Manufacturing Systems

Learning Curves

Learning Curves • Learning curves: the time required to perform a task decreases with increasing repetitions

Time per repetition

Learning Effect

Number of repetitions

Time per unit

Learning with Improvements

Average

Time

Improvements may create a scallop effect in the curve.

Applications of Learning Curves 1.Manpower planning and scheduling 2.Negotiated purchasing 3.Pricing new products 4.Budgeting, purchasing, and inventory planning 5.Capacity Planning

Time/cycles

Worker Learning Curves

A (underqualified) B (average) Standard time C (overqualified) One week

Training time

Cautions and Criticisms • Learning rates may differ from organization to organization • Projections based on learning curves should be viewed as approximations • Estimates based the first unit should be checked for valid times

Cautions and Criticisms • At some point the curve might level off or even tip upward • Some improvements may be more apparent than real • For the most part, the concept does not apply to mass production

Manufacturing Systems

Components of Manufacturing System • • • •

Production Machines Material Handling System Computer Control System Human Resources

Facility Layout • Which comes FIRST, the material handling system or the facilities layout? Layout is effected by: – Centralized vs. Decentralize Storage of WIP, Tooling,

& Supplies – Fixed Path vs. Variable Path Handling – Unit Load Size – Degree of Automation – Type and Level of Inventory and Control of Materials

Facility Layout and Material Handling • Handling less is BEST – Number of times handled may be more important than distance Layout or MHS First ? -- BOTH • Sequential approach which considers a number of alternative handling systems and the corresponding layout alternatives.

Modular Design Concepts Facility Re-layouts can be caused by – Changes in the design of an existing product or in the product set to be produced. – Changes in the production sequences or in the processing equipment. – Changes in the production quantities and schedules, which prompt capacity changes. – Changes in organizational structure or management philosophy. • Changes in requirements for space, equipment, and people.

Modular Design Concepts Flexibility achieved by: – Modular office equipment – Modular workstations – Modular material handling equipment – General purpose production equipment – Expandability of the total system design

Modular Facilities • Use of an interconnecting spine for material transport and movement of people. • Standard size modules to allow functions to be interchanged if relationships change. • Expand by extending the spine and adding modules -- creates minimal disruption to the existing facility. • Alternative spine configurations: straight line, "T", or "X".

Modular Material Handling Plan flexible, standardized systems for handling, storing, and controlling material within the facility. – Build in flexibility. – Standardize methods: unit loads, equipment, etc. – Integrate into a system as opposed to separate pieces serving only part of the facility.

Classification of Manufacturing Systems • • • •

Types of Operations Performed Number of Workstations Automation Level Part of Product Variety

Classification Scheme • Type I – Single Stations • Type II – Multi-Station Cells • Type III – Production Lines