With the advent of increasingly lightweight PET packages, blow molding takes on new importance in the beverage packaging process. In fact, poor bottle quality negatively affects quality on the entire production line and can even lead to total production shutdown. Material distribution holds the key to bottle quality. Early detection of material distribution problems can help protect an entire production run.
Until now, quality control during production has involved frequent sampling and measuring of bottles in the lab followed by manual blow molding process adjustment if necessary. In the time it takes to complete this step, production of out-of-tolerance bottles can continue for up to ninety minutes.
Equinox monitors and corrects bottle quality during production regardless of output rate. No samples are required because Equinox automatically measures the exact weight of every bottle base. If the system detects variations from the setpoint weight, it corrects the problem by adjusting certain blow molding parameters. No machine shutdown is required. In most cases, the automatic regulation occurs so quickly that no variation in material distribution exceeds the control limits set for the production mode.
Step 1: Infrared light monitors base weight.
Equinox automatically measures the exact weight of bottle bases using the INTELLIMASS system from Pressco Technology Inc., a quality control specialist and Sidel partner in the development of Equinox?. The system uses sensor modules that emit infrared light. That light is absorbed by PET at specific rates depending on mass of material that absorbs infrared radiation.
Step 2: Regulation by automatic adjustment of two parameters.
Sidel draws on its blow molding process expertise to perform a statistical analysis on this weight measurement. If the weight is beyond the tolerance limit based on the initial setpoint, then the blow molding machine`s control algorithm is automatically triggered, and the operator receives a warning about the problem. Two critical parameters that directly influence material distribution can be adjusted. Changes to pre-blow pressure regulate overall production on all stations, and modifying the start of pre-blow adjusts individual stations. These parameters are automatically adjusted until the weight stabilizes and returns to normal (indicating bottle quality and uniformity).
It takes about two minutes to completely stabilize the process. If Equinox is unable to return the base weight curve to within tolerance limits, it automatically lets the operator know which blow molding station is causing the problem so that the operator can either modify pressure flow or take other corrective measures.
Sidel is one of the world`s leading suppliers of equipment for food and beverage packaging. It has 5,300 employees around the world and is a division of Tetra Laval.
Pressco Technology Inc. is a U.S. company that specializes in developing machine vision inspection systems for the global food, beverage and container industries. Pressco is Sidel`s quality control partner.