) and at the wind operation (B, C) to neutralize the charge. This will prevent slowdowns, rejects, and operator shocks and will improve product quality.
Recommended Solutions:
Injection Molding
At the end of the injection molding process, as the parts fall into a collection bucket/container, static is generated. The charge, although small on each individual part, will create a very large static field as more and more parts enter the collection area. The result is dust and contaminates are attracted to the parts causing dirty parts and operator shocks.
Installing a static eliminator at the collection bin (A) will eliminate these charges.
Recommended Solutions:
Injection Molding – Small, Lightweight Parts
During injection molding of intricate, lightweight parts for the medical, pharmaceutical, and other industries, the presence of static electricity causes parts cling to mold ejectors or to the injection mold face during the open cycle of molding. Ideally the parts should drop freely from the mold ejectors down into a catch bin or tote. When static electricity is excessive and not controlled, the parts will not drop freely. This results in a loss of usable parts, clogging of ejectors, possible damage, downtime and a general slowdown of productivity, and loss of profit.
Installing high-performance static eliminating bar (A) at the mold effectively eliminates electrostatic charges on the parts, in turn allowing parts to fall freely into catch totes. In some cases, there is a further benefit to using air assisted static eliminators, as the air flow lightly directs the molded parts in their intended direction.
Static elimination may also be required on parts as they
move via conveyor or accumulate in totes (B,C).
Recommended Solutions:
In-Mold Labeling
During the In-Mold Labeling (IML)/Decorating process, a product label must be placed into the mold in a specific location. One of the most efficient methods for accomplishing this operation is via the use of an electrostatic charging system. This system consists of a Static Generator (A) and one or more charging devices, such as Charging Bars (B) or Charging Point Pinners.
By utilizing this equipment to apply an electrostatic charge onto the label, the label can be easily placed onto the mold’s surface. The electrostatic charge applied to the label creates a bonding force that enables the label to adhere to the mold surface, staying in position during the molding process.
In the illustration: The label is picked up, passed over a Charging Bar (B) and placed in the mold. The static charge holds it in position while the mold closes and the process is completed. Upon opening of the mold the label has been fused into the surface of the injection molded object.
Recommended Solutions:
Plastic Resin Transport
