There are three main factors leading to tool jumping: tool length, tool diameter, and tool stress
(1) Length of tool
When the diameter is the same, the length of the tool increases by one time, and its deformation will increase by three times. When machining, use as short a tool as possible to reduce the risk of tool jumping.
(2) Tool diameter
When the length is the same, when the diameter of the tool is reduced by one time, its deformation will increase by four times. When processing, if conditions permit, try to choose large-diameter tools or use reinforced tools to reduce the risk of tool breakage.
(3) Force condition of tool
The deformation of the tool is directly proportional to the force it receives in the processing process. The force received by the tool can be reduced by reducing the contact area between the tool and the workpiece. For example, when machining deep positions, the tool with small feed rate and fine R angle can be used to reduce the force on the tool in the machining process, so as to reduce the risk of tool breaking.
When the processing depth is greater than 120mm, the cutter can be installed twice, that is, first install the short handle to process to a depth of 100mm, and then install the extended handle to process the part below 100mm.
2. Cutting
Cutting refers to the situation that the milling amount of the tool is too large and the tool bar also hits the workpiece. The main reasons for cutting are that the safe height setting is unreasonable or not set at all, the processing method is improperly selected, the tool is improperly used, and the allowance setting of the second rough machining is less than that of the first rough machining.
(1) Excessive milling amount
Reduce milling consumption. The smaller the diameter of the tool, the smaller the milling amount should be. Under normal circumstances, the cutting amount of each roughing of the workpiece shall not exceed 0.5mm, and the cutting amount of semi finishing and finishing machining shall be smaller.
(2) Choose improper processing method
Change the mode of contour milling to that of cavity milling. When the machining allowance is greater than the tool diameter, the contour milling method cannot be selected.
(3) Improper safety height setting
The safety height should be greater than the fixture height. In most cases, the "direct" forward / backward mode cannot be selected, except for special workpieces.
(4) Improper setting of secondary rough machining allowance
Generally, the allowance of secondary rough machining should be 0.05mm larger than that of the first rough machining. If the allowance of the first rough machining is 0.3mm, the allowance of the second rough machining should be 0.35mm. Otherwise, the tool bar will easily hit the upper side wall.
In addition to the above reasons, cutting also occurs when trimming the knife path, so try not to trim the knife path. The most direct consequence of cutting is to damage tools and workpieces, and more seriously, it may damage the spindle of the machine tool.
3. Overcut
Overcutting refers to cutting the part that cannot be cut by the tool, causing damage to the workpiece. There are many reasons for workpiece overcutting, mainly including low precision of machine tool, cutting, bouncing, improper selection of cutting tools, etc. In addition, if the operator does not set the knife accurately, it may also cause overcut.