ME -PRODUCTION PLANNING AND CONTROL Notes-MECHANICAL

THIS BLOG IS ABOUT PRODUCTION PLANNING AND CONTROL.

Production planning and control is a tool available to the management to achieve the stated objectives.Thus, a production system is encompassed by the four factors. i.e, quantity, quality, cost and time.

Production planning starts with the analysis of the given data, i.e., demand for products, delivery schedule etc., and on the basis of the information available, a scheme of utilization of firms resources like machines, materials and men are worked out to obtain the target in the most economical way.Once the plan is prepared, then execution of plan is performed in line with the details given in the plan. Production control comes into action if there is any deviation between the actual and planned. The corrective action is taken so as to achieve the targets set as per plan by using control techniques.

Thus production planning and control can be defined as the “direction and coordination of firms’ resources towards attaining the prefixed goals.” Production planning and control helps to achieve uninterrupted flow of materials through production line by making available the materials at right time and required quantity.

Objectives of production planning and control

1. To deliver quality goods in required quantities to the customer in the required delivery schedule in order to achieve maximum customer satisfaction.

2. To ensure optimum utilization of resources/materials.

3. To minimize the production/manufacturing cycle time.

4. To maintain optimum inventory levels.

5. To schedule production facilities in optimum manner.

6. To coordinate the activities of different departments relating to production to achieve regular, steady and balanced flow of production.

7. To ensure confirmation of delivery commitments.

 8. To ensure production of quality products.

9. To keep the plant free from production bottleneck.

10. To ensure effective cost reduction and cost control.

11. To evaluate the performance of various shops & individuals.

12. To develop alternative plans inorder to meet any emergency or contingency.

13. To maintain spare capacity to deal with rush orders.

FUNCTIONS OF PRODUCTION PLANNING AND CONTROL

Functions of production planning and controlling is classified into:

1.      1. Pre-planning function 
      2. Planning function 
      3. Control function

1. PRE-PLANNING FUNCTION

Pre-planning is a macro level planning and deals with analysis of data and is an outline of the planning policy based upon the forecasted demand, market analysis and product design and development. This stage is concerned with process design (new processes and developments, equipment policy and replacement and work flow (Plant layout). The pre-planning function of PPC is concerned with decision-making with respect to methods, machines and work flow with respect to availability, scope and capacity.

2.PLANNING FUNCTION

The planning function starts once the task to be accomplished is specified, with the analysis of four M’s, i.e., Machines, Methods, Materials and Manpower. This is followed by process planning (routing). Both short-term (near future) and long-term planning are considered. Standardization, simplification of products and processes are given due consideration.

3.CONTROL FUNCTION

Control phase is effected by dispatching, inspection and expediting materials control, analysis of work-in-process. Finally, evaluation makes the PPC cycle complete and corrective actions are taken through a feedback from analysis. A good communication, and feedback system is essential to enhance and ensure effectiveness of PPC.

The functions of PPC can be explained with the following parameters:

1. Materials

The purpose of this function is to ensure correct start and end of each operation by providing raw materials, finished parts and semifinished components at required quantities and at required time for uninterruptedproduction process. This function includes the specification of materials, delivery dates,

variety reduction (standarisation) procurement and make or buy decision.

2. Methods

The purpose of this function is to find the best method of processing from the several alternatives. It also includes determining the best sequence of operations and planning of tools, jigs and fixtures etc.

3. Machines and equipment

This function is related with the detailed analysis of available production facilities, equipment downtime, maintenance policy procedure and schedule. It is also concerned with economy of Jigs & Fixture, equipment availability.Thus the duties include the analysis of facilities and making their availability with minimum downtime because of breakdowns.

4. Routing (Process Planning)

Routing means determination of path or route on which manufacturing operations will travel. It also establishes the sequence of operation to be followed in manufacturing a particular product. Generally route path is determined in advance. The several activities in routing/process planning includes

1. Fixation of path of travel.

2. Breaking down of operations to define each operation.

3. Deciding the setup time and process time for each operation.

5. Estimating

This function is concerned with estimation of operation time. The operation time can be worked out, once the overall method and sequence of operation is fixed and process sheet for each operation is available.

6. Loading and Scheduling

Allocating the jobs to the individual machine is known as machine loading. The purpose of this function is to load the machine according to their capability of performing the given task and according to their capacity. Scheduling is concerned with preparation of machine loads and assigning starting and due dates for each of the operation.

Here, the duties include:

1. Loading the machines as per their capability and capacity.

2. Determining the start and completion time for each operation.

3. Coordinating with sales department regarding delivery schedules.

7. Dispatching

Dispatching is the part of production control that translates the paper work into actual production. This is concerned with the execution of the planning functions.Dispatching is the release of orders and instructions for the starting of production in accordance with the route sheets and schedule charts.

