Computer Aided Manufacturing

What Does Computer Aided Manufacturing (CAM) Mean?

Graphics courtesy of BPIOpens in new window Computer Aided Manufacturing (CAM) is the use of computer systems to plan, manage and control the operations of a manufacturing plant. It involves all the support that can be provided by the computer in the manufacturing of any given product. This role may be broadly classified into two group:

1. Computer monitoring and control of the manufacturing process.
2. Manufacturing support applications which deal essentially with the preparations for actual manufacturing and post-manufacturing operations.

In the first category are such applications where the computer is directly interfaced with the manufacturing apparatus for monitoring and control functions in the manufacturing process.

For example, in a continuous process industry (chemical processing), a number of process parameters may be monitored. With built-in specifications in the computer memory, suitable actions may be initiated by the computer for the purpose of regulating the process.

Alternately, a human operator looking at the process may initiate the controlling action. This is not restricted to the chemical process industry but could include any other type as well, such as packaging.

In the second category, are all the support functions that computers can provide for the successful completion of manufacturing operations. The types of support that can be envisaged are:

• computer aided design and drafting,

• computer aided process planning,
• computer aided tool design,
• computer aided NC part programming,
• computer aided scheduling,
• computer aided material requirement planning, etc.

In all of these aspects, human beings are required in the application either to give input to the computer programs or to make the computer output for the required action.

Emergence of Computer-Aided Manufacturing (CAM)

By the time the use of in design computer began, NC technology had matured to become cost-effective for applications in machining. An important task in NC is part programming. A part program is simply a set of statements comprehensive to the control unit (MCU) that oversees slide and tool movements and other functions. In the case of components with complex geometries, part programmers had to carry out lengthy calculations, for which it was logical to use compilers. This gave rise to MCUs with built-in microprocessors—the building blocks of computers. The use of computers in extending the applications of NC technology, especially to part programming, was earlier termed computer-aided machining (CAM), and the associated technology was called computer numerical control (CNC). Later, CAM became an acronym for computer-aided manufacturing (note that manufacturing is a broader term than machining). CAM was coined to distinguish computer use in tasks other than design. With increasing use of computers in nondesign functions other than NC, the meaning of CAM has broadened over the years. Earlier, it used to denote computer use in part programming only. Today, it means any nondesign function of manufacturing that is computer-aided. In fact, in the literal sense at least, CAM is as broad in scope as CIM, except that the latter emphasizes integration. Since lack of integration is the main stumbling block to further use of computers in manufacturing. CIM is currently more talked about than CAM.

A second major problem develops over time when small problems cause operators to change the rate at which they run equipment. As these problems continue to build, the equipment output may only be half of that for which it was designed. This inefficiency then leads to the investment of additional capital in equipment, trying to meet the required production output.

2.    Improve Efficiency and Effectiveness

This goal focuses on insuring that maintenance activities that are carried out on the equipment are performed in a way that is cost effective. Studies have shown that nearly one-third of all maintenance activities are wasted. Therefore, this goal of TPM is important to lowering the cost of maintenance.

It is important for all to understand that basic maintenance planning and scheduling are crucial to achieving low-cost maintenance. The goal is to insure lean maintenance, with no waste in the maintenance process.

A secondary goal is to ensure that the maintenance activities are carried out in such a way that they have minimal impact on the up time or unavailability of the equipment. Planning, scheduling, and backlog control are again all important if unnecessary maintenance downtime is to be avoided. At this stage, maintenance and operations must have excellent communication in order to avoid downtime due to misunderstandings.

Developing an accurate database for each piece of equipment’s maintenance history is also the responsibility of the maintenance department. This history will allow the maintenance department to provide accurate data for decisions related to the plant or facility equipment.

For example, the maintenance department can provide input to equipment design and purchase decisions, assuring that equipment standardization is considered.

This aspect alone can contribute significant financial savings to the company. Standardization reduces inventory levels, training requirements, and start-up times. Accurate equipment histories also helps stores and purchasing not only reduce downtime, but also avoid carrying too much inventory.

3.    Early Equipment Management and Maintenance Prevention

The purpose of this goal is to reduce the amount of maintenance required by the equipment. The analogy that can be used here is the difference in the maintenance requirements for a car built in 1970 compared to a car built in 2000.

