Production management

Power point presentation on Unit 5

Production management

Presented by

Amey .V. Shejwal

Vaibhav .P. Urade

Rahul .Y. Borse

Nikhil .H. Patil

Pratik . A. Wankar

PLANNING ORGANIZATION

S h o p F lo o r C o n tro l

M a te ria ls R e so u rce p la n n ing

M a s te r P ro d uc tio n S ch e d u le

S a le s a nd O p e ra tio n s P lan

In p u t/O utp u t

C a p a c ity R e q u ire m e n ts P lan

R o u g h C ut C a p a c ity P la n n ing

R e so u rce P la n n ing

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A PRINCIPLE OF PLANNING:

A plan must cover a period at least equal to the time required to accomplish it.That is, the MS planning horizon must be at least as long as the lead time required to fabricate the MS items. This includes production and procurement time as well as engineering time in a custom design environment.

MASTER PLANNING

• Planning:-

– The principle of production planning and control

lies in the statement ‘First Plan Your Work and

then Work on Your Plan’.

– Main functions of production planning and

control includes planning, routing, scheduling,

dispatching and follow-up.

• Planning is deciding in advance what to do, how to do it, when to do it and

who is to do it. Planning bridges the gap from where we are, to where we

want to go. It makes it possible for things to occur which would not

otherwise happen.

• Routing may be defined as the selection of path which each part of the

product will follow, which being transformed from raw material to finished

products. Routing determines the most advantageous path to be followed

from department to department and machine to machine till raw material

gets its final shape.

• Scheduling determines the programmer for the operations. Scheduling may

be defined as ‘the fixation of time and date for each operation’ as well as it

determines the sequence of operations to be followed.

• Dispatching is concerned with the starting the processes. It

gives necessary authority so as to start a particular work,

which has already been planned under ‘Routing’ and

‘Scheduling’. Therefore, dispatching is ‘release of orders and

instruction for the starting of production for any item in

acceptance with the route sheet and schedule charts’.

• The function of FOLLOW-UP is to report daily the progress

of work in each shop in a prescribed preform and to

investigate the causes of deviations from the planned

performance.

• Planning Includes:-

– Clarifying the role and focuses of operation in the

organization

• It Involves :-

– Product planning

– Facilities designing

– Conversion Process

PRODUCTION PLANNING AND CONTROL HAS THREE PHASES NAMELY

• Production planning (PP) is responsible for

making the aggregate plan of using production

resources (workforce, equipment) and material

to meet customer orders.

• Typically, the plan covers a wide time horizon of

several months. Besides giving the date of

completing each customer order, production

planning determines the capacity and material

requirements of production over time.

Production planning state's:-• When materials should arrive,• Which activities should be outsourced to

subcontractors, • When to increase or decrease the workforce

level

LEAD TIME ESTIMATIONS

• According to the traditional approach, production planning in make to order production systems is still based on lead time estimations and on MRP logic

• In this approach, customer orders are segmented with milestones, and the time needed to reach the next milestone is estimated by production lead times. Estimates are based on past experience rather than on the actual production load

ACTUAL PRODUCTION CAPACITIES

• The MRP system determines the timing of these milestones backward from the due dates of the customer orders.

• At this stage of the planning process the actual production capacities are considered only implicitly, i.e., through the lead times, which again are based on historic data.

• In the subsequent stage, when the timing of production activities has already been set, production capacities are allocated to the specific customer orders.

• If in a certain period of time, the in-house capacity is not sufficient to meet demands, decisions are made as whether to extend the capacity of the scarce resource or to involve subcontractors.

