Northwind Foods: Calendars, Oven Capacity, and Subcontracted Baking
Northwind Foods produces sauces at two plants. Plant A's pasteurizer is the bottleneck at 1,200 liters per hour. Plant B runs a gluten-free line with two ovens; each oven holds 400 kg per batch and needs 45 minutes of heating plus 30 minutes of cooling before unloading. Production works two shifts, 06:00–14:00 and 14:00–22:00, Monday through Saturday. Preventive maintenance is booked every Friday from 22:00 to 02:00 and all day on the first Sunday of each month. Finite capacity scheduling currently shows on-time plans, but released production orders finish one to two days late, and gluten-free cost estimates omit oven energy and cleaning between allergen batches. Every resource was created with a single 24-hour calendar and capacity of 1. During peak weeks Northwind plans to subcontract gluten-free baking to a partner. The production planner needs a setup that schedules realistically and costs batches correctly.
1. Which calendars and resource settings must be changed so that finite capacity scheduling reflects the two shifts, maintenance, and the ovens' batch nature?
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Replace the 24-hour calendar with working time templates that reflect the two shifts and the maintenance windows. Create a template for Monday–Saturday 06:00–14:00 and 14:00–22:00, a Friday template with 22:00–02:00 blocked, and a first-Sunday template with the whole day closed. Build calendars from those templates and assign the calendar to the production unit, then let resources inherit it or assign explicitly. Set the pasteurizer capacity to 1,200 L/h and the ovens to a batch capacity of 400 kg per 75-minute cycle, rather than capacity 1. Flag the pasteurizer and ovens as bottlenecks so finite capacity scheduling respects them. The late orders occur because a 24-hour calendar tells scheduling that resources are available around the clock; the maintenance and shift constraints never enter the capacity calculation. After the change, run finite capacity scheduling and compare the planned finish dates with the actual one-to-two-day lateness.
2. How should the route be designed so that pasteurizer and oven capacities drive scheduling, and how should peak subcontracting be modeled?
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Model the pasteurizer operation with process quantity 1,200 L and a run time of 1 hour, so capacity is consumed proportionally to batch size. Model each oven as a separate resource in a resource group, with a route operation of process quantity 400 kg and a run time of 75 minutes; set queue time for loading and unloading rather than hiding it in run time. For peak subcontracting, add a route operation assigned to a resource of type Vendor, with the vendor's calendar and purchase lead time, and let the production order generate the subcontracting purchase order for the service. If the vendor supplies a sterile bag or other material, add a BOM line of type Vendor so it is not issued from Northwind stock. Scheduling then sees the vendor operation as finite external capacity, and the cost estimate includes the service. Do not simply extend internal capacity; that hides the vendor constraint and produces infeasible plans.
3. What cost category and costing sheet setup ensures oven energy and cleaning are included in the gluten-free batch estimate?
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Create cost categories for oven energy with a rate per hour and a cost group such as Energy, and for cleaning with a rate per batch and a cost group such as Cleaning. Assign the energy category to the oven route operation and the cleaning category to a separate cleaning operation that occurs between allergen batches. Build a costing sheet whose nodes use those cost groups and add an indirect cost rate if overhead must be recovered. Activate the costing sheet and the cost category prices with effective dates, then recalculate the gluten-free batch order. The current estimate omits these costs because the route operations either have no cost category or the category has no active price. Verify by comparing the calculated cost with a known batch; if energy is still missing, check that the route version is active and that the cost category is assigned to the correct operation, not only to the resource.