Here, the activities include:

1. Assigning definite work to definite machines, work centres and men.

2. Supplying required materials from store.

3. Providing jigs, fixture and making them available at correct point of use.

4. Releasing necessary work orders, time tickets etc. to authorise timely start of operation.

5. Recording start and finish time of each job on each machine (or) by each man.

8. Expediting (or) Follow up (or) Progressing

Follow up is the very important function for any production system. This is generally done after the dispatching function. Expediting is the control tool that keeps a close observation on theprogress of the work. It identifies the deviation from the actual production plan, then all deviations are investigated and suitable remedial measures are taken in order to complete the work by the planned date.

Here, the activities include:

1. Identification of bottlenecks, delays and interruption.

2. Devise action plans (remedies) for correcting the errors.

3. Following up and monitoring progress of work through all stages of Production

9. Inspection

Inspection is the quality control aspect of production planning and control. This function is related to maintenance of quality in production and of evaluating the efficiency of the processes, methods and labours so that improvements can be made to achieve the quality standard set by product design.

10. Evaluation

The main objective of this function is to improve performance.

The evaluating function is concerned with providing a feedback mechanism on a long-term basis so that the past experience can be used to improve upon the use of methods, facilities and resources in future period.

PRODUCTION SYSTEM

Production implies the creation of goods/services to satisfy human needs. Production is the process of transformation of inputs (resources), into outputs (good/services) using physical resources.

According to Cart Heyle, production is the process of transforming raw materials or purchased components/semi finished products into finished products for sale.

Production system consists of three main processes

1. Inputs

2. Conversion process

3. Outputs

Inputs : It includes raw materials, machines, drawings etc.

Conversion process : Conversion process includes welding, forging, machining, modeling, assembling etc. Conversion process adds value to raw materials by changing its shape, size or weight.

Outputs : It includes finished products, finished goods and services.

Types of Production System

According to the volume of production (quantity) and product standardization, the production systems are classified as

1. Job shop production

2. Batch production

3. Continuous production

4. Mass production

Job Shop Production

In Job shop production system, products are manufactured to meet the requirements of a specific order.

The quantity involved is small and the manufacturing of the product will take place as per the specification given by the customer. The distinguishing feature of job shop production system is low volume and high variety of products.

Examples: Space vehicles, aircraft, machine tools, special purpose machines etc.

According to the regularity of manufacturing. Job shop production is further classified into three types.

1. A small number of pieces produced only once.

2. A small number of pieces produced intermittently when the need a rises.

3. A small number of pieces produced periodically at known time interval.

Characteristics of Job shop production

1. General purpose machines and equipments are used to perform wide range of operations.

2. Highly skilled operators and supervisors are employed.

3. Flexible planning and control system to deal with the frequent changes in product requirements.

Merits

1. Due to the use of general purpose machines, it is suitable for producing variety of products.

2. The potential and skill of operators can be fully utilized.

Demerits

1. Production planning is complicated.

2. Higher setup and tooling cost due to frequent setup changes.

3. Higher inventory cost due to higher level of inventory at all levels.

Batch Production

In batch production system, the products are made in small batches and in large variety. Each batch contains identical items but every batch is different from the others.

Batch production plant includes machine shops, foundries, plastic moulding units, press shops, chemical and pharmaceutical units. It is characterized by the manufacture of limited number of products produced at regular interval and stocked awaiting sales.

This type of production system is further divided into three different categories.

1. A batch produced only once

2. A batch produced at irregular intervals

3. A batch produced at known intervals.

Characteristics of batch production

1. A large variety of products are manufactured in lots or batches.

2. Higher level of work-in-process inventory.

3. Amount of supervision required is less compared to job shop production.

Merits

1. Cost per unit is lower as compared to job production system.

2. Investment is lower in plant & machinery.

3. Better utilization of plant & machinery compared to job shop production.

Demerits

1. Material handling is complex because of irregular and longer flows.

2. Production planning and control is complex.

3. Higher setup costs due to frequent changes in setup.

Continuous Production

Production facilities for continuous production are arranged as per a predetermined sequence of production operations from the first operation to the finished product. The items are made to flow in a sequence of operations through material handling devices such as conveyers, transfer devices etc.

A highly rigid type of machine layout is used for continuous production.

Characteristics of Continuous Production

1. Material handling is fully automated.

2. Persons with limited skills can be used in the production line.

3. Process follows a predetermined sequence of operation.

Merits

1. Due to high volume of production the unit cost is low.

2. Products and process sequences are highly standardized.

Demerits

Very high investment is required for setting flow lines.

Mass Production

Mass production refers to the process of creating large number of similar products efficiently

Standardisation of products, process, materials, machines and uninterrupted flow of materials are the basic features of this system. Automobile assembly line is a typical example of mass production.

Characteristics of mass production

1. Special purpose machines having higher production rate is used.

2. Production volume is large.

3. Flow of materials, components and parts are continuous without any back tracking.

Merits

1. Higher rate of production with reduced cycle time.

2. Low in-process inventory.

3. Production cost per unit is low

4. Less skilled operators may be employed.

Demerits

1. Breakdown of one machine will stop an entire production line.

2. High investment in production facilities.

Fig 1.7 Types of production system