BEST PRACTICESES IN PRODUCTION PLANNING AND CONTROL
Production planning and control is defined as the process of planning the production in advance, setting the exact route of each item, fixing the starting and finishing times for each item, to give production orders to shop floors and to follow up the progress.
INTEGRATIVE NATURE OF PRODUCTION PLANS The procurement of raw materials, the quality control and inspection of raw materials, inventory levels of in process and finished goods, the production costs, the labour available, the machinery and equipments that is : available, the Warehousing capacity avail able tec., all have their influence on the planning of production operations which convert the raw material into finished goods. All the functions have inter-links and the more such inter-links are considered int eh planning process, the better will be the planning process
A production planning has many functions to perform
(a) Forecasting: Estimation of type, quantity and quality of future work
(b) Order writing: Giving authority to one or more persons to undertake a particular job.
(c) Product design: Collection of information regarding specifications, bill of materials, drawings, etc.
(d) Process planning and routing: Finding the most economical process of doing a work and (then) deciding how and where the work will be done
(e) Material control: It involves determining the requirements and control of materials.
(f) Tool control: It involves determining the requirements and control of tools used
(g) Loading: Assignment of work to manpower, machinery etc.
(h) Scheduling: It is the time phase of loading and determines when and in what sequence the work will be carried out. It fixes the starting as well as the finishing time for the job.
(i) Dispatching: It is the transition from planning to action phase. In this phase the worker is ordered to start the actual work.
(j) Progress reporting:
a. Data regarding the job progress is collected
b. It is interpreted by comparison with the preset level of performance
(k) Corrective action:
a. Expedition means taking action if the progress reporting indicates a deviation of the plan from the originally set targets.
b. Replanning – Replanning of the whole affair becomes essential, in case expediting fails to bring the deviated plan to its actual (right) path.
PRODUCTION CONTROL
· Receives work progress reports;
· Compares them with the scheduled plans;
· Removes causes of delays in production;
· Modifies the schedules or plant capacities; and
· Expedites the work.
DISPATCHING
(a) Store Issue Order: Authorize stores (department) to deliver required raw material.
(b) Tool Order: Authorize tool store to release the necessary tools. The tools can be collected by the tool room attendant.
(c) Job Order: Instruct the worker to proceed with the operation.
(d) Time Ticket. : it records the beginning and ending time of the operations and forms the basis for worker’s pay.
(e) Inspection Order: notify the inspectors to carried out necessarily inspections and report the quality of the component.
(f) Move Order: Authorize the movement of materials and components from one facility (machine) to another for further operations.
In addition, there are certain other dispatch aspects which have to be taken care of,
· All production information should be available before hand.
· Various order cards, and specification drawings should be ready.
· Equipments should be ready for use.
· Progress of various orders should be properly recorded on the Gantt charts or display boards.
· All production records should be properly maintained.
ROUTING
Routing lays down the flow of work in the plant. It determines what work is to be done and where and how it will be done. Taking from raw material to the finished product, routing decides the path and sequence of operations to be performed on the job from one machine to another. The purpose is to establish the optimum sequence of operations. Routing is related to considerations of layout, temporary storage of in-process inventory and material handling.
Routing in continuous industries does not present any problem because of the product type of layout, where the equipment is laid as per the sequence of operations required to be performed on the components (from raw material to the finished products).
Various procedural steps are as follows:
(a) The finished product is analyzed from the manufacturing standpoint in order to decide how many components can be made in the plant and how many others will be purchased (Make/Buy decision) from outside through vendors, by subcontracting, etc. Make/Buy decision depends upon the work load in the plant, availability of equipment and personnel to manufacture all components, and the economy associated with making all components within the plant itself.
(b) A parts list and a bill of materials is prepared showing name of the part, quantity, material specifications, amount of materials required, etc. The necessary materials thus can be procured.
(c) From production, standards – machine capacities, machine characteristics and the operations which must be performed at each stage of manufacture are established and listed in proper sequence on an operation and route sheet. The place where these operations will be performed is also decided.
Actually, operation sheet and route sheet are separate. An operation sheet shows every thing about the operations, i.e., operation description, their sequence, type of machinery, tools, set up and operation times, whereas a route sheet besides the sequence of operations and relation between operation and machine, also details the section (department) and the machines to whom the work will flow.
