Nov 2007
CAM software allows CNC programming to be accomplished at a much higher level than manual programming and is becoming very popular. Generally speaking, a CAM system helps the programmer in three major areas. It eliminates tedious and error-prone math calculations, makes it easy to program different kinds of machines with the same basic language, and automates tool path generation. "Technologies that cut cycle-time & boost productivity" Cutting cycle time is high on every manufacturer's mind. How would you describe the importance of 'cutting cycle time' in today's competitive business scenario? Manufacturing is growing rapidly and competition is heating up as well. To meet this challenge of growth, just adding machines is not enough. On one side we are talking about humongous growth in manufacturing sector, but on the other hand the companies are making wafer thin profits. There is a constant pressure to push up profitability. Metal cutting industry is tough and only efficient companies can survive. You must cut metal intelligently to remain profitable. Just buying an expensive CNC machine does NOT automatically guarantee high productivity. To make decent profits, you can either increase the product prices or reduce the input costs. With severe competition everywhere, increasing product prices is not an option and reducing costs is the only way to survive. What is the role of software in reducing cycle time?
CAM software allows CNC programming to be accomplished at a much higher level than manual programming and is becoming very popular. Generally speaking, a CAM system helps the programmer in three major areas. It eliminates tedious and error-prone math calculations, makes it easy to program different kinds of machines with the same basic language, and automates tool path generation. Everything that happens during a CNC cycle can be divided into as follows: On-line, productive tasks - These are the actual machining operations that occur during a CNC cycle. They are the milling, drilling, tapping, reaming, and any other machining operations that in some way further the completion of the workpiece. Minimizing cycle time in this area can be achieved in two ways. The first way is through careful process planning. Based on production quantity, the process engineer must select the appropriate machine tool, cutting tools, fixturing, and machining order in a way that matches the number of workpieces to be machined. Unfortunately, many times your company's processes have already been developed and implemented before you begin your cycle time reduction program. In this case, your second alternative is to optimize cutting operations. This involves properly selecting cutting tool materials, feeds, and speeds to machine workpieces as efficiently as possible with the current process. 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 CNC people usually target for improvement is wasted program execution time - things like rapid movements, tool changes, M-code execution and spindle acceleration/deceleration. Minimizing program execution time in this area is usually quite easy. It usually takes nothing more than cautiously 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. What does software do to reduce cycle time? Often the CNC programs in high volume production are written manually and the quality of the program depends solely on the skill of the programmer. The cycle time depends on the tool path and the cutting parameters used, and both these in this case depend on the ability of the programmer. The programmer must have a mix of skills - machining, tool selection, work holding, maths, etc., and programmers who are good at all these are hard to find. Also, there is usually barely enough time to write a single program and get it running. There is no time to think of various alternative strategies and arrive at the one that minimizes the cycle time. Cycle times will therefore usually be sub-optimal. This is where sensible good CAM software can come to the rescue. If it has user-configurable tool and cutting parameters databases, these can be configured by the veterans in the shop floor. The cutting parameters selection no longer depends on the skill of the programmer. If the software has a good auto-tool path generation capability, the tool path too need not be decided by the programmer. A low skilled machinist can make an efficient program with the lowest possible cycle time. He can develop a cycle time estimate, check the tool path simulation and study the motions and time in detail. He can revise the process or cutting parameters till he achieves the lowest and safest possible cycle time. Moreover, all this is done on a PC offline without much time pressure. The final CNC program with the lowest cycle time can be transferred to the machine with a DNC system. A very important factor that cannot be ignored is the capability of the software to calculate cycle times accurately. CAM software must have algorithms that consider complex cutting tool movements, machine characteristics, acceleration and deceleration etc. to calculate cycle time. For example CADEM’s CAPSmill and CAPSturn calculate cycle time within +/- 1% error and are used by many job shops to prepare job quotes. To consolidate, the major advantages a CAM software offers are: Scientifically determined cutting parameters are used from the database and not dependent on thumb rules of individual programmers which invariably lead to under-utilization of cutting tools. Low cutting parameters are the biggest cause of inefficiency on most shop floors. Interchangeability of programmers is easy. The original programmer of a part may have been transferred to another department or left the company, or even looking at a program after a few months. Complete documentation of the programming process enables programs to be changed with minimal effort by the same programmer or by a different programmer at a later date. The documentation is automatic and is in the following ways: All operations and tools in the part program are fully documented. CAM software generated cycle time is extremely accurate. It can be used to quickly try out different tools, processes and cutting parameters to arrive at the best possible combination. This is not possible in manual programming. The cycle time can also be used for part scheduling with a high degree of confidence. Cuts downtime and saves money. Cutting parameters can be standardized. A common problem on large shop floors with multiple programmers or programming done by operators is that different parameters are used for cutting the same material with the same tool. This is eliminated by using a CAM that remembers and learns and prompts optimized cutting parameters. Cuts downtime and saves money. Operator errors due to improper understanding of programs are eliminated. CAM software generates NC programs that are fully documented with tool names, operation names, program date, part number, etc. Saves time and money. Tools list is generated automatically by software can be given to the operator to mount the tools for any part. This eliminates errors like using wrong tools or mounting them in the wrong positions. Saves time and cuts costs. Inter-changing programs among machines. Once a program has been made in CAM software, the NC program for any machine can be quickly generated in seconds. In manual programming, on the other hand, if a program is manually written for a particular machine but that machine is unavailable, then the program must be re-written for a different machine. Saves time and cuts costs. Machine downtime caused by dry run testing of programs is drastically reduced since all or most of the dry run checking can be done on the PC. Cuts downtime and saves money. |
