They have improved design accuracy to around 1 micron for years. They are perfect payers. But when the tools are not properly balanced, their thorough and close attention to detail wastes. Using an unbalanced tool to machine the part is similar to shooting your own foot. The tool will experience normal wear after performing the design task. However, the tool design designed to perform that task is assumed to be well balanced.
If you use an unbalanced tool to do this, you are introducing new levels of wear, not just the tool and the spindle but also the part to be executed. Imbalance can have several effects: it introduces additional vibrations to the spindle and its components, which can wear the tool irregularly, reducing tool life and reducing the quality of the finished product. Correcting unbalanced properly balanced tools significantly reduces noise and vibration, which increases tool life and consistent part accuracy. The centrifugal force amplifies the vibration caused by the imbalance in a proportional relationship with the square of the velocity. The resulting increase in vibration minimizes the life of the bearings, bushings, shafts, spindles and gears.
In addition, if you do not balance the tool, there is a risk that the spindle manufacturer's warranty will be void. Many warranties specifically state that quality assurance is only effective if there is sufficient evidence that the tools used on the machine are properly balanced. In this respect, tool balancing can cause huge savings. Before balancing the tool, you need to measure the amount of imbalance and the angular position of each selected correction plane. These variables are measured on two universal types of balancing machines: non-rotating or gravity machines for measuring a single plane (stationary) imbalance, while rotary or centrifuges are used to measure a single plane and/or two planes (dynamic). balance. After measuring the magnitude and angle of the unbalance in the correct plane, you can correct it by adding material from the workpiece or removing the material. For components that are not cutters, the most widely used method of material addition is to weld weights on the components.
Other approaches to components that are slightly unbalanced include adding solder to the component body or adding weight to the pre-drilled hole. For tools, when you determine the imbalance, you must remove the material to get the right balance. The easiest and most effective way is to drill. This is a quick adjustment and the amount of material removed can be precisely controlled. Another option is milling, which is most effective for balancing thin-walled tools or forcing shallow cutting applications. In theory, a perfect balance is available when balancing the tool.
In real-world applications, the perfect balance is only achieved when it is very lucky because of cost considerations and tool limitations. Therefore, the level of accuracy must be set to allow a certain amount of residual imbalance to control the detrimental effects at an acceptable level. The accuracy given in ISO 1940 usually produces satisfactory results, but it is determined that the standard you are implementing is suitable for the tool to be balanced. For example, a machine tool will obviously use different values than a rigid load propeller. Tool selection and maintenance Tool balancing is not just about measuring unbalance and adding or removing weight. Tool selection is critical. Short, lightweight tools are easy to balance to good precision, while large, heavy tools are much more difficult and have a tendency to generate large vibrations.
You can also save time and cut costs by choosing a tool holder that has been pre-balanced or pre-machined to a minimum imbalance. Further, you can reduce the amount that must be balanced by routine maintenance and careful handling. Any surface damage to the shank will affect balance and concentricity. why? The effect of the shank defect is amplified when the rotational speed climbs. If your instrument measures a force that can be ignored at 1000 rpm, the force is increased by 100 times at 10,000 rpm and 400 times at 20,000 rpm. Excellent concentricity is also more important under the high speed spindle, because if the tool does not rotate on the spindle centerline, it becomes the primary factor for additional imbalance. However, the effect of the unbalanced shank is also evident at lower speeds.
A small imbalance can cause high forces in the damage of your machining center spindle bearings, and the continuous large radial force back leads to early bearing failure and expensive machine maintenance costs. Also, keep in mind that any adjustment (installation or removal of the tool assembly, tightening of the nut or any minor twist or weld) requires some degree of balance. Even if the balance of the disturbing tool is only a few grams X mm, this unbalance is converted into an increase in vibration, causing faster tool wear, deterioration of surface finish and deterioration of part shape accuracy (such as loss of roundness or straightness during boring). ).
Proper Accuracy = Better Balance In addition to proper maintenance and handling of high quality toolholders, it is important that the tool components are properly mounted to the machine tool spindle. In order to obtain a firm and stable connecting shank, the matching spindle taper should be as accurate as possible. The difference between the good and the poor shank is especially noticeable at high speeds. You may have the best balanced tool in the world, but if it's not properly connected to the spindle, you are asking for trouble. When you think that many of the machining centers sold today are equipped with spindles with a maximum speed of 10,000 rpm or more, you have to conclude that the quality of the shank must be at the same level as the performance of the spindle. They must be strong, centered, properly balanced, and free of surface damage and contamination. If this is not the case, vibration will definitely occur, which will produce chatter and reduce tool life and surface finish. Not all tools need to be balanced, especially when the process causes cost increases and extra steps. Whether to balance the tool should be based on the specific situation.
The balance is most outstanding at high speeds, but balancing the tool at any speed produces better dimensional accuracy, improved surface finish and longer tool life. Balanced tools produce the best parts. Although it requires some extra time and care, the right balance will extend the life of your tools and spindles and increase the available time, and produce accurate, high-quality parts for your customers.
