Computer Numerical Control

Showing posts with label Mass production. Show all posts

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.

My Bestfriend's Name Is CNC: A Company’s Perspective

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CNC machine tools are praised all over the world because of three major factors: automation, accuracy and versatility. Human (operator) intervention is reduced to minimal levels because CNC machines can run on its own after it is programmed. Also, when the program is perfected, the CNC machine can run the instructions perfectly on its own.

Remember that any CNC machine can also be programmed to do special one-time tasks such as a dry-run, which will help the operator oversee what will happen when s/he leaves the CNC machine to do its tasks alone. Accuracy also goes hand in hand with repeatability. Again, once the program is perfected, the CNC machine can perform that task PERFECTLY even until 7 or 7000 times.

Lastly, versatility also works in the form of “task memory” that these CNC machines have. Once a program has been performed even for just one production run, it can be easily recollected the next time that the company needs the program. This saves time for setting up and loading of different programs.

The CNC sure simplifies the work of thousands of factories and machine shops worldwide. However, no matter how great CNC sounds like, it is something that doesn’t fit in some industries. Like, perhaps, in the cosmetic industry, or in the show-business. Those examples are way too obvious. On the other hand, in these two major mechanical industries, CNC is almost synonymous to “hero”.

THE METAL INDUSTRY

Think of Metal. Metal. Perhaps the easiest metal that you can imagine is that of…a spoon. Now, imagine ANY spoon done with bare hands. After that, imagine a thousand spoons done with bare hands. It’s so tedious you might even consider suicide if you are assigned to such a job.

The metal industry has been operating on CNC for ages. In fact, if you search CNC in the internet, you will instantly find metal companies topping the list. The major CNC centers that you will find in most metal machining processes are “CNC turning centers”, “CNC machining centers”, “CNC grinding centers” and “CNC drill and tap centers”.

Some of the CNC programs that are connected with the metal industry are milling, drilling, reaming, boring and tapping. Moreover, any metal that has any curved side have experienced some form of knurling, grooving, turning and/or threading.

Fabrication, in manufacturing, refers to processes that are executed on thin plates/sheets. These sheets are cut, punched, and bent to form their finishing shapes. CNC also stars in almost every aspect of metal fabrication.

THE WOODWORKING INDUSTRY

While the most beautiful wood-worked products are most likely hand-made, you cannot deny that a wide array of tools and furniture HAVE to be NOT hand-made to save time and for mass production levels. There’s just too much work and not to many hands. In light with this, CNC has worked wonders for this industry.

Important woodworking processes include cutting, framing, carving and engraving. The most useful woodworking CNC product is the CNC router table. It is capable of carving elaborate 2D and 3D designs. Moreover, it is also capable of material change while repeating the same design. Since contemporary furniture is often a splash of different materials (e.g. Wood, aluminum and/or plastic), any CNC router is capable of reproducing the same design EVEN in different kinds of materials by just altering the router bit.

Although many local, middle-sized enterprise owners are skeptical about using employing CNC in their manufacturing operations, there have been many success stories to sway them to using it anyway. In the Metal and Woodworking industries, CNC has proven itself time and again to be efficient.

It saves time and efforts in production and (more importantly) back-jobs. If you’re venturing to one of these industries, remember that the word "labor" isn’t something social anymore - it’s technological. And start calling CNC your best friend.

Understanding CNC

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Have you ever asked yourself how machines in a factory know exactly when to stop making the parts they’re supposed to make? Well, this is all because of Computer Numerical Control (CNC). But to understand CNC, you have to know what Numerical Control (NC) is.

HISTORY

NC machines were first introduced after the 2nd world war as mass production became the trend. These machines were given a set of instructions in punched cards. However, these machines were hard-wired and their parameters were difficult to change.

These NC machines still required a great deal of human intervention. To illustrate this point, try to take a look at a drill press. A lot of actions have to be taken in order to manufacture a product. The process is actually so complicated that a person has to do something almost every step of the production process. This created an avenue for errors to take place as the likelihood of fatigue increased with the quantity growth.

CNC then came into the picture when computers were introduced. Punched cards were replaced by floppy disks, cables, and other software transfer media. This made it easier to manage and edit data.

Production and manufacturing were revolutionized by the increased automation of CNC machines. These machines allowed a degree of added control over the quality and consistency of the components that were manufactured without any additional strain on the operators. This reduced the frequency of errors and allowed the operators time to perform additional tasks. Furthermore, this automation allowed a greater degree of flexibility in the way components are held in the manufacturing process.

With the advent of Computer Aided Manufacturing (CAM), even programming CNC machines is a snap. These programs actually take the bulk of the programming process to make the operation less tedious. However, to be an effective programmer of CNC machines, you have to know what the machine you’re working on will be doing. That is why machinists are often the best people for the job.

The ease that the machines provide is hinged heavily on the quality of the machine. Low-cost CNC machines oftentimes have many functions that have to be manually activated. High-cost machines, however, are almost fully automated. The operator only has to load or unload workpieces. Once the cycle has been initiated, the operator just has to sit back and watch for any malfunctions. The stress on the operator is so low that some even complain of boredom in the middle of a cycle.

CODING

The programming language that CNC uses is called a G-Code. These codes actually position the parts and do the work. To be able to have a machine work properly, you have to input the correct variables such as axes, reference points, the machine accessories, and whatnot. Every machine has a different set of variables so you have to be careful to take note of the differences.