The difference between an operation sheet and a route sheet is that an operation sheet remains same for the components if the order is repeated but the route sheet may have to be revised if certain machines are already committed to other orders (jobs) on hand.
(d) The next step is to determine the lot size or the number of components to be manufactured in one lot or batch. In the case of an order from a particular customer, it is generally equal to a number within 10% of the order quantity. In other cases the principle of economic batch quantity can be applied (refer Chapter 24)10 determine the batch size.
(e) Standard scrap factors (single or cumulative) and the places (i.e., after a particular operation or assembly) where scrap is very likely to occur are identified. The actual scrap in each batch can be recorded on the control chart. Causes for points out of control limits are explored and corrected. The variables like workers, machinery and schedules may also be adjusted to minimize scrap.The cost of the component is analyzed and estimated through the information obtained in steps (a) to (e) above. The cost consists of material and labour charges, and other specific and general indirect expenses
PROGRESS CONTROL
Once the actual production has started, it becomes essential to keep an eye at the progress of the work so that, if required, timely corrective action can be taken. Progress control means – trying to achieve the standards set, i.e., a certain level of efficiency or a certain volume of production in a specified duration. The system of progress control should be such that it furnishes timely, adequate and accurate information about the progress made, delay and under-or-over-loading.
(a) Setting up a system to watch and record the progress of the operating facility (production section).
(b) Making a report of the work progress or work accomplishment.
· Control group for necessary control action, and
· Accounting group for recording material and labour expenditures.
(c) Interpretation of the information contained in the progress report by the control group
(d) Taking corrective action, if necessary.
CHARTS FOR THE WORK ACCOMPLISHMENT
Progress charts are normally employed for this purpose. They compare the work progress against a prescribed target, and point out the failure to achieve the same, thus progress charts draw attention for an action or investigation.
The chart construction may have the following four forms
1. The Bar Chart
2. The Curve chart
3. The Gantt Chart and
4. Mechanical chart
1. The Bar Chart consists of a number of bars. Each bar ahs its length proportional to the activity duration. A bar chart is generally used to point out and analyze interrelated data which otherwise is difficult to read.
2. A Curve Chart is a graph between two variables (like, number of days and number of items produced) marked along the X and Y axes. As the days pass, the number of items being produced is marked over the graph. When all such points are joined they indicate the production trend.
Both the bar and curve charts show the past data. They are not readily adaptable to current or future action.
3. The Gantt Chart was developed by Henry L. Gantt. It is frequently used to keep track of multiple machine schedules. Gantt chart is actually a modified bar chart, wherein load is marked against a time scale with one horizontal bar or line allocated to each machine. A Gantt chart displays the following.
1. Plans for future.
2. Progress on present operations
3. Past achievements till date,
4. Relationship among several variables
5. It focuses attention on situations threatening delays
6. It tells whether a plan has fallen short and if the delivery dates can e met, and
7. A cursor attracted to the Gantt chart can be moved across the chart to know the work progress till any particular day.
FOLLOW UP OR EXPEDITING Follow up serves as a catalytic agent to fuse the various separate and unrelated production activities into the unified whole that means progress. Follow up is concerned with the reporting of production date and the investigating of any deviation from the predetermined production (or time) schedules. Follow up ensures that the promise (i.e. of delivery dates) is backed up by performance.
Exception principle, the scheduling group (on the basis of progress reports), explores the jobs behind the schedule. The expediting group takes up such jobs, procures necessary materials, tools, etc. i.e., (expediting group) solves all problems related to these jobs and intimates the scheduling group to reschedule them.
According to fathering principle each expeditor is made responsible for a job or a group of jobs for which he arranges the tools, materials, equipment, etc. Such a system works very well for controlling large projects
LINE BALANCING The assembly line should be balanced. Each work station should have the same operation time and the various operations should be sequenced properly.
There should be perfect balance between the output rates of the parts and the subassemblies. However, it is not always possible that the parts reach in a steady stream immediately before subassembly. This may be because of the limitations as regards materials, men and equipments or it may be economical to manufacture and supply parts in batches. The flow control section has to cope with such situations and thus carry big inventories and arrange facilities for storage.
