Production Scheduling & Tracking System

The Problem

A manufacturer of china and other ceramic ware consolidated several smaller and inefficient production kilns into a single, larger, modern kiln.

The ware is loaded onto "Kiln Cars." These cars travel on railroad type tracks. Each car is uniquely numbered, and is assigned to a particular station where the car is unloaded, and then reloaded, for another trip through the kiln. A round trip through the kiln could take up to twenty hours.

The production system is configured with ten load/unload stations. Each station is set up to handle a fixed type of china with a limited number of kiln cars.

These process constraints mean that production has to be carefully planned so that the right type of car is available to be loaded when the greenware is arriving. Due to the limited number of cars, individual cars have to be scheduled into the kiln in an optimum order to assure uninterrupted production.

Additionally, with critical orders, it is important to have timely and accurate information to keep the customer informed of progress and shipping schedule.

This manufacturer needed to be able to schedule production and adjust the manufacturing schedules to insure a smooth flow of work, and to be able to track components of an order from entry into the production area, through the kiln as a finished product.

The Solution

The kiln and car motion control was implemented by the kiln manufacturer using an Allen Bradley PLC 5-25. Panelmatic Systems, Inc. (PSI) was contracted to implement the supervisory control, employing USData's FactoryLink Man Machine Interface (MMI) Software package.

Working closely with the client's production managers, PSI obtained a firm understanding of the kiln operations and production requirements. PSI then wrote a Functional Control Description (FCD) of the desired process.

An on-line, relational database was the heart of the supervisory system. The main database fields included such informational items as the kiln car number, car type, the car's assigned load/unload station number, the type of ware on the car, the quantity of ware on the car, estimated time out of the kiln, and the car location.

Bar code readers were installed at key locations of the system. When cars passed the bar code readers, the supervisory system reorganized the locational status changes from the unload area to the loaded area, from the loaded area to the kiln, or from the kiln to the unload area. Linked lists were used to keep an accurate picture of the location of any car, at any time.

Operator interface screens were developed which combined the use of graphics and SQL database queries. This allowed the production managers to look at the system from various perspectives.

C-Language code was used to implement the production scheduling features. Three scheduling systems were implemented.

• The kiln operation can be strictly time based. This is a first in/ first out system based on the time a car is loaded with ware. A queue is established such that the oldest loaded car is the next car picked up to go into the kiln.

• The second mode of operation allows production based scheduling. Management decides how many cars are to be loaded at each station, for each shift, on a daily basis. The supervisor enters the production figures on a graphical representation of the stations. A function key is used to allow database calculations to be performed. The manager is able to scan the proposed production line-up and make a decision on it's acceptability. The optimum pickup schedule for each station is then established. A second function key transfers the proposed list to the working queue.

• The third scheduling mode is manual. Managers develop a schedule and enter the pickup order.

The Benefits

PSI designed, and successfully commissioned, a PC-based supervisory control for this kiln operation that delivered these benefits to our client:

• Automated scheduling features reduced management time required to generate schedules. Manual features allowed management to adjust or override the schedule to meet unforeseen conditions.

• Improved scheduling reduces lost time and generates productivity increases.

• Reduced response time to customer inquiries adds to customer satisfaction.

Copyright 1997 Panelmatic Inc. All rights Reserved