Bakery Oven Control
Project Scope:
To give an existing oven control panel a new HMI which would enable the Operators to have better Control, Recipe Selection, Alarm Functionality, and add Data Logging.
The Back Story:
The oven had an HMI in place which had become obsolete. In seeking a replacement HMI model, the bakery decided it was also a good time to upgrade the functions of the HMI and improve upon the control and efficiency of the oven.
There are 3 Zones in the Oven and each Zone has an Upper and Lower PID controlled section. PID controllers were already in place, but it was unknown if they were set up properly and all indications were that zone temperature control was not in compliance with making good consistent products.
The existing HMI allowed for viewing and changing set points for each zone as well as monitoring the temperature of each zone. Operators could also select a recipe and the recipe would determine the temperature set point for each zone, upper and lower. Recipes could be added and altered by a person properly logged into the HMI.
What Was Missing:
No or Limited Alarm Annunciation or Explanations
No Oven Speed Control
No Data Logging
No Auto tuning of the Zones
No Ability to Grow and Change to Meet New Customer Demands
No Remote Control or Viewing of Processes
Solutions:
After having the customer define exactly what they wanted in a new HMI and control system, the following items were added -
1. By adding in communications to 4 motor drive controls, the recipes were now able to define, Line Speed and 3 fan speed controls (one for each zone) which were important in all aspects of delivering a good product and improving Quality Control Management.
2. PID Auto tuning and a thorough explanation of how to use this technique gave the maintenance crew tools they did not previously have and also added to the Quality Control of the products.
3. Alarms - Annunciation and Descriptions were added to aid both the Operators and Maintenance staff in troubleshooting any problems that may arise in the system.
4. Data Logging and Trending - Giving both Historical and Real Time trending as well as the ability to log data, gives the company a record of production and window into the processes so that efficiency can be monitored and adjustments made as needed to insure a good quality and consistent product is being manufactured.
5. The HMI panel can be updated by using a USB drive or Micro SD card which eliminates the need for any cables, programs or PCs to be used in the update process. With this method, any maintenance technician can add an updated program to the HMI, ensuring the future changes can be made easily and expediently.
End Results:
The bakery now has control over their oven, can view in historical and real time the trend for the oven, can monitor and control each Zone's Temperature and Fan Speeds, Line Speed through the oven and can use the logged data to better analyze the processes and fine tune recipes as needed.
The Operators have good visual feedback about the products they are producing and can make necessary adjustments if needed. They are also now aware of any problems that occur and are given helpful tips about how to correct and problems that may arise.
For the cost of an HMI, some programming time and the addition of motor drive controls with communications, they have essentially created a new oven with out the major expenses of buying and installing a new oven and controls.
All this was accomplished with only 8 - 10 hours of downtime on the oven, so the loss of that downtime is easily recovered in the improved quality of the products. Time for Operators to change over from one product to the next was greatly reduced. Maintenance Technicians can now trouble shoot and solve problems as they occur, reducing downtime. Quality Control Experts and Coporate Management can review logged data to improve recipes and processes and confirm current operations conform to GMP practices.
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