LOB is a manual planning and scheduling technique similar in nature to MRP (material resource planning)
LOB is not directly concerned with the resources expended but is utilized in determining production progress in terms of per cent of task completion. Major bottlenecks in the production process are emphasized.
LOB technique can be regarded as a slightly more sophisticated form of the Gantt chart, the objective being to study the progress of jobs at regular intervals, to compare progress on each operation with the progress necessary to satisfy the eventual delivery requirements, and to identify those operations in which progress is unsatisfactory.
LOB technique consists of five main stages, all utilizing graphic aids:
1. A graphical representations of the delivery objective.
The objective chart shows the expected schedule of products (i.e. scheduled deliveries) and the actual completion rate (i.e. actual deliveries made by a date) A dip in actual deliveries line below the scheduled deliveries line is an obvious cause for alarm
2. A chart of the production program showing the sequence and duration of all activities required to produce a product.
· A chart of the operations required to complete one unit of the finished product is called the program plan.
· Each major row of activities is associated with one component of the final assembly
· The final completion date is zero and the time scale runs from right left.
· The completed chart serves as a reference to the amount of lead time by which each event must precede final completion. Events must be completed by their respective lead times to maintain anticipated output.
· Objective chart and Program plan are prerequisites for use of the LOB technique. They need to be constructed only once for any job, unlike the following documents which must be constructed each time the schedule and progress is examined.
3. A progress cart of the current status of component completion.
Progress chart shows the number of items which have been finished at each of the critical or important operations at a given date.The results can then be depicted by means of a histogram
4. A line-of-balance drawn to show the relationship of component progress to the output needed to meet the delivery schedule.
Since the object of the exercise is to compare actual progress with scheduled progress, the information given in progress chart must be compared to required progress. This is done by constructing a line on the progress chart which shows the requisite number of items which should have been finished at each operations at the time of review.
This line-the Line-of-Balance-can be constructed analytically or graphically, the latter method being perhaps the more convenient. The L.O.B., shows the total number of items which should have been finished at each operation.
5. Analysis of progress
In comparing required progress with actual progress it is again convenient to work backwards, beginning with the last operation.If shortage occurs, we must obviously attempt to ascertain the reasons. If operations other than those considered as critical are the cause of shortages, then those operations must be included in subsequent versions of the progress and line-of-balance chart
INTEGRATIVE NATURE OF PRODUCTION PLANS The procurement of raw materials, the quality control and inspection of raw materials, inventory levels of in process and finished goods, the production costs, the labour available, the machinery and equipments that is : available, the Warehousing capacity avail able tec., all have their influence on the planning of production operations which convert the raw material into finished goods. All the functions have inter-links and the more such inter-links are considered int eh planning process, the better will be the planning process
A production planning has many functions to perform
(a) Forecasting: Estimation of type, quantity and quality of future work
(b) Order writing: Giving authority to one or more persons to undertake a particular job.
(c) Product design: Collection of information regarding specifications, bill of materials, drawings, etc.
(d) Process planning and routing: Finding the most economical process of doing a work and (then) deciding how and where the work will be done
(e) Material control: It involves determining the requirements and control of materials.
(f) Tool control: It involves determining the requirements and control of tools used
(g) Loading: Assignment of work to manpower, machinery etc.
(h) Scheduling: It is the time phase of loading and determines when and in what sequence the work will be carried out. It fixes the starting as well as the finishing time for the job.
(i) Dispatching: It is the transition from planning to action phase. In this phase the worker is ordered to start the actual work.
(j) Progress reporting:
a. Data regarding the job progress is collected
b. It is interpreted by comparison with the preset level of performance
(k) Corrective action:
a. Expedition means taking action if the progress reporting indicates a deviation of the plan from the originally set targets.
b. Replanning – Replanning of the whole affair becomes essential, in case expediting fails to bring the deviated plan to its actual (right) path.
PRODUCTION CONTROL
· Receives work progress reports;
· Compares them with the scheduled plans;
· Removes causes of delays in production;
· Modifies the schedules or plant capacities; and
· Expedites the work.
DISPATCHING
(a) Store Issue Order: Authorize stores (department) to deliver required raw material.
(b) Tool Order: Authorize tool store to release the necessary tools. The tools can be collected by the tool room attendant.
(c) Job Order: Instruct the worker to proceed with the operation.
