15.Shop Floor Planning and Control

Shop Floor Planning and Control

• It is about production facility• Includes principles of planning, scheduling and

controlling of production operations• Integrates the factors of production

Management of shop floor planning

• Differs for made to stock and made to order• Flow control• Customer order broken and jobs routed

through route sheets

Production Activity Control

• MRP+PAC(when , where and how)• PAC is concerned with priority control and

capacity control• Objectives

Operations Planning and Scheduling

• What is scheduling?• Priority sequencing, detailed scheduling,

loading, expediting, input and output control• Activities in SPC Assigning priorities, dispatching lists, updating

WIP, Input/output control, measuring efficiency

Objectives of Scheduling

• Prevent unbalanced use of time• Utilise machines and labour effectively• Reduce idle time and fix up delivery dates• Helps to allocate scarce resources

Criteria to evaluate different possible schedules

• Providing when customer wants• Minimising production time, idle time of

workers and machines, costs and WIP

Elements of Scheduling

• Demand forecasts• Aggregate Scheduling• Production plan• MPS• Priority planning• Capacity planning• Facility loading• Evaluation of work load• sequencing

Information needed for Scheduling Process

• Jobs, activities, employees, Equipment, machines, facilities

• Problems of Scheduling Lack of information, resource constraint,

absenteeism, type of production

Scheduling Process

• Process focused-non standard products in small batches-work centres organised around the type of operations

• Scheduling in process focused production is complex :

orders processed against set dates lots are small assigning and reassigning of workers and

machines happen often

Scheduling Techniques• Forward Scheduling, Backward Scheduling• Stages in scheduling(loading and dispatching) finite and infinite loading Charts for finite and infinite loading Gantt load chart and Gantt scheduling chart

Priority Sequencing

• Criteria ( setup costs, WIP, Idle time, job flow time etc)

• Single criterion rules• First come first served, Shortest Processing

time, Longest operation time, Least or Minimum slack job first

• Earliest due date, truncated shortest processing job first, preferred customer order, random selection, cost overtime, least change over cost

Dynamic Sequencing Rules

• Dynamic Slack Rule• Dynamic Slack for remaining

operations(smallest d/r is selected)• Critical ratio rule = days remaining/days

required for processing(lowest cr)

• Implications of product focused scheduling• Techniques involved in solving product

focused scheduling are : batch scheduling and scheduling for delivery schedules

Batch production

• Between job shop and continuous production.• Determine LOT and when to begin• Lot : trade off between setup costs and

inventory carrying costs

EBQ OR ERL

CASE 1 Instantaneous supply with no simultaneous

consumption CASE 2 Non Instantaneous with simultaneous

consumption

• Complexities of EBQ Set up costs and inventory costs might not

tally with EBQ lots –split up because of interruption bottle neck Assumption that constant demand might not

be metEBQ based on current information

Line Balancing

• Arranging production Line • Procedure: determine the tasks, how they

should be performed, task time, cycle time, assign the task to each worker

• Assemble the tasks into work station• Assemble work stations, evaluate the

efficiency

Determination of Cycle Time

• Ct=available time per period/no of units required per period

• Balancing efficiency=theoretical no of workers /actual no of workers

• Line balancing methods heuristic method, linear programming ,

dynamic programming, computerised line balancing

Types of Heuristic methods

• Incremental Heuristic method• Longest task heuristic• Computerised Line Balancing