PROJECT MANAGEMENT

7. PROJECT MANAGEMENT
Syllabus
Definition and scope of project, Technical design, Financing, Contracting, Implementation and performance monitoring. Implementation plan for top management, Planning Budget, Procurement Procedures, Construction, Measurement & Verification.
7.1 Introduction
Project management is concerned with the overall planning and co-ordination of a project from conception to completion aimed at meeting the stated requirements and ensuring completion on time, within cost and to required quality standards.
Project management is normally reserved for focused, non-repetitive, time-limited activities with some degree of risk and that are beyond the usual scope of operational activities for which the organization is responsible.
7.2 Steps in Project Management
The various steps in a project management are:
1. Project Definition and Scope
2. Technical Design
3. Financing
4. Contracting
5. Implementation
6. Performance Monitoring
7.2.1 Project Definition and Scope
What is a Project?
“A project is a one-shot, time-limited, goal-directed, major undertaking, requiring the commitment of varied skills and resources”.
A project is a temporary endeavor undertaken to create a unique product or service. A project is temporary in that there is a defined start (the decision to proceed) and a defined end (the achievement of the goals and objectives). Ongoing business or maintenance operations are not projects. Energy conservation projects and process improvement efforts that result in better business processes or more efficient operations can be defined as projects. Projects usually include constraints and risks regarding cost, schedule or performance outcome.

Four Basic Elements of Project Management
A successful Project Manager must simultaneously manage the four basic elements of a project: resources, time, cost, and scope. Each element must be managed effectively. All these elements are interrelated and must be managed together if the project, and the project manager, is to be a success.
Managing Resources
A successful Project Manager must effectively manage the resources assigned to the project. This includes the labor hours of the project team. It also includes managing labor subcontracts and vendors. Managing the people resources means having the right people, with the right skills and the proper tools, in the right quantity at the right time.
However, managing project resources frequently involves more than people management. The project manager must also manage the equipment (cranes, trucks and other heavy equipment) used for the project and the material (pipe, insulation, computers, manuals) assigned to the project.
Managing Time and Schedule
Time management is a critical skill for any successful project manager. The most common cause of bloated project budgets is lack of schedule management. Fortunately there is a lot of software on the market today to help you manage your project schedule or timeline.
Any project can be broken down into a number of tasks that have to be performed. To prepare the project schedule, the project manager has to figure out what the tasks are, how long they will take, what resources they require, and in what order they should be done.
Managing Costs
Often a Project Manager is evaluated on his or her ability to complete a project within budget. The costs include estimated cost, actual cost and variability. Contingency cost takes into account influence of weather, suppliers and design allowances.
How the 80/20 Rule can help a project manager?
The 80/20 Rule means that in anything a few (20 percent) are vital and many (80 percent) are trivial. Successful Project Managers know that 20 percent of the work (the first 10 percent and the last 10 percent) consumes 80 percent of your time and resources.
Project Management Life Cycle
The process flow of Project management processes is shown in Figure 7.1. The various elements of project management life cycle are
a) Need identification
b) Initiation
c) Planning
d) Executing
e) Controlling

f) Closing out
Figure 7.1 Process Flow of a Project Management Process
a) Need Identification
The first step in the project development cycle is to identify components of the project. Projects may be identified both internally and externally:
􀂃 Internal identification takes place when the energy manager identifies a package of energy saving opportunities during the day-to-day energy management activities, or from facility audits.
􀂃 External identification of energy savings can occur through systematic energy audits undertaken by a reputable energy auditor or energy service company.
In screening projects, the following criteria should be used to rank-order project opportunities.
􀂃 Cost-effectiveness of energy savings of complete package of measures (Internal rate of return, net present value, cash flow, average payback)
􀂃 Sustainability of the savings over the life of the equipment.
􀂃 Ease of quantifying, monitoring, and verifying electricity and fuel savings.
􀂃 Availability of technology, and ease of adaptability of the technology to Indian conditions.
􀂃 Other environmental and social cost benefits (such as reduction in local pollutants, e.g. SOx)
b) Initiation
Initiating is the basic processes that should be performed to get the project started. This starting point is critical because those who will deliver the project, those who will use the

project, and those who will have a stake in the project need to reach an agreement on its initiation. Involving all stakeholders in the project phases generally improves the probability of satisfying customer requirements by shared ownership of the project by the stakeholders. The success of the project team depends upon starting with complete and accurate information, management support, and the authorization necessary to manage the project.
c) Planning
The planning phase is considered the most important phase in project management. Project planning defines project activities that will be performed; the products that will be produced, and describes how these activities will be accomplished and managed. Project planning defines each major task, estimates the time, resources and cost required, and provides a framework for management review and control. Planning involves identifying and documenting scope, tasks, schedules, cost, risk, quality, and staffing needs.
The result of the project planning, the project plan, will be an approved, comprehensive document that allows a project team to begin and complete the work necessary to achieve the project goals and objectives. The project plan will address how the project team will manage the project elements. It will provide a high level of confidence in the organization’s ability to meet the scope, timing, cost, and quality requirements by addressing all aspects of the project.
d) Executing
Once a project moves into the execution phase, the project team and all necessary resources to carry out the project should be in place and ready to perform project activities. The project plan is completed and base lined by this time as well. The project team and the project manager’s focus now shifts from planning the project efforts to participating, observing, and analyzing the work being done.
The execution phase is when the work activities of the project plan are executed, resulting in the completion of the project deliverables and achievement of the project objective(s). This phase brings together all of the project management disciplines, resulting in a product or service that will meet the project deliverable requirements and the customers need. During this phase, elements completed in the planning phase are implemented, time is expended, and money is spent.
In short, it means coordinating and managing the project resources while executing the project plan, performing the planned project activities, and ensuring they are completed efficiently.
e) Controlling
Project Control function that involves comparing actual performance with planned performance and taking corrective action to get the desired outcome when there are significant differences. By monitoring and measuring progress regularly, identifying

