Tuesday, July 8, 2008

CAM: A Vital Component of CNC

Computer Aided Manufacturing started being used by automotive and aerospace component manufacturing companies. This sped up the manufacturing process and thus increased efficiency ratings. However, the introduction of CAD into the industrial sector did not eliminate the need for skilled professionals.

In fact, the operation of this program requires a higher degree of skill in terms of being computer literate.

Flaws

The CAM system is a flawless solution. However speedy the system becomes, it still has faults that may hamper production. Since CAM generates a code for the least capable machine, an improperly set CAM software required heavy manual editing. In this case, editing such a code is a tedious and drawn-out process that takes a lot of time and effort (something that big-time companies cannot spare).

Another problem that you have to face is the data exchange that has to take place when integrating CAM with other components (CAD/CAM/CAE PLM). It becomes necessary for the CAM operator to export the data in a more compatible data format. And since the output stack of CAM is a G-code text file—sometimes containing thousands of commands—the operator is then faced with a very serious time problem.

CAM cannot reason. In this case, it cannot figure out the right toolpath for mass production. Operators would still have to select the type of tool to be used, the machining process that should be followed, and the path to be used. This means that the CAM cannot adjust to wear issues and sudden changes. It needs to be reprogrammed to be able to work efficiently. Furthermore, mass production increases the likelihood of errors to occur in the production cycle.

PROS

CAM can cut cycle time significantly. This means that with the proper people and the proper tools, a more efficient production method can be obtained. A lower cycle time means that you can produce more components in a lesser time. And since the main users of CAM and CNC are big manufacturers with deadlines, it is of the utmost priority to cut cycle time.

Another advantage that could be gained by CAM software is the increase in machine life. Since the process is automated, the system can keep track of certain variables that allow it to adjust to the conditions of the machine that is operating under it. This means that the life of the machine can be extended by adjusting the performance of the machine in order to avoid overworking it.

Quality can also be taken into account in this scenario. It is because the system also monitors slight differences in the production environment. Furthermore, the intricate designs that cannot be achieved by human engineers can be achieved by the machines. Also, these designs can be completed at a faster rate compared to manual operations. Another factor that should be considered would be the error ratio of the production of any components.

Conclusion

So, CAM is a very important aspect of production. However, the need for skilled operators still exists as programming and setting up these machines decide the fate of the manufacturing process. However, the increased automation and efficiency provided by such a system makes programming and setting up of these systems the only jobs of the operators.

This also allows operators to be more productive as they do not have to watch any single machine for more than the required amount of time.

How To Effectively Consider CNC

In the employment world, the phrase “manual labor” is often associated with jobs which are dirty, psychologically sickening, or worse, both. Small to medium-size manufacturing enterprises are moving towards using the CNC(Computer Numerical Control) in their major manufacturing processes because of its fame in accuracy, flexibility and automation. If you’re one of these entrepreneurs, don’t jump in the bandwagon just yet.

Acquiring a CNC machine is more than just buying additional equipment; it also has a social aspect in it. Here is the low down:

PEOPLE-WISE

First, you have to consider the people who are working in your shop. How many people will be displaced if you buy a CNC machine? Keep in mind that a CNC machine is multi-operational; so it’s possible that a couple of laborers will be erased from the production team. Experts say that the healthy ratio is at least one-sixth (1/6) of your whole labor force.

You will be saving time and effort, yes, and that is the best thing about having a CNC machine. However, you might be worrying about actually terminating people because, to put it bluntly, you won’t need them anymore. A CNC machine, just like any machine, will need an operator. Instructions used by a CNC machine for operational execution are composed of CNC “words/codes” and is in the form of a “sentence”.

Does one of your people ever have experience with a CNC machine before? Can s/he formulate CNC instructions? If the answer to both questions are “yes”, then that’s absolutely good news. However, if you answered “no” to at least one of the questions, then there are more things to evaluate.

Are your people capable of fast-learning? If it pains you to terminate them because they have been good employees in the past, train them on how to use the CNC machine and how to compose instructions for it. There are plenty of free training kits online.

COMPANY-WISE

There’s a corporate adage that goes: “Innovate or die”. There’s a lot of truth in that. A purchase of any CNC machine symbolizes a company’s decision to innovate to increase productivity. However, there are a few things that you need to note.

Review your company’s history. How long should you innovate drastically in terms of production? CNC equipment is expensive. It is an investment. In the long run, you may be forced to buy new equipment more often. Consider CNC heavily if you feel that your company innovates faster than other companies in terms of the industry that you belong to. After all, you can easily alter designs and material when you have CNC powered operations.

