Process Planning

Unit III MBA II

VIMR, Satna (MP)

Presented By-

Surendra Pratap Mourya

Asst. Professor

VIMR, Satna(MP)

Process Planning

• Process planning is also called manufacturing planning, material processing, process engineering, and machine routing. It is the act of preparing detailed work instructions to produce a part. It is a complete description of specific stages in the production process.
• “Process Planning is the systematic determination of the methods by which a product is to be manufactured economically and competitively”

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American Society of Tool and Manufacturing Engineers

OBJECTIVES

• To prepare a set of instructions that describes how to manufacture the product and its parts.
• To prepare a detailed specification which lists the operations, tools and facilities.
• To prepare the functional requirements of the product, quantity, tools and equipment, and eventually the cost to manufacture.

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PROCESS PLANNING ACTIVITIES

APPROACHES TO PROCESS PLANNING

• MANUAL PROCESS PLANNING
• COMPUTER AIDED PROCESS PLANNING (CAPP)
1. Retrieval type
2. Generative type

MANUAL PROCESS PLANNING

• Examining and interpreting the drawings
• Making decisions on machining process selection.
• Equipment selection, tools etc.
• Dependent on the skill and judgment of the process planner.
• Different planners may produce different proces plans.

COMPUTER AIDED PROCESS PLANNING (CAPP)

• Reduces routine clerical work
• Generates rational, consistent and optimal plans
• Interfaces CAD and CAM

AGGREGATE PLANNING

• Aggregate planning is the process of developing, analyzing, and maintaining a preliminary, approximate schedule of the overall operations of an organization.
• The aggregate plan generally contains targeted sales forecasts, production levels, inventory levels, and customer backlogs. This schedule is intended to satisfy the demand forecast at a minimum cost.

• The process of determining output levels of product groups over the coming 6 to 18 months on a weekly or monthly basis ; the plan identifies the overall level of outputs in support of the business plan.
• Aggregate planning involves translating long-term forecast demand into specific production rates

and the corresponding labor requirements for the intermediate term.

Aggregate Planning Strategies

There are two pure planning strategies available to the aggregate planner:

1. Level Strategy
2. Chase Strategy

Level Strategy

• A level strategy seeks to produce an aggregate plan that maintains a steady production rate and a steady employment level.
• In order to satisfy changes in customer demand, the firm must raise or lower inventory levels in anticipation of increased or decreased levels of forecast demand.

• The firm maintains a level workforce and a steady rate of output when demand is low. This allows the firm to establish higher inventory levels than are currently needed.
• As demand increases, the firm is able to continue a steady production rate/steady employment level, while allowing the inventory surplus to absorb the increased demand

Chase Strategy

• A chase strategy implies matching demand and capacity period by period.
• This could result in a considerable amount of hiring, firing or laying off of employees; insecure and unhappy employees; increased inventory carrying costs; problems with labor unions; and erratic utilization of plant and equipment.

• It also implies a great deal of flexibility on the firm's part. The major advantage of a chase strategy is

that it allows inventory to be held to the lowest level possible, and for some firms this is a considerable savings.

• Most firms embracing the just-in-time production concept utilize a chase strategy approach to aggregate planning

Scheduling

• Prescribing of when and where each operation necessary to manufacture the product is to be performed.
• Establishing of times at which to begin and complete each event or operation comprising a procedure
• It mainly concerns with time element and job priorities.

Objectives of Scheduling

• Meet due date
• Minimize WIP inventory

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• Minimize the average flow time through the systems Provide for high machine/worker (time) utilization (minimization of ideal time)

• Reduce set up cost
• Minimize production and worker costs

Scheduling issues

Scheduling deals with the timing of operations.

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• Hospital
• Operating room use
• Patient admissions
• Nursing, security, maintenance staffs
• Out patient treatments College
• Classrooms and audiovisual equipment's
• Students and instructor schedule
• Graduate and under graduate students

Manufacture

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• Production of goods
• Purchase of goods
• Workers Restaurant
• Chef waiters, bartenders
• Delivery of fresh food
• Opening of dining areas Air lines
• Maintenance of aircr aft
• Departure timetables
• Flight crews, catering, gate, and ticketing personnel

Principle of Scheduling

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

Types of scheduling

1. Forward Scheduling
2. Backward Scheduling

Forward Scheduling

• With forward scheduling, processing starts immediately when a job is received, regardless of its due date.
• Forward scheduling is commonly used in job shops where customers place their orders on “ needed as soon as possible basis”.
• Each job activity scheduled for completion as soon as possible, which allows you to determine the job’s earliest possible completion date.

The job is due at the end of week 10, but it can be finished as early as the end of week 7. With forward scheduling, it is not unusual for jobs to be finished before their due date. The disadvantage to finishing a job early is that it causes an inventory buildup if items are not delivered before the due date.

Backward Scheduling

• With backward scheduling, you begin scheduling the job’s last activity so that the job is finished right on the due date.
• It is often used in assembly type industries and commit in advance to specific delivery dates.
• It is the process of assigning the start and finishing time to the waiting jobs to be done when it is due, but done before.
• To do this, you start with the due date and work backward, calculating when to start the last activity, when to start the next- to-last activity, and so forth.

Figure below gives an example of backward scheduling. Backward scheduling shows you how late the job can be started and still be finished on time. When you are using backward scheduling and forward scheduling together, a difference between the start time of the first activity indicates slack in the schedule. Slack means that you can start a job immediately but you do not have to do so. You can start it any time up to the start time in your backward schedule and still meet the due date.

Work Measurement

• A management tool to achieve higher productive efficiency of a firm by observing manual work done by human being and designing a more systematic way of doing the same job.
• It is mainly concerned with discovering the best way of doing a job.

Methods

1. Time Study
2. Motion Study

1. Time Study

• It determines the amount of time required to perform a job by a worker following a particular method.
• “ The art of observing and recording the time required to do each detailed element of an industrial operation.” - Kimball

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Objective of Time Study

• Target time for each job
• Sound comparison of alternative methods
• Useful incentive scheme with target times
• Lead to proper balance of work distribution
• Forecast for future manpower and related cost
• Allocate the labor to the jobs in proposition to work

Techniques of Time Study

• Direct Time Study
• Stop Watch Approach
• Analytic Estimation
• Work Sampling
• Indirect Time Study
• Synthetic timing data
• Predetermined time and motion study

Method of Time Study

• Select the worker with average skill and ability.
• Obtain all necessary information required to perform some work to be recorded like machine, quality, layout, time requires, standard etc.
• Divide job into separate elements which facilitates accurate study.
• Time each element using stop watch by observing on floor.
• Record sufficient number of reading for getting accurate results.
• Rate the operator on the basis of speed, effort, knowledge of the job and pace of working.

Motion Study

• Also known as Method Study.
• Systematic recording, analysis and critical examination of existing and proposed ways of doing work and development and application of easier and more effective work methods to perform job with less effort and reduced cost.
• This study is done before time study.

Objectives

• To Improve layout and process design of factory
• To improve method of doing work
• Examination of weaknesses of production process
• Effective use of human efforts
• Measurement of work values to determine correct wage rates
• Ensure proper performance of workers

Method of conducting Motion Study

• Selection of the job to be studied
• Collection, recording and presentation of work related information at the place where job under study is conducted, by direct visual observation of all movements in work process.
• Analysis of information collected in step 2
• Suggestion on the basis of above analysis
• Implementation of new work method or suggested improvements.