The 1970 car was tuned up every 30-40,000 miles. The 2000 car is guaranteed for the first 100,000 miles. This change was not brought about by accident. The design engineers carefully studied the maintenance and engineering data, allowing changes to be made in the automobile that reduce the amount of maintenance. The same can be true of equipment in a plant or facility.

Unfortunately, most companies do not keep the data necessary to make these changes, either internally or through the equipment vendor. As a result, unnecessary maintenance is performed on the equipment, raising the overall maintenance cost.

4.    Training to Improve the Skills of All People Involved

Employees must have the skills and knowledge necessary to contribute in a TPM environment. This requirement involves not only the maintenance department personnel, but also the operations personnel. Providing the proper level of training insures that the overall equipment effectiveness is not negatively impacted by any employee who did not have the knowledge or skill necessary to perform job duties.

Once employees have the appropriate skills and knowledge, their input on equipment improvement needs to be solicited by senior management. In most companies, this step only takes the form of a suggestion program. However, it needs to go well beyond that; it should also include a management with an open doors policy. Such a policy indicates that managers from the front line to the top are open and available to listen to and give consideration to employee suggestions.

A step further is the response that should be given to each discussion. It is no longer sufficient to say “That won’t work” or “We are not considering that now.” In order to keep communication flowing freely, reasons must be given.

Therefore, managers must develop and utilize good communication and management skills. Otherwise, employee input will be destroyed and the ability to capitalize on the greatest savings generator in the company will be lost.

5.    Involving Operators (Occupants) in Routine Maintenance

This goal finds maintenance tasks related to the equipment that the operators can take ownership of and perform. These tasks may amount to anywhere from 10-40% of the routine maintenance tasks performed on the equipment.

Maintenance resources that were formerly engaged in these activities can then be redeployed in more advanced maintenance activities such as predictive maintenance or reliability focused maintenance activities.

Cost-Benefit of These Goals

The questions now raised are: Are these goals all worth it? These questions are answered positively and quickly because results are as follows:

Productivity

• 100-200% increases
• 50-100% increase in rates of operation
• 500% decrease in breakdowns

Quality

• 100% decrease in defects
• 50% decrease in client claims

Costs

• 50% decrease in labor costs
• 30% decrease in maintenance costs
• 30% decrease in energy costs

Inventory

• 50% reduction on inventory levels
• 100% increase in inventory turns

Safety

• Elimination of environmental and safety violations

Morale

• 200% increase in suggestions
• Increased participation of employees in small group meetings

With all of these benefits, it is important for all companies to recognize the importance and value that productive maintenance can bring to the company.

Any company trying to achieve World Class status through other programs such as Computer Integrated Manufacturing (CIM)Opens in new window, Just in Time (JIT)Opens in new window, Total Quality Control (TQC)Opens in new window, Total Employee Involvement (TEI)Opens in new window, or Lean ManufacturingOpens in new window, will soon find that these programs will not work without total reliability of the company’s assets, which is the primary responsibility of the maintenance organization. In particular, Just in Time, Total Quality Control, and Total Productive Maintenance are all essential.

Without full utilization of these three programs, the goal of being globally competitive will never be reached.

History of TPM

From where did TPM evolve? What spurred its development? TPM originated in Japan and was an equipment management strategy designed to support the Total Quality Management strategy. The Japanese realized that companies cannot produce a consistent quality product with poorly-maintained equipment.

TPM thus began in the 1950s and focused primarily on the preventive maintenance. As new equipment was installed, the focus was on implementing the preventive maintenance recommendations by the equipment manufacturer. A high value was placed on equipment that operated at designed specifications with no break-downs. During these same years, a research group was formed which later became the Japanese Institute of Plant Management (JIPM)Opens in new window.

During the 1960s, TPM focused on productive maintenance, recognizing the importance of reliability, maintenance, and economic efficiency in plant design. This focus took much of the data collected about equipment during the 1950s and fed it back into the design, procurement, and construction phases of equipment management. By the end of the 1960s, JIPM had established and awarded a PM prize to companies that excelled in maintenance activities.

Then in the 1970s, TPM evolved to a strategy focused on achieving PM efficiency through a comprehensive system based on respect for individuals and total employee participation. It was at this time that “Total” was added to productive maintenance. By the mid-1970s, the Japanese began to teach TPM strategies internationally and were recognized for their results.

This process was an evolutionary one that took time, not because it was technically difficult to produce the results, but because of the efforts to change the organizational culture so that it valued the “Total” concept.