In most companies, “Innovation” is another word for “saving”. It means saving time, effort and space. In using CNC machines, the first two factors are sure savings while the third is not. People doing the labor and CNC machines often occupy the same amount of space. Do not romanticize a “clearing of clutter” effect when you buy a CNC machine. You will keep up, in terms of production; but CNC equipment also occupies a lot of space. So in that aspect, it’s pretty much the same thing.

Another thing that you have to be reminded of is the level of accuracy that your company needs to produce. Intricate patterns on metal/wood will DEMAND CNC accuracy. So any time that you feel your company is ready for such innovation and accuracy, consider employing CNC in your manufacturing.

At the end of the day, the last aspect that you need to evaluate is you, yourself. As the owner/head manager, you have to KNOW AND UNDERSTAND the CNC machine and the software well. This is the biggest battle that you have to face.

The equation to improvement is simple a really good machine plus a really good operator (you). Do not easily be blinded by the salesmen’s poetry.

How CNC Helps Companies

The advent of Computers lessened the need for human intervention in almost all aspects of our daily lives. This is especially true in the industrial sector now that production is virtually automated.

Precision and accuracy

Computer numerical control has been able to help companies in terms of precision. With the need for more complex designs and more complex operations, human workers could not cope with the required precision that comes with advancement. CNC machines were able to alter that idea by allowing increased precision and lesser error ratios with regards to production.

Another important improvement that CNC has brought with it is the increased accuracy. The dimensions of components have to be very accurate. And since an increase in production speed also increases the error ratio, CNC has helped lower that ratio by the increased level of automation and the error detection capabilities that computers have.

Speed

In the industrial sector, speed is of the essence. With CNC technology, the normal production capacity has been increased exponentially. This means that effective and accurate production methods have been developed. Mass production requires more scrutiny for errors and mistakes. However, anomalies can also be corrected. The programming structures of CNC machines can be altered in a fast way. This means that mistakes do not have as serious an impact as they had before CNC was improved to this level.

Machine versatility

CNC machines have become very versatile with regards to the tools that they use. They can easily be assigned to different tasks and thus can be very productive. Tools and networks can be switched without compromising the speed of the production. Aside from this, one machine can do more than one task at a time. This exceeds the normal human capacities as it allows more tasks to be accomplished at a faster rate than before.

Furthermore, when one machine tool breaks down, it can easily be pulled off the grid to prevent it from affecting the whole production cycle. It can then be replaced or repaired on the spot.

Lesser human intervention

Since component production is a very tedious and repetitive operation, human error skyrockets as time passes. This is due to fatigue and other factors. Furthermore, the ability of a person degrades due to psychological and emotional factors. This means that if a person works on the same job for a certain amount of time, the person may eventually get bored or tired or both. This increases the possibility for the human to commit an error and thus causes a drop in the efficiency rating of that person. A machine, however, does not get tired or bored. A machine does not have any concern at all.

Therefore, a machine increases efficiency ratings by speeding up production and eliminating or reducing factors that threaten efficiency. In this case, one must simply program the machine to start a cycle. Furthermore, humans have to be fed, paid, and rested. Machines only have to be rested when failures occur to often and they do not need to be paid or fed.

This brings us to the conclusion that companies will be able to save a lot in the long run. While investing in CNC machines is not cheap, maintenance will only cost a fraction of what will be paid to manual laborers.

Data Transfer Methods of CNC

A CNC machine cannot function without a program. And a program cannot make its way to the machine without an effective data transfer system. So, what are the methods of data transfer and how effective are they in conveying data from one point to the next?

Punched tape

The first data transfer method is the punched tape. It consists of a long strip of paper with holes punched in it to store data. The holes represent a set of data that tells the machine how to move and what to do.

This method has proven to be very versatile and very useful. It has proven to withstand the test of time as numerous magnetic storage devices have deteriorated over time even to the extent of being unreadable while punched tape has been shown to be fine decades and perhaps even centuries later. Repair is also not a problem as specially designed splices can put two end together virtually unchanged. Furthermore, punched tape can be visually decoded should the need arise. This means that human accessibility is also not a problem.

Floppy Disk

While punched tape is quite a long roll of paper, a floppy disk is a small magnetic storage device that is more space efficient than punched tape. It can also be used to store simple programs.

Floppy disks virtually revolutionized the way data could be stored and transferred from one point to another. It allowed users to store and transfer data faster than punched tape allowed. Furthermore, the data within a floppy could be easily edited at any point as long as you have the proper program to read it. However, this method has proven to be quite problematic in the long run as floppies have a tendency to degrade alarmingly fast. A floppy could be unreadable after only 3 years.

