Manufacturing Planning and Control MPC 6th Edition Chapter 4a McGraw-Hill/Irwin Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved. Advanced Sales and Operations Planning Within the Sales and Operations Planning (SOP) process, modeling procedures can be used to establish overall production and inventory plans. The basic issue is what levels of resources should be provided in each period. Powerful and easily accessible tools are available for solving these models. 4a-2 Agenda What is advanced SOP? Mathematical programming Linear programming Mixed integer programming Lawn King example Principles 4a-3 Linear Programming Hiring Costs m Minim ize C t 1 H Firing Costs Labor Costs Overtime Costs H t CF Ft CR X t COOt CI I t CUU t Inventory Costs subject to I t 1 X t Ot I t Dt I t Bt Inventory Constraints X t A1tWt U t 0 Regular Production Constraint Ot A2tWt St 0 Overtime Production Constraint Wt Wt 1 H t Ft 0 Idle Time Costs Workforce Change Constraint W0 A3 I 0 A4 Wm A5 Initializing Constraints 4a-4 LP Assumptions Item Value Regular-time cost per employee per month $1,828 Overtime cost/unit $33.04 Inventory carrying cost per unit per month $1.77 Hiring cost/employee $800 Firing cost/employee $1,500 Regular-time productivity (units per month per 83 employee) Maximum overtime units/month 17 Ending inventory ≥ 2,000 units August inventory 16,460 units August employees 72 4a-5 LP Model and Solution Changing cells (decision variables) 4a-6 LP Settings and Options Minimize total costs Constraints •Ending workforce = actual (72) •Reg. production <= capacity •OT production <= capacity •Monthly inventory >= 2,000 •Ending inventory (August) = actual (16,460) •Hires/Fires must be integers 4a-7 Principles To ensure credibility, the match between the real world and the model should be as close as possible. Relatively homogeneous product lines (or portions of lines) allows for a closer match between model and reality. Before the potential of advance techniques can be realized, the firm must invest in training, enhance data, improve basic MPC practices, and determine clear objectives. 4a-8 Principles Management must realize that significant efforts in model formulation, understanding, testing, and explanation are important to successful applications. Advance techniques must be built on a foundation of good basic practices. Spreadsheet-based models offer executives a better choice. 4a-9 Quiz – Chapter 4a The objective of a Linear Programming planning approach is to ___________. Microsoft Excel has both Linear Programming and Mixed Integer Programming capabilities. (True/False) A key step in the modeling process is to identify assumptions. (True/False) Determination of inventory holding costs is generally a simple process with few assumptions. (True/False) The Advanced Sales and Operations process can be implemented as soon as a firm starts using Sales and Operations Planning. (True/False) 4a-10