OPERATIONS PLANNING AND SCHEDULING SYSTEMS

• Operations planning and scheduling systems concern

with the volume and timing of outputs, the utilization

of operations capacity at desired levels for

competitive effectiveness. These systems must fit

together activities at various levels, form top to

bottom, in support of one another, as shown in Fig

COMPONENTS OF OPERATIONS PLANNING AND SCHEDULING SYSTEM

• THE BUSINESS PLAN

– The business plan is an agreement between all functional areas—

finance, production, marketing, engineering, R & D—about the level

of activity and the products they are committed to support. The

business plan is not concerned with all the details and specific timing

of the actions for executing the plan. Instead, it determines a feasible

general posture for competing to achieve its major goals

• AGGREGATE PRODUCTION (OUTPUT) PLANNING

– The process of determining output levels of product groups over the

coming six to eighteen months on a weekly or monthly basis. It

identifies the overall level of outputs in support of the business plan

• AGGREGATE CAPACITY PLANNING– It is the process of testing the feasibility of aggregate output

plans and evaluating overall capacity utilization. A statement of desired output is useful only if it is feasible. Thus, it addresses the supply side of the firm’s ability to meet the demand. As a result, the aggregate planning process balances output levels, capacity constraints, and temporary capacity adjustments to meet demand and utilize capacity at desired levels during the coming months

• MASTER PRODUCTION SCHEDULING– MPS is a schedule showing week by week how many of each

product must be produced according to customer orders and demand forecasts. Its purpose is to meet the demand for individual products in the product group.

• SHOP FLOOR CONTROL– Shop floor control involves the activities that execute and

control shop operations namely loading, sequencing, detailed scheduling and expediting jobs in production. It coordinates the weekly and daily activities that get jobs done.

• LOADING

– Each job (customer order) may have its unique product specification and, hence, it is unique through various work centers in the facility. As new job orders are released, they are assigned or allocated among the work centers, thus establishing how much of a load each work center must carry during the coming planning period. This assignment is known as loading (sometimes called shop loading as machine loading).

• SEQUENCING– This stage establishes the priorities for jobs in the queues (waiting lines) at the work

centers. Priority sequencing specifies the order in which the waiting jobs are processed; it

requires the adoption of a priority sequencing rule.

• EXPEDITING– Expediting is a process of tracking a job’s progress and taking special actions to move it

through the facility. In tracking a job’s progress, special action may be needed to keep the

job moving through the facility on time

THE MODEL OF THE PLANNER AND SCHEDULER

PRODUCTION PLANNER

• The challenge of production planning is the timing of the activities in medium term, over a typically 3-6 months long time horizon with a time unit of one week.

• The generated plans must comply with the project deadlines,– obtain effective utilization of the resources

with finite capacity,– keep stock levels low, and on the whole,

minimize the cost of the production.

PLANNER WORKS WITH THE FOLLOWING INPUT DATA

• Specification of customer orders as given in the

master production schedule;

• Bill of Materials (BOMs) of products;

• Routings (sequence, processing time and

resource requirements) of operations; and

• Detailed calendar of available resource

(machine, workforce) capacities.

SCHEDULING

• It is responsible for making detailed, executable schedules that

achieve the goals set by production plans. Hence, scheduling

has to assign finite capacity resources to production operations

as well as to determine their order of execution.

• So as to guarantee that all shop orders can be executed in time

and that load on resources never exceeds available capacity,

scheduling has to unify the resource and temporal aspects of

production at the most detailed level of aggregation

SCHEDULING PRODUCTION

• Before production begins the manager must

know what product is being produced and how

many.

• This information is gained through production

planning and control personnel

• Before production begins the manager must

know what product is being produced and how

many.

• This information is gained through production

planning and control personnel

SCHEDULING PRODUCTION – 4 MAIN TASKS

• Routing: deciding where the work is to be done

• Scheduling: deciding when the work is to be started

and completed

• Dispatching: issuing work orders to start actual

production

• Expediting: seeing that the work is progressing on

schedule

• Routing: deciding where the work is to be done

• Scheduling: deciding when the work is to be started

and completed

• Dispatching: issuing work orders to start actual

production

• Expediting: seeing that the work is progressing on

schedule

PRINCIPLES OF SCHEDULING

1. The principle of optimum task size: Scheduling tends to achieve maximum efficiency when the task sizes are small, and all tasks of same order of magnitude.

2. Principle of optimum production plan: The planning should be such that it imposes and equal load on all plants.

3. Principle of optimum sequence: Scheduling tends to achieve the maximum efficiency when the work is planned so that work hours are normally used in the same sequence.

