OVERVIEW – BATCHING AND MIXING CONTROLS:
A Global manufacturer and leader in hydraulic hose manufacturing and supply contracted with Sterling Systems & Controls to create a custom engineered Batching and Mixing Controls System to improve the rubber compounding batch integrity and increase overall production through automation.
The customer needed to update its existing aged batching system. The new system would need to add more capability and automate the handling of bulk dry and liquid materials, scales, and manually weighed materials that are introduced into the Banbury® [The Banbury mixer type is ideally suited to the specific requirements of multi-step mixing applications such as is found in the rubber industry. Criteria such as good intake and discharge behavior, excellent dispersion and distribution quality, and optimal cooling are ideal.]
Overcoming the old batching system interlock of not being able to process different formulas at the same time was another challenge. The limitation of the old system resulted in substantial lost production time. The company determined that Sterling Systems & Controls’ customized automation capabilities were the perfect fit to satisfy their demands.
Sterling Systems solved the customer batching and mixing controls problems and met their challenge by designing the new control system to incorporate four main processes: The Hand Add Weighing Process, the Main Batching Process, the Mixing Process and the Batch-Off Process. Each Manual Add Station consists of a control panel (provided new by Sterling Systems) with a PanelView Plus HMI and an Ethernet weight instrument. The system allows the Hand Add Stations to batch ahead and pre-stage totes for the main batching process. Hand Add HMI screens prompt the operator to place a container on the scale and to use an RFID scanner to scan container tags. The system then displays which ingredient to weigh into the container in a predetermined sequence to complete the batch. The system utilizes bins with limit switches on the lids in order to confirm that the correct ingredient has been selected and after confirming, the operator is prompted to weigh the specified amount of the required ingredient. The operator continued the entire batch sequence weighing each ingredient in this manner. As the operator completes each tote, it is placed on the Hand Add Conveyor.
The Main Batching Process is controlled from the main control panel (supplied new by Sterling Systems)
using an integrated dual screen display and industrial computer running Rockwell FactoryTalk View to provide a wide touch screen operator interface and a dedicated mixer display monitor. Password protected ingredient codes, bin assignments and formulation data are entered into the batching computer either at the main control or via the remote access through Sterling Systems’ provided WebCentral™ software application. The scheduling operator will select the formula and create a batch schedule. The batching process screen displays a graphical schedule.
By integrating an RFID reader and a scale, the system verifies with the RFID verification that the ingredients have been weighed within tolerance and all starting conditions for the mixer are met. The system starts the Banbury mixer at a formula specified speed, introduces scaled ingredients, energizes the mixer pneumatic ram and sets pressure. It then prompts for and confirms the addition of Hand Add ingredients at appropriate times during the batch, based on mixer power usage, time and/or batch temperature conditions programmed for the selected formula. The system continuously monitors and verifies mixer health and batch temperature are within tolerance. Once a scale finishes discharging, it will automatically begin weighing the next batch or formula while the mixer is processing the current batch in order to maximize batch throughput.
BATCHING AND MIXING CONTROLS – THE RESULTS:
Sterling Systems & Controls custom engineered an HMI-PLC based batching/mixing control system that consisted of a Main PLC Control Panel using Allen Bradley Control Logix PLC with Rockwell’s FactoryTalk HMI software, a PanelView Plus HMI based Rubber Hand Add Station, Minor Ingredient Weighed Hand Add Controls, and a Mixer Hand Add Check-Weigh control system. The customer’s existing RFID scanners were incorporated into the Sterling system to ensure batch integrity. Additionally, a WebCentral database access software package was included to provide access to the plant floor data from PC’s on the corporate network. Panel mounted Manual/Off/Automatic selectors with a master key switch provided true manual backup in case of a PLC failure.
- The new Weighing System is responsible for the automatic and semiautomatic weighing of raw material ingredients used to produce the customer’s finished products.
- Control system tracks the raw material data and ensure that each weighment is accurately scaled.
- Due to the control systems’ data tracking and management capabilities the end user is able to maintain inventory and usage of each raw material and VALIDATE that the correct materials are used in each batch process.
- Records are created and maintained by the control system including batch summaries, cycle time, production, raw materials, finished product, lot data, actual weights and batch operator information.
Banbury® is a registered trademark of Farel Corporation.