Aside from the G-Code, logical commands or parametric programming can be used to make the process more time-efficient. This type of programming language shortens lengthy programs with incremental passes. A loop can also be programmed thereby removing the need for coding repetitions.

Because of these features, parametric programming is more efficient than CAM. It allows users to directly and efficiently make performance adjustments. It also allows extensions to the functionality of the machine it is running on.

And that makes CNC.

CAM: A Vital Component of CNC

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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.

Programming 101: CNC

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After World War II, people realized that they have to manufacture goods at a faster rate and at a lower cost. Hence, mass production trending came to be. Those events led to the development of the Numerical Control (NC) machines which in turn led to the Computer Numerical Control (CNC).

HOW TO PROGRAM A CNC MACHINE

CNC programming uses a code similar in structure to BASIC. So, if you know how to construct a simple counting program, chances are, you already know what a G-Code looks like. However, there a few other things you have to consider before you start encoding instructions.

The first thing that you have to do is to assign values for each of the variables. These variables include the programmable motion directions (axes), and the reference point for the axes. The values that you assign to these variables dictate the movement of the machine.

The next thing that you have to do is to take into account the accessories of the machine. Many machines have accessories that are designed to enhance the capabilities of the basic device. However, using these accessories requires you to include them in the coding system. This means that if you want a more efficient machine, you will have to know the machine inside out.

READING CODES

After those steps, you have to create a subprogram that will deal with the math. This step will then allow your machine to compute the necessary variables and effectively operate without stopping to ask the operator what the limitations are.

To show you what these codes look like, here’s an example from Wikipedia:

#100=3 (bolt circle radius)
#101=10 (how many holes)
#102=0 (x position of ctr of bolthole)
#103=0 (y position of ctr of bolthole)
#104=0 (angle of first hole
Tool call,
spindle speed,and offset pickup,etc
G43 in some cases (tool length pickup)
G81(drill cycle)
call sub program
N50
G80
M30

Subprogram
N100
#105=((COS#104)*#100) (x location)
#106=((SIN#104)*#100) (y location)
x#105 y#106 (remember your G81 code is modal)
If #100 GT 360 goto N50
#100=(#100+(360/#101))
Goto 100

In the code above, the machine is a drill. The operator utilized a loop in order to keep the machine from stopping. The subprogram then governs the cycle of the machine. This code is still quite a simple code. Other machines require the inclusion of the maximum RPM in the coding.

An easier way of programming CNC machines would be the use of Computer Aided Manufacturing (CAM). This system takes on the brunt of programming so that it doesn’t seem so tedious and frustrating. It is still similar to BASIC.

Another programming enhancement that was developed was the parametric programs or the logical commands. These programs were designed to shorten lengthy codes in order to make them user friendly. However, these codes do not always use the same language with every machine. The language and sequence often varies depending on the typ of machine you will be working on.

The operator has to know what the machine can do or what it was made to do before attempting to program it. You should be able to visualize the machine doing what you want it to do.

But, you don’t have to be a math wizard or a programming genius. You just have to know what your machine does and what you want it to do.

Pros and Cons in Sheet Metal Manipulation with CNC

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The advancement of technology allowed sheet metal designs to be more complicated. However, this level of complication has surpassed human capabilities (as far as mass production is concerned). The required accuracy for the intricacy of the designs can only be provided by Computer Numerical Controlled (CNC) machines.

The Punch press

An example of a CNC machine that is used in sheet metal manipulation is the punch press. This device uses hydraulic, pneumatic, or electrical power to exert immense pressure to shape the metal and cut it according to the designs. Being computer aided, this machine is capable of rapid positioning and therefore, fast production. Manual punch presses compromise speed for accuracy therefore lessening efficiency.

The punch press works by receiving instructions from a program in a computer. This allows the operator to sit back and relax once the cycle (rapid positioning, punching, and switching of tools) has been initiated. These machines perform operations with accuracy that is measured by the thousandth of an inch.

Introduction of these machines into the sheet metal industry sped up production significantly. And to stay competitive in the global market, such an edge would be needed. However, technology finds ways to improve on this.

New devices

Today, presses have newer versions. The turret punch press is capable of sorting sheet metal into their respective design classes. This means that the new punch presses can operate virtually unattended. Steel manufacturing companies invest in these machines should it mean streamlining of their jobs and increasing production capabilities.

Newer CNC machines can even alert operators who are not in the area if a problem crops up during the sheet metal punching process. This happens by enabling the CNC machine to keep track of the operators' phones. Therefore, the workload of the operator is relaxed to the point that he/she does not even need to be in the area of operation.

The drawback

However, these machines do not come cheap. A lot of time, money, and effort have to be spent in order to operate the machine to its fullest capacity. Furthermore, there is a shortage of people who are skilled enough to operate such machines. An operator has to be knowledgeable with BASIC programming language, fundamental machining processes, design awareness, and accessory functions.

Furthermore, knowledge of Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) is a big factor in being able to control such machinery. So the capital that you have to spend on understanding these machines have to be justified with the caliber of the operator that you have.

Another drawback that is present is the compatibility of the machines with the current technology that the company has. If they are incompatible, it takes even more time and money to replace current facilities or to restructure the factory in order t accommodate such devices.

The Conclusion

so, if you're a big company and you want to stay in the race, you have to consider and reconsider investing into these things. The investment may be worth itself a hundred times over but it is a rather risky choice to step into something new. You have to restructure your work schedules, change the requirements for operators, and provide proper training to operators that you want to keep.

These things will cost a lot and will take a while before they reflect what they really are worth.