SCHEDULING PRODUCTION

• The line production routing sheet is used to help schedule.

• The goal is to use 100% of the manufacturing plant.• Schedules are based on:

– Sales forecasts by day, week, and month for each product – Inventory levels for both raw materials and finished

products– Manufacturing capacity to be schedules in terms of the

number of products that can be produced per hour or day

• Schedules determine the parts or products that should be manufactured each day the plant operates

• The line production routing sheet is used to help schedule.

• The goal is to use 100% of the manufacturing plant.• Schedules are based on:

– Sales forecasts by day, week, and month for each product – Inventory levels for both raw materials and finished

products– Manufacturing capacity to be schedules in terms of the

number of products that can be produced per hour or day

• Schedules determine the parts or products that should be manufactured each day the plant operates

SCHEDULING PRODUCTION

• Production schedules most also consider lead

time, including the time it takes to:

– Order and receive materials and parts that must be

purchased

– Make parts from materials

– Assemble parts into products

– Package products for delivery

• Production schedules most also consider lead

time, including the time it takes to:

– Order and receive materials and parts that must be

purchased

– Make parts from materials

– Assemble parts into products

– Package products for delivery

THE SCHEDULER

• The ultimate goal of scheduling is to unfold the medium term

production plan into an executable detailed schedule.

• The scheduler has to determine the order of the operations and

the resource allocations with respect to the technological,

temporal and capacity constraints. Our short-term scheduler

performs finite capacity scheduling with respect to detailed

technological and capacity constraints.

• The scheduling horizon is as long as the time unit of the

planner (i.e., one week), while the scheduling time unit is 0.1

hour.

• The set of operations to be scheduled are determined

by disaggregating the activities that fall into a given

time unit in the medium-term production plan.

• If an activity covers several weeks, then its operations

are distributed in this period proportional to the

activity’s intensities.

• Typically, schedules are generated for the next few

weeks only.

• The master schedule (MS) is a presentation

of the demand, including

– The forecast and

– The backlog (customer orders received),

– The master production schedule (the supply plan),

– The projected on hand (POH) inventory,

– The available-to-promise (ATP) quantity

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Figure 1

Is the “key” link

Is the “key” in developing the

master schedule

Creates demand requirements

Creates demand requirements

Calculates net requirements

The master schedule (MS) is a key link in the manufacturing planning and control chain.

The MS interfaces with marketing, distribution planning, production planning, and capacity planning. The MS drives the material requirements planning (MRP) system.

Master scheduling calculates the quantity required to meet demand requirements from all sources (seethe example case on next page).

Input-Output Control & Operation Scheduling

RELATİONSHİP OF MASTER SCHEDULİNG TO OTHER MPC ACTİVİTİES

INPUTS TO SCHEDULING

1. Performance standards: The information regarding the performance standards (standard times for operations) helps to know the capacity in order to assign required machine hours to the facility.

2. Units in which loading and scheduling is to be expressed.

3. Effective capacity of the work center.

4. Demand pattern and extent of flexibility to be provided for rush orders.

5. Overlapping of operations.

6. Individual job schedules

SCHEDULING STRATEGIES

These strategies are grouped into four classes:

1. Detailed scheduling: Detailed scheduling for specific jobs that are arrived from customers is impracticable in actual manufacturing situation. Changes in orders, equipment breakdown, and unforeseen events deviate the plans.

2. Cumulative scheduling: Cumulative scheduling of total work load is useful especially for long range planning of capacity needs. This may load the current period excessively and under load future periods. It has some means to control the jobs.

3. Cumulative detailed: Cumulative detailed combination is both feasible and practical approach. If master schedule has fixed and flexible portions.

4. Priority decision rules: Priority decision rules are scheduling guides that are used independently and in conjunction with one of the above strategies, i.e., first come first serve. These are useful in reducing Work-In-Process (WIP) inventory.