(d) Time Ticket. : it records the beginning and ending time of the operations and forms the basis for worker’s pay.
(e) Inspection Order: notify the inspectors to carried out necessarily inspections and report the quality of the component.
(f) Move Order: Authorize the movement of materials and components from one facility (machine) to another for further operations.
In addition, there are certain other dispatch aspects which have to be taken care of,
· All production information should be available before hand.
· Various order cards, and specification drawings should be ready.
· Equipments should be ready for use.
· Progress of various orders should be properly recorded on the Gantt charts or display boards.
· All production records should be properly maintained.
ROUTING
Routing lays down the flow of work in the plant. It determines what work is to be done and where and how it will be done. Taking from raw material to the finished product, routing decides the path and sequence of operations to be performed on the job from one machine to another. The purpose is to establish the optimum sequence of operations. Routing is related to considerations of layout, temporary storage of in-process inventory and material handling.
Routing in continuous industries does not present any problem because of the product type of layout, where the equipment is laid as per the sequence of operations required to be performed on the components (from raw material to the finished products).
Various procedural steps are as follows:
(a) The finished product is analyzed from the manufacturing standpoint in order to decide how many components can be made in the plant and how many others will be purchased (Make/Buy decision) from outside through vendors, by subcontracting, etc. Make/Buy decision depends upon the work load in the plant, availability of equipment and personnel to manufacture all components, and the economy associated with making all components within the plant itself.
(b) A parts list and a bill of materials is prepared showing name of the part, quantity, material specifications, amount of materials required, etc. The necessary materials thus can be procured.
(c) From production, standards – machine capacities, machine characteristics and the operations which must be performed at each stage of manufacture are established and listed in proper sequence on an operation and route sheet. The place where these operations will be performed is also decided.
Actually, operation sheet and route sheet are separate. An operation sheet shows every thing about the operations, i.e., operation description, their sequence, type of machinery, tools, set up and operation times, whereas a route sheet besides the sequence of operations and relation between operation and machine, also details the section (department) and the machines to whom the work will flow.
The difference between an operation sheet and a route sheet is that an operation sheet remains same for the components if the order is repeated but the route sheet may have to be revised if certain machines are already committed to other orders (jobs) on hand.
(d) The next step is to determine the lot size or the number of components to be manufactured in one lot or batch. In the case of an order from a particular customer, it is generally equal to a number within 10% of the order quantity. In other cases the principle of economic batch quantity can be applied (refer Chapter 24)10 determine the batch size.
(e) Standard scrap factors (single or cumulative) and the places (i.e., after a particular operation or assembly) where scrap is very likely to occur are identified. The actual scrap in each batch can be recorded on the control chart. Causes for points out of control limits are explored and corrected. The variables like workers, machinery and schedules may also be adjusted to minimize scrap.The cost of the component is analyzed and estimated through the information obtained in steps (a) to (e) above. The cost consists of material and labour charges, and other specific and general indirect expenses
PROGRESS CONTROL
Once the actual production has started, it becomes essential to keep an eye at the progress of the work so that, if required, timely corrective action can be taken. Progress control means – trying to achieve the standards set, i.e., a certain level of efficiency or a certain volume of production in a specified duration. The system of progress control should be such that it furnishes timely, adequate and accurate information about the progress made, delay and under-or-over-loading.
(a) Setting up a system to watch and record the progress of the operating facility (production section).
(b) Making a report of the work progress or work accomplishment.
· Control group for necessary control action, and
· Accounting group for recording material and labour expenditures.
(c) Interpretation of the information contained in the progress report by the control group
(d) Taking corrective action, if necessary.
CHARTS FOR THE WORK ACCOMPLISHMENT
Progress charts are normally employed for this purpose. They compare the work progress against a prescribed target, and point out the failure to achieve the same, thus progress charts draw attention for an action or investigation.
The chart construction may have the following four forms
1. The Bar Chart
2. The Curve chart
3. The Gantt Chart and
4. Mechanical chart
1. The Bar Chart consists of a number of bars. Each bar ahs its length proportional to the activity duration. A bar chart is generally used to point out and analyze interrelated data which otherwise is difficult to read.