Linking Top floor to SHOP floor
Some users define cycle time as the time it takes to load, run, and unload one workpiece. This time can be easily measured by simply timing how long it takes to go from pressing the cycle start button for one workpiece to the pressing of cycle start for the next workpiece. However, you must remember the other things that add time to a production run that are not included in this simplistic definition. Tool maintenance time, machine downtime, operator break time, and time spent searching for inserts and hand tools are among the many things that are not considered in this definition. CNC users are usually so concerned with minimizing program execution time that they overlook other, more severe waste of time. Another way of defining cycle time is as the average time taken to produce each workpiece. For example, the actual cycle time may be 1 minute but the machine may be idle for 10 minutes between every cycle. This means your average time to produce a part is 11 minutes. Any time that the machine sits idle during a production run, cycle time is increasing. This includes time taken for workpiece loading/unloading, tool maintenance, and workpiece inspections. Anything you can do to minimize these times will effectively reduce cycle time. Off-line, non-productive tasks - These are tasks performed during the machining cycle that do nothing to further the completion of the workpiece. Examples include offset setting to maintain workpiece size, workpiece measurements that are done during the machining cycle and the corresponding SPC data entry. Since these tasks are done while the machine is producing workpieces, they do not actually add to cycle time. However, you should not discount the value of minimizing the amount of time an operator spends on these tasks. Possibly you can free the operator to be performing off-line productive tasks if he has little or nothing to do during lengthy machining cycles. These functions at least involve some tasks that are related to the machining cycle. But consider those terribly non-productive tasks that may be occurring while your CNC machines sit idle. Wasted time spent searching for tools, measuring devices and other components needed during the production run add to cycle time. Personal time the operator takes to answer phone calls or talk with other employees add to cycle time. Truly anything that happens while the machine sits idle must be considered as adding to the cycle time. To solve real time problems, you need information in real time. This can be achieved only with the implementation of an automatic tracking system that can monitor the shop floor 24 x 7. Information technology has been used extensively in functions like sales, inventory, purchase, accounts, HR and payrolls to increase efficiency and realize better returns. Decision makers have quick access to accurate and current data on any issues in these IT enabled departments. Unfortunately, IT stops at the door to the shop floor. Individual production and CNC machines on the shop floor are isolated islands of cost with no information on how much they have produced or what they are doing at a particular instant. Traditionally, production data has been collected manually from machines and fed into computers. No accurate data is available for help in enhancing productivity, like actual cycle times, load / unload times, and the durations, causes for production stoppages and reasons for machine downtime. The production data is usually available only the next day, and vital decisions have to be made on the basis of this old data. The net result of such decisions is poor machine utilization, poor productivity and poor profitability. What does CADEM have to offer in this arena? We specialize in developing software products for improving the productivity of CNC machining. Our range of uniquely designed CAD/CAM software products is helping manufacturers around the globe to cut metal intelligently and remain profitable in the highly competitive metal cutting industry. Apart from Conversational CAD/CAM software (CAPSturn and CAPSmill), we have NCnet DNC systems and SHOPtrack- Wireless productivity monitoring systems.
Our products are installed in about 10000 CNC shops around the world. They are recommended and sold as OE by almost every CNC machines builder in India and a few companies abroad. We take pride in being one of the very few technology driven software product developers in India. We pioneered the CAD/CAM software development in 1990. Cadem is the only company that develops CAD/CAM software products for metal cutting in India. Tell us about your experience in India - are the Indian customers aware of this concept and take necessary steps to reduce cycle time thereby enhancing productivity? India is rich in terms of use of the latest manufacturing technologies. CAD/CAM and production tracking systems are no more new to the users here. The situation 12 years ago was however different. CNC users used to laugh at us when we said they would get 3 floppies for Rs. 1.5 lakhs. Most of the manufacturing shops did not even have a PC in their plants. Thinsg have changed now - drafting boards are scrapped, drawings are made in CAD software, programming is done through software, software is creeping into every aspect of the shop floor. Users are fast becoming aware of how software can help them use the spare capacities on their machines hidden under the tons of downtime.
In fact we think that Indian metal cutting companies are far more forward-looking and ready to invest in technology products than their counterparts in Europe and USA. Leaving the large companies aside, the metal cutting industry here is predominantly run by first or second generation entrepreneurs who are technology-savvy and ready to invest in software, when compared to the doubting Thomases elsewhere. We cater to a real large spectrum of CNC users worldwide. You can find Cadem software in small one man job shops in the dusty lanes of Faridabad and in SMEs at Rajkot and Aurangabad, also in large corporate like TATA, TYCO, Weatherford, Titan, XOMOX and Maruthi Udyog. Globally, you can see Cadem in places like Volkswagen’s plant at Uitenhage in South Africa, in defense aerospace contractor Smiths Aerospace in Dayton, USA, and in Thai-Suzuki’s motorcycle plant near Bangkok. To this list add most CNC machine builders in India like HMT, LMW, Lokesh, Ace Designers and cutting tool companies like Seco Tools and Kennametal. * * * * * * * * * *
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