Formulation management: from lab to plant.

The larger manufacturers have, until now, held an advantage in efficiency and quality control. They have enjoyed the benefit of in-house programmers and systems analysts - all geared toward large scale production and total automation. They could justify greater expense to insure continued efficient production. Smaller companies that could not sustain the cost outlay needed for an automated production environment were clearly at a disadvantage

Now, with the advent of PC-based compound management systems, automation becomes available to the smaller plant at reasonable expense - costs that can be recovered, in most cases within one year, through reduced waste of both materials and time. In today's environment, there are many advantages to PC-based systems. These include flexibility, ease in learning and maintenance, and more value; additionally, with lower operating expenses and enhanced efficiency, small companies can enjoy a more competitive edge in their respective markets. Chemix and its Weighing Scale Option (WSO) offer formulations management and quality control to rival the mainframe-based systems.

Design philosophy

We studied the entire production process in order to meet the most pressing needs of the plant operators. We established the need for an easy-to-use software application that could be learned and mastered upon the first usage, with no prior computer experience. This was a central requirement in the design of our WSO. We realize that operations can not be delayed for weeks, or even days, while plant operators learn a new computer application.

Our system is designed so that plant operators can master the process within minutes. The possibility for mistakes associated with memorizing recipes is eliminated. Now they may devote more time to what they do best: producing.

Our goal was to provide an integrated production system that could be quickly mastered and become second nature soon thereafter. We were able to accomplish this by first focusing on what makes things simple, and observing how people actually use computers on a day-to-day basis. We examined what would make operations easier in ways that would also permit one to enjoy the experience. Basically, we found that, the less there is for operators to recall, the easier it is to become second nature.

We used this observation in the following ways:

* Only one menu. All activities to be performed are shown on a single menu. There are no additional menus or levels in which the operator can get lost.

* No codes to remember. There are no formula codes or special function key codes to remember. Whenever there is a need to make a selection (example: a formula), a list of options is available from which the user can choose. All keyfunctions are displayed at the bottom of the screen. Thus, there is no confusion, no chance of an operator shooting himself in the foot.

* No complex keyboard. With only a few applicable functions for the operator to learn, there is no need for the distraction of a full-sized keyboard. A big-button" telephone keypad has been adapted for operations involving use of protective gloves.

Additionally, the WSO enhances plant operations as an assistant to the operator; a tool designed to help, not intimidate, production personnel. In demonstrations of our system to various robber production environments, we learned that we have achieved our design goals. With the Chemix WSO, plant operators may now enhance their productivity without becoming computer experts. We believe that this is a primary mission of modern software development, since computer software is only as useful as one' s ability to use it.

Needs summary

In our studies of various rubber production environments, while allowing for individuality, we were able to discern a number of needs common to all rubber compound production plants. Justifiably, the smaller manufacturers displayed greatest interest in accuracy of measurement, quality control and data integration - more so than bookkeeping, which can easily be maintained with current commercial accounting software.

We established certain design and usage guidelines for the WSO:

* Compounds produced to design specs.

* On-site measurements (eliminate need for pre-weigh bags from outside sources).

* Minimum operator training time (15 min. or less), and

* Error-tracking, directly to the source.

An effective production system should reject any compound that does not meet design specifications. Any override of the system should be recorded automatically in a log. Moreover, all production-related data should be automatically documented as it occurs, thus eliminating human transcription errors and time lost in registering the data by hand. All operational details, every ingredient used, should be logged and made easily available for future study, with a few simple keystrokes.

With the WSO, all this is accomplished promptly and efficiently, while thoroughly enhancing productivity and quality control. The only requirement: a weighing-scale capable of interfacing with a personal computer (i.e., through a serial port).

The WSO assists the plant operator in accurate measure of the correct chemicals, continual monitoring of acceptable tolerances and specification adjustments, in mid-process, if needed. By addressing these needs, production speed, accuracy and ability to correct errors are all thoroughly enhanced.

System description

The weighing scale option is the logical extension to the Chemix program. With Chemix, you create the compound taking into account raw materials, their ideal weight, specifications, and establish the upper and lower limits (ref. 1).

WSO then oversees the production phase process by interacting closely with plant operators. The system is very simple to use. The operators need not face the cumbersome task of learning a full-sized keyboard. Rather, a simple big button touch-style telephone keypad has been modified for usage. All of the operator's functions, and no others, may be performed with it.

We begin with a single main menu that consists of four selections: initial setup, schedule-formula weighing, floor schedule and view weight sequence. All four functions can be initiated from the main menu. The operator begins his day with initial setup. Here the date, user' s ID and the scale to be used are selected and entered. The system then provides the day's schedule (compounds, weighing sequences, etc.). The operator is ready to begin.

Schedule-formula weighing, sequenced to mixer schedule, displays what formula is to be weighed, how many batches needed and the scheduled production start-date (or "weigh in" date). Formulas are then displayed for the operator. Please take note that only formulas that the operator is authorized to see will be shown. Plant operators may only see what they have been cleared to see. Should a given day's work call for a higher security formula, the chemist can temporarily permit it. The schedule may be modified at any time prior to actual production. Once production starts, a tag appears to signify that no further changes can be made. At this point, alterations may not be made; however, at the end of the current production schedule, one may still add more formulas for later production.

The floor schedule segment displays "today's" production schedule; therefore, only those ingredients to be weighed on that scale, by that operator, are shown. When operations begin, the system highlights the raw materials to be used, quantifies needed, a short description (bin #, color), physical location within the plant, and in what order they are to be weighed. Also given are the materials' acceptable tolerances. If a material is not measured to within the formulated parameters, a warning appears, flashing on-screen, to notify the operator of the error. The system will not proceed until the error is corrected. A supervisor may choose to override the system; if so, his ID, and the fact that he bypassed, is automatically recorded.

Each ingredient is highlighted on-screen for the operator to weigh. Once completed, the ingredient is automatically logged, rolled off from the display, and the next ingredient is highlighted, and so forth. The system displays the materials' weighing sequence in the order in which it is to be weighed; hence, there is very little chance for the operator to get lost in the system. At shifts end, the floor supervisor may review the results of the day's scheduled weighings via View Weight. Any out-of-tolerance weight measurement that has been allowed through a bypass of the system, is clearly indicated on the report.

Conclusion

As we have seen, the Chemix Weighing Scale Option serves the industry as a logical and viable alternative to earlier methods. Many companies can improve productivity with its use. This program does not intimidate, but rather, assists the operator in ways that are both easy and rewarding. Production efficiency is thoroughly enhanced. Waste is minimized. Consequently, a previously unattainable level of quality control is achieved.

References

1. "Computer aided rubber compounded management using Chemix" by Dr. Sushil Bhatia and Jeremy Young, presented at the 142nd Meeting of the Rubber Division, ACS, Nashville, TN, Nov. '92.