variances from plan, and taking corrective action if required, project control ensures that project objectives are met.
f) Closing out
Project closeout is performed after all defined project objectives have been met and the customer has formally accepted the project’s deliverables and end product or, in some instances, when a project has been cancelled or terminated early. Although, project closeout is a routine process, it is an important one. By properly completing the project closeout, organizations can benefit from lessons learned and information compiled. The project closeout phase is comprised of contract closeout and administrative closure.
7.2.2 Technical Design
For a project to be taken up for investment, its proponent must present a sound technical feasibility study that identifies the following components:
􀂉 The proposed new technologies, process modifications, equipment replacements and other measures included in the project.
􀂉 Product/technology/material supply chain (e.g., locally available, imported, reliability of supply)
􀂉 Commercial viability of the complete package of measures (internal rate of return, net present value, cash flow, average payback).
􀂉 Any special technical complexities (installation, maintenance, repair), associated skills required.
􀂉 Preliminary designs, including schematics, for all major equipment needed, along with design requirements, manufacturer’s name and contact details, and capital cost estimate.
􀂉 Organizational and management plan for implementation, including timetable, personnel requirements, staff training, project engineering, and other logistical issues.
7.2.3 Financing
When considering a new project, it should be remembered that other departments in the organization would be competing for capital for their projects. However, it is also important to realize that energy efficiency is a major consideration in all types of projects, whether they are:
• Projects designed to improve energy efficiency
• Projects where energy efficiency is not the main objective, but still plays a vital role.
The funding for project is often outside the control of the project manager. However, it is important that you understand the principles behind the provision of scarce funds.
Project funds can be obtained from either internal or external sources.

Internal sources include:
• Direct cash provision from company reserves
• From revenue budget (if payback is less than one year)
• New share capital
Funding can become an issue when energy efficiency projects have previously been given a lower priority than other projects. It is worth remembering that while the prioritization of projects may not be under our control, the quality of the project submission is.
External sources of funds include:
• Bank loans
• Leasing arrangement
• Payment by savings i.e. A deal arranged with equipment supplier
• Energy services contract
• Private finance initiative
The availability of external funds depends on the nature of your organization. The finance charges on the money you borrow will have a bearing on the validity of your project.
Before applying for money, discuss all the options for funding the project with your finance managers.
It is reiterated that energy savings often add substantially to the viability of other non-energy projects.
7.2.4 Contracting
Since a substantial portion of a project is typically executed through contracts, the proper management of contracts is critical to the successful implementation of the project. In this context, the following should be done.
• The competence and capability of all the contractors must be ensured. One weak link can affect the timely performance of the contract.
• Proper discipline must be enforced among contractors and suppliers by insisting that they should develop realistic and detailed resource and time plans that are matching with the project plan.
• Penalties may be imposed for failure to meet contractual obligations. Likewise, incentives may be offered for good performance.
• Help should be extended to contractors and suppliers when they have genuine problems.
• Project authorities must retain independence to off-load contracts (partially or wholly) to other parties where delays are anticipated.
If the project is to implemented by an outside contractor, several types of contract may be used to undertake the installation and commissioning:

􀂃 Traditional Contract: All project specifications are provided to a contractor who purchases and installs equipment at cost plus a mark-up or fixed price.
􀂃 Extended Technical Guarantee/Service: The contractor offers extended guarantees on the performance of selected equipment and / or service/maintenance agreements.
􀂃 Extended Financing Terms: The contractor provides the option of an extended lease or other financing vehicle in which the payment schedule can be based on the expected savings.
􀂃 Guaranteed Saving Performance Contract: All or part of savings is guaranteed by the contractor, and all or part of the costs of equipment and/or services is paid down out of savings as they are achieved.
􀂃 Shared Savings Performance Contract: The contractor provides the financing and is paid an agreed fraction of actual savings as they are achieved. This payment is used to pay down the debt costs of equipment and/or services.
7.2.5 Implementation
The main problems faced by project manager during implementation are poor monitoring of progress, not handling risks and poor cost management.
a) Poor monitoring of progress: Project managers some times tend to spend most of their time in planning activity and surprisingly very less time in following up whether the implementation is following the plan. A proactive report generated by project planner software can really help the project manager to know whether the tasks are progressing as per the plan.
b) Not handling risks: Risks have an uncanny habit of appearing at the least expected time. In spite of the best efforts of a project manager they are bound to happen. Risks need immediate and focused attention. Delay in dealing with risks cause the problem to aggravate and has negative consequences for the project.
c) Poor cost management: A project manager's success is measured by the amount of cost optimization done for a project. Managers frequently do all the cost optimization during the planning stages but fail to follow through during the rest of the stages of the project. The cost graphs in the Project planner software can help a manager to get a update on project cost overflow. The cost variance (The difference between approved cost and the projected cost should be always in the minds of the project managers).

Project Planning Techniques
The three basic project planning techniques are Gantt chart, CPM and PERT. All monitor progress and costs against resource budgets.
Gantt Chart
Gantt charts are also called Bar charts. The use of Gantt charts started during the industrial revolution of the late 1800's. An early industrial engineer named Henry Gantt developed these charts to improve factory efficiency.
Gantt chart is now commonly used for scheduling the tasks and tracking the progress of energy management projects. Gantt charts are developed using bars to represent each task. The length of the bar shows how long the task is expected to take to complete. Duration is easily shown on Gantt charts. Sequence is not well shown on Gantt Charts (Refer Figure 7.2).
Figure 7.2 Gantt Chart
If, for example, the start of Task C depends on both Activity B and Activity E, then any delay to Task E will also delay Task C. We just don't have enough information on the Gantt chart to know this information.
CPM - Critical Path Method
DuPont developed a Critical Path Method (CPM) designed to address the challenge of shutting down chemical plants for maintenance and then restarting the plants once the maintenance had been completed.
Complex project, like the above example, require a series of activities, some of which must be performed sequentially and others that can be performed in parallel with other activities. This collection of series and parallel tasks can be modeled as a network.
CPM models the activities and events of a project as a network. Activities are shown as nodes on the network and events that signify the beginning or ending of activities are shown as arcs or lines between the nodes. The Figure 7.3 shows an example of a CPM network diagram:

Figure 7.3 CPM Diagram
Steps in CPM Project Planning
1. Specify the individual activities.
2. Determine the sequence of those activities.
3. Draw a network diagram.
4. Estimate the completion time for each activity.
5. Identify the critical path (longest path through the network)
6. Update the CPM diagram as the project progresses.
1. Specify the individual activities
All the activities in the project are listed. This list can be used as the basis for adding sequence and duration information in later steps.
2. Determine the sequence of the activities
Some activities are dependent on the completion of other activities. A list of the immediate predecessors of each activity is useful for constructing the CPM network diagram.
3. Draw the Network Diagram
Once the activities and their sequences have been defined, the CPM diagram can be drawn. CPM originally was developed as an activity on node network.
4. Estimate activity completion time
The time required to complete each activity can be estimated using past experience. CPM does not take into account variation in the completion time.
5. Identify the Critical Path
The critical path is the longest-duration path through the network. The significance of the critical path is that the activities that lie on it cannot be delayed without delaying the project. Because of its impact on the entire project, critical path analysis is an important aspect of project planning.
The critical path can be identified by determining the following four parameters for each activity:
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• ES - earliest start time: the earliest time at which the activity can start given that its precedent activities must be completed first.
• EF - earliest finish time, equal to the earliest start time for the activity plus the time required to complete the activity.
• LF - latest finish time: the latest time at which the activity can be completed without delaying the project.
• LS - latest start time, equal to the latest finish time minus the time required to complete the activity.
The slack time for an activity is the time between its earliest and latest start time, or between its earliest and latest finish time. Slack is the amount of time that an activity can be delayed past its earliest start or earliest finish without delaying the project.
The critical path is the path through the project network in which none of the activities have slack, that is, the path for which ES=LS and EF=LF for all activities in the path. A delay in the critical path delays the project. Similarly, to accelerate the project it is necessary to reduce the total time required for the activities in the critical path.
6. Update CPM diagram
As the project progresses, the actual task completion times will be known and the network diagram can be updated to include this information. A new critical path may emerge, and structural changes may be made in the network if project requirements change.
CPM Benefits
• Provides a graphical view of the project.
• Predicts the time required to complete the project.
• Shows which activities are critical to maintaining the schedule and which are not.
CPM Limitations
While CPM is easy to understand and use, it does not consider the time variations that can have a great impact on the completion time of a complex project. CPM was developed for complex but fairly routine projects with minimum uncertainty in the project completion times. For less routine projects there is more uncertainty in the completion times, and this uncertainty limits its usefulness.
PERT
The Program Evaluation and Review Technique (PERT) is a network model that allows for randomness in activity completion times. PERT was developed in the late 1950's for the U.S. Navy's Polaris project having thousands of contractors. It has the potential to reduce both the time and cost required to complete a project.

The Network Diagram
In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed. Project network models represent activities and milestones by arcs and nodes.
PERT is typically represented as an activity on arc network, in which the activities are represented on the lines and milestones on the nodes. The Figure 7.4 shows a simple example of a PERT diagram.
Figure 7.4 PERT Chart
The milestones generally are numbered so that the ending node of an activity has a higher number than the beginning node. Incrementing the numbers by 10 allows for new ones to be inserted without modifying the numbering of the entire diagram. The activities in the above diagram are labeled with letters along with the expected time required to complete the activity.
Steps in the PERT Planning Process
PERT planning involves the following steps:
1. Identify the specific activities and milestones.
2. Determine the proper sequence of the activities.
3. Construct a network diagram.
4. Estimate the time required for each activity.
5. Determine the critical path.
6. Update the PERT chart as the project progresses.
1. Identify activities and milestones
The activities are the tasks required to complete the project. The milestones are the events marking the beginning and end of one or more activities.

2. Determine activity sequence
This step may be combined with the activity identification step since the activity sequence is known for some tasks. Other tasks may require more analysis to determine the exact order in which they must be performed.
3. Construct the Network Diagram
Using the activity sequence information, a network diagram can be drawn showing the sequence of the serial and parallel activities.
4. Estimate activity times
Weeks are a commonly used unit of time for activity completion, but any consistent unit of time can be used.
A distinguishing feature of PERT is its ability to deal with uncertainty in activity completion times. For each activity, the model usually includes three time estimates:
• Optimistic time (OT) - generally the shortest time in which the activity can be completed. (This is what an inexperienced manager believes!)
• Most likely time (MT) - the completion time having the highest probability. This is different from expected time. Seasoned managers have an amazing way of estimating very close to actual data from prior estimation errors.
• Pessimistic time (PT) - the longest time that an activity might require.
The expected time for each activity can be approximated using the following weighted average:
Expected time = (OT + 4 x MT+ PT) / 6
This expected time might be displayed on the network diagram.
Variance for each activity is given by:
[(PT - OT) / 6]2
5. Determine the Critical Path
The critical path is determined by adding the times for the activities in each sequence and determining the longest path in the project. The critical path determines the total time required for the project.
If activities outside the critical path speed up or slow down (within limits), the total project time does not change. The amount of time that a non-critical path activity can be delayed without delaying the project is referred to as slack time.
If the critical path is not immediately obvious, it may be helpful to determine the following four quantities for each activity:
• ES - Earliest Start time
• EF - Earliest Finish time
• LS - Latest Start time

• LF - Latest Finish time
These times are calculated using the expected time for the relevant activities. The ES and EF of each activity are determined by working forward through the network and determining the earliest time at which an activity can start and finish considering its predecessor activities.
The latest start and finish times are the latest times that an activity can start and finish without delaying the project. LS and LF are found by working backward through the network. The difference in the latest and earliest finish of each activity is that activity's slack. The critical path then is the path through the network in which none of the activities have slack.
The variance in the project completion time can be calculated by summing the variances in the completion times of the activities in the critical path. Given this variance, one can calculate the probability that the project will be completed by a certain date.
Since the critical path determines the completion date of the project, the project can be accelerated by adding the resources required to decrease the time for the activities in the critical path. Such a shortening of the project sometimes is referred to as project crashing.
6. Update as project progresses
Make adjustments in the PERT chart as the project progresses. As the project unfolds, the estimated times can be replaced with actual times. In cases where there are delays, additional resources may be needed to stay on schedule and the PERT chart may be modified to reflect the new situation.
Benefits of PERT
PERT is useful because it provides the following information:
• Expected project completion time.
• Probability of completion before a specified date.
• The critical path activities that directly impact the completion time.
• The activities that have slack time and that can lend resources to critical path activities.
• Activities start and end dates.
Limitations of PERT
The following are some of PERT's limitations:
• The activity time estimates are somewhat subjective and depend on judgment. In cases where there is little experience in performing an activity, the numbers may be only a guess. In other cases, if the person or group performing the activity estimates the time there may be bias in the estimate.