RS232

This method is actually a set of standards for serial binary signals that connects between computers, terminals, and modems. This is a fast and efficient way to transfer data.

This cable connects a CNC machine to a computer that has floppy disk support thus eliminating the need for punched tape. This allows the operator to input data remotely and even while accomplishing other tasks. However, it need to be used in conjunction with an effective data storage device so as to have backups in case of emergencies.

Networks

Networks are a set of computers that are linked together to make data sharing easier. In an industrial scenario, networks allow a number of different users to individually create a program for the machine to run on.

This method allows multiple users to access and transfer data remotely. This allows for a faster and more efficient check-and-balance system for the programmer and the data verifier. Furthermore, different parts of the program can be completed by different programmers and then compiled by one user. This makes program creation a fast and easy process.

Manual Data Input (MDI)

MDI allows users to input commands directly into the CNC machine’s memory. This may seem to be an effective way of telling the machine what to do but it actually has a lot of drawbacks to it.

Despite it being the fastest way of telling the machine what to do, it is also a very risky and tedious operation as it requires the use of the machine’s terminal. Furthermore, the construction of a program is not as fast as opposed to the network method. It only allows one user to access the machine thus making it a long and drawn-out process.

Another disadvantage that comes with MDI is that it limits the operator to only one task at a time. However, MDI allows the most control over the machine compared to other methods.

CNC Programming Tips the Professional Way

When a program is completed and sent to the Computer Numerical Control Machine, the programming process is over. All calculations were made and the algorithm fully written. But the question is the programmer’s job really finished? When is the programmer’s responsibility really over? And how can we evaluate the type of program that the Computer Numerical Control Machine programmer did?

The fairest and reasonable answer to those questions would basically when a part has been machined under the most optimized working conditions. Therefore the Programmer’s responsibility does not end after he or she finishes the program. We could say that the program at this stage is still very much in the development process, because most of the programming considerations were based on certain assumptions and there are a lot of external factors that may affect the outcome of the product.

Every Computer Numerical Control programmer should have an effort to be in the touch with the actual production. In the field of software development, Constant communication with your colleagues as well as actual machine operators of the CNC will help you to improve your own program. Because most of the time the CNC machine operators are a good source of constructive ideas, improvements and suggestions.

A good CNC programmer should talk, ask questions to them and most importantly listen to what they have to say. Programmers who never put their foot in the actual machining process and think they are always right are all on the wrong track. Exchanging ideas with CNC machine operators, asking questions and seeking answers is the only way to be fully aware of what is going on in the machine.

Whenever you start a Computer Numerical Control Program the first time it is important to check its Program Integrity. A new and unproved program is a potential source of problems. During Manual Programming in CNC, mistakes are more common than when the program is made in a CAM program.

A good way to look at a new program is through the machine operator’s perspective. Experienced Machine Operators take a direct approach when running a program for the first time. That means that they wont take any chances of mistakes with the actual running of a program therefore a good programmer must take note of any comments that the Machine operator will say about the program.

What does an experienced Machine Operator look for in a new part of a program? Most of the Machine operators would say that the first and most important thing to be checked on a Computer Numerical Control Program is its consistency. Therefore a machine operator looks at how a CNC programmer does its own programming, is the way you create your own algorithms the same as the other ones. Machine Operators take note with this kind of Information.

Upgrading your CNC Program

Whenever you upgrade your own program, it means that you are strengthening or enriching it, therefore making it better than it was before. Upgrading would be based on this standard, It is to decrease the production cost without compromising the quality of the part being manufactured or the safety of the Computer Numerical Control Machine Operator.

One of the Most Common forms of Program Optimization is doing some minor changes to the spindle as well as the feed rates of the machines. This process is called cycle time optimization, slightly increasing the spindle speed and feed rates of these machines will decrease the time it takes to finish the part.

And when we compare it to mass production, saving one second for each part in a batch of 3600 pieces would mean an hour saved. Efficiency in the rate of production is a very important aspect in Mass Production.

Pad Printing with CNC

Pad printing is a process where a 2-D object is transferred into a 3-D object. It is done by using an indirect offset printing process that involves an image being transferred from the printing plate via silicone pad over a surface that is to be printed.

Pad printing is used on a lot of industries that includes medical, automotive, promotional, apparel, electronics, appliances, sport equipment and toys. Pads are three dimensional objects typically molded of silicone rubber. They function as a transfer vehicle that picks up ink from the printing plate, and then transferring to the thing to be printed upon.

