Production scheduling

Production scheduling is important in multiproduct operations. With proper planning and the ability to hold some product in inventory, campaigns can be extended to reduce the frequency of turnarounds. If the demand for a particular product is small, frequent small batches may best suit the schedule. However, too small a batch in an oversized piece of equipment can result in levels too low for proper agitation or in incomplete coverage of heat transfer surfaces. These conditions may aggravate fouling problems or cause instability in the process. 

Similar batch products are often distinguished by minor differences in  

Such differences may often be accommodated without scrupulous cleaning of equipment between batches. If two products are made which differ only in, for example, the amount of antioxidant ttiat is added, only minimi cleaning may be needed before switching production. Certain overhead equipment may not be affected at all. 

Consider the following example in which a plant is to make five different products. These involve three different compounds. Ci and C2 are quite similar, while D is different in character. Each is produced in one of the two solvents, A and B. The formulations (in arbitrary units) are given in the following example  

There is hardly any difference between Products III and TV, and so one would expect to be able to produce them in succession with a minimum of cleaning. Products I and II also are quite similar, differing only in concentration. These, too, should be produced in immediate succession. If Product II has a substantially higher viscosity, it may be well to schedule it first, since the more 

---

Juice factories frequently employ field persons to advise growers on the appHcation of sprays to the growing crops so that residues on harvested fmit are within prescribed limits. They also may sample the crop before harvest for analysis, and coordinate harvesting with factory production schedules. Payment for raw materials is frequently based on specifications that are either official government grades or stated market standards. Official graders may be employed to test each load. 

The usual procedure in the manufacture of chrome-tanned leathers is the use of a continuous bate, pickle, and tan method. The hides or skins remain in the dmm from the lime washing through the chrome tanning stages. The entire process usually takes about 22—24 hours. The bate, pickle, and tan can be done faster, but most tanners find that a one-day cycle fits well into production scheduling and results in a quaUty leather. 

The shuttle kiln consists of a firing chamber with two or more kiln cars on which the bricks to be fired are set. While one load of brick is being fired, a second is being set. Somewhat similar is the beU top or top-hat kiln which is raised and lowered above and over the kiln cars to be fired. These kilns are more expensive to operate than tunnel kilns but provide flexibiUty in burning conditions and production schedules. 

Other constrains (availability and delivery schedule of tools, production schedules)... 

Summarize the fmdings and recommendations in a brief pre-assessment report, and present and review this with management. This will reaffirm management s commitment to the next phase. Include in the pre-assessment report a list of actions or steps that the team intends to follow in the next phase. If some of these steps involve field measurements, then highlight these and their possible effects on production schedules and personnel assignments. Use the steps in Phase II as a guide to developing the recommended actions. 

Inventory policy - how the organization will maintain economic order quantities to meet its production schedules... 

In order that your subcontractors can achieve 100% on-time delivery, you need to provide the same type of information and make the same commitments as your customer will to enable you to meet 100% on-time delivery to them (see Part 2 Chapter 15). You therefore need to inform your subcontractors of your production schedule and release orders to your subcontractors based on that schedule. If operating under a ship-to-stock system, you will need a means of notifying your subcontractor when stocks drop to the minimum level. Under such arrangements, you do not need a purchase order for every delivery as one order specifying the shipment rate will suffice. A good maxim to work by is ... 

The nonconformity data should be collected and quantified using one of the seven quality tools (see Part 2 Chapter 14), preferably the Pareto analysis. You can then devise a plan to reduce the 20% of causes that account for 80% of the nonconformities. However, take care not to degrade other processes by your actions (see Theorg ofcon-staints in Part 2 Chapter 2). The plan should detail the action to be taken to eliminate the cause and the date by which a specified reduction is to be achieved. You should also monitor the reduction. The appropriate data collection measures therefore need to be in place to gather the data at a rate commensurate with the production schedule. Monthly analysis may be too infrequent analysis by shift may be more appropriate. 

How do you ensure your production schedules are order driven ... 

Space time yield refers to the quantity of product that can be produced in a reactor in a given time. It is a function of both selectivity and activity. Maximum efficiency is reached when this number is high, but if production schedules are not full, lower numbers may be tolerated. Acceptable catalyst life can be extended if space-time yield demands are not heavy. Catalyst cost thus becomes a function of the demands put upon it. 

Inspection. While work on the contract of the purchaser is being performed, the purchaser s inspector shall have reasonable access to the appropriate parts of the manufacturer s works concerning the manufacture of the equipment ordered hereunder. Inspection shall be made at the works prior to shipment, unless otherwise specified, and shall be conducted so as not to interfere unnecessarily with the works operation or production schedules. 

Edward H Bowman, Production Scheduling by the Transportation Method of Lmear Programming, Operations Research, 4, 100-3 (1956). 

Problem of approximation, 52 Product ensemble, 198 Production scheduling problem, 297 Profit maximization, 286 Programming, dynamic, 305 Programming, linear (see Linear programming)... 

Representation. The solution space is composed of discrete combinatorial alternatives of batch production schedules. For example, in the permutation flowshop problem, where the batches are assumed to be executed in the same order on each unit, there are A number of solutions, where N is the number of batches. We must find a way to compactly represent this solution space, in such a way that significant portions of the space can be characterized with respect to our objective as either poor or good without explicitly enumerating them. 

S.P. Sanoff, D. Poilevey, Integrated information processing for production scheduling and control. Comput. Integr. Manuf., 4 (1991) 164—175. 

---