• The underestimation of the project completion time due to alternate paths becoming critical is perhaps the most serious.
7.2.6 Performance Monitoring
Once the project is completed, performance review should be done periodically to compare actual performance with projected performance. Feedback on project is useful in several ways:
a) It helps us to know how realistic were the assumptions underlying the project
b) It provides a documented log of experience that is highly valuable in decision making in future projects
c) It suggests corrective action to be taken in the light of actual performance
d) It helps in uncovering judgmental biases
e) It includes a desired caution among project sponsors.
Performance Indicators (PIs) are an effective way of communicating a project’s benefits, usually as part of a performance measuring and reporting process. Performance Indicators are available for a wide range of industries and allow a measure of energy performance to be assigned to a process against which others can be judged.
Depending on the nature of the project, savings are determined using engineering calculations, or through metering and monitoring, utility meter billing analysis, or computer simulations.
Implementation Plan for Top Management
As a result of energy audit, many energy saving opportunities would emerge. These could be classified broadly as measures with and without investment. House keeping measures and moderate cost measures need no intervention from top management. However, top management need to be appraised of these measures.
In case of projects where considerable investment are required, project manager has to rank the list of projects based on the technical feasibility and financial analysis indicated in the previous chapter (Simple payback, IRR, ROI etc.) and submit the same to the top management for appraisal and approval. This will help top management in allocating resources and other facilities.
Planning Budget
Budget requirement varies depending upon the duration and size of the project. For projects involving long duration with multiple tasks and procurements, resources have to be allocated judiciously as and when required. Top management should ensure that this is done to ensure successful completion of project.

Procurement Procedures
Having identified the material and equipment required for the project, the next step is to identify the various vendors, provide specifications, invite quotations, and carryout discussions with select vendors. For medium to high value items, tendering process can be adopted. Tenders have to be evaluated for technical and financial aspects. It would be desirable to have purchase manager as part of energy efficiency team to facilitate smooth procurement process.
Construction
During the construction phase, plant may need to be shutdown. Careful planning is required, so that the task is carried out without affecting the production. Project manager has to be aware of the annual maintenance schedule, holidays, annual maintenance or any major breakdown period during which anyway plant will be shutdown. Construction activity should be carefully supervised by energy and project manager so as to ensure quality and safety.
Measurement & Verification (M&V)
Facility energy savings are determined by comparing the energy use before and after the installation of energy conservation measures. The “before” case is called the baseline; the “after” case is referred to as the post-installation or performance period. Proper determination of savings includes adjusting for changes that affect energy use but that are not caused by the conservation measures. Such adjustments may account for differences in capacity utilization, raw material quality, product mix and other parameters, between the baseline and performance periods.
In general,
Savings = (Baseline Energy Use)adjusted - Post-Installation Energy Use
For example in a paper mill a variety of products depending on thickness (Grams per Square meter) are made. If energy consumption is evaluated as kCals or kWh per tonne of paper the figures could be misleading. Under these circumstances the measurement and verification system is to be designed accounting for these variations.

The Figure 7.5 shows a Gantt chart for a simple energy management project, i.e. Replacing an existing boiler with an energy efficient boiler.
As already mentioned, Gantt chart is the simplest and quickest method for formal planning. Gantt charts can be very useful in planning projects with a limited number of tasks and with few inter-relationships. This chart typically depicts activities as horizontal lines whose length depends on the time needed to complete the activities. These lines can be progressively overprinted to show how much of activity has been completed.
Drawing a Gantt chart requires information on:
􀂃 The logic of the tasks;
􀂃 The duration of the tasks;
􀂃 The resources available to complete the tasks.

􀀹 10/10: In this Numerator denotes the Earliest Event Occurrence Time and Denominator is the Latest Event Occurrence Time.
􀀹 The Critical Path for this network is: A-B-C-D-I-J.
􀀹 The events on the critical path have zero slack.
􀀹 Dummy activity has no duration
􀀹 The total duration for the completion of the project is 110 days based on the critical path.
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QUESTIONS
1.
List down various steps in project management.
2.
Describe briefly any of the projects you have undertaken and how was the project managed?
3.
What are the criteria for screening of projects?
4.
What are the aspects you would look for in the technical design of the project?
5.
What are the ways in which financing can be enabled for an energy efficiency investment?
6.
What are the aspects to be considered in the management of contract?
7.
Briefly explain the different types of contracts.
8.
What are the hurdles faced in the implementation of a project?
9.
Make a Gantt chart for your preparation of energy manager/energy auditor examination. Split into to as many components as possible.
10.
In project management PERT refers to
(a) Project Energy Rating Time (b) Projected Energy Rating Terms (c) Petroleum Energy Revolutionary Technology (d) Program Evaluation and Review Technique.
11.
Explain the importance of performance monitoring.
12.
Explain the need for measurement and verification.
REFERENCES
1. Principles of Project Management, NPC publication
2. Project Management, Tata McGraw Hill – S.Choudhury
3. Projects: Planning, Analysis, Selection, Implementation and Review, Tata McGraw Hill – S.Choudhury

CASTING PROCESS

CASTING PROCESS

1:Basic steps

Industrialprocess

·          Description
The metal casting process has been divided into the following five major operations:

                                                                         Obtaining the Casting Geometry :
The process is referred as the study of the geometry of parts and plans, so as to improve the life and quality of casting.

·         Casting Patternmaking :
In pattern making, a physical model of casting, i.e. a pattern is used to make the mold. The mold is made by packing some readily formed aggregated materials, like molding sand, around the pattern. After the pattern is withdrawn, its imprint leaves the mold cavity that is ultimately filled with metal to become the casting.
n case, the castings is required to be hollow, such as in the case of pipe fittings, additional patterns, known as cores, are used to develop these cavities.

·         Coremaking & Molding :

In core making, cores are formed, (usually of sand) that are placed into a mold cavity to form the interior surface of the casting. Thus the annul space between the mold-cavity surface and the core is what finally becomes the casting.
Molding is a process that consists of different operations essential to develop a mold for receiving molten metal.

·         Alloy Melting and Pouring :
Melting is a process of preparing the molten material for casting. It is generally done in a specifically designated part of foundry, and the molten metal is transported to the pouring area wherein the molds are filled.

·         Casting Cleaning :
Cleaning is a process that refers to the different activities performed for the removal of sand, scale, and excess metal from the casting.
However, all the operations may not apply to each casting method but such processes play an important role to comply with environmental guidelines.

Obtaining the Casting Geometry

A foundry may pour a casting having little knowledge of how a casting cools down or how the metal freezes within the mold. However, if proper planning is not done the result can be gas or shrink porosity within the casting. To improve the quality of a casting the foundry engineer studies the geometry of the part and plans how the heat removal is to be controlled.

It is important to find the suitable casting geometry so as to meet the structural and solidification shrinkage needs. For some alloys, finding the right geometry can be very simple. For other alloys, obtaining that geometry is the real essence of superior casting design. In the case, that geometry is not found for difficult alloys, the foundry engineer should resort to "thermal trickery" to achieve fluid flow and heat transfer patterns, which the geometry fails to deliver.