TYPES OF SCHEDULING

• Types of scheduling can be categorized as forward scheduling and backward scheduling

• Forward scheduling is commonly used in job shops where customers place their orders on “needed as soon as possible” basis. Forward scheduling determines start and finish times of next priority job by assigning it the earliest available time slot and from that time, determines when the job will be finished in that work center

• Backward scheduling is often used in assembly type industries and commit in advance to specific delivery dates. Backward scheduling determines the start and finish times for waiting jobs by assigning them to the latest available time slot that will enable each job to be completed just when it is due, but done before.

• By assigning jobs as late as possible, backward scheduling minimizes inventories since a job is not completed until it must go directly to the next work centre on its routing. Forward and backward scheduling methods are shown in Fig

SCHEDULING METHODOLOGY

• The scheduling methodology depends upon the type

of industry, organization, product, and level of

sophistication required. They are:

1. Charts and boards,

2. Priority decision rules,

3. Mathematical programming methods

GANTT CHARTS AND BOARDS• Gantt charts and associated scheduling boards have been

extensively used scheduling devices in the past, although many of the charts are now drawn by computer. Gantt charts are extremely easy to understand and can quickly reveal the current or planned situation to all concerned. They are used in several forms, namely,

a) Scheduling or progress charts, which depicts the sequential schedule;

b) Load charts, which show the work assigned to a group of workers or machines; and

c) Record a chart, which are used to record the actual operating times and delays of workers and machines.

PRIORITY DECISION RULES

Priority decision rules are simplified guidelines for determining the sequence in which jobs will be done. In some firms these rules take the place of priority planning systems such as MRP systems. Following are some of the priority rules followed

MATHEMATICAL PROGRAMMING METHODS

• Scheduling is a complex resource allocation problem. Firms process capacity, labour skills, materials and they seek to allocate their use so as to maximize a profit or service objective, or perhaps meet a demand while minimizing costs. The following are some of the models used in scheduling and production control.

(a) Linear programming model: Here all the constraints and objective functions are formulated as a linear equation and then problem is solved for optimality. Simplex method, transportation methods and assignment method are major methods used here.

(b) PERT/CPM network model: PERT/CPM network is the network showing the sequence of operations for a project and the precedence relation between the activities to be completed.

RCCP

WHAT IS RCCP?

• The most common problem which is encountered in operating MRP based systems is the existence of an overstated MPS. An overstated master production schedule is the one which orders more than the production resources can complete. An overstated MPS causes:-

• raw materials and WIP inventories to increase because more materials are purchased and released to the shop than are completed and shipped.

• It also causes a buildup of queues on the shop floor. • Since jobs have to wait to be processed, actual lead times increase,

causing ship dates to be missed. • As lead times increase, forecast over the planning horizon becomes less

accurate. • This is because, forecasts are more accurate for shorter periods than for

longer ones. Thus, overstated master production schedules lead to missed due dates

Because of all the above given reasons, validating the MPS with respect to available capacity is an extremely important step in MRP. The term used for this validation exercise is “Rough Cut Capacity Planning (RCCP)”.

There are three approaches to perform rough cut capacity planning:

1. Capacity planning using overall factors (CPOF) :It is the least detailed approach. Capacity requirement is quickly computed but is insensitive to shifts in product mix.

2. “Bill of labor” (or bill of required types of machine hours) approach : It involves multiplying two matrices, “the bill of labor” and the “master production schedule”. This approach picks up shifts in product mix, but does not consider lead time offsets. It strictly assumes a lot-for-lot policy for setting lot sizes. When other techniques, such as economic order quantity etc. is used, then this approach gives a very rough estimate. 3. “Resource Profile” approach :It is exactly same as “Bill of labor approach”, except that it takes lead-time offsets into account. Again, it strictly assumes a lot-for-lot policy for setting lot sizes as in the case of “bill of labor approach”.

An Overview of Capacity Management

The following is a tentative master schedule for 12 weeks at a syringe plant in Babylon:

A= large syringe B= medium syringe C= small syringe

Determine the load on department (1) over the next 12 weeks. The load profile for department (1)over the next 12 weeks is found by multiplying the labor requirement in department(1)for each product by the quantity of that product to be produced in each week and summing the hours required for all products in each week. 

