Routing and scheduling

Production management

1. Dr.R.Priya P roduction and M a terials Management

2. Routing Routing is the selection of paths or routes over which each piece is to travel in being transformed from raw material into finished product

3. Importance of Routing To determine the best and cheapest sequence of operations and to ensure that this sequence is followed. Determination of routes demands deliberation and concentration of mind. Routing constitutes a function which can been worked out and recorded. Once a good route has been worked out and recorded, it can be used for further similar jobs. The degrees of detail in routing varies with the factory and the product. The department in which each operation is to be performed and the machine tool to be used in each case. To be successful routing, requires that the route clerk should have a thorough knowledge of the product. Complete knowledge of the capacity and characteristics of every machine and process.

4. Routing Procedure The finished products are analysed from the manufacturing standpoint in order to decide how many components can be made in the plant and how many can be purchased from outside sources. ( Make or Buy decision) Parts-list and a bill of materials are prepared showing name of the part, quantity,material specifications, amount of materials required etc., Machines capacities, their characteristics and the operations which must be performed at each stage of manufacture are established and listed.

5. Preparation of route sheet A route sheet contains a complete description of the item to be manufactures, the details of each operation required in manufacturing process, the set up time and standard operation time etc., Route sheet also provides the best sequence for the desired operations taking into consideration the resources available. This can be done by the sequencing, assignment, critical path etc., Consideration The machines are to be operated at full capacity The product passes through those work centres which are manned by best possible personnel. The route is shortest and economical The in-charge should be well acquainted with operations

6. Factors Type of Manufacture – type of production Characteristics of individual machines –age, speed, capacity, tooling etc., Availability of alternative routing – breakdown and absent alternative Human factors – visual exactness, physical limitations, intelligence, emotional stability etc.,

7. Scheduling

8. Definition Scheduling is the determination of the time that should be required to perform each operation and and also the time necessary to perform the entire series as routed, making allowance for all factors concerned.

9. Scheduling Problems Fluctuating demand Have a static production programme Have a fluctuating production programme Have acombination of two systems Multi-product scheduling in Batch production The Assignment Problem Scheduling orders with Random Arrivals Product Sequencing

10. objectives Maximum utilisation of the plant at minimum cost Ensure the requirement of Manpower is optimum and evenly distributes Process up-to-date information regarding availablity of material, expected date of delivery, material rejection, shortage, purchase orders cancelled, etc., Update yourself with data on each machine Have complete information on performance standards Obtain quick feedback

11. Forms of schedule A production flow programme A production master programme for integrating work on large objects A cumulative output progress chart An outline master programme A schedule for breakdown of orders A cycle schedule A detailed schedule

12. Inputs of scheduling Performance standards Unit of measurement Effective capacity per work centre Extent of rush orders Overlapping of operations Individual job schedules

13. Drawing a job schedule The constant information is entered first in the schedule which is followed by batch quantity. The variable information such as operation number, operation description, machines and effective capacity is entered The time is calculated by using the relation Time for an operation = Std. time/price * Batch quantity / 60 The length of operation run will be calculated Operation run = Time for operation / Effective capacity / day Each operation run is shown

14. Load schedule or load chart The amalgamation of individual job scheduleor load chart indicates the work to be carried out in each section or department of the company during the specific period. Load chart enable us to know the accumulated load on each machine at a given time, and enable us to determine the allocation of the machine for future orders.

15. Factors influencing scheduling Degree of centralisation Relative job priority Items with fewest remaining operations are scheduled first Delivery commitment of critical items Penalty clause items Long pending jobs Certain customers Jobs which feed more work to work centres Critical items holding other plants Jobs currently being by competitiors Load charts accumulation

16. Procedure for scheduling Preparation of individual job schedule Assign start and finish dates to each operation on the job schedule Post of each schedule onto the load chart Setting delivery date for an item

17. Reducing problems Product simplification Jon enlargement programme Sub-contracting Reallocation of resources to suit work content Minimation of rush orders Creating controlled work-in-process blanks Reducing job split-ups Simplifying available resources Improving progress chasing

18. Despatching and follow up

19. Definition Despatching is the routine of setting productive activities in motion through the release of orders and instructions, in accordance with previously planned time and sequence, embodied in route sheets and schedule charts.

20. Functions Despatches assign work to definite machines or work places and men in order of priority and in proper sequence Issuing the required materials, tools, jigs, fixtures, dice and gauges for various jobs etc., Release of necessary order and production forms Guiding and controlling materials and operations in processing Contacting routing and scheduling sections

21. Forms by dispatcher Material requisition Job cards Labour cards or wage payment cards Move cards Inspection cards Tool and guage tickets

22. Despatching rules Simple Rules Earliest due date First come first served Combination rules Minimum slack Critical ratio

23. Follow up Follow up or expediting or progressing is that branch of production control procedure which regulates the progress of materials and parts through production process.

24. Qualities of a follow up person Tenacity Processed responsibility Product responsibility

25. Problems of follow up Obtaining information Mechanical counting Operator work record Use of job card Use of detachable tickets Problem of volume

26. Types of follow up Materials Work-in-progress Assembly and erection