Thermal trickery is a highly effective technique but is expensive. By eliminating thermal trickery with good design, it is possibleto achieve cost less production, processing and assembly.

The conventional method of obtaining the casting geometry is by sending blueprint drawings to the foundry. However, the development of computer hardware and software for making and analyzing solid models has enabled a quantum leap in the use of section modules to add features like increase in the stiffness of structural components and reducing the stress within them. In fact, these tools are making the power of metal casting geometry much more accessible to design engineers because they enhance significantly the ability to visualize in three dimensions. Casting Geometry plays a significant role in the casting yield.

Advantages of Good Casting Geometry

·         Reduces defects, post casting operations, and rejected castings

·         Significantly reduce energy and environmental impacts

·         Saves energy

·         Improves overall quality and life of casting

·         Casting Patternmaking

·         It's the science of making an original pattern or form which will be used to make a mold. The mold will allow for mass production of the original pattern by poring some sort of casting material such as metal, resin, plaster, or other material. A pattern can be both simple and complex for e.g an object that has detail on only one side like a plaque, or with detail on all sides, like a machine part. Factors that go into making a pattern includes durability, shrinkage, machine allowances, draft and undercuts.

In sand casting, the pattern is usually of wood, whereas it may be of metal or other materials in pressure or centrifugal casting. The patternmaker also decides where the sprues and risers (inlet and outlet for molten material) will be placed with respect to the pattern. Objects which have holes or depressions in some of its parts are taken care of by inserting cores. Sometimes patterns may also contain chills, solid pieces of the final material, to enable rapid cooling, resulting in quench hardening in the neighborhood of the chill.

As sand casting methods have paved the way for die casting and thin mold casting (the mold is made of a thin, workable refractory material), patterns are not much in use today, though they may still be used for small or specialized jobs.

Coremaking & Molding

Molds by themselves can only have the external shape of the pattern. That is why cores are placed inside the mold to form internal cavities. Cores are produced in a core box, which is a permanent mold, developed in tandem with the pattern. It helps in flowing the molten metal to all sides of the cores.

Cores are supported either on core prints or by metal supports called chaplets. Generally the foundry molds are made of sand grains bonded together to form the desired shape of the casting. Sand is used because it is cheap, resists deformation when heated, offers a great variety of casting sizes and complexities. It also offers the added advantage of reuse of a large portion of the sand in future molds. However pattern making, melting, cleaning, and finishing operations are essentially the same whether or not sand molds are used in the casting process.

Alloy Melting and Pouring

The preparation of molten metal for casting is referred to as melting. It is usually done in a specifically designated area of the foundry, and the molten metal is transferred to the pouring area where the molds are filled. Melting may be done by gas or electricity. Various methods of pouring the molten metal are in use (e.g. gravity pouring, bottom pouring, vacuum or pressure assisted pouring).

The melting process begins with the metal specification for the casting, determining the type of scrap metal to be used to 'charge' the furnace. Once charged, the furnace uses electrodes, each supplying roughly 6,500 amps of electricity, to melt the scrap metal. Samples are taken at various points in the melt process, to ascertain the chemical composition of the molten metal. Using a spectrometer as a guide, alloys are added to the furnace to bring the molten metal to the proper specification.

At a temperature of around 3,000° F the metal reaches the desired specification. It is then poured into a preheated ladle for transfer to the pouring lines. At the pouring lines, molten metal is 'poured' into the requisite molds. Due to the lifting pressure of molten steel, molds will often be 'weighted' or 'clamped' to prevent them from separating at the Cope/Drag meeting point. Thereafter, the mold is allowed to cool for approximately 30 minutes before it is taken to the shakeout. Poured molds are then dumped into a vibrating conveyor, wherein they are broken up by the vibration, exposing the casting for removal.

Finally the sand from the mold is separated and processed through a reclamation system for further use.

Casting Cleaning

The fifth and the final stage of casting process is cleaning. The process refers to different activities that are performed to remove the sand, scale and excess metal from the casting. Some of the activities performed in cleaning are -

·         The casting is separated from the mold and transported to the cleaning department.

·         Burned-on sand and scale are removed.

·         Excess metal is removed (Fins, wires, parting line fins, and gates).

·         Subsequently the casting can be upgraded using welding or other such as procedures.

·         Final testing and inspection to check for any defects.

Advantages:

·         Improves the surface appearance and finish of casting

·         Improves overall quality and functionality by removing impurities, such as sand, scale and excess metal

Finally the sand from the mold is separated and processed through a reclamation system for further use.

Molds and Die Making

The change in cultural patterns and increase in outsourcing to different less developed countries has led to a drastic reformation in the industry of dies and molds. Let us see what all is required to excel in this new milieu.

The globalization is having an adverse effect on the local die and mold industry, which already is a tough and competitive business. The mold and die makers need to reorient their plans in order to meet the new standards. The process is already begun with various companies, which are either small or medium in size, entering into new supportive and collaborative efforts. Various syndications and acquisitions taking place substantiate this change.

Earlier tool making was considered as a highly skillful art. But not anymore today. With the advent of new technological tools like parametric modeling in 3D, tooling at rapid pace and machining at high speed etc, anybody can enter into tool making using right blend of these technological tools. The business structures of yore are fast becoming redundant and the need of the hour is to focus on value instead of cost, to make progress. The tool and die makers should target suitable markets. They should also invest in developing products, which are specialized materials, in proper course of action and of course on the cognizance of the customers' needs. Summarily, the whole competition should be on value rather than cost.

Consultant Glenn Beall advised Modern Plastics that although quite a few processors have tried to aggrandize their businesses by taking care of various additional services like inventory facility, doing finishing making of packages, assembling and even decorating for their original equipment manufacturers (OEM), it is not good enough. Providing additional services would only be useful and beneficial if they are coupled with some specialty like provision of an in-house or internal painting line or perhaps the capability of electroplating. Mere offering of more services is not tantamount to adding value.

To obtain the end products in mold and die making a flow process, which is uninterrupted, is applied on a mixture, which can bind and also be used again. Such a mixture mainly consists of ventonite clay, a lubricant like oil, and sand. All of these are mixed together in such a way that on the mixture the desired impressions can be made to form back to back molds and dies. The mixture is then made to move through many zones wherein some work is performed on them. This is accomplished by using a conveyor belt, which takes the mixture through these zones. The conveyor belt is again required for spreading of mixture on it.

