EOAT for In-Mold Labeling: 
Feasibility for Low Cavitation

The benefits of IML are clear. Film laminates can replace paper or plastic labels and the print and color do not fade or peel off of the part. The film consists of several layers that include coatings, print, color, and a micro-porous backing sheet. The advantage of molding films onto plastic parts is that the micro-porous backing sheet allows the plastic to flow into the pores creating a permanent bond. Another advantage is the film will shrink with the cooling part so you won't see any ripples on the surface. When the IML process is automated you also get consistent positioning of the labels on your molded parts. In short, you get better looking product that is going to stay that way.

Automating the IML process is where the cost justification comes into play. It is obviously not cost effective to have an operator place a label into the mold in between molding cycles because of added cycle time. The labels must be precisely staged and then transferred (via robot with End-of-Arm Tooling - EOAT) into the mold in a repeatable manner.

Labels can be staged in a number of ways depending on the amount of operator interface you want to have. Simple manual slide tables can be used to stage the labels in the robot cell guarding when the operator can place the labels in custom nests for each cycle or if the robot is capable of picking from a stack of labels. Rotary tables or lift tables can be utilized when the operator interface is desired to be limited. Whichever option you choose the staging equipment needs to locate the labels positively with the same orientation, as the labels will be placed into the mold. It also needs to have label presence and orientations sensing to ensure the labels are placed into the mold consistently and correctly. The staging equipment may also need to locate the robotic EOAT within the nest. This way the robot will pick up the labels with precision, which allows precision placement in the mold. All 3 are examples of cost effective ways to present the labels to the robot/EOAT for low cavitation applications.

It is desirable to have a full servo robot for IML automation. Cartesian robots and articulating robots have shown to be equally capable of the accuracy and flexibility needed. The EOAT must secure the label firmly and locate the label precisely in the mold as well as secure the molded parts. The EOAT may need to dock in the staging equipment and the mold for positive label positioning. The labels are held in the mold by means of an electrostatic charge. The charge applicators can be located on the EOAT or outside of the mold depending on how well the label holds the charge, humidity considerations, and dust and dirt attraction. If the charge applicator is placed on the EOAT then the robot will need to control the power to the charging unit.

Also, additional cables will need to be run through the robot cable tracks to transmit the charge from the charging unit to the charge applicators. If the charge applicators are located outside of the mold then the EOAT must be equipped with a vacuum plate with an antistatic, high resistivity pad to keep the electrostatic field on the label. Making low cavitation IML cost effective requires dependable equipment and good quality labels. Costs range between EU 19,000 - 40,000 depending on the application for the staging equipment, EOAT, and charging equipment. Some questions you should have answered before getting your vendors involved are:

• How many cavities/labels in the mold?
• What material is being molded?
• What is the mold daylight?
• Which side of the mold are we inserting on (Core or Cavity)?
• Is the mold textured or will it be textured?
• Are we placing the label close to a mold gate?
• What type of accuracy do we need on label placement?
• Do we need to secure the finished part as well as place the label?
• Can we modify the mold to include EOAT locators if needed?
• What make/model of robot and is it a full servo?
• What is the payload of the robot?
• Can the robot use vacuum confirmation or a switch to sense the top of the stack of labels?
• What type of staging equipment is needed?