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Production Planning and control

1.0 Production:

Production is an organized activity of transforming raw materials or components

into finished products which satisfy the human needs.

2.0 productivity:

It is the ratio of the volume of output to the quantity of the resources employed inachieving the production. It is the efficiency of the operations involved.

3.0 Types of manufacture:

1. Continuous or process manufacture:

A product passes through various processes to become a final product. The

finished part of one process will be the raw material for the next process

and the final process turns out to be the finished product.Ex: Textiles, sugar, paper industries.

2. Synthetic or assembly Industry:

Many raw materials are brought together in manufacturing process to

make a final product in synthetic industry.

Ex: Cement, Soap, Pants, Plastics etc.Various components are assembled together to make a final product in

assembly industry.

Ex: Cycle, Automobile, radio, TV, etc.

3. Analytical industry:One product is analyzed and many products are obtained as final products.Ex: Crude oil refinery

4. Job order Industry:

In the job order industry different products as per the orders received aremanufactured. Each job will be different from one another. There will be

no standard product for manufacture and sell continuously.

Types:1. Open job shop 2. Closed job shop

In open job shop, the orders from external customers are accepted and

executed. Orders once received may not be repeated.

In closed job shop, the industry caters to the internal requirements only.

They do no accept external orders. It produces inventorial items of

standard design, which have demand in the market. The items areproduced repetitively.

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4.0 Types of production:

1. Job or Unit production 2. Mass production 3. Batch production

4.1 Job or Unit production:

This type of production is used for the items which can not be produced in largescale.

Individual requirements of consumers can be met.

These are generally small in size ( Ship building is an exception)

Tools, dies are the examples for unit production

Flexible and uses general purpose machines.

Each job is unique and may not be repeated.

Advantages:

1. Easy to manage. 4. Lower risk

2. Individual requirements can be met. 5. Flexibility in operations

3. Inexpensive & easily started

Disadvantages:1. Lower operational economy

2. Higher raw material costs.3. Skilled and intelligent workers are needed.

4.2 Mass production:

It is a large scale and continuous production.

Special layouts, special purpose equipment and costly jigs and fixtures are used.

Standardization and simplification of products are made.

Needs materials handling equipment as it handles materials in large scale.

Advantages:

1. Large scale operations economy.2. Automation and use of SPMs reduces wastage.

3. Increased productivity and Quality.

4. Overheads are distributed on large quantities.

5. Due to automation a few skilled and the rest semi skilled workers are needed.6. Demand can be forecast and produced in advance resulting in ready

availability.

Disadvantages:

1. Lack of flexibility

2. Idle cost is high in case of lack of orders.

3. Individual and lower requirements can not be met.

4. Monotony in operations.

4.3 Batch production:

It is a stage in between Job production and mass production.

The products are manufactured in lots or batches at regular intervals.

Some of the machines may be special purpose and the rest are general purpose.

More varieties of products are produced.

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Advantages:

1. Less capital requirement compare to mass production.2. The risk involved is less due to the variety of products.

3. More economy as compared to job production.

4. Higher flexibility in operations.Disadvantages:1. Cost of sales and advertisement is more.

2. Cost of raw materials may be high due to low quantity.

5.0 Production planning and control:

It has three phases - Planning, Action and control

The planning phase involves in preparation of process details, selection of

equipments and tools to be used, fixing the time schedules of each operation and

selection persons to perform the tasks.

The action phase releases the required orders and instructions to commence the

work.

The control phase ensures that the planned programme is progressing as per the

plan and takes necessary steps to correct at appropriate time if deviations are

observed.

5.1 Principles of PPC:

1. To select the least expensive method.2. Production of right quality of product in right quantity at right time.

3. Plan the work and work to the plan.

4. Best utilization of the resources available and minimizing the idle time of theequipment.

5. Prompt and shortest delivery schedules.

6. Coordination and liaison with various departments.7. Status reports and progress reports.

5.2 Functions of PPC:

1. Planning 4. Dispatching2. Routing 5. Follow up

3. Scheduling 6. Inspection

5.2.1 Planning:

It is the first step for all activities. Planning department decides each element of

the job in anticipation that what work shall be done where, how and when.