The process of smoothening and rolling is carried out to make the mixture uniform and consistent according to the specifications. After that a mold maker is used to impress upon the mixture in order to get mold or dies. Further, a material, which can harden the mold or die, is injected into it.

Whole of the product is then heated so that finished and cured product can be obtained from the hardenable material. The mixture is then finally separated from the final product that is cured and finished, and is transferred back to the stage from where the entire process started. Again another conveyor belt is used for transferring the mixture. The mixture again goes through the same steps to form finished products like structural material.

Offshore outsourcing of manufacturing by the automobile sector has also contributed greatly to the decline of the traditional strategies. The ones who have suffered the most because of this transportation to other economical locations are small shops, which are owned by families and employ about 5 to 100 workers. The reason being a large dependence of mold and die makers on the transportation industry, particularly automotive.

The subcontracting to other economical locations has come as a bane for the tool shops that are small. Statistics reveal that North America has lost somewhere around 150,000 jobs of tooling since 2000 just because of this outsourcing. The reason is obvious from the fact that around 60% of stamping dies and about 40% of plastic molds are engaged directly or indirectly by the automotive industry worldwide. Apart from this, over a period of five years, the market of machinery used for molding injections has gone down by about 50% in United States.

It can thus be inferred from all this data that the industry of molds and dies has ceased to be merely a skillful occupation. In fact, it has graduated into becoming a very competitive, multifaceted business. Survival and rise in this industry today would only be possible if the people involved pay attention to certain new parameters. These parameters include devoting their energies to a particular skill, strengthening their services, trying to make their products more valuable, and of course seeking markets, which could be their forte.

Hot Forming Process

Hot forming process is used very frequently for casting of industrial products and parts. In this process, heat is applied to soften the piece of metal. This metal or raw material is available in the form of sheet, bar, tube or wire. Then some form of pressure is used to alter the shape of the metal. The hot forming process can form a variety of complex parts and hold relatively tight tolerances.

Most of the hot forming processes are complex in nature and involves adiabatic heating, die chill and microstructural changes. Hot forming process includes various operations in the manufacturing of high quality, critical components and parts. In most cases, the cost-effective production of near-net shape components depends on the interactions between casting, ingot breakdown, extrusion, closed-die forging, heat treatment and machining.

Advantages

·         The metal "springback" effect is reduced and the part's ductility is improved.

·         The desired shape is achieved with relatively low pressure and minimal residual part stress.

·         Produces superior grain flow and microstructure that improves the part's mechanical properties.

·         Relatively high production rates with minimal defects.

The following casting processes can be categorized under Hot Forming Process:

·         Centrifugal Casting

·         Ceramic Mold Casting

·         Extrusion

·         Forging

·         Full Mold Casting

·         Investment Casting

·         Permanent Mold Cast

·         Plaster Mold Casting

·         Powder Metallurgy

·         Sand Casting

·         Shell Mold Casting

Centrifugal Casting

Related Pages

·         Centrifuging

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·         Semi Centrifugal Casting

This process can be categorized as similar to that of permanent mold method. Here as the molten metal is being poured, a permanent metal mold revolves about its axis at high speeds ranging from 300 to 3000 rpm. This can be in horizontal, vertical or inclined positions. As a result, the molten metal is centrifugally thrown towards the inside mold wall. There it solidifies after cooling. It's usually a fine grain casting with a very fine-grained outer diameter.

Molds for centrifugal castings can be divided into three types.

The Permanent Mold: Made of steel, iron or graphite. Inside surface is coated with a thin refractory wash to increase mold life. The mold is preheated before coating, so as to dry the coating and improve the adherence to the mold surface.

Rammed Mold: It consists of a steel metal flask, lined with a layer of refractory molding mix. The inside lining is coated with a refractory wash which is baked until dry and hard.

Spun or Centrifugally Cast Mold: In the metal flask a predetermined mass of refractory material in slurry form is poured.

The flask on rotation makes the refractory materials centrifuged onto the wall of the flask. The rotation is stopped and the liquid portion of the slurry drained off. It leaves the mold with a refractory coating, to be baked until dry before use.

Features of Centrifugal Casting

·         Castings can be made in almost any length, thickness and diameter.

·         Different wall thicknesses can be produced from the same size mold.

·         Eliminates the need for cores.

·         Resistant to atmospheric corrosion, a typical situation with pipes.

·         Mechanical properties of centrifugal castings are excellent.

·         Only cylindrical shapes can be produced with this process.

·         Size limits are upto 3 m (10 feet) diameter and 15 m (50 feet) length.

·         Wall thickness range from 2.5 mm to 125 mm (0.1 - 5.0 in).

·         Tolerance limit: on the OD can be 2.5 mm (0.1 in) on the ID can be 3.8 mm (0.15 in).

·         Surface finish ranges from 2.5 mm to 12.5 mm (0.1 - 0.5 in) rms.

Applications of Centrifugal Casting:
Typical materials that can be cast with this process are iron, steel, stainless steels and alloys of aluminum, copper and nickel. Two materials can be cast by introducing a second material during the process. Typical parts made by this process are pipes, boilers, pressure vessels, flywheels, cylinder liners and other parts that are axi-symmetric.

There are two types of Centrifugal Casting:

·         Semi-Centrifugal Casting

·         Centrifuging

Ceramic Mold Casting

This process use a method very near to plaster mold casting. Plaster, plastic, wood, metal or rubber is used for making the pattern.

A ceramic slurry comprising zircon, fused silica and a bonding agent is first poured over the pattern. Like rubber it hardens quickly. It is then peeled of the pattern and reassembled as a mold. The volatile materials are removed in a low temperature oven. Ceramic mold, with high temperature pours is obtained after it is baked in a furnace at about 1000 °C (1832 °F) .

Features of Ceramic Mold Casting

·         Tolerances: 0.4 %,

·         Surface finish: 2 - 4 µm (.075 - .15 µin)

·         Wall thickness: may be as small as 1.25 mm (.050 in),

·         Weights: Range from 60 g (2oz) to a 1000kg

·         Draft allowance: 1° recommended.

·         Patterns: Reusable and cheap.

·         Casting size: generally not restricted except above 100 lb

Ceramic Mold Casting can be performed by two distinct procedures:
True Ceramic Molding: Here, the refractory grain is first bonded with calcium or ammonium phosphates. The ceramic molds are generally made by the dry pressing method. Where molds are made by pressing clay mixture with some percentage of moisture in dies under a pressure of 1-10 ton/sq inch. The mold is finally ready after they are stripped from the dies and baked in a furnace at temperatures that range between 1650-2400°F (899°C and 1316°C).

