Original publication date: June 1992
Heurikon Historical Highlights
A series of articles for The Horizon
by Jeffrey Mattox
EEKK and Del-Monte Corporations
In the 1970s, washing machines were not very high-tech; they certainly didn’t have computers in them. However, if the washing system was destined for a bean-packing plant, computers were in order.
We were asked to build such a system by the EEKK Corporation of Schaumburg, Illinois. EEKK provided control systems and related equipment to the food processing industry, and they wanted us to build a controller for use in two Del-Monte bean-packing plants. One of the plants was in Florida, and the other was near Stevens Point, Wisconsin (just south of the city on highway 51).
There are many different types of equipment in an automated bean-packing plant. There are bean sorters, washers, cutters, conveyor belts, and so on, and each piece of machinery has to be cleaned and washed once each day. However, during the short, three-month packing season each year, the plant runs 24-hour per day, and the the time it takes to clean the equipment cuts into their production time.
The general washing sequence was to rinse each food-processing machine, then apply a chemical, wait for a specified amount of time for it to work, then rinse the chemical off. That sounds fairly simple, but there were two factors that made things more difficult. First, the piping system only had a limited capacity, so only one set of valves could be open at a time. Second, once the washing chemical had been applied, it had to be rinsed off within a certain time window — not too soon or too late — otherwise the chemical would not work properly.
The Del-Monte plants had been shutting down operations for four to six hours each night while six workers went through each plant with water and chemical hoses and sprayed the equipment. Cleaning was a time consuming and labor intensive operation.
Our Infamous MLP-8080 to the Rescue
We designed a controller around our MLP-8080 board that could sequence up to 64 sets of water and chemical values. It had eight timing programs that could specify rinse, wash, wait, and final rinse times for various types of processing equipment. When the operator pushed the start button, the computer would examine the database and devise a sequence for operating the valves to wash all the equipment in the least amount of time.
At some points during the sequencing, the wash and rinse cycles for different sequences would overlap. That is, the system could be rinsing a bean cutting machine, while simultaneously applying the chemical to a conveyor belt and doing a final rinse on a third machine. Once it started a chemical application, however, the computer had already determined that it would be able to rinse off the chemical during the allowed time window.
As usual in those days, we wrote the program in machine language, and it was very complicated. Rolls of paper tape were strewn about the shop, and the Teletype machine gave out a constant background chatter.
Switches on the font panel of the washing control system allowed the operator to select which pieces of the plant’s bean-packing machinery should be included in the washing cycle. The exact timings for the various washing cycles were entered via the keypad and thumb-wheel switches at the bottom. While the system was running, the large 7-segment displays at the top of the panel showed the time remaining in each phase of the overlapping washing cycles. The bean-plant washing system was housed in a huge enclosure, which was about the size of a Foto-Mat booth. EEKK painted it bright yellow, so it really looked peculiar.
I can easily recall one specific problem we had while building the system. For some reason, we couldn’t buy stranded 50-conductor ribbon cable; it only came with solid wire. I don’t think they made much stranded ribbon cable back then — and 50-conductor ribbon cable was not as widely used as it is today. The solid wire we were able to get was very hard to flex, and the crimps at the connectors were unreliable. Every time we attached or removed a ribbon cable, we ran the risk of causing a loose connection.
The computer-controlled system had many advantages over the old manual system that Del-Monte had been using. After we put the new system on-line, it took only one person to start the operation and one worker to go through the plant with a hose and clean around the hard-to-get-at places. And, because of the computer’s smarts, the whole plant could be cleaned in only two hours.
The plant manager at Stevens Point reports that our computer equipment was in operation there for nearly ten years. They have since switched to an Allen-Bradley sequencer. The Florida plant stopped processing beans in 1980.
NEXT MONTH: Our 100-pound “portable” computer.
UPDATE June 2009: I called the Stevens Point plant to see if our equipement was still there. The plant manager told me they had been using our system up until a few years ago, and it was still operational. What a nice surprise.