Requirements:

1. Details of the product along with drawings and specifications.

2. Quality and quantity needed.

3. Details of the equipment, tools and personnel available.

4. Standard time for each job.

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5. Information about stores and delivery time.

Steps involved:

1. Selection of process

Current production commitments

Quantity to be produced

Delivery dates Quality standards

2. Selection of material

3. Selection of jigs and fixtures4. Preparation of process layouts/ charts

5. Providing the set up time and standard time

6. Determining the economic batch quantity

5.2.2 Routing:

It is the selection of the path which each part of the product will follow while

being transformed from raw material to finished product.It is the sequence of operations to be adopted while manufacturing. Routing

determines the best and cheapest sequence of operations and to see that thesequence is followed rigidly.

Routing depends on the type of manufacture.

Continuous industry: The route is decided in the beginning as per the process

and remains same. The further control over the route is not needed

Assembly industry: Each component needs a different route. It needs goodtechnical knowledge of the PPC staff.

Job order industry: Since different products are made, each product needs itsown routing. Every time a different route has to be prepared suiting the product.

5.2.3 Scheduling:

It is the fixation of time and date for each operation. The start and finish times for

each operation are fixed initially. Schedules also indicate the sequence of

operations. The planning department prepares the schedules.

Railway map is an example for routing where as railway time table is an example

for scheduling.

Types of schedules:

1. Master schedule: It is a weekly or monthly breaking of the productionrequirement for each product.

2. Shop schedule: These are prepared after the master schedule. The detailedscheduling of each product are given in these schedules.

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5.2.4 Dispatch:

Dispatch is the release of orders to start the work in accordance with route sheetsand schedule charts. It gives the necessary authority to start the work.

Functions:1. Issue of work orders to the concerned shops.

2. Issue of materials from stores to the respective machines.

3. Issue of Machine loading and schedule charts.4. Issue of inspection orders.

5. Issue of Tools, jigs & fixtures and other essential articles.

Forms used:

1. Work order 4. Move tickets ( MIRs.)

2. Time cards 5. Tool tickets

3. Inspection tickets

5.2.5 Follow up:

This comes under control phase. It regulates and reviews the progress of the work.It ensures that the production is being performed as per the schedules.

Functions:

1. Material follow-up2. Job progress

3. Assembly

4. Control charts

The basic function of the follow-up is to identify and avoid delays and take

remedial actions in the right time.

Causes for delays:

1. Shortage or delay of materials2. Equipment break-down

3. Errors in routing and scheduling

4. Lack of proper tools etc.

5. Maximum rejection and rework

5.2.6 Inspection:

Inspection is carried out for confirming that the products are made as per the pre-determined specifications or standards.

During inspection the defective products are rejected. In-process inspection aims

at reducing the rejections of the finished products by eliminating the defectiveparts for further processing.

Inspection of raw materials, tools and equipment ensures the quality of the

finished product.

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PPC ensures that the QC department functions effectively and provides the

necessary liaison between production and QC.

5.3 Progress control charts:

These charts are used in progress reporting. Progress charts compare the progress

of the work against a prescribed target and point out the failures to achieve. They

draw attention for an action or investigation.

Types:

1. Bar chart:Each operation is represented by a line showing the duration of the

operation against a time scale.

Activity Time in days

0 5 10 15 20

A

B

C

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------------------------------------

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2. Curve chart:

It is the graph between two variables like the No. of items produced V/S

No. of days.

3. Gantt chart:

It is a modified bar chart, where in load is marked against a time scalewith one horizontal bar or line allocated to each machine.

Gantt chart displays

1. Plan for future

2. Progress on present operations3. Past achievements till date

4. Relationship among several variables

5. Focuses attention on situations likely to get delayed6. Shows short falls of the planes

7. Cursor attached to the chart shows the work progress as on a particular

date

Types:1. Order control chart

2. Machine load chart

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Order control chart machine load chart