Shaw Process: Shaw process or the Ethyl silicate variation takes place in the following way. A consistent slurry is made by blending together a mixture of graded refractory filler, hydrolyzed ethyl silicate, and a liquid catalyst. It is then poured in the pattern and allowed to jell. After this, the mold is stripped and heated using a high pressure gas torch. It is then cooled, assembled and fired before pouring is done. Some times the Shaw process and the lost wax process are used in combination to gain the advantages of both the processes.

Application of Ceramic Mold Casting
Parts made from this process include impellers, complex cutting tools, plastic mold tooling etc.

Extrusion Process

Extrusion process is used for manufacturing long and straight metal parts. The shape of the cross-sections can be solid round, rectangular, to T shapes, L shapes and Tubes etc. Extrusion is done by squeezing the metal in a die by using a mechanical or hydraulic press.

Extrusion is capable of producing compressive and shear forces in the stock material. As tensile is not produced, this makes very high deformity a possibility without actually tearing the metal. A wear resistant material lines the cavity in which the raw material is contained . This helps to resist the high radial loads as the material is pushed into the die.
Features of Extrusion Process:

·         Cost effective: Minimizes the need for secondary machining process.

·         Surface finish: For steel is 3 µm; (125 µ in), for Aluminum and Magnesium -0.8 µm (30 µ in).

·         Cross-section: Wide variety of cross-sections can be made.

·         Minimum thickness: For steel 3 mm (0.120 in), for Aluminum and Magnesium 1mm (0.040 in).

·         Minimum cross section: For steel 250 mm (0.4 in) for steel.

·         Corner and fillet radii: 0.4 mm (0.015 in) for Aluminum and Magnesium, for steel the minimum corner radius is 0.8mm (0.030 in) and 4 mm (0.120 in) fillet radius.

An example of Hot Extrusion Process using Aluminium Alloy is briefly described here:
The alloyed press bars are cut into smaller pieces and heated up in an induction furnace to 450ñ500°C. The bar is then pressed with very high force using speeds between 5ñ50 m/min through a hollowed tool. As a result a profile is formed. The length of the profile ranges between 25ñ45 m. Immediately after the pressing operation, profile is cooled with air or water.

The profile is straightened and internal stresses released by stretching it in a pulling machine just after cooling. The profile is then cut into required lengths. Finally ageing gives the strength of the material. Which can be done by natural ageing at normal temperature or artificial ageing done at elevated temperature of 170ñ185°C.

Application of Extrusion Process: Trim parts as used in automobile and construction equipment, railings, window frame members, structural parts etc.

Extrusion can be of two types
Hot Extrusion
Generally done at fairly high temperatures, approximately at 50 to 75 % of the melting point of the metal. The pressures range from 35-700 MPa (5076 - 101,525 psi). To cool down the high temperatures and pressures and its adverse effect on the die life as well as other components, good lubrication is a must. Oil graphite and glass powder is preferred as lubricants.

Application of Hot Extrusion:
Aluminium, copper with their alloys are successfully used to manufacture products using hot extrusion process. Electrical wires, bars and tubes are some of the items produced.

Cold Extrusion
Cold extrusion takes place at room temperature or slightly elevated temperatures. This process is useful for withstanding the stresses created by extrusion.

The advantages of cold extrusion are:

·         No oxidation process .

·         Good mechanical properties provided the temperatures created are below the re-crystallization temperature. Good surface finish

Application of Cold Extrusion:
Examples of the metals that can be extruded are copper, lead, tin, aluminum alloys, titanium, molybdenum, vanadium, steel. Which are used to make parts like collapsible tubes, gear blanks, aluminum cans, cylinders etc.

In automobile sector they have found wide applications in Injection technology; Engine control; Fuel supply; Automatic transmissions Seat technology; Safety systems (restraint systems).

Forging Process

Related Pages

·         Impression Die Forgings

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·         Net Shape

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·         Open Die Forgings

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·         Press Forgings

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·         Roll Forgings

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·         Swaging

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·         Upset Forgings

Forging technology occupies a very important place among all the manufacturing processes as it produces parts with excellent properties and with minimal wastage. Through a series of operations, metals with very simple geometry are physically deformed into products of complex configuration.

In the forging process the metal is heated up by applying compressive force and given shape by plastic deformation. The compressive force is applied by hammer blows using a power hammer or a press. Powered by compressed air, hydraulics electricity or steam. The weight of the hammer can be 500 pounds to thousands of pounds. Forging has the capacity to refine the grain structure and improve the physical properties of the metal.

Forging products are consistent, without the defects of porosity, inclusion or voids, finishing operations like machining and coating operations like painting or plating can also be done very easily.

Typically a forged metal results in the following:

·         Drawing Out of the Metal: Increased length decreased cross-section.

·         Upsetting the Metal: Decrease in length decreased cross-section.

·         Change in Length; Change in Cross-section: Resulting in favourable grain flow for strong parts.

Tips for Selecting the Right Forging Technology

·         Technology to remain competitive must come out with cost effective alternatives. That is the reason computer aided techniques like CAD, CAM, CAE and Finite Element Analysis (FEA) based computer simulation, are used to selecting the right forging process.

·         Understanding the forged material's flow behaviour under processing conditions.

·         Knowledge of the die geometry and materials.

·         Environmental considerations.

·         Evaluating the mechanics of deformation process-stress and strain.

·         Friction and Lubricating process.

·         Nature of the Forging equipment.

Applications of Forging Process:
Wide variety of uses in different kinds of Industries:

Automobile Industry: Wheel spindles, kingpins, axle beams and shafts, torsion bars, ball studs, idler arms and steering arm.

Agro-Industries: Engine and transmission components, levers, gears, shafts and spindles to tie-rod ends, spike harrow teeth and cultivator shafts.

Aerospace: Bulkheads, hinges, wing roots, engine mounts, brackets, beams, shafts, landing gear cylinders and struts, wheels, brake carriers and discs and arresting hooks, blades, buckets couplings etc.

Hand Tools: Sledges, pliers, hammers, wrenches and garden tools, as well as wire-rope clips, sockets, hooks, turnbuckles and eye bolts are common examples.

Industrial Equipment: Connecting rods, blanks, blocks, cylinders, discs, elbows, rings, T's, shafts and sleeves.

