©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 1 Ch 3 Manufacturing Models and Metrics Sections: 1.Mathematical Models of Production Performance 2.Manufacturing Costs

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 2 Production Concepts and Mathematical Models  Production rate R p  Production capacity PC  Utilization U  Availability A  Manufacturing lead time MLT  Work-in-progress WIP

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 3 Operation Cycle Time Typical cycle time for a production operation: T c = T o + T h + T th where T c = cycle time, T o = processing time for the operation, T h = handling time (e.g., loading and unloading the production machine), and T th = tool handling time (e.g., time to change tools)

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 4 Production Rate Batch production: batch time T b = T su + QT c Average production time per work unit T p = T b /Q Production rate R p = 1/T p Job shop production: For Q = 1, T p = T su + T c For quantity high production: R p = R c = 60/T p since T su /Q  0 For flow line production T c = T r + Max T o and R c = 60/T c

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 5 Production Capacity Plant capacity for facility in which parts are made in one operation (n o = 1): PC w = n S w H s R p where PC w = weekly plant capacity, units/wk Plant capacity for facility in which parts require multiple operations (n o > 1): PC w = where n o = number of operations in the routing

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 6 Utilization and Availability Utilization: U = where Q = quantity actually produced, and PC = plant capacity Availability: A = where MTBF = mean time between failures, and MTTR = mean time to repair

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 7 Availability - MTBF and MTTR Defined

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 8 Manufacturing Lead Time MLT = n o (T su + QT c + T no ) where MLT = manufacturing lead time, n o = number of operations, T su = setup time, Q = batch quantity, T c = cycle time per part, and T no = non-operation time

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 9 Work-In-Process WIP = where WIP = work-in-process, pc; A = availability, U = utilization, PC = plant capacity, pc/wk; MLT = manufacturing lead time, hr; S w = shifts per week, H sh = hours per shift, hr/shift

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 10 Costs of Manufacturing Operations  Two major categories of manufacturing costs: 1.Fixed costs - remain constant for any output level 2.Variable costs - vary in proportion to production output level  Adding fixed and variable costs TC = FC + VC(Q) where TC = total costs, FC = fixed costs (e.g., building, equipment, taxes), VC = variable costs (e.g., labor, materials, utilities), Q = output level.

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 11 Fixed and Variable Costs

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 12 Manufacturing Costs  Alternative classification of manufacturing costs: 1.Direct labor - wages and benefits paid to workers 2.Materials - costs of raw materials 3.Overhead - all of the other expenses associated with running the manufacturing firm  Factory overhead  Corporate overhead

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 13 Typical Manufacturing Costs

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 14 Overhead Rates Factory overhead rate: FOHR = Corporate overhead rate: COHR = where DLC = direct labor costs

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 15 Cost of Equipment Usage Hourly cost of worker-machine system: C o = C L (1 + FOHR L ) + C m (1 + FOHR m ) where C o = hourly rate, $/hr; C L = labor rate, $/hr; FOHR L = labor factory overhead rate, C m = machine rate, $/hr; FOHR m = machine factory overhead rate