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Since tool grinding is not part of the processing plant's core competencies, careful analysis is required to confirm that the in-plant grinding is reasonable.
The processing plant must be able to designate a full-time operator to operate the machine. It is not difficult to train the CNC tool for the operator, but he must have 5 years of experience in operating the CNC machine. In addition, the operator must also have good knowledge of tooling. Processing plants can determine whether it is reasonable to equip a CNC grinding machine based on financial and flexibility reasons. From a financial perspective, processing plants that use standard tools cost at least $200,000 a year in tool regrind. However, if you use a non-standard tool or a frequent tool changer, you can quickly re-grind these tools if equipped with an internal regrind facility.
Advantages of CNC Grinding There are a number of problems with manual grinding machines that grind tools inside the company. For example, grinding a tool requires multiple machines. For example, grinding a drill requires a slotting machine, a cylindrical grinding machine and a sharpening machine. This requires multiple setups. In contrast, a CNC grinding machine requires only one setup for a complete set of grinding. At the same time, the footprint of a CNC grinding machine is smaller than that of multiple manual grinding machines. Another problem is the contamination of the carbide chips produced by the non-closed manual machine. Most importantly, manual grinding machines rely on the skill of the operator, and this has become an increasingly scarce resource.
Finally, manual grinding takes much longer than CNC grinding. As the tool geometry becomes more complex, the grinding time increases dramatically.
One issue that the outreach involves is the lack of flexibility. For example, if a tool used in a processing plant has a special geometry or is involved in development work that requires rapid resolution of tool features, it may encounter very long regrind times. In addition, the quality controllability of the re-grinding tool of the processing plant is small. In the process of the outreach, the re-grinding plant determines the timing of each project, so the processing plant is likely to find that the tool to be re-grinded is discharged to the end of a long queue. Processing plants that perform internal grinding can control the timing of prioritization and re-grinding of tools.
Consistency issues CNC grinding is not only faster than manual grinding, but it also produces better, more consistent tools because it does not depend on the operator's skill. Many high-speed machining centers use tools with complex geometries, such as drill bits with different helical configurations for each tooth, or drill bits with varying spirals throughout the tool. Such a tool is difficult or impossible to achieve good results by manual grinding. With a variety of software options, the new CNC machine can easily grind complex tool geometries.
The CNC grinding of the drill bit ensures that there are no deviations in diameter, inter-tooth space and tool radius, so each tool will be evenly cut. The inconsistency of these features can result in additional stress on each tooth, reducing tool life. The consistency of the tool ensures uninterrupted cutting for a long time, so the tool change time can be specified according to the actual situation, thus completely using the available life of the tool. In addition, the number of tool passes required for a workpiece can be accurately determined by production scheduling, thereby reducing tool inventory. Good tools have the least heat and low vibration, so the machine has a longer life, less maintenance, and a higher surface roughness. In addition, CNC grinding can also use higher toughness tool materials that ensure higher cutting speeds and better surface finish.
Typically, manual grinding is done in dry grinding conditions, while CNC grinding has many coolant options. The use of high-pressure coolant prevents the cutting edge from heating up, which results in higher cutting speeds and longer tool life.
The most important factor in achieving economical high productivity is cutting speed, not tool cost or tool life. For example, industry data shows that a 30% reduction in tool costs can only reduce the cost per product by 1%. Similarly, a 50% increase in tool life can only reduce product costs by 1%. However, a 20% increase in cutting speed (although tool costs are increased by 50%) can reduce the cost per product by 15%. High-quality tools ground by CNC can easily cut up to 20% faster than manual grinding tools.
The total cost of the external cost re-grinding tool involves the cost of the production tool, plus the cost of spare parts necessary to maintain production during the re-grinding of the tool, as well as the cost of service and transportation, and more importantly, the delay in the regrind service. The cost of production losses. These costs add a significant amount to the annual expenses. For example, a square end mill with an outer diameter of 0.5 inches (12.7 mm) and a length of 3 inches (75 mm) is used for 20 times of cutting, 4 hours per cut, and the working condition is 8 hours per shift for 250 days per year, assuming re-grinding. With a turnaround time of 10 days, the annual cost of using external tool grinding is $206,000. If the same tool is changed 40 times and the duty cycle is shortened to 2 hours, the annual expenditure will rise to $824,000. The true cost of internal CNC grinding tools, including machine tool costs, operator costs, and shop floor expenses, is much lower than the cost of outsourced tool grinding. For example, the cost of purchasing and operating a $240,000 CNC grinding machine at an average cost of $28.09 per hour (costs for depreciation, interest, land, energy, maintenance, and machine consumables). The typical operator cost is $18.33 per hour, and the total cost of running such a CNC grinding machine is $46.42 per hour. For the square end mills with a 0.5 inch outer diameter and a 3 inch long tool change 20 or 40 times, the annual internal tool regrind cost is about 1/4 of the external regrind.
CNC self-reliance for tool grinding
Processing plants should consider CNC tool grinding for a number of reasons, including CNC tool grinding to produce high-quality, long-life tools with high process flexibility and controllability while saving money.