Examples of pad printing are the printing of labels on the keys on a keyboard or the logo of a toy manufacturer on a Frisbee. The unique properties of a silicone pad allow it to pick the image up in a variety of surfaces such as a flat, cylindrical, spherical, compound angle, textures, concave surfaces or a convex surface.

In presses that uses pad printing with Computer Numeric Control (CNC), the substrate or a material that can be printed on, such as paper, film, plastic, fabric, cellophane, or steel, is stationary and the silicone pads are programmed to print one image at a time.

With a press that uses Computer Numeric Control, the substrate is stationary and the pads are all programmed to one image at a time to achieve a multicolor print.

Though the robotic actions of these presses that uses Computer Numeric Control seems rather complicated, it allows simple setting procedures that enable several programs to be inputted into the machine. All actions are controlled by servo-motor drives giving a very smooth and highly controllable printing action, also giving stroke lengths to be infinitely variable to the dimensions of the machine. Manufacturers even claim that using presses with pad printing capability that uses Computer Numeric Control gives considerable energy savings to the industry.

The Computer Numeric system of control can be built on standard machines or modular assemblies that can be produced to suit any application. The degree of complexity is regulated only by the imagination of the designer of the product/s and the number of modules he wishes to use to complete his desired quota.

All of the elements of component manipulation can be achieved by combining with multiple closed cups, pad cleaning, varying pad-stroke lengths, alternative pad shapes and a lot more. This type of system is often used where items must be printed in line with other assembly processes, or for complex multiple prints on different surfaces.

The flexibility of a Computer Numeric Controlled press comes close to producing the ideal machine for a particular application. Although a CNC press is substantially more expensive than that of a conventional pneumatic press. If the workload can justify the use of a CNC press for the increase in investment, then the CNC press is well worth considering.

Although it is wise to not be carried away by the current technology at hand, it still must be a capable printer.

Cycle Time Reduction Principles for CNC Machining Equipment

What is the definition of cycle time?

Cycle time is defined to be the time that happens from the time a task or series of tasks is initiated to the time a task is completed. Example, the cycle time is the time a shipping order is printed to the time it is loaded on the truck and the system is updated. An alternate definition would be is the time it takes to load, run, and unload on workpiece.

Cycle time of a machine can be simply measured by timing how long it takes from pressing the button to start the cycle for the first workpiece to the pressing the next button for the next workpiece.

Production quantities in an industry dictate that the more workpieces you run, the more important it is to achieve the goal of lowering the cycle time.

Everything and anything that happens in a Computer Numerical Control (CNC) machining equipment can be divided into four categories:

1.) On-line, productive tasks:

These are the actual machining operations that occur during a CNC cycle. These are the milling, drilling, tapping, reaming, and any other machining operation that in some way furthers the completion of the workpiece. To minimize the cycle time in these areas, there are two ways in which this can be achieved. One would be through careful process planning.

The process engineer must select an appropriate machine tool, cutting tools, fixturing, and machining order in a way that it matches the number of workpieces to be machined that will be based on the production quantity. The cycle time will be a reflection of the processes being used to machine workpieces.

If in the many times that your company’s processes have already been developed and implemented before you begin your cycle time reduction program, then your second alternative is to optimize cutting operations for this would involve properly selecting cutting tool materials, feeds, and speeds to machine workpieces as efficiently as possible with the current process.

2.) On-line, non-productive tasks:

These are tasks that occur during the machining cycle that do not actually further the completion of the workpiece. The first thing Computer Numerical Control people often target for improvement is wasted program execution time. These are the things like rapid movements, tool changes, M-code execution and spindle acceleration/deceleration. Reducing program execution time in this area is usually easy.

It often takes nothing more than carefully monitoring the production run for a few workpieces to find those times when the program can be modified to eliminate noticeable pauses during the cycle. Although keep in mind that the worker for these machines must not overlook other processes for they may be so concerned with minimizing program execution that they overlook other operations, resulting in severe wastes of cycle time.

3.) Off-line, non-productive tasks:

These are the tasks performed in the machining cycle that do nothing to further the completion of the workpiece. Since these types of tasks are done while the machine is producing workpieces, they do not actually add to the cycle time. It is possible to free the operator of the machines of performing off-line productive tasks if they have little, or nothing to do during lengthy machine cycles.

4.) Off-line, productive tasks:

These are the tasks done away by the CNC machine, while the machine is producing workpieces, which would further the completion of the workpiece. This is extremely helpful during lengthy CNC cycles, tasks in this category can reduce the time it takes to complete the production run dramatically, which would effectively reduce cycle time.