Determine the load on department (1) over the next 12 weeks. found by multiplying the labor requirement in department(1)for each product by the quantity of that product to be produced in each week and summing the hours required for all products in each week.

Hours required in each week

• Determine the load on department (2) over the next 12 weeks

found by multiplying the labor requirement in department(2)for each product by the quantity of that product to be produced in each week and summing the hours required for all products in each week.

Hours required in each week

Sum=684 

• Determine the load on department (3) over the next 12 weeks

found by multiplying the labor requirement in department(3)for each product by the quantity of that product to be produced in each week and summing the hours required for all products in each week.

Hours required in each week

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PROCESS PLANNING

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INTRODUCTION

• Process Planning Known as:– manufacturing planning– material processing– process engineering– machine routing Definition:– act of preparing detailed work instructions to produce a part– it’s a function within the manufacturing facility (see figure)– establishes processes and parameters used to convert part from initial

form to final form– predetermined in an engineering drawing– person who develops process plan: often called process planner

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• Functions included in process planning:

– Raw material preparation

– Processes selection

– Process sequencing

– Machining parameter selection

– Tool path planning

– Machine selection

– Fixture selection

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• Factors Affecting Process Plan Selection: – Shape – Tolerance – Surface finish – Size – Material type – Quantity – Value of the product – Urgency – Manufacturing system itself

• Two approaches to carry out task of process planning: – Manual Process Planning – Computer Aided Process Planning (CAPP)

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Manual Process Planning

• Process planner must have following knowledge: – Ability to interpret an engineering drawing – Familiarity with manufacturing processes and practice – Familiarity with tooling and fixtures – Know what resources are available in the shop – Know how to use reference books (e.g. machinability data

handbooks) – Ability to do computations on machining time and cost – Familiarity with raw materials

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• Some necessary steps to prepare a process plan : – Study overall shape of part identify features, all critical ⇒

dimensions – Thoroughly study the drawing; try to identify all

manufacturing features and notes – Determine best raw material shape to use if raw stock not

given – Identify datum surfaces; Use information on datum

surfaces to determine the setups – Select machines for each setup. – Determine rough sequence of operations necessary to

create all the features for each setup

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Process Plan

• Process Plan :– operation sheet – route sheet – operation planning summary

• Detailed plan contains: – route – processes – process parameters – machine and tool selections – fixtures

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• The level of details in the plan depends on the application:

Operation: a process

Operation Plan (Op-plan): description of an operation includes tools, machines to be used, process parameters, machining time, etc.

Op-plan sequence: Summary of a process plan

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Examples of Process Plans

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Processes Selection• A wide variety of manufacturing processes are used to produce

a workpiece

• These processes can be classified as: – Casting processes – Forming and shaping processes – Machining processes – Joining processes – Finishing processes

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• Features that must be considered in selecting machining

processes include:

– part features

– required dimensional and geometric accuracy and tolerance

– required surface finish

– available resources, including NC machines and cutting

tools

– cost

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E x a m p le : M a ch in in g P ro cesses S electio n

• Select the machining processes for the part shown

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• Solution: – Top flat surface – Outer profile – Three holes

• Recommended machining processes for features are :– Face-milling: the top surface – Rough-milling: the outer profile – Finish-milling: the outer profile – Center-drilling: the three holes – Drilling: the three holes

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Typical processing sequence

• Typical processing sequence to fabricate a discrete part –

– A basic process

– One or more secondary processes

– Operations to enhance physical properties

– Finishing processes

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Typical processing sequence

Basic processes

Secondary processes

Property-enhancing processes

Finishing processes

Finished part

Raw materials

Property enhancing properties not always required

Additional secondary processes sometimes required following

property enhancement

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Computer Aided process planning

• During the last several decades, there has been considerable interest in automating the process planning function by computer systems

• Shop people knowledgeable in manufacturing processes are gradually retiring

• An alternative approach to process planning is needed and computer-aided process planning(CAPP) provides this alternative

• CAPP Systems• CAPP systems are designed around either of two approaches :

– Retrieval systems – Generative systems