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In the Manufacturing world, building the correct amount of the needed product at the appropriate time separates a very successful company from the rest of the pack. Many companies have assembly lines or machines that can churn out product at a high rate of speed—only to find that requirements have changed, and the changes were not communicated. At a time when customer service is of paramount importance, a competitive company must be highly responsive to customer needs (i.e., flexible). A good shop floor control system can be the competitive edge that a manufacturing company needs to be competitive.

This paper will define shop floor control and give some case study examples of shop floor control in a traditional manu­facturing environment as well as the necessity of shop floor control in a dynamic JIT environment. We will also look at shop floor control from the perspective of both management and the production floor.

Shop floor control is defined as a system for utilizing data from the shop floor to maintain and communicate status information on orders and at work centers. In practice, a working definition is an individual on the shop floor, a supervisor, lead person or team leader, using the system data base and communicating the status of work to the scheduling individual, a master schedule planner or man­ager. The status of work is compared to the capacity of the work center, which then becomes a question of balance and priority. While this is certainly a simplified definition of shop floor control, the basics remain clear: if a manufactur­ing plant has 100 hours of capacity and 500 hours of work, the chances are pretty good that the work is not going to be completed. A good shop floor control system will commu­nicate this information before it is too late.

Getting Started—Issuing Work to the Floor

The first step in controlling the shop floor is actually getting work to the floor. Whether your company is issuing jobs via a work order packet or has a CRT on the floor flashing the next priority, the two ingredients of successful shop floor control are these—material and capacity. With­out sufficient material or capacity, there is no MRPII or ERP system on the planet that will be of much help meeting current due dates. There are some very basic rules that have been around since Henry Ford began rolling model T's off his assembly line that certainly warrant repeating.

Work should not be issued to the floor if all of the material is not available. This may be manufacturing's most vio­lated rule. There is the rationale in manufacturing that it is better (i.e., more efficient) to put work on the floor with material shortages, batch in tote pans at a subassembly level, and then put all available labor on the job when the shorted material arrives. While this technique may have gotten a few facilities out of a jam, it is definitely not the recommended method of operation. There are risks asso­ciated with this practice that will sooner or later negatively

impact the process. The risks could be a quality issue where a defect is being built into the batched subassemblies that would be caught at final test—only when final test is started, there are several days of subassemblies that may need to be reworked. A customer requested revision change would have the same adverse affect. The customer could also change priorities, leaving manufacturing with the dilemma of either holding tote pans full of subassem­blies that are not at a reportable level or having to finish the build, using valuable resources. The resources could be capacity or material that could better be utilized to provide the customer with the product being requested.
The second most violated rule may be issuing work to the shop floor without adequate capacity. While MRPII sys­tems assume that capacity is infinite, this is not actually the case. There are methods of increasing capacity (over­time, increasing the work force, consignment) that require some flexibility, but are still finite. This means that work must be released to the shop floor in quantities consistent with the capacity of the shop floor. It is important that the due date be realistic. Nothing is as frustrating or demor­alizing to a supervisor or team leader than receiving work with a due date that is unattainable or even past due. There is not a good reason to release past due orders. Orders released that are over capacity or with unrealistic due dates make the schedulers and productions job even more challenging (i.e., difficult). For example, in Figure 1, work center 200500 has a daily capacity of 200 units. Today's date is February 1st. This is the schedule for work center 200500. From looking at this schedule, which job is needed the most? All things being equal, the listed order is probably the correct order, but this example certainly begs for questioning. Do we really need jobs 001 and 002? Has the customer been calling and asking for these jobs? Are these actual due dates or perceived due dates? Is there a fudge factor attached to the due dates because past history indicated due dates had no real meaning at the XYZ Company? There are questions that should be addressed and it's important that scheduling and the shop floor communicate with each other.

To be Continued