Manufacturing Master Schedule
PART II.
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On the surface, Company A appears to be a nicely bundled continuous-flow operation. All component parts except hardware are molded in-house on the press line. Some parts go to the assembly area to be built into truck hoods or truck tops. The truck hoods are painted with primer and share a paint line with the tops that are painted in multiple colors to a finished state. Other molded components go directly from the press line to a second paint line that paints primer only. In all cases after painting, the products are packaged for shipment. It would appear that one bill of material per end item, with a routing from start to finish would be appropriate. In utilizing this single-thread concept, the end items would be master-scheduled, leaving all lower levels to be planned in an MRP fashion. A typical BOM would look like this:
As "clean" as this sounds, the approach leaves something to be desired. In order to understand the weaknesses we need to examine the resources:
Because of these constraints, top-level master scheduling will not provide control over the critical resources, the presses. Also, scheduling by end item does not provide the controls needed at the primer line. Clearly, the objective is to maximize control over the resources that control the output of the plant. To do so, MPS and BOM changes are required. Scheduling Company A The Press Line is the first candidate for master schedule control, but only for those presses that are regulating throughput (bottlenecks). The presses that do not control the throughput of the follow-on resources are left to MRP. The bottleneck presses require a good deal of attention. After all, by definition, they are regulating the flow of product through the entire process. With these thoughts in mind we must develop a schedule for the bottleneck presses that maximizes their output. This maximization is accomplished through the application of any number of techniques such as batch splitting, minimizing down time by scheduling preventive maintenance, reducing setup times, maximizing the quality of incoming material to the presses and improving molding processes to el iminate scrap at the presses. After applying the techniques and maximizing the presses' output, we have produced a schedule that can be used to drive the other resources. We now use the press schedule to backward-schedule the Compound Room (upstream activity), and to forward-schedule the downstream activities (Figure 1). By master-scheduling the bottleneck presses, we are assured of maximizing the total system's output. It would not be logical to assume that all of our planning considerations could be accommodated by back-scheduling the presses from an end-item explosion, in a typical MRP fashion. Once the MPS is completed, the BOM must be created, or adjusted, to provide the ability to execute the schedule. In this case, since the MPS is in midstream of the product flow, multiple bills must be created. Conceptually, the outcome we have created is the scheduling of the actual resources, the presses. But, in application we must produce a schedule for those parts that run over those resources. Each of the MPS items must have a BOM to develop requirements for the Compound Room. One of those bills might look like this:
The demand on the Compound Room is the projected output plan for the bottleneck presses. We can input that demand schedule to MRP and let it do the balance of the planning for the Compound Room. There is another resource we should consider for master scheduling; the Paint Primer Line. The reason for master scheduling this resource is that it must be scheduled in accordance with whatever is produced from the presses. The actual and planned output from the presses becomes the demand that is loaded into the primer line MPS. Now the primer line can be scheduled in accordance with its peculiar requirements. And, in a fashion identical to the press line, bills of material must be developed for the primer line's MPS items. By scheduling Company A as has been described, several advantages are achieved:
2. Inventories can be controlled better because both push and pull techniques are employed. To be Continued STAY CONNECTED To stay current on bullet-proofed manufacturing solutions, subscribe to our free ezine, "The Business Basics and Best Practices Bulletin." Simply fill in the below form and click on the subscribe button. We'll also send you our free Special Report, "Five Change Initiatives for Personal and Company Success." Your
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