Methods of Forging

·         Impression Die Forgings

·         Net Shape

·         Open Die Forgings

·         Press Forgings

·         Roll Forgings

·         Swaging

·         Upset Forgings

Full Mold Casting

Full-mold casting technique is quite similar to investment casting, but here polystyrene foam is used as the pattern. The foam pattern is laced with a refractory material. The pattern is put in an encasing of one-piece sand mold, during the pouring of the metal. The foam vaporizes and its place is taken by the metal.
Features

·         Complex shaped castings: Possible without any draft or flash.

·         Minimum wall thicknesses: 2.5 mm

·         Tolerances: Can be held to 3% on dimensions.

·         Surface finish: From 2.5µm to 25µm (0.1µin to 1.0 µin) rms.

·         Size limits: From 400 g (1 lb) to several tons.

·         Draft allowance: Required.

Application of Full Mold Casting:
Materials cast with this process are aluminum, iron, steels, nickel alloys, copper alloys to produce pump housings, manifolds, and auto brake components.

This process is commonly known as the lost wax casting process. It got its name because of the fact that ancient Egyptians used it to make gold jewelry hence the name Investment. Very intricate shapes with high accuracy can be made in this process.

Additionally metals which are hard to machine or fabricate can be cast with this process. Parts that cannot be produced otherwise by normal manufacturing processes like turbine blades with complex shapes, or airplane parts that needs to withstand high temperatures are examples of this process.

(A) The pattern assembly is covered with ceramic to produce a monolithic mold

(B) Melting the assembly for a precise mold cavity; firing the mold to remove residues of the pattern; developing the bond and preheating the mold ready for casting; pouring

(C) Finally knockout, cutoff and finishing processes.

The process works like this first a mold is made by making a pattern. Wax or some other materials can be used that can be melted away. The wax pattern is dipped in refractory slurry, which coats the wax pattern and a skin is subsequently formed. It is then dried. The process of dipping in the slurry and drying is continued till a firm thickness is achieved. The pattern is placed in an oven and the wax melted. This leads to a mold which can be easily filled with the molten metal.

The wax pattern can be made by a duplicating process using a stereo lithography or a similar model that has been fabricated by a computerized solid model master.

The slurry materials used are a mixture of plaster of Paris, a binder and, a refractory material. Powdered silica is used for low temperature melts. For higher temperature melts, an alumina-silicate is used as the refractory material. While silica is used as a binder. Additional coatings of sillimanite and ethyl silicate may be applied to increase the quality of the finished product.. The mold thus produced is ready for use as light castings. It may be reinforced by placing it in a bigger container and adding more slurry.

Before the pouring operation, the mold is pre-heated at about 1000ºC (1832ºF) to remove traces of wax. Pouring can be done in gravity, pressure or vacuum conditions. Mold permeability factor is to be kept in mind when using pressure, to allow the air to escape as the pouring is made.

Features of Investment Casting

·         Allows undercuts in the pattern

·         Tolerances of 0.5 % of length are possible, and for small dimensions it can be as low as 0.15%.

·         Weight of the castings can range from a few grams to 35 kg (0.1 oz to 80 lb)

·         Minimum wall thicknesses are about 1 mm to 0.5 mm (0.040-0.020 in)

·         Parts do not require machining because of the closer tolerances.

·         Smooth surface finish.

·         Excellent production rates, particularly for small components

·         Thorough dimensional accuracy and consistency

·         High integrity castings

·         Machining can be eliminated

·         Minimal shot blast and grinding needed

Application of Investment Casting:
Typically materials that can be cast with this process are Aluminum alloys, Bronzes, Stainless steels, Stellite etc. Glass mold accessory castings, Valves and fittings, Gears, Levers and Splines are some of the popular usages.


The steps as depicted in the figures include: Making of heat-disposable wax or plastic patterns, and assembling them onto the gating system

Limitations
Time consuming process and costly. Exceptional surface finish possible but minute lacuna can cause rejection of castings as a result scrap rates can be high.

Few important tips before starting with an Investment casting process ·         Follow instructions carefully and seek the advice of investment casting experts. ·         Start with a reasonable size casting. Bigger projects are harder and can take longer periods. For example Ring or jewelry-sized castings can be made easily with Investment casting process. ·         Start early:The process takes a long time, and castings don’t always come out easily that is the reason for starting early.

Permanent Mold Cast

This process utilizes, a metal as the mold material. Ideally cast iron or Meehanite (a dense cast iron) is used. Metal or sand is used for cores. Thin layers of Clay or sodium silicate is used for coating the cavity surfaces, as they are heat resistant. The molds are pre-heated at a temperature upto 200ºC (392ºF) before the metal is poured into the cavity. Proper precaution is needed for ensuring thermal balance. This can be facilitated by using external water cooling or suitable radiation techniques.

Features of Permanent Mold Cast:

·         Allows use of different patterns.

·         Lowers cost of production, although that depends upon the complexity of the part produced.

·         Wall Thickness - typical considerations apply here such as 3mm for lengths under 75 mm), radius (inside radius = nominal wall thickness, outside radius = 3 x nominal wall thickness)

·         Draft Angles - 1 to 3º on outside surfaces, 2 to 5º on inside surfaces)

·         Tolerance is 2% of linear dimensions.

·         Surface Finish ranges from 2.5 µm to 7.5 µm (100 µin to 250 µin).

·         Part Sizes range from 50 g to 70 kg (1.5 ounces to 150 lb).

·         Casting method is clean with little waste and no fumes. The process avoids the contamination problems that generally sand foundries deal with.

Application of Permanent Mold Cast:
Most common materials used are small and medium sized parts made of aluminum, magnesium and brass. Products include gears, splines, wheels, gear housings, pipe fittings, fuel injection housings, and automotive engine pistons.

Permanent Mold Castings can take various forms such as:

Slush Casting
A special type of permanent mold casting, where the molten metal is not solidified completely. After obtaining the desired wall thickness the semi- solidified molten metal is poured out.

Useful for making hollow ornamental objects such as lamps, candlesticks, statues etc.

Low Pressure Permanent Mold Casting
Yet another variation of the permanent mold casting. Instead of using gravity to help in the metal pour and flow, a low pressure of 1 atmosphere gas is applied to the molten metal. The pressure on the melt causes the mold to be completely filled up and compensates for any shrinkage on cooling. Mechanical properties are superior to permanent mold casting by about 5%.

Vacuum Permanent Mold Casting
Also a variation of the permanent mold casting. Thin wall castings can be made here. The yields are generally high since no risers are used. The mechanical properties are better than the traditional permanent mold casting by 10-15% Castings sizes can range from 200 g to 4.5 kg (6 oz to 10 lb).