2. A Curve Chart is a graph between two variables (like, number of days and number of items produced) marked along the X and Y axes. As the days pass, the number of items being produced is marked over the graph. When all such points are joined they indicate the production trend.
Both the bar and curve charts show the past data. They are not readily adaptable to current or future action.
3. The Gantt Chart was developed by Henry L. Gantt. It is frequently used to keep track of multiple machine schedules. Gantt chart is actually a modified bar chart, wherein load is marked against a time scale with one horizontal bar or line allocated to each machine. A Gantt chart displays the following.
1. Plans for future.
2. Progress on present operations
3. Past achievements till date,
4. Relationship among several variables
5. It focuses attention on situations threatening delays
6. It tells whether a plan has fallen short and if the delivery dates can e met, and
7. A cursor attracted to the Gantt chart can be moved across the chart to know the work progress till any particular day.
FOLLOW UP OR EXPEDITING Follow up serves as a catalytic agent to fuse the various separate and unrelated production activities into the unified whole that means progress. Follow up is concerned with the reporting of production date and the investigating of any deviation from the predetermined production (or time) schedules. Follow up ensures that the promise (i.e. of delivery dates) is backed up by performance.
Exception principle, the scheduling group (on the basis of progress reports), explores the jobs behind the schedule. The expediting group takes up such jobs, procures necessary materials, tools, etc. i.e., (expediting group) solves all problems related to these jobs and intimates the scheduling group to reschedule them.
According to fathering principle each expeditor is made responsible for a job or a group of jobs for which he arranges the tools, materials, equipment, etc. Such a system works very well for controlling large projects
LINE BALANCING The assembly line should be balanced. Each work station should have the same operation time and the various operations should be sequenced properly.
There should be perfect balance between the output rates of the parts and the subassemblies. However, it is not always possible that the parts reach in a steady stream immediately before subassembly. This may be because of the limitations as regards materials, men and equipments or it may be economical to manufacture and supply parts in batches. The flow control section has to cope with such situations and thus carry big inventories and arrange facilities for storage.
LOB is a manual planning and scheduling technique similar in nature to MRP (material resource planning)
LOB is not directly concerned with the resources expended but is utilized in determining production progress in terms of per cent of task completion. Major bottlenecks in the production process are emphasized.
LOB technique can be regarded as a slightly more sophisticated form of the Gantt chart, the objective being to study the progress of jobs at regular intervals, to compare progress on each operation with the progress necessary to satisfy the eventual delivery requirements, and to identify those operations in which progress is unsatisfactory.
LOB technique consists of five main stages, all utilizing graphic aids:
1. A graphical representations of the delivery objective.
The objective chart shows the expected schedule of products (i.e. scheduled deliveries) and the actual completion rate (i.e. actual deliveries made by a date) A dip in actual deliveries line below the scheduled deliveries line is an obvious cause for alarm
2. A chart of the production program showing the sequence and duration of all activities required to produce a product.
· A chart of the operations required to complete one unit of the finished product is called the program plan.
· Each major row of activities is associated with one component of the final assembly
· The final completion date is zero and the time scale runs from right left.
· The completed chart serves as a reference to the amount of lead time by which each event must precede final completion. Events must be completed by their respective lead times to maintain anticipated output.
· Objective chart and Program plan are prerequisites for use of the LOB technique. They need to be constructed only once for any job, unlike the following documents which must be constructed each time the schedule and progress is examined.
3. A progress cart of the current status of component completion.
Progress chart shows the number of items which have been finished at each of the critical or important operations at a given date.The results can then be depicted by means of a histogram
4. A line-of-balance drawn to show the relationship of component progress to the output needed to meet the delivery schedule.
Since the object of the exercise is to compare actual progress with scheduled progress, the information given in progress chart must be compared to required progress. This is done by constructing a line on the progress chart which shows the requisite number of items which should have been finished at each operations at the time of review.
This line-the Line-of-Balance-can be constructed analytically or graphically, the latter method being perhaps the more convenient. The L.O.B., shows the total number of items which should have been finished at each operation.
5. Analysis of progress
In comparing required progress with actual progress it is again convenient to work backwards, beginning with the last operation.If shortage occurs, we must obviously attempt to ascertain the reasons. If operations other than those considered as critical are the cause of shortages, then those operations must be included in subsequent versions of the progress and line-of-balance chart
